NOISSUE Flatten gui and logic libraries into MultiMC

launcher/BaseInstaller.cpp

@@ -0,0 +1,61 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QFile>
+
+#include "BaseInstaller.h"
+#include "minecraft/MinecraftInstance.h"
+
+BaseInstaller::BaseInstaller()
+{
+
+}
+
+bool BaseInstaller::isApplied(MinecraftInstance *on)
+{
+    return QFile::exists(filename(on->instanceRoot()));
+}
+
+bool BaseInstaller::add(MinecraftInstance *to)
+{
+    if (!patchesDir(to->instanceRoot()).exists())
+    {
+        QDir(to->instanceRoot()).mkdir("patches");
+    }
+
+    if (isApplied(to))
+    {
+        if (!remove(to))
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool BaseInstaller::remove(MinecraftInstance *from)
+{
+    return QFile::remove(filename(from->instanceRoot()));
+}
+
+QString BaseInstaller::filename(const QString &root) const
+{
+    return patchesDir(root).absoluteFilePath(id() + ".json");
+}
+QDir BaseInstaller::patchesDir(const QString &root) const
+{
+    return QDir(root + "/patches/");
+}

launcher/BaseInstaller.h

@@ -0,0 +1,44 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+
+class MinecraftInstance;
+class QDir;
+class QString;
+class QObject;
+class Task;
+class BaseVersion;
+typedef std::shared_ptr<BaseVersion> BaseVersionPtr;
+
+class BaseInstaller
+{
+public:
+    BaseInstaller();
+    virtual ~BaseInstaller(){};
+    bool isApplied(MinecraftInstance *on);
+
+    virtual bool add(MinecraftInstance *to);
+    virtual bool remove(MinecraftInstance *from);
+
+    virtual Task *createInstallTask(MinecraftInstance *instance, BaseVersionPtr version, QObject *parent) = 0;
+
+protected:
+    virtual QString id() const = 0;
+    QString filename(const QString &root) const;
+    QDir patchesDir(const QString &root) const;
+};

launcher/BaseInstance.cpp

@@ -0,0 +1,275 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseInstance.h"
+
+#include <QFileInfo>
+#include <QDir>
+#include <QDebug>
+
+#include "settings/INISettingsObject.h"
+#include "settings/Setting.h"
+#include "settings/OverrideSetting.h"
+
+#include "FileSystem.h"
+#include "Commandline.h"
+
+BaseInstance::BaseInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir)
+    : QObject()
+{
+    m_settings = settings;
+    m_rootDir = rootDir;
+
+    m_settings->registerSetting("name", "Unnamed Instance");
+    m_settings->registerSetting("iconKey", "default");
+    m_settings->registerSetting("notes", "");
+    m_settings->registerSetting("lastLaunchTime", 0);
+    m_settings->registerSetting("totalTimePlayed", 0);
+    m_settings->registerSetting("lastTimePlayed", 0);
+
+    // Custom Commands
+    auto commandSetting = m_settings->registerSetting({"OverrideCommands","OverrideLaunchCmd"}, false);
+    m_settings->registerOverride(globalSettings->getSetting("PreLaunchCommand"), commandSetting);
+    m_settings->registerOverride(globalSettings->getSetting("WrapperCommand"), commandSetting);
+    m_settings->registerOverride(globalSettings->getSetting("PostExitCommand"), commandSetting);
+
+    // Console
+    auto consoleSetting = m_settings->registerSetting("OverrideConsole", false);
+    m_settings->registerOverride(globalSettings->getSetting("ShowConsole"), consoleSetting);
+    m_settings->registerOverride(globalSettings->getSetting("AutoCloseConsole"), consoleSetting);
+    m_settings->registerOverride(globalSettings->getSetting("ShowConsoleOnError"), consoleSetting);
+    m_settings->registerOverride(globalSettings->getSetting("LogPrePostOutput"), consoleSetting);
+
+    m_settings->registerPassthrough(globalSettings->getSetting("ConsoleMaxLines"), nullptr);
+    m_settings->registerPassthrough(globalSettings->getSetting("ConsoleOverflowStop"), nullptr);
+}
+
+QString BaseInstance::getPreLaunchCommand()
+{
+    return settings()->get("PreLaunchCommand").toString();
+}
+
+QString BaseInstance::getWrapperCommand()
+{
+    return settings()->get("WrapperCommand").toString();
+}
+
+QString BaseInstance::getPostExitCommand()
+{
+    return settings()->get("PostExitCommand").toString();
+}
+
+int BaseInstance::getConsoleMaxLines() const
+{
+    auto lineSetting = settings()->getSetting("ConsoleMaxLines");
+    bool conversionOk = false;
+    int maxLines = lineSetting->get().toInt(&conversionOk);
+    if(!conversionOk)
+    {
+        maxLines = lineSetting->defValue().toInt();
+        qWarning() << "ConsoleMaxLines has nonsensical value, defaulting to" << maxLines;
+    }
+    return maxLines;
+}
+
+bool BaseInstance::shouldStopOnConsoleOverflow() const
+{
+    return settings()->get("ConsoleOverflowStop").toBool();
+}
+
+void BaseInstance::iconUpdated(QString key)
+{
+    if(iconKey() == key)
+    {
+        emit propertiesChanged(this);
+    }
+}
+
+void BaseInstance::invalidate()
+{
+    changeStatus(Status::Gone);
+    qDebug() << "Instance" << id() << "has been invalidated.";
+}
+
+void BaseInstance::changeStatus(BaseInstance::Status newStatus)
+{
+    Status status = currentStatus();
+    if(status != newStatus)
+    {
+        m_status = newStatus;
+        emit statusChanged(status, newStatus);
+    }
+}
+
+BaseInstance::Status BaseInstance::currentStatus() const
+{
+    return m_status;
+}
+
+QString BaseInstance::id() const
+{
+    return QFileInfo(instanceRoot()).fileName();
+}
+
+bool BaseInstance::isRunning() const
+{
+    return m_isRunning;
+}
+
+void BaseInstance::setRunning(bool running)
+{
+    if(running == m_isRunning)
+        return;
+
+    m_isRunning = running;
+
+    if(!m_settings->get("RecordGameTime").toBool())
+    {
+        emit runningStatusChanged(running);
+        return;
+    }
+
+    if(running)
+    {
+        m_timeStarted = QDateTime::currentDateTime();
+    }
+    else
+    {
+        QDateTime timeEnded = QDateTime::currentDateTime();
+
+        qint64 current = settings()->get("totalTimePlayed").toLongLong();
+        settings()->set("totalTimePlayed", current + m_timeStarted.secsTo(timeEnded));
+        settings()->set("lastTimePlayed", m_timeStarted.secsTo(timeEnded));
+
+        emit propertiesChanged(this);
+    }
+
+    emit runningStatusChanged(running);
+}
+
+int64_t BaseInstance::totalTimePlayed() const
+{
+    qint64 current = settings()->get("totalTimePlayed").toLongLong();
+    if(m_isRunning)
+    {
+        QDateTime timeNow = QDateTime::currentDateTime();
+        return current + m_timeStarted.secsTo(timeNow);
+    }
+    return current;
+}
+
+int64_t BaseInstance::lastTimePlayed() const
+{
+    if(m_isRunning)
+    {
+        QDateTime timeNow = QDateTime::currentDateTime();
+        return m_timeStarted.secsTo(timeNow);
+    }
+    return settings()->get("lastTimePlayed").toLongLong();
+}
+
+void BaseInstance::resetTimePlayed()
+{
+    settings()->reset("totalTimePlayed");
+    settings()->reset("lastTimePlayed");
+}
+
+QString BaseInstance::instanceType() const
+{
+    return m_settings->get("InstanceType").toString();
+}
+
+QString BaseInstance::instanceRoot() const
+{
+    return m_rootDir;
+}
+
+SettingsObjectPtr BaseInstance::settings() const
+{
+    return m_settings;
+}
+
+bool BaseInstance::canLaunch() const
+{
+    return (!hasVersionBroken() && !isRunning());
+}
+
+bool BaseInstance::reloadSettings()
+{
+    return m_settings->reload();
+}
+
+qint64 BaseInstance::lastLaunch() const
+{
+    return m_settings->get("lastLaunchTime").value<qint64>();
+}
+
+void BaseInstance::setLastLaunch(qint64 val)
+{
+    //FIXME: if no change, do not set. setting involves saving a file.
+    m_settings->set("lastLaunchTime", val);
+    emit propertiesChanged(this);
+}
+
+void BaseInstance::setNotes(QString val)
+{
+    //FIXME: if no change, do not set. setting involves saving a file.
+    m_settings->set("notes", val);
+}
+
+QString BaseInstance::notes() const
+{
+    return m_settings->get("notes").toString();
+}
+
+void BaseInstance::setIconKey(QString val)
+{
+    //FIXME: if no change, do not set. setting involves saving a file.
+    m_settings->set("iconKey", val);
+    emit propertiesChanged(this);
+}
+
+QString BaseInstance::iconKey() const
+{
+    return m_settings->get("iconKey").toString();
+}
+
+void BaseInstance::setName(QString val)
+{
+    //FIXME: if no change, do not set. setting involves saving a file.
+    m_settings->set("name", val);
+    emit propertiesChanged(this);
+}
+
+QString BaseInstance::name() const
+{
+    return m_settings->get("name").toString();
+}
+
+QString BaseInstance::windowTitle() const
+{
+    return "MultiMC: " + name().replace(QRegExp("[ \n\r\t]+"), " ");
+}
+
+// FIXME: why is this here? move it to MinecraftInstance!!!
+QStringList BaseInstance::extraArguments() const
+{
+    return Commandline::splitArgs(settings()->get("JvmArgs").toString());
+}
+
+shared_qobject_ptr<LaunchTask> BaseInstance::getLaunchTask()
+{
+    return m_launchProcess;
+}

launcher/BaseInstance.h

@@ -0,0 +1,270 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <cassert>
+
+#include <QObject>
+#include "QObjectPtr.h"
+#include <QDateTime>
+#include <QSet>
+#include <QProcess>
+
+#include "settings/SettingsObject.h"
+
+#include "settings/INIFile.h"
+#include "BaseVersionList.h"
+#include "minecraft/auth/MojangAccount.h"
+#include "MessageLevel.h"
+#include "pathmatcher/IPathMatcher.h"
+
+#include "net/Mode.h"
+
+#include "minecraft/launch/MinecraftServerTarget.h"
+
+class QDir;
+class Task;
+class LaunchTask;
+class BaseInstance;
+
+// pointer for lazy people
+typedef std::shared_ptr<BaseInstance> InstancePtr;
+
+/*!
+ * \brief Base class for instances.
+ * This class implements many functions that are common between instances and
+ * provides a standard interface for all instances.
+ *
+ * To create a new instance type, create a new class inheriting from this class
+ * and implement the pure virtual functions.
+ */
+class BaseInstance : public QObject, public std::enable_shared_from_this<BaseInstance>
+{
+    Q_OBJECT
+protected:
+    /// no-touchy!
+    BaseInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString &rootDir);
+
+public: /* types */
+    enum class Status
+    {
+        Present,
+        Gone // either nuked or invalidated
+    };
+
+public:
+    /// virtual destructor to make sure the destruction is COMPLETE
+    virtual ~BaseInstance() {};
+
+    virtual void saveNow() = 0;
+
+    /***
+     * the instance has been invalidated - it is no longer tracked by MultiMC for some reason,
+     * but it has not necessarily been deleted.
+     *
+     * Happens when the instance folder changes to some other location, or the instance is removed by external means.
+     */
+    void invalidate();
+
+    /// The instance's ID. The ID SHALL be determined by MMC internally. The ID IS guaranteed to
+    /// be unique.
+    virtual QString id() const;
+
+    void setRunning(bool running);
+    bool isRunning() const;
+    int64_t totalTimePlayed() const;
+    int64_t lastTimePlayed() const;
+    void resetTimePlayed();
+
+    /// get the type of this instance
+    QString instanceType() const;
+
+    /// Path to the instance's root directory.
+    QString instanceRoot() const;
+
+    /// Path to the instance's game root directory.
+    virtual QString gameRoot() const
+    {
+        return instanceRoot();
+    }
+
+    QString name() const;
+    void setName(QString val);
+
+    /// Value used for instance window titles
+    QString windowTitle() const;
+
+    QString iconKey() const;
+    void setIconKey(QString val);
+
+    QString notes() const;
+    void setNotes(QString val);
+
+    QString getPreLaunchCommand();
+    QString getPostExitCommand();
+    QString getWrapperCommand();
+
+    /// guess log level from a line of game log
+    virtual MessageLevel::Enum guessLevel(const QString &line, MessageLevel::Enum level)
+    {
+        return level;
+    };
+
+    virtual QStringList extraArguments() const;
+
+    /// Traits. Normally inside the version, depends on instance implementation.
+    virtual QSet <QString> traits() const = 0;
+
+    /**
+     * Gets the time that the instance was last launched.
+     * Stored in milliseconds since epoch.
+     */
+    qint64 lastLaunch() const;
+    /// Sets the last launched time to 'val' milliseconds since epoch
+    void setLastLaunch(qint64 val = QDateTime::currentMSecsSinceEpoch());
+
+    /*!
+     * \brief Gets this instance's settings object.
+     * This settings object stores instance-specific settings.
+     * \return A pointer to this instance's settings object.
+     */
+    virtual SettingsObjectPtr settings() const;
+
+    /// returns a valid update task
+    virtual shared_qobject_ptr<Task> createUpdateTask(Net::Mode mode) = 0;
+
+    /// returns a valid launcher (task container)
+    virtual shared_qobject_ptr<LaunchTask> createLaunchTask(
+            AuthSessionPtr account, MinecraftServerTargetPtr serverToJoin) = 0;
+
+    /// returns the current launch task (if any)
+    shared_qobject_ptr<LaunchTask> getLaunchTask();
+
+    /*!
+     * Create envrironment variables for running the instance
+     */
+    virtual QProcessEnvironment createEnvironment() = 0;
+
+    /*!
+     * Returns a matcher that can maps relative paths within the instance to whether they are 'log files'
+     */
+    virtual IPathMatcher::Ptr getLogFileMatcher() = 0;
+
+    /*!
+     * Returns the root folder to use for looking up log files
+     */
+    virtual QString getLogFileRoot() = 0;
+
+    virtual QString getStatusbarDescription() = 0;
+
+    /// FIXME: this really should be elsewhere...
+    virtual QString instanceConfigFolder() const = 0;
+
+    /// get variables this instance exports
+    virtual QMap<QString, QString> getVariables() const = 0;
+
+    virtual QString typeName() const = 0;
+
+    bool hasVersionBroken() const
+    {
+        return m_hasBrokenVersion;
+    }
+    void setVersionBroken(bool value)
+    {
+        if(m_hasBrokenVersion != value)
+        {
+            m_hasBrokenVersion = value;
+            emit propertiesChanged(this);
+        }
+    }
+
+    bool hasUpdateAvailable() const
+    {
+        return m_hasUpdate;
+    }
+    void setUpdateAvailable(bool value)
+    {
+        if(m_hasUpdate != value)
+        {
+            m_hasUpdate = value;
+            emit propertiesChanged(this);
+        }
+    }
+
+    bool hasCrashed() const
+    {
+        return m_crashed;
+    }
+    void setCrashed(bool value)
+    {
+        if(m_crashed != value)
+        {
+            m_crashed = value;
+            emit propertiesChanged(this);
+        }
+    }
+
+    virtual bool canLaunch() const;
+    virtual bool canEdit() const = 0;
+    virtual bool canExport() const = 0;
+
+    bool reloadSettings();
+
+    /**
+     * 'print' a verbose description of the instance into a QStringList
+     */
+    virtual QStringList verboseDescription(AuthSessionPtr session, MinecraftServerTargetPtr serverToJoin) = 0;
+
+    Status currentStatus() const;
+
+    int getConsoleMaxLines() const;
+    bool shouldStopOnConsoleOverflow() const;
+
+protected:
+    void changeStatus(Status newStatus);
+
+signals:
+    /*!
+     * \brief Signal emitted when properties relevant to the instance view change
+     */
+    void propertiesChanged(BaseInstance *inst);
+
+    void launchTaskChanged(shared_qobject_ptr<LaunchTask>);
+
+    void runningStatusChanged(bool running);
+
+    void statusChanged(Status from, Status to);
+
+protected slots:
+    void iconUpdated(QString key);
+
+protected: /* data */
+    QString m_rootDir;
+    SettingsObjectPtr m_settings;
+    // InstanceFlags m_flags;
+    bool m_isRunning = false;
+    shared_qobject_ptr<LaunchTask> m_launchProcess;
+    QDateTime m_timeStarted;
+
+private: /* data */
+    Status m_status = Status::Present;
+    bool m_crashed = false;
+    bool m_hasUpdate = false;
+    bool m_hasBrokenVersion = false;
+};
+
+Q_DECLARE_METATYPE(shared_qobject_ptr<BaseInstance>)
+//Q_DECLARE_METATYPE(BaseInstance::InstanceFlag)
+//Q_DECLARE_OPERATORS_FOR_FLAGS(BaseInstance::InstanceFlags)

launcher/BaseVersion.h

@@ -0,0 +1,59 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+#include <QString>
+#include <QMetaType>
+
+/*!
+ * An abstract base class for versions.
+ */
+class BaseVersion
+{
+public:
+    virtual ~BaseVersion() {}
+    /*!
+     * A string used to identify this version in config files.
+     * This should be unique within the version list or shenanigans will occur.
+     */
+    virtual QString descriptor() = 0;
+
+    /*!
+     * The name of this version as it is displayed to the user.
+     * For example: "1.5.1"
+     */
+    virtual QString name() = 0;
+
+    /*!
+     * This should return a string that describes
+     * the kind of version this is (Stable, Beta, Snapshot, whatever)
+     */
+    virtual QString typeString() const = 0;
+
+    virtual bool operator<(BaseVersion &a)
+    {
+        return name() < a.name();
+    };
+    virtual bool operator>(BaseVersion &a)
+    {
+        return name() > a.name();
+    };
+};
+
+typedef std::shared_ptr<BaseVersion> BaseVersionPtr;
+
+Q_DECLARE_METATYPE(BaseVersionPtr)

launcher/BaseVersionList.cpp

@@ -0,0 +1,99 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BaseVersionList.h"
+#include "BaseVersion.h"
+
+BaseVersionList::BaseVersionList(QObject *parent) : QAbstractListModel(parent)
+{
+}
+
+BaseVersionPtr BaseVersionList::findVersion(const QString &descriptor)
+{
+    for (int i = 0; i < count(); i++)
+    {
+        if (at(i)->descriptor() == descriptor)
+            return at(i);
+    }
+    return BaseVersionPtr();
+}
+
+BaseVersionPtr BaseVersionList::getRecommended() const
+{
+    if (count() <= 0)
+        return BaseVersionPtr();
+    else
+        return at(0);
+}
+
+QVariant BaseVersionList::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid())
+        return QVariant();
+
+    if (index.row() > count())
+        return QVariant();
+
+    BaseVersionPtr version = at(index.row());
+
+    switch (role)
+    {
+    case VersionPointerRole:
+        return qVariantFromValue(version);
+
+    case VersionRole:
+        return version->name();
+
+    case VersionIdRole:
+        return version->descriptor();
+
+    case TypeRole:
+        return version->typeString();
+
+    default:
+        return QVariant();
+    }
+}
+
+BaseVersionList::RoleList BaseVersionList::providesRoles() const
+{
+    return {VersionPointerRole, VersionRole, VersionIdRole, TypeRole};
+}
+
+int BaseVersionList::rowCount(const QModelIndex &parent) const
+{
+    // Return count
+    return count();
+}
+
+int BaseVersionList::columnCount(const QModelIndex &parent) const
+{
+    return 1;
+}
+
+QHash<int, QByteArray> BaseVersionList::roleNames() const
+{
+    QHash<int, QByteArray> roles = QAbstractListModel::roleNames();
+    roles.insert(VersionRole, "version");
+    roles.insert(VersionIdRole, "versionId");
+    roles.insert(ParentVersionRole, "parentGameVersion");
+    roles.insert(RecommendedRole, "recommended");
+    roles.insert(LatestRole, "latest");
+    roles.insert(TypeRole, "type");
+    roles.insert(BranchRole, "branch");
+    roles.insert(PathRole, "path");
+    roles.insert(ArchitectureRole, "architecture");
+    return roles;
+}

launcher/BaseVersionList.h

@@ -0,0 +1,121 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QVariant>
+#include <QAbstractListModel>
+
+#include "BaseVersion.h"
+#include "tasks/Task.h"
+#include "QObjectPtr.h"
+
+/*!
+ * \brief Class that each instance type's version list derives from.
+ * Version lists are the lists that keep track of the available game versions
+ * for that instance. This list will not be loaded on startup. It will be loaded
+ * when the list's load function is called. Before using the version list, you
+ * should check to see if it has been loaded yet and if not, load the list.
+ *
+ * Note that this class also inherits from QAbstractListModel. Methods from that
+ * class determine how this version list shows up in a list view. Said methods
+ * all have a default implementation, but they can be overridden by plugins to
+ * change the behavior of the list.
+ */
+class BaseVersionList : public QAbstractListModel
+{
+    Q_OBJECT
+public:
+    enum ModelRoles
+    {
+        VersionPointerRole = Qt::UserRole,
+        VersionRole,
+        VersionIdRole,
+        ParentVersionRole,
+        RecommendedRole,
+        LatestRole,
+        TypeRole,
+        BranchRole,
+        PathRole,
+        ArchitectureRole,
+        SortRole
+    };
+    typedef QList<int> RoleList;
+
+    explicit BaseVersionList(QObject *parent = 0);
+
+    /*!
+     * \brief Gets a task that will reload the version list.
+     * Simply execute the task to load the list.
+     * The task returned by this function should reset the model when it's done.
+     * \return A pointer to a task that reloads the version list.
+     */
+    virtual shared_qobject_ptr<Task> getLoadTask() = 0;
+
+    //! Checks whether or not the list is loaded. If this returns false, the list should be
+    //loaded.
+    virtual bool isLoaded() = 0;
+
+    //! Gets the version at the given index.
+    virtual const BaseVersionPtr at(int i) const = 0;
+
+    //! Returns the number of versions in the list.
+    virtual int count() const = 0;
+
+    //////// List Model Functions ////////
+    QVariant data(const QModelIndex &index, int role) const override;
+    int rowCount(const QModelIndex &parent) const override;
+    int columnCount(const QModelIndex &parent) const override;
+    QHash<int, QByteArray> roleNames() const override;
+
+    //! which roles are provided by this version list?
+    virtual RoleList providesRoles() const;
+
+    /*!
+     * \brief Finds a version by its descriptor.
+     * \param descriptor The descriptor of the version to find.
+     * \return A const pointer to the version with the given descriptor. NULL if
+     * one doesn't exist.
+     */
+    virtual BaseVersionPtr findVersion(const QString &descriptor);
+
+    /*!
+     * \brief Gets the recommended version from this list
+     * If the list doesn't support recommended versions, this works exactly as getLatestStable
+     */
+    virtual BaseVersionPtr getRecommended() const;
+
+    /*!
+     * Sorts the version list.
+     */
+    virtual void sortVersions() = 0;
+
+protected
+slots:
+    /*!
+     * Updates this list with the given list of versions.
+     * This is done by copying each version in the given list and inserting it
+     * into this one.
+     * We need to do this so that we can set the parents of the versions are set to this
+     * version list. This can't be done in the load task, because the versions the load
+     * task creates are on the load task's thread and Qt won't allow their parents
+     * to be set to something created on another thread.
+     * To get around that problem, we invoke this method on the GUI thread, which
+     * then copies the versions and sets their parents correctly.
+     * \param versions List of versions whose parents should be set.
+     */
+    virtual void updateListData(QList<BaseVersionPtr> versions) = 0;
+};

launcher/ColorCache.cpp

@@ -0,0 +1,35 @@
+#include "ColorCache.h"
+
+
+/**
+ * Blend the color with the front color, adapting to the back color
+ */
+QColor ColorCache::blend(QColor color)
+{
+    if (Rainbow::luma(m_front) > Rainbow::luma(m_back))
+    {
+        // for dark color schemes, produce a fitting color first
+        color = Rainbow::tint(m_front, color, 0.5);
+    }
+    // adapt contrast
+    return Rainbow::mix(m_front, color, m_bias);
+}
+
+/**
+ * Blend the color with the back color
+ */
+QColor ColorCache::blendBackground(QColor color)
+{
+    // adapt contrast
+    return Rainbow::mix(m_back, color, m_bias);
+}
+
+void ColorCache::recolorAll()
+{
+    auto iter = m_colors.begin();
+    while(iter != m_colors.end())
+    {
+        iter->front = blend(iter->original);
+        iter->back = blendBackground(iter->original);
+    }
+}

launcher/ColorCache.h

@@ -0,0 +1,119 @@
+#pragma once
+#include <QtGui/QColor>
+#include <rainbow.h>
+#include <MessageLevel.h>
+#include <QMap>
+
+class ColorCache
+{
+public:
+    ColorCache(QColor front, QColor back, qreal bias)
+    {
+        m_front = front;
+        m_back = back;
+        m_bias = bias;
+    };
+
+    void addColor(int key, QColor color)
+    {
+        m_colors[key] = {color, blend(color), blendBackground(color)};
+    }
+
+    void setForeground(QColor front)
+    {
+        if(m_front != front)
+        {
+            m_front = front;
+            recolorAll();
+        }
+    }
+
+    void setBackground(QColor back)
+    {
+        if(m_back != back)
+        {
+            m_back = back;
+            recolorAll();
+        }
+    }
+
+    QColor getFront(int key)
+    {
+        auto iter = m_colors.find(key);
+        if(iter == m_colors.end())
+        {
+            return QColor();
+        }
+        return (*iter).front;
+    }
+
+    QColor getBack(int key)
+    {
+        auto iter = m_colors.find(key);
+        if(iter == m_colors.end())
+        {
+            return QColor();
+        }
+        return (*iter).back;
+    }
+
+    /**
+     * Blend the color with the front color, adapting to the back color
+     */
+    QColor blend(QColor color);
+
+    /**
+     * Blend the color with the back color
+     */
+    QColor blendBackground(QColor color);
+
+protected:
+    void recolorAll();
+
+protected:
+    struct ColorEntry
+    {
+        QColor original;
+        QColor front;
+        QColor back;
+    };
+
+protected:
+    qreal m_bias;
+    QColor m_front;
+    QColor m_back;
+    QMap<int, ColorEntry> m_colors;
+};
+
+class LogColorCache : public ColorCache
+{
+public:
+    LogColorCache(QColor front, QColor back)
+        : ColorCache(front, back, 1.0)
+    {
+        addColor((int)MessageLevel::MultiMC, QColor("purple"));
+        addColor((int)MessageLevel::Debug, QColor("green"));
+        addColor((int)MessageLevel::Warning, QColor("orange"));
+        addColor((int)MessageLevel::Error, QColor("red"));
+        addColor((int)MessageLevel::Fatal, QColor("red"));
+        addColor((int)MessageLevel::Message, front);
+    }
+
+    QColor getFront(MessageLevel::Enum level)
+    {
+        if(!m_colors.contains((int) level))
+        {
+            return ColorCache::getFront((int)MessageLevel::Message);
+        }
+        return ColorCache::getFront((int)level);
+    }
+
+    QColor getBack(MessageLevel::Enum level)
+    {
+        if(level == MessageLevel::Fatal)
+        {
+            return QColor(Qt::black);
+        }
+        return QColor(Qt::transparent);
+    }
+};

launcher/ColumnResizer.cpp

@@ -0,0 +1,199 @@
+/*
+* Copyright 2011 Aurélien Gâteau <agateau@kde.org>
+* License: BSD-3-Clause
+*/
+#include <ColumnResizer.h>
+
+#include <QDebug>
+#include <QEvent>
+#include <QFormLayout>
+#include <QGridLayout>
+#include <QTimer>
+#include <QWidget>
+
+class FormLayoutWidgetItem : public QWidgetItem
+{
+public:
+    FormLayoutWidgetItem(QWidget* widget, QFormLayout* formLayout, QFormLayout::ItemRole itemRole)
+    : QWidgetItem(widget)
+    , m_width(-1)
+    , m_formLayout(formLayout)
+    , m_itemRole(itemRole)
+    {}
+
+    QSize sizeHint() const
+    {
+        QSize size = QWidgetItem::sizeHint();
+        if (m_width != -1) {
+            size.setWidth(m_width);
+        }
+        return size;
+    }
+
+    QSize minimumSize() const
+    {
+        QSize size = QWidgetItem::minimumSize();
+        if (m_width != -1) {
+            size.setWidth(m_width);
+        }
+        return size;
+    }
+
+    QSize maximumSize() const
+    {
+        QSize size = QWidgetItem::maximumSize();
+        if (m_width != -1) {
+            size.setWidth(m_width);
+        }
+        return size;
+    }
+
+    void setWidth(int width)
+    {
+        if (width != m_width) {
+            m_width = width;
+            invalidate();
+        }
+    }
+
+    void setGeometry(const QRect& _rect)
+    {
+        QRect rect = _rect;
+        int width = widget()->sizeHint().width();
+        if (m_itemRole == QFormLayout::LabelRole && m_formLayout->labelAlignment() & Qt::AlignRight) {
+            rect.setLeft(rect.right() - width);
+        }
+        QWidgetItem::setGeometry(rect);
+    }
+
+    QFormLayout* formLayout() const
+    {
+        return m_formLayout;
+    }
+
+private:
+    int m_width;
+    QFormLayout* m_formLayout;
+    QFormLayout::ItemRole m_itemRole;
+};
+
+typedef QPair<QGridLayout*, int> GridColumnInfo;
+
+class ColumnResizerPrivate
+{
+public:
+    ColumnResizerPrivate(ColumnResizer* q_ptr)
+    : q(q_ptr)
+    , m_updateTimer(new QTimer(q))
+    {
+        m_updateTimer->setSingleShot(true);
+        m_updateTimer->setInterval(0);
+        QObject::connect(m_updateTimer, SIGNAL(timeout()), q, SLOT(updateWidth()));
+    }
+
+    void scheduleWidthUpdate()
+    {
+        m_updateTimer->start();
+    }
+
+    ColumnResizer* q;
+    QTimer* m_updateTimer;
+    QList<QWidget*> m_widgets;
+    QList<FormLayoutWidgetItem*> m_wrWidgetItemList;
+    QList<GridColumnInfo> m_gridColumnInfoList;
+};
+
+ColumnResizer::ColumnResizer(QObject* parent)
+: QObject(parent)
+, d(new ColumnResizerPrivate(this))
+{}
+
+ColumnResizer::~ColumnResizer()
+{
+    delete d;
+}
+
+void ColumnResizer::addWidget(QWidget* widget)
+{
+    d->m_widgets.append(widget);
+    widget->installEventFilter(this);
+    d->scheduleWidthUpdate();
+}
+
+void ColumnResizer::updateWidth()
+{
+    int width = 0;
+    Q_FOREACH(QWidget* widget, d->m_widgets) {
+        width = qMax(widget->sizeHint().width(), width);
+    }
+    Q_FOREACH(FormLayoutWidgetItem* item, d->m_wrWidgetItemList) {
+        item->setWidth(width);
+        item->formLayout()->update();
+    }
+    Q_FOREACH(GridColumnInfo info, d->m_gridColumnInfoList) {
+        info.first->setColumnMinimumWidth(info.second, width);
+    }
+}
+
+bool ColumnResizer::eventFilter(QObject*, QEvent* event)
+{
+    if (event->type() == QEvent::Resize) {
+        d->scheduleWidthUpdate();
+    }
+    return false;
+}
+
+void ColumnResizer::addWidgetsFromLayout(QLayout* layout, int column)
+{
+    Q_ASSERT(column >= 0);
+    QGridLayout* gridLayout = qobject_cast<QGridLayout*>(layout);
+    QFormLayout* formLayout = qobject_cast<QFormLayout*>(layout);
+    if (gridLayout) {
+        addWidgetsFromGridLayout(gridLayout, column);
+    } else if (formLayout) {
+        if (column > QFormLayout::SpanningRole) {
+            qCritical() << "column should not be more than" << QFormLayout::SpanningRole << "for QFormLayout";
+            return;
+        }
+        QFormLayout::ItemRole role = static_cast<QFormLayout::ItemRole>(column);
+        addWidgetsFromFormLayout(formLayout, role);
+    } else {
+        qCritical() << "Don't know how to handle layout" << layout;
+    }
+}
+
+void ColumnResizer::addWidgetsFromGridLayout(QGridLayout* layout, int column)
+{
+    for (int row = 0; row < layout->rowCount(); ++row) {
+        QLayoutItem* item = layout->itemAtPosition(row, column);
+        if (!item) {
+            continue;
+        }
+        QWidget* widget = item->widget();
+        if (!widget) {
+            continue;
+        }
+        addWidget(widget);
+    }
+    d->m_gridColumnInfoList << GridColumnInfo(layout, column);
+}
+
+void ColumnResizer::addWidgetsFromFormLayout(QFormLayout* layout, QFormLayout::ItemRole role)
+{
+    for (int row = 0; row < layout->rowCount(); ++row) {
+        QLayoutItem* item = layout->itemAt(row, role);
+        if (!item) {
+            continue;
+        }
+        QWidget* widget = item->widget();
+        if (!widget) {
+            continue;
+        }
+        layout->removeItem(item);
+        delete item;
+        FormLayoutWidgetItem* newItem = new FormLayoutWidgetItem(widget, layout, role);
+        layout->setItem(row, role, newItem);
+        addWidget(widget);
+        d->m_wrWidgetItemList << newItem;
+    }
+}

launcher/ColumnResizer.h

@@ -0,0 +1,41 @@
+/*
+* Copyright 2011 Aurélien Gâteau <agateau@kde.org>
+* License: BSD-3-Clause
+*/
+#ifndef COLUMNRESIZER_H
+#define COLUMNRESIZER_H
+
+#include <QFormLayout>
+
+#include <QtCore/QObject>
+#include <QtCore/QList>
+
+class QEvent;
+class QGridLayout;
+class QLayout;
+class QWidget;
+
+class ColumnResizerPrivate;
+class ColumnResizer : public QObject
+{
+    Q_OBJECT
+public:
+    ColumnResizer(QObject* parent = 0);
+    ~ColumnResizer();
+
+    void addWidget(QWidget* widget);
+    void addWidgetsFromLayout(QLayout*, int column);
+    void addWidgetsFromGridLayout(QGridLayout*, int column);
+    void addWidgetsFromFormLayout(QFormLayout*, QFormLayout::ItemRole role);
+
+private Q_SLOTS:
+    void updateWidth();
+
+protected:
+    bool eventFilter(QObject*, QEvent* event);
+
+private:
+    ColumnResizerPrivate* const d;
+};
+
+#endif /* COLUMNRESIZER_H */

launcher/Commandline.cpp

@@ -0,0 +1,483 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Commandline.h"
+
+/**
+ * @file libutil/src/cmdutils.cpp
+ */
+
+namespace Commandline
+{
+
+// commandline splitter
+QStringList splitArgs(QString args)
+{
+    QStringList argv;
+    QString current;
+    bool escape = false;
+    QChar inquotes;
+    for (int i = 0; i < args.length(); i++)
+    {
+        QChar cchar = args.at(i);
+
+        // \ escaped
+        if (escape)
+        {
+            current += cchar;
+            escape = false;
+            // in "quotes"
+        }
+        else if (!inquotes.isNull())
+        {
+            if (cchar == '\\')
+                escape = true;
+            else if (cchar == inquotes)
+                inquotes = 0;
+            else
+                current += cchar;
+            // otherwise
+        }
+        else
+        {
+            if (cchar == ' ')
+            {
+                if (!current.isEmpty())
+                {
+                    argv << current;
+                    current.clear();
+                }
+            }
+            else if (cchar == '"' || cchar == '\'')
+                inquotes = cchar;
+            else
+                current += cchar;
+        }
+    }
+    if (!current.isEmpty())
+        argv << current;
+    return argv;
+}
+
+Parser::Parser(FlagStyle::Enum flagStyle, ArgumentStyle::Enum argStyle)
+{
+    m_flagStyle = flagStyle;
+    m_argStyle = argStyle;
+}
+
+// styles setter/getter
+void Parser::setArgumentStyle(ArgumentStyle::Enum style)
+{
+    m_argStyle = style;
+}
+ArgumentStyle::Enum Parser::argumentStyle()
+{
+    return m_argStyle;
+}
+
+void Parser::setFlagStyle(FlagStyle::Enum style)
+{
+    m_flagStyle = style;
+}
+FlagStyle::Enum Parser::flagStyle()
+{
+    return m_flagStyle;
+}
+
+// setup methods
+void Parser::addSwitch(QString name, bool def)
+{
+    if (m_params.contains(name))
+        throw "Name not unique";
+
+    OptionDef *param = new OptionDef;
+    param->type = otSwitch;
+    param->name = name;
+    param->metavar = QString("<%1>").arg(name);
+    param->def = def;
+
+    m_options[name] = param;
+    m_params[name] = (CommonDef *)param;
+    m_optionList.append(param);
+}
+
+void Parser::addOption(QString name, QVariant def)
+{
+    if (m_params.contains(name))
+        throw "Name not unique";
+
+    OptionDef *param = new OptionDef;
+    param->type = otOption;
+    param->name = name;
+    param->metavar = QString("<%1>").arg(name);
+    param->def = def;
+
+    m_options[name] = param;
+    m_params[name] = (CommonDef *)param;
+    m_optionList.append(param);
+}
+
+void Parser::addArgument(QString name, bool required, QVariant def)
+{
+    if (m_params.contains(name))
+        throw "Name not unique";
+
+    PositionalDef *param = new PositionalDef;
+    param->name = name;
+    param->def = def;
+    param->required = required;
+    param->metavar = name;
+
+    m_positionals.append(param);
+    m_params[name] = (CommonDef *)param;
+}
+
+void Parser::addDocumentation(QString name, QString doc, QString metavar)
+{
+    if (!m_params.contains(name))
+        throw "Name does not exist";
+
+    CommonDef *param = m_params[name];
+    param->doc = doc;
+    if (!metavar.isNull())
+        param->metavar = metavar;
+}
+
+void Parser::addShortOpt(QString name, QChar flag)
+{
+    if (!m_params.contains(name))
+        throw "Name does not exist";
+    if (!m_options.contains(name))
+        throw "Name is not an Option or Swtich";
+
+    OptionDef *param = m_options[name];
+    m_flags[flag] = param;
+    param->flag = flag;
+}
+
+// help methods
+QString Parser::compileHelp(QString progName, int helpIndent, bool useFlags)
+{
+    QStringList help;
+    help << compileUsage(progName, useFlags) << "\r\n";
+
+    // positionals
+    if (!m_positionals.isEmpty())
+    {
+        help << "\r\n";
+        help << "Positional arguments:\r\n";
+        QListIterator<PositionalDef *> it2(m_positionals);
+        while (it2.hasNext())
+        {
+            PositionalDef *param = it2.next();
+            help << "  " << param->metavar;
+            help << " " << QString(helpIndent - param->metavar.length() - 1, ' ');
+            help << param->doc << "\r\n";
+        }
+    }
+
+    // Options
+    if (!m_optionList.isEmpty())
+    {
+        help << "\r\n";
+        QString optPrefix, flagPrefix;
+        getPrefix(optPrefix, flagPrefix);
+
+        help << "Options & Switches:\r\n";
+        QListIterator<OptionDef *> it(m_optionList);
+        while (it.hasNext())
+        {
+            OptionDef *option = it.next();
+            help << "  ";
+            int nameLength = optPrefix.length() + option->name.length();
+            if (!option->flag.isNull())
+            {
+                nameLength += 3 + flagPrefix.length();
+                help << flagPrefix << option->flag << ", ";
+            }
+            help << optPrefix << option->name;
+            if (option->type == otOption)
+            {
+                QString arg = QString("%1%2").arg(
+                    ((m_argStyle == ArgumentStyle::Equals) ? "=" : " "), option->metavar);
+                nameLength += arg.length();
+                help << arg;
+            }
+            help << " " << QString(helpIndent - nameLength - 1, ' ');
+            help << option->doc << "\r\n";
+        }
+    }
+
+    return help.join("");
+}
+
+QString Parser::compileUsage(QString progName, bool useFlags)
+{
+    QStringList usage;
+    usage << "Usage: " << progName;
+
+    QString optPrefix, flagPrefix;
+    getPrefix(optPrefix, flagPrefix);
+
+    // options
+    QListIterator<OptionDef *> it(m_optionList);
+    while (it.hasNext())
+    {
+        OptionDef *option = it.next();
+        usage << " [";
+        if (!option->flag.isNull() && useFlags)
+            usage << flagPrefix << option->flag;
+        else
+            usage << optPrefix << option->name;
+        if (option->type == otOption)
+            usage << ((m_argStyle == ArgumentStyle::Equals) ? "=" : " ") << option->metavar;
+        usage << "]";
+    }
+
+    // arguments
+    QListIterator<PositionalDef *> it2(m_positionals);
+    while (it2.hasNext())
+    {
+        PositionalDef *param = it2.next();
+        usage << " " << (param->required ? "<" : "[");
+        usage << param->metavar;
+        usage << (param->required ? ">" : "]");
+    }
+
+    return usage.join("");
+}
+
+// parsing
+QHash<QString, QVariant> Parser::parse(QStringList argv)
+{
+    QHash<QString, QVariant> map;
+
+    QStringListIterator it(argv);
+    QString programName = it.next();
+
+    QString optionPrefix;
+    QString flagPrefix;
+    QListIterator<PositionalDef *> positionals(m_positionals);
+    QStringList expecting;
+
+    getPrefix(optionPrefix, flagPrefix);
+
+    while (it.hasNext())
+    {
+        QString arg = it.next();
+
+        if (!expecting.isEmpty())
+        // we were expecting an argument
+        {
+            QString name = expecting.first();
+/*
+            if (map.contains(name))
+                throw ParsingError(
+                    QString("Option %2%1 was given multiple times").arg(name, optionPrefix));
+*/
+            map[name] = QVariant(arg);
+
+            expecting.removeFirst();
+            continue;
+        }
+
+        if (arg.startsWith(optionPrefix))
+        // we have an option
+        {
+            // qDebug("Found option %s", qPrintable(arg));
+
+            QString name = arg.mid(optionPrefix.length());
+            QString equals;
+
+            if ((m_argStyle == ArgumentStyle::Equals ||
+                 m_argStyle == ArgumentStyle::SpaceAndEquals) &&
+                name.contains("="))
+            {
+                int i = name.indexOf("=");
+                equals = name.mid(i + 1);
+                name = name.left(i);
+            }
+
+            if (m_options.contains(name))
+            {
+                /*
+                if (map.contains(name))
+                    throw ParsingError(QString("Option %2%1 was given multiple times")
+                                           .arg(name, optionPrefix));
+*/
+                OptionDef *option = m_options[name];
+                if (option->type == otSwitch)
+                    map[name] = true;
+                else // if (option->type == otOption)
+                {
+                    if (m_argStyle == ArgumentStyle::Space)
+                        expecting.append(name);
+                    else if (!equals.isNull())
+                        map[name] = equals;
+                    else if (m_argStyle == ArgumentStyle::SpaceAndEquals)
+                        expecting.append(name);
+                    else
+                        throw ParsingError(QString("Option %2%1 reqires an argument.")
+                                               .arg(name, optionPrefix));
+                }
+
+                continue;
+            }
+
+            throw ParsingError(QString("Unknown Option %2%1").arg(name, optionPrefix));
+        }
+
+        if (arg.startsWith(flagPrefix))
+        // we have (a) flag(s)
+        {
+            // qDebug("Found flags %s", qPrintable(arg));
+
+            QString flags = arg.mid(flagPrefix.length());
+            QString equals;
+
+            if ((m_argStyle == ArgumentStyle::Equals ||
+                 m_argStyle == ArgumentStyle::SpaceAndEquals) &&
+                flags.contains("="))
+            {
+                int i = flags.indexOf("=");
+                equals = flags.mid(i + 1);
+                flags = flags.left(i);
+            }
+
+            for (int i = 0; i < flags.length(); i++)
+            {
+                QChar flag = flags.at(i);
+
+                if (!m_flags.contains(flag))
+                    throw ParsingError(QString("Unknown flag %2%1").arg(flag, flagPrefix));
+
+                OptionDef *option = m_flags[flag];
+/*
+                if (map.contains(option->name))
+                    throw ParsingError(QString("Option %2%1 was given multiple times")
+                                           .arg(option->name, optionPrefix));
+*/
+                if (option->type == otSwitch)
+                    map[option->name] = true;
+                else // if (option->type == otOption)
+                {
+                    if (m_argStyle == ArgumentStyle::Space)
+                        expecting.append(option->name);
+                    else if (!equals.isNull())
+                        if (i == flags.length() - 1)
+                            map[option->name] = equals;
+                        else
+                            throw ParsingError(QString("Flag %4%2 of Argument-requiring Option "
+                                                       "%1 not last flag in %4%3")
+                                                   .arg(option->name, flag, flags, flagPrefix));
+                    else if (m_argStyle == ArgumentStyle::SpaceAndEquals)
+                        expecting.append(option->name);
+                    else
+                        throw ParsingError(QString("Option %1 reqires an argument. (flag %3%2)")
+                                               .arg(option->name, flag, flagPrefix));
+                }
+            }
+
+            continue;
+        }
+
+        // must be a positional argument
+        if (!positionals.hasNext())
+            throw ParsingError(QString("Don't know what to do with '%1'").arg(arg));
+
+        PositionalDef *param = positionals.next();
+
+        map[param->name] = arg;
+    }
+
+    // check if we're missing something
+    if (!expecting.isEmpty())
+        throw ParsingError(QString("Was still expecting arguments for %2%1").arg(
+            expecting.join(QString(", ") + optionPrefix), optionPrefix));
+
+    while (positionals.hasNext())
+    {
+        PositionalDef *param = positionals.next();
+        if (param->required)
+            throw ParsingError(
+                QString("Missing required positional argument '%1'").arg(param->name));
+        else
+            map[param->name] = param->def;
+    }
+
+    // fill out gaps
+    QListIterator<OptionDef *> iter(m_optionList);
+    while (iter.hasNext())
+    {
+        OptionDef *option = iter.next();
+        if (!map.contains(option->name))
+            map[option->name] = option->def;
+    }
+
+    return map;
+}
+
+// clear defs
+void Parser::clear()
+{
+    m_flags.clear();
+    m_params.clear();
+    m_options.clear();
+
+    QMutableListIterator<OptionDef *> it(m_optionList);
+    while (it.hasNext())
+    {
+        OptionDef *option = it.next();
+        it.remove();
+        delete option;
+    }
+
+    QMutableListIterator<PositionalDef *> it2(m_positionals);
+    while (it2.hasNext())
+    {
+        PositionalDef *arg = it2.next();
+        it2.remove();
+        delete arg;
+    }
+}
+
+// Destructor
+Parser::~Parser()
+{
+    clear();
+}
+
+// getPrefix
+void Parser::getPrefix(QString &opt, QString &flag)
+{
+    if (m_flagStyle == FlagStyle::Windows)
+        opt = flag = "/";
+    else if (m_flagStyle == FlagStyle::Unix)
+        opt = flag = "-";
+    // else if (m_flagStyle == FlagStyle::GNU)
+    else
+    {
+        opt = "--";
+        flag = "-";
+    }
+}
+
+// ParsingError
+ParsingError::ParsingError(const QString &what) : std::runtime_error(what.toStdString())
+{
+}
+}

launcher/Commandline.h

@@ -0,0 +1,250 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Authors: Orochimarufan <orochimarufan.x3@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <exception>
+#include <stdexcept>
+
+#include <QString>
+#include <QVariant>
+#include <QHash>
+#include <QStringList>
+
+/**
+ * @file libutil/include/cmdutils.h
+ * @brief commandline parsing and processing utilities
+ */
+
+namespace Commandline
+{
+
+/**
+ * @brief split a string into argv items like a shell would do
+ * @param args the argument string
+ * @return a QStringList containing all arguments
+ */
+QStringList splitArgs(QString args);
+
+/**
+ * @brief The FlagStyle enum
+ * Specifies how flags are decorated
+ */
+
+namespace FlagStyle
+{
+enum Enum
+{
+    GNU,     /**< --option and -o (GNU Style) */
+    Unix,    /**< -option and -o  (Unix Style) */
+    Windows, /**< /option and /o  (Windows Style) */
+#ifdef Q_OS_WIN32
+    Default = Windows
+#else
+        Default = GNU
+#endif
+};
+}
+
+/**
+ * @brief The ArgumentStyle enum
+ */
+namespace ArgumentStyle
+{
+enum Enum
+{
+    Space,          /**< --option value */
+    Equals,         /**< --option=value */
+    SpaceAndEquals, /**< --option[= ]value */
+#ifdef Q_OS_WIN32
+    Default = Equals
+#else
+        Default = SpaceAndEquals
+#endif
+};
+}
+
+/**
+ * @brief The ParsingError class
+ */
+class ParsingError : public std::runtime_error
+{
+public:
+    ParsingError(const QString &what);
+};
+
+/**
+ * @brief The Parser class
+ */
+class Parser
+{
+public:
+    /**
+     * @brief Parser constructor
+     * @param flagStyle the FlagStyle to use in this Parser
+     * @param argStyle the ArgumentStyle to use in this Parser
+     */
+    Parser(FlagStyle::Enum flagStyle = FlagStyle::Default,
+           ArgumentStyle::Enum argStyle = ArgumentStyle::Default);
+
+    /**
+     * @brief set the flag style
+     * @param style
+     */
+    void setFlagStyle(FlagStyle::Enum style);
+
+    /**
+     * @brief get the flag style
+     * @return
+     */
+    FlagStyle::Enum flagStyle();
+
+    /**
+     * @brief set the argument style
+     * @param style
+     */
+    void setArgumentStyle(ArgumentStyle::Enum style);
+
+    /**
+     * @brief get the argument style
+     * @return
+     */
+    ArgumentStyle::Enum argumentStyle();
+
+    /**
+     * @brief define a boolean switch
+     * @param name the parameter name
+     * @param def the default value
+     */
+    void addSwitch(QString name, bool def = false);
+
+    /**
+     * @brief define an option that takes an additional argument
+     * @param name the parameter name
+     * @param def the default value
+     */
+    void addOption(QString name, QVariant def = QVariant());
+
+    /**
+     * @brief define a positional argument
+     * @param name the parameter name
+     * @param required wether this argument is required
+     * @param def the default value
+     */
+    void addArgument(QString name, bool required = true, QVariant def = QVariant());
+
+    /**
+     * @brief adds a flag to an existing parameter
+     * @param name the (existing) parameter name
+     * @param flag the flag character
+     * @see addSwitch addArgument addOption
+     * Note: any one parameter can only have one flag
+     */
+    void addShortOpt(QString name, QChar flag);
+
+    /**
+     * @brief adds documentation to a Parameter
+     * @param name the parameter name
+     * @param metavar a string to be displayed as placeholder for the value
+     * @param doc a QString containing the documentation
+     * Note: on positional arguments, metavar replaces the name as displayed.
+     *       on options , metavar replaces the value placeholder
+     */
+    void addDocumentation(QString name, QString doc, QString metavar = QString());
+
+    /**
+     * @brief generate a help message
+     * @param progName the program name to use in the help message
+     * @param helpIndent how much the parameter documentation should be indented
+     * @param flagsInUsage whether we should use flags instead of options in the usage
+     * @return a help message
+     */
+    QString compileHelp(QString progName, int helpIndent = 22, bool flagsInUsage = true);
+
+    /**
+     * @brief generate a short usage message
+     * @param progName the program name to use in the usage message
+     * @param useFlags whether we should use flags instead of options
+     * @return a usage message
+     */
+    QString compileUsage(QString progName, bool useFlags = true);
+
+    /**
+     * @brief parse
+     * @param argv a QStringList containing the program ARGV
+     * @return a QHash mapping argument names to their values
+     */
+    QHash<QString, QVariant> parse(QStringList argv);
+
+    /**
+     * @brief clear all definitions
+     */
+    void clear();
+
+    ~Parser();
+
+private:
+    FlagStyle::Enum m_flagStyle;
+    ArgumentStyle::Enum m_argStyle;
+
+    enum OptionType
+    {
+        otSwitch,
+        otOption
+    };
+
+    // Important: the common part MUST BE COMMON ON ALL THREE structs
+    struct CommonDef
+    {
+        QString name;
+        QString doc;
+        QString metavar;
+        QVariant def;
+    };
+
+    struct OptionDef
+    {
+        // common
+        QString name;
+        QString doc;
+        QString metavar;
+        QVariant def;
+        // option
+        OptionType type;
+        QChar flag;
+    };
+
+    struct PositionalDef
+    {
+        // common
+        QString name;
+        QString doc;
+        QString metavar;
+        QVariant def;
+        // positional
+        bool required;
+    };
+
+    QHash<QString, OptionDef *> m_options;
+    QHash<QChar, OptionDef *> m_flags;
+    QHash<QString, CommonDef *> m_params;
+    QList<PositionalDef *> m_positionals;
+    QList<OptionDef *> m_optionList;
+
+    void getPrefix(QString &opt, QString &flag);
+};
+}

launcher/DefaultVariable.h

@@ -0,0 +1,35 @@
+#pragma once
+
+template <typename T>
+class DefaultVariable
+{
+public:
+    DefaultVariable(const T & value)
+    {
+        defaultValue = value;
+    }
+    DefaultVariable<T> & operator =(const T & value)
+    {
+        currentValue = value;
+        is_default = currentValue == defaultValue;
+        is_explicit = true;
+        return *this;
+    }
+    operator const T &() const
+    {
+        return is_default ? defaultValue : currentValue;
+    }
+    bool isDefault() const
+    {
+        return is_default;
+    }
+    bool isExplicit() const
+    {
+        return is_explicit;
+    }
+private:
+    T currentValue;
+    T defaultValue;
+    bool is_default = true;
+    bool is_explicit = false;
+};

launcher/DesktopServices.cpp

@@ -0,0 +1,149 @@
+#include "DesktopServices.h"
+#include <QDir>
+#include <QDesktopServices>
+#include <QProcess>
+#include <QDebug>
+
+/**
+ * This shouldn't exist, but until QTBUG-9328 and other unreported bugs are fixed, it needs to be a thing.
+ */
+#if defined(Q_OS_LINUX)
+
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+template <typename T>
+bool IndirectOpen(T callable, qint64 *pid_forked = nullptr)
+{
+    auto pid = fork();
+    if(pid_forked)
+    {
+        if(pid > 0)
+            *pid_forked = pid;
+        else
+            *pid_forked = 0;
+    }
+    if(pid == -1)
+    {
+        qWarning() << "IndirectOpen failed to fork: " << errno;
+        return false;
+    }
+    // child - do the stuff
+    if(pid == 0)
+    {
+        // unset all this garbage so it doesn't get passed to the child process
+        qunsetenv("LD_PRELOAD");
+        qunsetenv("LD_LIBRARY_PATH");
+        qunsetenv("LD_DEBUG");
+        qunsetenv("QT_PLUGIN_PATH");
+        qunsetenv("QT_FONTPATH");
+
+        // open the URL
+        auto status = callable();
+
+        // detach from the parent process group.
+        setsid();
+
+        // die. now. do not clean up anything, it would just hang forever.
+        _exit(status ? 0 : 1);
+    }
+    else
+    {
+        //parent - assume it worked.
+        int status;
+        while (waitpid(pid, &status, 0))
+        {
+            if(WIFEXITED(status))
+            {
+                return WEXITSTATUS(status) == 0;
+            }
+            if(WIFSIGNALED(status))
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+#endif
+
+namespace DesktopServices {
+bool openDirectory(const QString &path, bool ensureExists)
+{
+    qDebug() << "Opening directory" << path;
+    QDir parentPath;
+    QDir dir(path);
+    if (!dir.exists())
+    {
+        parentPath.mkpath(dir.absolutePath());
+    }
+    auto f = [&]()
+    {
+        return QDesktopServices::openUrl(QUrl::fromLocalFile(dir.absolutePath()));
+    };
+#if defined(Q_OS_LINUX)
+    return IndirectOpen(f);
+#else
+    return f();
+#endif
+}
+
+bool openFile(const QString &path)
+{
+    qDebug() << "Opening file" << path;
+    auto f = [&]()
+    {
+        return QDesktopServices::openUrl(QUrl::fromLocalFile(path));
+    };
+#if defined(Q_OS_LINUX)
+    return IndirectOpen(f);
+#else
+    return f();
+#endif
+}
+
+bool openFile(const QString &application, const QString &path, const QString &workingDirectory, qint64 *pid)
+{
+    qDebug() << "Opening file" << path << "using" << application;
+#if defined(Q_OS_LINUX)
+    // FIXME: the pid here is fake. So if something depends on it, it will likely misbehave
+    return IndirectOpen([&]()
+    {
+        return QProcess::startDetached(application, QStringList() << path, workingDirectory);
+    }, pid);
+#else
+    return QProcess::startDetached(application, QStringList() << path, workingDirectory, pid);
+#endif
+}
+
+bool run(const QString &application, const QStringList &args, const QString &workingDirectory, qint64 *pid)
+{
+    qDebug() << "Running" << application << "with args" << args.join(' ');
+#if defined(Q_OS_LINUX)
+    // FIXME: the pid here is fake. So if something depends on it, it will likely misbehave
+    return IndirectOpen([&]()
+    {
+        return QProcess::startDetached(application, args, workingDirectory);
+    }, pid);
+#else
+    return QProcess::startDetached(application, args, workingDirectory, pid);
+#endif
+}
+
+bool openUrl(const QUrl &url)
+{
+    qDebug() << "Opening URL" << url.toString();
+    auto f = [&]()
+    {
+        return QDesktopServices::openUrl(url);
+    };
+#if defined(Q_OS_LINUX)
+    return IndirectOpen(f);
+#else
+    return f();
+#endif
+}
+
+}

launcher/DesktopServices.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <QUrl>
+#include <QString>
+
+/**
+ * This wraps around QDesktopServices and adds workarounds where needed
+ * Use this instead of QDesktopServices!
+ */
+namespace DesktopServices
+{
+    /**
+     * Open a file in whatever application is applicable
+     */
+    bool openFile(const QString &path);
+
+    /**
+     * Open a file in the specified application
+     */
+    bool openFile(const QString &application, const QString &path, const QString & workingDirectory = QString(), qint64 *pid = 0);
+
+    /**
+     * Run an application
+     */
+    bool run(const QString &application,const QStringList &args, const QString & workingDirectory = QString(), qint64 *pid = 0);
+
+    /**
+     * Open a directory
+     */
+    bool openDirectory(const QString &path, bool ensureExists = false);
+
+    /**
+     * Open the URL, most likely in a browser. Maybe.
+     */
+    bool openUrl(const QUrl &url);
+}

launcher/Env.cpp

@@ -0,0 +1,211 @@
+#include "Env.h"
+#include "net/HttpMetaCache.h"
+#include "BaseVersion.h"
+#include "BaseVersionList.h"
+#include <QDir>
+#include <QCoreApplication>
+#include <QNetworkProxy>
+#include <QNetworkAccessManager>
+#include <QDebug>
+#include "tasks/Task.h"
+#include "meta/Index.h"
+#include "FileSystem.h"
+#include <QDebug>
+
+
+struct Env::Private
+{
+    QNetworkAccessManager m_qnam;
+    shared_qobject_ptr<HttpMetaCache> m_metacache;
+    std::shared_ptr<IIconList> m_iconlist;
+    shared_qobject_ptr<Meta::Index> m_metadataIndex;
+    QString m_jarsPath;
+    QSet<QString> m_features;
+};
+
+static Env * instance;
+
+/*
+ * The *NEW* global rat nest of an object. Handle with care.
+ */
+
+Env::Env()
+{
+    d = new Private();
+}
+
+Env::~Env()
+{
+    delete d;
+}
+
+Env& Env::Env::getInstance()
+{
+    if(!instance)
+    {
+        instance = new Env();
+    }
+    return *instance;
+}
+
+void Env::dispose()
+{
+    delete instance;
+    instance = nullptr;
+}
+
+shared_qobject_ptr< HttpMetaCache > Env::metacache()
+{
+    return d->m_metacache;
+}
+
+QNetworkAccessManager& Env::qnam() const
+{
+    return d->m_qnam;
+}
+
+std::shared_ptr<IIconList> Env::icons()
+{
+    return d->m_iconlist;
+}
+
+void Env::registerIconList(std::shared_ptr<IIconList> iconlist)
+{
+    d->m_iconlist = iconlist;
+}
+
+shared_qobject_ptr<Meta::Index> Env::metadataIndex()
+{
+    if (!d->m_metadataIndex)
+    {
+        d->m_metadataIndex.reset(new Meta::Index());
+    }
+    return d->m_metadataIndex;
+}
+
+
+void Env::initHttpMetaCache()
+{
+    auto &m_metacache = d->m_metacache;
+    m_metacache.reset(new HttpMetaCache("metacache"));
+    m_metacache->addBase("asset_indexes", QDir("assets/indexes").absolutePath());
+    m_metacache->addBase("asset_objects", QDir("assets/objects").absolutePath());
+    m_metacache->addBase("versions", QDir("versions").absolutePath());
+    m_metacache->addBase("libraries", QDir("libraries").absolutePath());
+    m_metacache->addBase("minecraftforge", QDir("mods/minecraftforge").absolutePath());
+    m_metacache->addBase("fmllibs", QDir("mods/minecraftforge/libs").absolutePath());
+    m_metacache->addBase("liteloader", QDir("mods/liteloader").absolutePath());
+    m_metacache->addBase("general", QDir("cache").absolutePath());
+    m_metacache->addBase("ATLauncherPacks", QDir("cache/ATLauncherPacks").absolutePath());
+    m_metacache->addBase("FTBPacks", QDir("cache/FTBPacks").absolutePath());
+    m_metacache->addBase("ModpacksCHPacks", QDir("cache/ModpacksCHPacks").absolutePath());
+    m_metacache->addBase("TechnicPacks", QDir("cache/TechnicPacks").absolutePath());
+    m_metacache->addBase("FlamePacks", QDir("cache/FlamePacks").absolutePath());
+    m_metacache->addBase("skins", QDir("accounts/skins").absolutePath());
+    m_metacache->addBase("root", QDir::currentPath());
+    m_metacache->addBase("translations", QDir("translations").absolutePath());
+    m_metacache->addBase("icons", QDir("cache/icons").absolutePath());
+    m_metacache->addBase("meta", QDir("meta").absolutePath());
+    m_metacache->Load();
+}
+
+void Env::updateProxySettings(QString proxyTypeStr, QString addr, int port, QString user, QString password)
+{
+    // Set the application proxy settings.
+    if (proxyTypeStr == "SOCKS5")
+    {
+        QNetworkProxy::setApplicationProxy(
+            QNetworkProxy(QNetworkProxy::Socks5Proxy, addr, port, user, password));
+    }
+    else if (proxyTypeStr == "HTTP")
+    {
+        QNetworkProxy::setApplicationProxy(
+            QNetworkProxy(QNetworkProxy::HttpProxy, addr, port, user, password));
+    }
+    else if (proxyTypeStr == "None")
+    {
+        // If we have no proxy set, set no proxy and return.
+        QNetworkProxy::setApplicationProxy(QNetworkProxy(QNetworkProxy::NoProxy));
+    }
+    else
+    {
+        // If we have "Default" selected, set Qt to use the system proxy settings.
+        QNetworkProxyFactory::setUseSystemConfiguration(true);
+    }
+
+    qDebug() << "Detecting proxy settings...";
+    QNetworkProxy proxy = QNetworkProxy::applicationProxy();
+    d->m_qnam.setProxy(proxy);
+    QString proxyDesc;
+    if (proxy.type() == QNetworkProxy::NoProxy)
+    {
+        qDebug() << "Using no proxy is an option!";
+        return;
+    }
+    switch (proxy.type())
+    {
+    case QNetworkProxy::DefaultProxy:
+        proxyDesc = "Default proxy: ";
+        break;
+    case QNetworkProxy::Socks5Proxy:
+        proxyDesc = "Socks5 proxy: ";
+        break;
+    case QNetworkProxy::HttpProxy:
+        proxyDesc = "HTTP proxy: ";
+        break;
+    case QNetworkProxy::HttpCachingProxy:
+        proxyDesc = "HTTP caching: ";
+        break;
+    case QNetworkProxy::FtpCachingProxy:
+        proxyDesc = "FTP caching: ";
+        break;
+    default:
+        proxyDesc = "DERP proxy: ";
+        break;
+    }
+    proxyDesc += QString("%1:%2")
+                     .arg(proxy.hostName())
+                     .arg(proxy.port());
+    qDebug() << proxyDesc;
+}
+
+QString Env::getJarsPath()
+{
+    if(d->m_jarsPath.isEmpty())
+    {
+        return FS::PathCombine(QCoreApplication::applicationDirPath(), "jars");
+    }
+    return d->m_jarsPath;
+}
+
+void Env::setJarsPath(const QString& path)
+{
+    d->m_jarsPath = path;
+}
+
+void Env::enableFeature(const QString& featureName, bool state)
+{
+    if(state)
+    {
+        d->m_features.insert(featureName);
+    }
+    else
+    {
+        d->m_features.remove(featureName);
+    }
+}
+
+bool Env::isFeatureEnabled(const QString& featureName) const
+{
+    return d->m_features.contains(featureName);
+}
+
+void Env::getEnabledFeatures(QSet<QString>& features) const
+{
+    features = d->m_features;
+}
+
+void Env::setEnabledFeatures(const QSet<QString>& features) const
+{
+    d->m_features = features;
+}

launcher/Env.h

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <memory>
+#include "icons/IIconList.h"
+#include <QString>
+#include <QMap>
+
+#include "QObjectPtr.h"
+
+class QNetworkAccessManager;
+class HttpMetaCache;
+class BaseVersionList;
+class BaseVersion;
+
+namespace Meta
+{
+class Index;
+}
+
+#if defined(ENV)
+    #undef ENV
+#endif
+#define ENV (Env::getInstance())
+
+
+class Env
+{
+    friend class MultiMC;
+private:
+    struct Private;
+    Env();
+    ~Env();
+    static void dispose();
+public:
+    static Env& getInstance();
+
+    QNetworkAccessManager &qnam() const;
+
+    shared_qobject_ptr<HttpMetaCache> metacache();
+
+    std::shared_ptr<IIconList> icons();
+
+    /// init the cache. FIXME: possible future hook point
+    void initHttpMetaCache();
+
+    /// Updates the application proxy settings from the settings object.
+    void updateProxySettings(QString proxyTypeStr, QString addr, int port, QString user, QString password);
+
+    void registerIconList(std::shared_ptr<IIconList> iconlist);
+
+    shared_qobject_ptr<Meta::Index> metadataIndex();
+
+    QString getJarsPath();
+    void setJarsPath(const QString & path);
+
+    bool isFeatureEnabled(const QString & featureName) const;
+    void enableFeature(const QString & featureName, bool state = true);
+    void getEnabledFeatures(QSet<QString> & features) const;
+    void setEnabledFeatures(const QSet<QString> & features) const;
+
+protected:
+    Private * d;
+};

launcher/Exception.h

@@ -0,0 +1,32 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QString>
+#include <QDebug>
+#include <exception>
+
+class Exception : public std::exception
+{
+public:
+    Exception(const QString &message) : std::exception(), m_message(message)
+    {
+        qCritical() << "Exception:" << message;
+    }
+    Exception(const Exception &other)
+        : std::exception(), m_message(other.cause())
+    {
+    }
+    virtual ~Exception() noexcept {}
+    const char *what() const noexcept
+    {
+        return m_message.toLatin1().constData();
+    }
+    QString cause() const
+    {
+        return m_message;
+    }
+
+private:
+    QString m_message;
+};

launcher/ExponentialSeries.h

@@ -0,0 +1,43 @@
+
+#pragma once
+
+template <typename T>
+inline void clamp(T& current, T min, T max)
+{
+    if (current < min)
+    {
+        current = min;
+    }
+    else if(current > max)
+    {
+        current = max;
+    }
+}
+
+// List of numbers from min to max. Next is exponent times bigger than previous.
+
+class ExponentialSeries
+{
+public:
+    ExponentialSeries(unsigned min, unsigned max, unsigned exponent = 2)
+    {
+        m_current = m_min = min;
+        m_max = max;
+        m_exponent = exponent;
+    }
+    void reset()
+    {
+        m_current = m_min;
+    }
+    unsigned operator()()
+    {
+        unsigned retval = m_current;
+        m_current *= m_exponent;
+        clamp(m_current, m_min, m_max);
+        return retval;
+    }
+    unsigned m_current;
+    unsigned m_min;
+    unsigned m_max;
+    unsigned m_exponent;
+};

launcher/FileSystem.cpp

@@ -0,0 +1,457 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "FileSystem.h"
+
+#include <QDir>
+#include <QFile>
+#include <QSaveFile>
+#include <QFileInfo>
+#include <QDebug>
+#include <QUrl>
+#include <QStandardPaths>
+#include <QTextStream>
+
+#if defined Q_OS_WIN32
+    #include <windows.h>
+    #include <string>
+    #include <sys/utime.h>
+    #include <winnls.h>
+    #include <shobjidl.h>
+    #include <objbase.h>
+    #include <objidl.h>
+    #include <shlguid.h>
+    #include <shlobj.h>
+#else
+    #include <utime.h>
+#endif
+
+namespace FS {
+
+void ensureExists(const QDir &dir)
+{
+    if (!QDir().mkpath(dir.absolutePath()))
+    {
+        throw FileSystemException("Unable to create folder " + dir.dirName() + " (" +
+                                      dir.absolutePath() + ")");
+    }
+}
+
+void write(const QString &filename, const QByteArray &data)
+{
+    ensureExists(QFileInfo(filename).dir());
+    QSaveFile file(filename);
+    if (!file.open(QSaveFile::WriteOnly))
+    {
+        throw FileSystemException("Couldn't open " + filename + " for writing: " +
+                                  file.errorString());
+    }
+    if (data.size() != file.write(data))
+    {
+        throw FileSystemException("Error writing data to " + filename + ": " +
+                                  file.errorString());
+    }
+    if (!file.commit())
+    {
+        throw FileSystemException("Error while committing data to " + filename + ": " +
+                                  file.errorString());
+    }
+}
+
+QByteArray read(const QString &filename)
+{
+    QFile file(filename);
+    if (!file.open(QFile::ReadOnly))
+    {
+        throw FileSystemException("Unable to open " + filename + " for reading: " +
+                                  file.errorString());
+    }
+    const qint64 size = file.size();
+    QByteArray data(int(size), 0);
+    const qint64 ret = file.read(data.data(), size);
+    if (ret == -1 || ret != size)
+    {
+        throw FileSystemException("Error reading data from " + filename + ": " +
+                                  file.errorString());
+    }
+    return data;
+}
+
+bool updateTimestamp(const QString& filename)
+{
+#ifdef Q_OS_WIN32
+    std::wstring filename_utf_16 = filename.toStdWString();
+    return (_wutime64(filename_utf_16.c_str(), nullptr) == 0);
+#else
+    QByteArray filenameBA = QFile::encodeName(filename);
+    return (utime(filenameBA.data(), nullptr) == 0);
+#endif
+}
+
+bool ensureFilePathExists(QString filenamepath)
+{
+    QFileInfo a(filenamepath);
+    QDir dir;
+    QString ensuredPath = a.path();
+    bool success = dir.mkpath(ensuredPath);
+    return success;
+}
+
+bool ensureFolderPathExists(QString foldernamepath)
+{
+    QFileInfo a(foldernamepath);
+    QDir dir;
+    QString ensuredPath = a.filePath();
+    bool success = dir.mkpath(ensuredPath);
+    return success;
+}
+
+bool copy::operator()(const QString &offset)
+{
+    //NOTE always deep copy on windows. the alternatives are too messy.
+    #if defined Q_OS_WIN32
+    m_followSymlinks = true;
+    #endif
+
+    auto src = PathCombine(m_src.absolutePath(), offset);
+    auto dst = PathCombine(m_dst.absolutePath(), offset);
+
+    QFileInfo currentSrc(src);
+    if (!currentSrc.exists())
+        return false;
+
+    if(!m_followSymlinks && currentSrc.isSymLink())
+    {
+        qDebug() << "creating symlink" << src << " - " << dst;
+        if (!ensureFilePathExists(dst))
+        {
+            qWarning() << "Cannot create path!";
+            return false;
+        }
+        return QFile::link(currentSrc.symLinkTarget(), dst);
+    }
+    else if(currentSrc.isFile())
+    {
+        qDebug() << "copying file" << src << " - " << dst;
+        if (!ensureFilePathExists(dst))
+        {
+            qWarning() << "Cannot create path!";
+            return false;
+        }
+        return QFile::copy(src, dst);
+    }
+    else if(currentSrc.isDir())
+    {
+        qDebug() << "recursing" << offset;
+        if (!ensureFolderPathExists(dst))
+        {
+            qWarning() << "Cannot create path!";
+            return false;
+        }
+        QDir currentDir(src);
+        for(auto & f : currentDir.entryList(QDir::Files | QDir::Dirs | QDir::NoDotAndDotDot | QDir::Hidden | QDir::System))
+        {
+            auto inner_offset = PathCombine(offset, f);
+            // ignore and skip stuff that matches the blacklist.
+            if(m_blacklist && m_blacklist->matches(inner_offset))
+            {
+                continue;
+            }
+            if(!operator()(inner_offset))
+            {
+                qWarning() << "Failed to copy" << inner_offset;
+                return false;
+            }
+        }
+    }
+    else
+    {
+        qCritical() << "Copy ERROR: Unknown filesystem object:" << src;
+        return false;
+    }
+    return true;
+}
+
+bool deletePath(QString path)
+{
+    bool OK = true;
+    QFileInfo finfo(path);
+    if(finfo.isFile()) {
+        return QFile::remove(path);
+    }
+
+    QDir dir(path);
+
+    if (!dir.exists())
+    {
+        return OK;
+    }
+    auto allEntries = dir.entryInfoList(QDir::NoDotAndDotDot | QDir::System | QDir::Hidden |
+                                        QDir::AllDirs | QDir::Files,
+                                        QDir::DirsFirst);
+
+    for(auto & info: allEntries)
+    {
+#if defined Q_OS_WIN32
+        QString nativePath = QDir::toNativeSeparators(info.absoluteFilePath());
+        auto wString = nativePath.toStdWString();
+        DWORD dwAttrs = GetFileAttributesW(wString.c_str());
+        // Windows: check for junctions, reparse points and other nasty things of that sort
+        if(dwAttrs & FILE_ATTRIBUTE_REPARSE_POINT)
+        {
+            if (info.isFile())
+            {
+                OK &= QFile::remove(info.absoluteFilePath());
+            }
+            else if (info.isDir())
+            {
+                OK &= dir.rmdir(info.absoluteFilePath());
+            }
+        }
+#else
+        // We do not trust Qt with reparse points, but do trust it with unix symlinks.
+        if(info.isSymLink())
+        {
+            OK &= QFile::remove(info.absoluteFilePath());
+        }
+#endif
+        else if (info.isDir())
+        {
+            OK &= deletePath(info.absoluteFilePath());
+        }
+        else if (info.isFile())
+        {
+            OK &= QFile::remove(info.absoluteFilePath());
+        }
+        else
+        {
+            OK = false;
+            qCritical() << "Delete ERROR: Unknown filesystem object:" << info.absoluteFilePath();
+        }
+    }
+    OK &= dir.rmdir(dir.absolutePath());
+    return OK;
+}
+
+
+QString PathCombine(const QString & path1, const QString & path2)
+{
+    if(!path1.size())
+        return path2;
+    if(!path2.size())
+        return path1;
+    return QDir::cleanPath(path1 + QDir::separator() + path2);
+}
+
+QString PathCombine(const QString & path1, const QString & path2, const QString & path3)
+{
+    return PathCombine(PathCombine(path1, path2), path3);
+}
+
+QString PathCombine(const QString & path1, const QString & path2, const QString & path3, const QString & path4)
+{
+    return PathCombine(PathCombine(path1, path2, path3), path4);
+}
+
+QString AbsolutePath(QString path)
+{
+    return QFileInfo(path).absolutePath();
+}
+
+QString ResolveExecutable(QString path)
+{
+    if (path.isEmpty())
+    {
+        return QString();
+    }
+    if(!path.contains('/'))
+    {
+        path = QStandardPaths::findExecutable(path);
+    }
+    QFileInfo pathInfo(path);
+    if(!pathInfo.exists() || !pathInfo.isExecutable())
+    {
+        return QString();
+    }
+    return pathInfo.absoluteFilePath();
+}
+
+/**
+ * Normalize path
+ *
+ * Any paths inside the current folder will be normalized to relative paths (to current)
+ * Other paths will be made absolute
+ */
+QString NormalizePath(QString path)
+{
+    QDir a = QDir::currentPath();
+    QString currentAbsolute = a.absolutePath();
+
+    QDir b(path);
+    QString newAbsolute = b.absolutePath();
+
+    if (newAbsolute.startsWith(currentAbsolute))
+    {
+        return a.relativeFilePath(newAbsolute);
+    }
+    else
+    {
+        return newAbsolute;
+    }
+}
+
+QString badFilenameChars = "\"\\/?<>:;*|!+\r\n";
+
+QString RemoveInvalidFilenameChars(QString string, QChar replaceWith)
+{
+    for (int i = 0; i < string.length(); i++)
+    {
+        if (badFilenameChars.contains(string[i]))
+        {
+            string[i] = replaceWith;
+        }
+    }
+    return string;
+}
+
+QString DirNameFromString(QString string, QString inDir)
+{
+    int num = 0;
+    QString baseName = RemoveInvalidFilenameChars(string, '-');
+    QString dirName;
+    do
+    {
+        if(num == 0)
+        {
+            dirName = baseName;
+        }
+        else
+        {
+            dirName = baseName + QString::number(num);;
+        }
+
+        // If it's over 9000
+        if (num > 9000)
+            return "";
+        num++;
+    } while (QFileInfo(PathCombine(inDir, dirName)).exists());
+    return dirName;
+}
+
+// Does the folder path contain any '!'? If yes, return true, otherwise false.
+// (This is a problem for Java)
+bool checkProblemticPathJava(QDir folder)
+{
+    QString pathfoldername = folder.absolutePath();
+    return pathfoldername.contains("!", Qt::CaseInsensitive);
+}
+
+// Win32 crap
+#if defined Q_OS_WIN
+
+bool called_coinit = false;
+
+HRESULT CreateLink(LPCSTR linkPath, LPCSTR targetPath, LPCSTR args)
+{
+    HRESULT hres;
+
+    if (!called_coinit)
+    {
+        hres = CoInitialize(NULL);
+        called_coinit = true;
+
+        if (!SUCCEEDED(hres))
+        {
+            qWarning("Failed to initialize COM. Error 0x%08lX", hres);
+            return hres;
+        }
+    }
+
+    IShellLink *link;
+    hres = CoCreateInstance(CLSID_ShellLink, NULL, CLSCTX_INPROC_SERVER, IID_IShellLink,
+                            (LPVOID *)&link);
+
+    if (SUCCEEDED(hres))
+    {
+        IPersistFile *persistFile;
+
+        link->SetPath(targetPath);
+        link->SetArguments(args);
+
+        hres = link->QueryInterface(IID_IPersistFile, (LPVOID *)&persistFile);
+        if (SUCCEEDED(hres))
+        {
+            WCHAR wstr[MAX_PATH];
+
+            MultiByteToWideChar(CP_ACP, 0, linkPath, -1, wstr, MAX_PATH);
+
+            hres = persistFile->Save(wstr, TRUE);
+            persistFile->Release();
+        }
+        link->Release();
+    }
+    return hres;
+}
+
+#endif
+
+QString getDesktopDir()
+{
+    return QStandardPaths::writableLocation(QStandardPaths::DesktopLocation);
+}
+
+// Cross-platform Shortcut creation
+bool createShortCut(QString location, QString dest, QStringList args, QString name,
+                          QString icon)
+{
+#if defined Q_OS_LINUX
+    location = PathCombine(location, name + ".desktop");
+
+    QFile f(location);
+    f.open(QIODevice::WriteOnly | QIODevice::Text);
+    QTextStream stream(&f);
+
+    QString argstring;
+    if (!args.empty())
+        argstring = " '" + args.join("' '") + "'";
+
+    stream << "[Desktop Entry]"
+           << "\n";
+    stream << "Type=Application"
+           << "\n";
+    stream << "TryExec=" << dest.toLocal8Bit() << "\n";
+    stream << "Exec=" << dest.toLocal8Bit() << argstring.toLocal8Bit() << "\n";
+    stream << "Name=" << name.toLocal8Bit() << "\n";
+    stream << "Icon=" << icon.toLocal8Bit() << "\n";
+
+    stream.flush();
+    f.close();
+
+    f.setPermissions(f.permissions() | QFileDevice::ExeOwner | QFileDevice::ExeGroup |
+                     QFileDevice::ExeOther);
+
+    return true;
+#elif defined Q_OS_WIN
+    // TODO: Fix
+    //    QFile file(PathCombine(location, name + ".lnk"));
+    //    WCHAR *file_w;
+    //    WCHAR *dest_w;
+    //    WCHAR *args_w;
+    //    file.fileName().toWCharArray(file_w);
+    //    dest.toWCharArray(dest_w);
+
+    //    QString argStr;
+    //    for (int i = 0; i < args.count(); i++)
+    //    {
+    //        argStr.append(args[i]);
+    //        argStr.append(" ");
+    //    }
+    //    argStr.toWCharArray(args_w);
+
+    //    return SUCCEEDED(CreateLink(file_w, dest_w, args_w));
+    return false;
+#else
+    qWarning("Desktop Shortcuts not supported on your platform!");
+    return false;
+#endif
+}
+}

launcher/FileSystem.h

@@ -0,0 +1,127 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include "Exception.h"
+#include "pathmatcher/IPathMatcher.h"
+
+#include <QDir>
+#include <QFlags>
+
+namespace FS
+{
+
+class FileSystemException : public ::Exception
+{
+public:
+    FileSystemException(const QString &message) : Exception(message) {}
+};
+
+/**
+ * write data to a file safely
+ */
+void write(const QString &filename, const QByteArray &data);
+
+/**
+ * read data from a file safely\
+ */
+QByteArray read(const QString &filename);
+
+/**
+ * Update the last changed timestamp of an existing file
+ */
+bool updateTimestamp(const QString & filename);
+
+/**
+ * Creates all the folders in a path for the specified path
+ * last segment of the path is treated as a file name and is ignored!
+ */
+bool ensureFilePathExists(QString filenamepath);
+
+/**
+ * Creates all the folders in a path for the specified path
+ * last segment of the path is treated as a folder name and is created!
+ */
+bool ensureFolderPathExists(QString filenamepath);
+
+class copy
+{
+public:
+    copy(const QString & src, const QString & dst)
+    {
+        m_src = src;
+        m_dst = dst;
+    }
+    copy & followSymlinks(const bool follow)
+    {
+        m_followSymlinks = follow;
+        return *this;
+    }
+    copy & blacklist(const IPathMatcher * filter)
+    {
+        m_blacklist = filter;
+        return *this;
+    }
+    bool operator()()
+    {
+        return operator()(QString());
+    }
+
+private:
+    bool operator()(const QString &offset);
+
+private:
+    bool m_followSymlinks = true;
+    const IPathMatcher * m_blacklist = nullptr;
+    QDir m_src;
+    QDir m_dst;
+};
+
+/**
+ * Delete a folder recursively
+ */
+bool deletePath(QString path);
+
+QString PathCombine(const QString &path1, const QString &path2);
+QString PathCombine(const QString &path1, const QString &path2, const QString &path3);
+QString PathCombine(const QString &path1, const QString &path2, const QString &path3, const QString &path4);
+
+QString AbsolutePath(QString path);
+
+/**
+ * Resolve an executable
+ *
+ * Will resolve:
+ *   single executable (by name)
+ *   relative path
+ *   absolute path
+ *
+ * @return absolute path to executable or null string
+ */
+QString ResolveExecutable(QString path);
+
+/**
+ * Normalize path
+ *
+ * Any paths inside the current directory will be normalized to relative paths (to current)
+ * Other paths will be made absolute
+ *
+ * Returns false if the path logic somehow filed (and normalizedPath in invalid)
+ */
+QString NormalizePath(QString path);
+
+QString RemoveInvalidFilenameChars(QString string, QChar replaceWith = '-');
+
+QString DirNameFromString(QString string, QString inDir = ".");
+
+/// Checks if the a given Path contains "!"
+bool checkProblemticPathJava(QDir folder);
+
+// Get the Directory representing the User's Desktop
+QString getDesktopDir();
+
+// Create a shortcut at *location*, pointing to *dest* called with the arguments *args*
+// call it *name* and assign it the icon *icon*
+// return true if operation succeeded
+bool createShortCut(QString location, QString dest, QStringList args, QString name, QString iconLocation);
+}

launcher/FileSystem_test.cpp

@@ -0,0 +1,164 @@
+#include <QTest>
+#include <QTemporaryDir>
+#include <QStandardPaths>
+#include "TestUtil.h"
+
+#include "FileSystem.h"
+
+class FileSystemTest : public QObject
+{
+    Q_OBJECT
+
+    const QString bothSlash = "/foo/";
+    const QString trailingSlash = "foo/";
+    const QString leadingSlash = "/foo";
+
+private
+slots:
+    void test_pathCombine()
+    {
+        QCOMPARE(QString("/foo/foo"), FS::PathCombine(bothSlash, bothSlash));
+        QCOMPARE(QString("foo/foo"), FS::PathCombine(trailingSlash, trailingSlash));
+        QCOMPARE(QString("/foo/foo"), FS::PathCombine(leadingSlash, leadingSlash));
+
+        QCOMPARE(QString("/foo/foo/foo"), FS::PathCombine(bothSlash, bothSlash, bothSlash));
+        QCOMPARE(QString("foo/foo/foo"), FS::PathCombine(trailingSlash, trailingSlash, trailingSlash));
+        QCOMPARE(QString("/foo/foo/foo"), FS::PathCombine(leadingSlash, leadingSlash, leadingSlash));
+    }
+
+    void test_PathCombine1_data()
+    {
+        QTest::addColumn<QString>("result");
+        QTest::addColumn<QString>("path1");
+        QTest::addColumn<QString>("path2");
+
+        QTest::newRow("qt 1") << "/abc/def/ghi/jkl" << "/abc/def" << "ghi/jkl";
+        QTest::newRow("qt 2") << "/abc/def/ghi/jkl" << "/abc/def/" << "ghi/jkl";
+#if defined(Q_OS_WIN)
+        QTest::newRow("win native, from C:") << "C:/abc" << "C:" << "abc";
+        QTest::newRow("win native 1") << "C:/abc/def/ghi/jkl" << "C:\\abc\\def" << "ghi\\jkl";
+        QTest::newRow("win native 2") << "C:/abc/def/ghi/jkl" << "C:\\abc\\def\\" << "ghi\\jkl";
+#endif
+    }
+
+    void test_PathCombine1()
+    {
+        QFETCH(QString, result);
+        QFETCH(QString, path1);
+        QFETCH(QString, path2);
+
+        QCOMPARE(FS::PathCombine(path1, path2), result);
+    }
+
+    void test_PathCombine2_data()
+    {
+        QTest::addColumn<QString>("result");
+        QTest::addColumn<QString>("path1");
+        QTest::addColumn<QString>("path2");
+        QTest::addColumn<QString>("path3");
+
+        QTest::newRow("qt 1") << "/abc/def/ghi/jkl" << "/abc" << "def" << "ghi/jkl";
+        QTest::newRow("qt 2") << "/abc/def/ghi/jkl" << "/abc/" << "def" << "ghi/jkl";
+        QTest::newRow("qt 3") << "/abc/def/ghi/jkl" << "/abc" << "def/" << "ghi/jkl";
+        QTest::newRow("qt 4") << "/abc/def/ghi/jkl" << "/abc/" << "def/" << "ghi/jkl";
+#if defined(Q_OS_WIN)
+        QTest::newRow("win 1") << "C:/abc/def/ghi/jkl" << "C:\\abc" << "def" << "ghi\\jkl";
+        QTest::newRow("win 2") << "C:/abc/def/ghi/jkl" << "C:\\abc\\" << "def" << "ghi\\jkl";
+        QTest::newRow("win 3") << "C:/abc/def/ghi/jkl" << "C:\\abc" << "def\\" << "ghi\\jkl";
+        QTest::newRow("win 4") << "C:/abc/def/ghi/jkl" << "C:\\abc\\" << "def" << "ghi\\jkl";
+#endif
+    }
+
+    void test_PathCombine2()
+    {
+        QFETCH(QString, result);
+        QFETCH(QString, path1);
+        QFETCH(QString, path2);
+        QFETCH(QString, path3);
+
+        QCOMPARE(FS::PathCombine(path1, path2, path3), result);
+    }
+
+    void test_copy()
+    {
+        QString folder = QFINDTESTDATA("data/test_folder");
+        auto f = [&folder]()
+        {
+            QTemporaryDir tempDir;
+            tempDir.setAutoRemove(true);
+            qDebug() << "From:" << folder << "To:" << tempDir.path();
+
+            QDir target_dir(FS::PathCombine(tempDir.path(), "test_folder"));
+            qDebug() << tempDir.path();
+            qDebug() << target_dir.path();
+            FS::copy c(folder, target_dir.path());
+            c();
+
+            for(auto entry: target_dir.entryList())
+            {
+                qDebug() << entry;
+            }
+            QVERIFY(target_dir.entryList().contains("pack.mcmeta"));
+            QVERIFY(target_dir.entryList().contains("assets"));
+        };
+
+        // first try variant without trailing /
+        QVERIFY(!folder.endsWith('/'));
+        f();
+
+        // then variant with trailing /
+        folder.append('/');
+        QVERIFY(folder.endsWith('/'));
+        f();
+    }
+
+    void test_getDesktop()
+    {
+        QCOMPARE(FS::getDesktopDir(), QStandardPaths::writableLocation(QStandardPaths::DesktopLocation));
+    }
+
+// this is only valid on linux
+// FIXME: implement on windows, OSX, then test.
+#if defined(Q_OS_LINUX)
+    void test_createShortcut_data()
+    {
+        QTest::addColumn<QString>("location");
+        QTest::addColumn<QString>("dest");
+        QTest::addColumn<QStringList>("args");
+        QTest::addColumn<QString>("name");
+        QTest::addColumn<QString>("iconLocation");
+        QTest::addColumn<QByteArray>("result");
+
+        QTest::newRow("unix") << QDir::currentPath()
+                              << "asdfDest"
+                              << (QStringList() << "arg1" << "arg2")
+                              << "asdf"
+                              << QString()
+                         #if defined(Q_OS_LINUX)
+                              << MULTIMC_GET_TEST_FILE("data/FileSystem-test_createShortcut-unix")
+                         #elif defined(Q_OS_WIN)
+                              << QByteArray()
+                         #endif
+                                 ;
+    }
+
+    void test_createShortcut()
+    {
+        QFETCH(QString, location);
+        QFETCH(QString, dest);
+        QFETCH(QStringList, args);
+        QFETCH(QString, name);
+        QFETCH(QString, iconLocation);
+        QFETCH(QByteArray, result);
+
+        QVERIFY(FS::createShortCut(location, dest, args, name, iconLocation));
+        QCOMPARE(QString::fromLocal8Bit(TestsInternal::readFile(location + QDir::separator() + name + ".desktop")), QString::fromLocal8Bit(result));
+
+        //QDir().remove(location);
+    }
+#endif
+};
+
+QTEST_GUILESS_MAIN(FileSystemTest)
+
+#include "FileSystem_test.moc"

launcher/Filter.cpp

@@ -0,0 +1,31 @@
+#include "Filter.h"
+
+Filter::~Filter(){}
+
+ContainsFilter::ContainsFilter(const QString& pattern) : pattern(pattern){}
+ContainsFilter::~ContainsFilter(){}
+bool ContainsFilter::accepts(const QString& value)
+{
+    return value.contains(pattern);
+}
+
+ExactFilter::ExactFilter(const QString& pattern) : pattern(pattern){}
+ExactFilter::~ExactFilter(){}
+bool ExactFilter::accepts(const QString& value)
+{
+    return value == pattern;
+}
+
+RegexpFilter::RegexpFilter(const QString& regexp, bool invert)
+    :invert(invert)
+{
+    pattern.setPattern(regexp);
+    pattern.optimize();
+}
+RegexpFilter::~RegexpFilter(){}
+bool RegexpFilter::accepts(const QString& value)
+{
+    auto match = pattern.match(value);
+    bool matched = match.hasMatch();
+    return invert ? (!matched) : (matched);
+}

launcher/Filter.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <QString>
+#include <QRegularExpression>
+
+class Filter
+{
+public:
+    virtual ~Filter();
+    virtual bool accepts(const QString & value) = 0;
+};
+
+class ContainsFilter: public Filter
+{
+public:
+    ContainsFilter(const QString &pattern);
+    virtual ~ContainsFilter();
+    bool accepts(const QString & value) override;
+private:
+    QString pattern;
+};
+
+class ExactFilter: public Filter
+{
+public:
+    ExactFilter(const QString &pattern);
+    virtual ~ExactFilter();
+    bool accepts(const QString & value) override;
+private:
+    QString pattern;
+};
+
+class RegexpFilter: public Filter
+{
+public:
+    RegexpFilter(const QString &regexp, bool invert);
+    virtual ~RegexpFilter();
+    bool accepts(const QString & value) override;
+private:
+    QRegularExpression pattern;
+    bool invert = false;
+};

launcher/GZip.cpp

@@ -0,0 +1,115 @@
+#include "GZip.h"
+#include <zlib.h>
+#include <QByteArray>
+
+bool GZip::unzip(const QByteArray &compressedBytes, QByteArray &uncompressedBytes)
+{
+    if (compressedBytes.size() == 0)
+    {
+        uncompressedBytes = compressedBytes;
+        return true;
+    }
+
+    unsigned uncompLength = compressedBytes.size();
+    uncompressedBytes.clear();
+    uncompressedBytes.resize(uncompLength);
+
+    z_stream strm;
+    memset(&strm, 0, sizeof(strm));
+    strm.next_in = (Bytef *)compressedBytes.data();
+    strm.avail_in = compressedBytes.size();
+
+    bool done = false;
+
+    if (inflateInit2(&strm, (16 + MAX_WBITS)) != Z_OK)
+    {
+        return false;
+    }
+
+    int err = Z_OK;
+
+    while (!done)
+    {
+        // If our output buffer is too small
+        if (strm.total_out >= uncompLength)
+        {
+            uncompressedBytes.resize(uncompLength * 2);
+            uncompLength *= 2;
+        }
+
+        strm.next_out = (Bytef *)(uncompressedBytes.data() + strm.total_out);
+        strm.avail_out = uncompLength - strm.total_out;
+
+        // Inflate another chunk.
+        err = inflate(&strm, Z_SYNC_FLUSH);
+        if (err == Z_STREAM_END)
+            done = true;
+        else if (err != Z_OK)
+        {
+            break;
+        }
+    }
+
+    if (inflateEnd(&strm) != Z_OK || !done)
+    {
+        return false;
+    }
+
+    uncompressedBytes.resize(strm.total_out);
+    return true;
+}
+
+bool GZip::zip(const QByteArray &uncompressedBytes, QByteArray &compressedBytes)
+{
+    if (uncompressedBytes.size() == 0)
+    {
+        compressedBytes = uncompressedBytes;
+        return true;
+    }
+
+    unsigned compLength = std::min(uncompressedBytes.size(), 16);
+    compressedBytes.clear();
+    compressedBytes.resize(compLength);
+
+    z_stream zs;
+    memset(&zs, 0, sizeof(zs));
+
+    if (deflateInit2(&zs, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (16 + MAX_WBITS), 8, Z_DEFAULT_STRATEGY) != Z_OK)
+    {
+        return false;
+    }
+
+    zs.next_in = (Bytef*)uncompressedBytes.data();
+    zs.avail_in = uncompressedBytes.size();
+
+    int ret;
+    compressedBytes.resize(uncompressedBytes.size());
+
+    unsigned offset = 0;
+    unsigned temp = 0;
+    do
+    {
+        auto remaining = compressedBytes.size() - offset;
+        if(remaining < 1)
+        {
+            compressedBytes.resize(compressedBytes.size() * 2);
+        }
+        zs.next_out = (Bytef *) (compressedBytes.data() + offset);
+        temp = zs.avail_out = compressedBytes.size() - offset;
+        ret = deflate(&zs, Z_FINISH);
+        offset += temp - zs.avail_out;
+    } while (ret == Z_OK);
+
+    compressedBytes.resize(offset);
+
+    if (deflateEnd(&zs) != Z_OK)
+    {
+        return false;
+    }
+
+    if (ret != Z_STREAM_END)
+    {
+        return false;
+    }
+    return true;
+}

launcher/GZip.h

@@ -0,0 +1,10 @@
+#pragma once
+#include <QByteArray>
+
+class GZip
+{
+public:
+    static bool unzip(const QByteArray &compressedBytes, QByteArray &uncompressedBytes);
+    static bool zip(const QByteArray &uncompressedBytes, QByteArray &compressedBytes);
+};
+

launcher/GZip_test.cpp

@@ -0,0 +1,57 @@
+#include <QTest>
+#include "TestUtil.h"
+
+#include "GZip.h"
+#include <random>
+
+void fib(int &prev, int &cur)
+{
+    auto ret = prev + cur;
+    prev = cur;
+    cur = ret;
+}
+
+class GZipTest : public QObject
+{
+    Q_OBJECT
+private
+slots:
+
+    void test_Through()
+    {
+        // test up to 10 MB
+        static const int size = 10 * 1024 * 1024;
+        QByteArray random;
+        QByteArray compressed;
+        QByteArray decompressed;
+        std::default_random_engine eng((std::random_device())());
+        std::uniform_int_distribution<uint8_t> idis(0, std::numeric_limits<uint8_t>::max());
+
+        // initialize random buffer
+        for(int i = 0; i < size; i++)
+        {
+            random.append((char)idis(eng));
+        }
+
+        // initialize fibonacci
+        int prev = 1;
+        int cur = 1;
+
+        // test if fibonacci long random buffers pass through GZip
+        do
+        {
+            QByteArray copy = random;
+            copy.resize(cur);
+            compressed.clear();
+            decompressed.clear();
+            QVERIFY(GZip::zip(copy, compressed));
+            QVERIFY(GZip::unzip(compressed, decompressed));
+            QCOMPARE(decompressed, copy);
+            fib(prev, cur);
+        } while (cur < size);
+    }
+};
+
+QTEST_GUILESS_MAIN(GZipTest)
+
+#include "GZip_test.moc"

launcher/GuiUtil.cpp

@@ -0,0 +1,131 @@
+#include "GuiUtil.h"
+
+#include <QClipboard>
+#include <QApplication>
+#include <QFileDialog>
+
+#include "dialogs/ProgressDialog.h"
+#include "net/PasteUpload.h"
+#include "dialogs/CustomMessageBox.h"
+
+#include "MultiMC.h"
+#include <settings/SettingsObject.h>
+#include <DesktopServices.h>
+#include <BuildConfig.h>
+
+QString GuiUtil::uploadPaste(const QString &text, QWidget *parentWidget)
+{
+    ProgressDialog dialog(parentWidget);
+    auto APIKeySetting = MMC->settings()->get("PasteEEAPIKey").toString();
+    if(APIKeySetting == "multimc")
+    {
+        APIKeySetting = BuildConfig.PASTE_EE_KEY;
+    }
+    std::unique_ptr<PasteUpload> paste(new PasteUpload(parentWidget, text, APIKeySetting));
+
+    if (!paste->validateText())
+    {
+        CustomMessageBox::selectable(
+            parentWidget, QObject::tr("Upload failed"),
+            QObject::tr("The log file is too big. You'll have to upload it manually."),
+            QMessageBox::Warning)->exec();
+        return QString();
+    }
+
+    dialog.execWithTask(paste.get());
+    if (!paste->wasSuccessful())
+    {
+        CustomMessageBox::selectable(parentWidget, QObject::tr("Upload failed"),
+                                     paste->failReason(), QMessageBox::Critical)->exec();
+        return QString();
+    }
+    else
+    {
+        const QString link = paste->pasteLink();
+        setClipboardText(link);
+        CustomMessageBox::selectable(
+            parentWidget, QObject::tr("Upload finished"),
+            QObject::tr("The <a href=\"%1\">link to the uploaded log</a> has been placed in your clipboard.").arg(link),
+            QMessageBox::Information)->exec();
+        return link;
+    }
+}
+
+void GuiUtil::setClipboardText(const QString &text)
+{
+    QApplication::clipboard()->setText(text);
+}
+
+static QStringList BrowseForFileInternal(QString context, QString caption, QString filter, QString defaultPath, QWidget *parentWidget, bool single)
+{
+    static QMap<QString, QString> savedPaths;
+
+    QFileDialog w(parentWidget, caption);
+    QSet<QString> locations;
+    auto f = [&](QStandardPaths::StandardLocation l)
+    {
+        QString location = QStandardPaths::writableLocation(l);
+        QFileInfo finfo(location);
+        if (!finfo.exists())
+            return;
+        locations.insert(location);
+    };
+    f(QStandardPaths::DesktopLocation);
+    f(QStandardPaths::DocumentsLocation);
+    f(QStandardPaths::DownloadLocation);
+    f(QStandardPaths::HomeLocation);
+    QList<QUrl> urls;
+    for (auto location : locations)
+    {
+        urls.append(QUrl::fromLocalFile(location));
+    }
+    urls.append(QUrl::fromLocalFile(defaultPath));
+
+    w.setFileMode(single ? QFileDialog::ExistingFile : QFileDialog::ExistingFiles);
+    w.setAcceptMode(QFileDialog::AcceptOpen);
+    w.setNameFilter(filter);
+
+    QString pathToOpen;
+    if(savedPaths.contains(context))
+    {
+        pathToOpen = savedPaths[context];
+    }
+    else
+    {
+        pathToOpen = defaultPath;
+    }
+    if(!pathToOpen.isEmpty())
+    {
+        QFileInfo finfo(pathToOpen);
+        if(finfo.exists() && finfo.isDir())
+        {
+            w.setDirectory(finfo.absoluteFilePath());
+        }
+    }
+
+    w.setSidebarUrls(urls);
+
+    if (w.exec())
+    {
+        savedPaths[context] = w.directory().absolutePath();
+        return w.selectedFiles();
+    }
+    savedPaths[context] = w.directory().absolutePath();
+    return {};
+}
+
+QString GuiUtil::BrowseForFile(QString context, QString caption, QString filter, QString defaultPath, QWidget *parentWidget)
+{
+    auto resultList = BrowseForFileInternal(context, caption, filter, defaultPath, parentWidget, true);
+    if(resultList.size())
+    {
+        return resultList[0];
+    }
+    return QString();
+}
+
+
+QStringList GuiUtil::BrowseForFiles(QString context, QString caption, QString filter, QString defaultPath, QWidget *parentWidget)
+{
+    return BrowseForFileInternal(context, caption, filter, defaultPath, parentWidget, false);
+}

launcher/GuiUtil.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <QWidget>
+
+namespace GuiUtil
+{
+QString uploadPaste(const QString &text, QWidget *parentWidget);
+void setClipboardText(const QString &text);
+QStringList BrowseForFiles(QString context, QString caption, QString filter, QString defaultPath, QWidget *parentWidget);
+QString BrowseForFile(QString context, QString caption, QString filter, QString defaultPath, QWidget *parentWidget);
+}

launcher/HoeDown.h

@@ -0,0 +1,76 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <hoedown/html.h>
+#include <hoedown/document.h>
+#include <QString>
+#include <QByteArray>
+
+/**
+ * hoedown wrapper, because dealing with resource lifetime in C is stupid
+ */
+class HoeDown
+{
+public:
+    class buffer
+    {
+    public:
+        buffer(size_t unit = 4096)
+        {
+            buf = hoedown_buffer_new(unit);
+        }
+        ~buffer()
+        {
+            hoedown_buffer_free(buf);
+        }
+        const char * cstr()
+        {
+            return hoedown_buffer_cstr(buf);
+        }
+        void put(QByteArray input)
+        {
+            hoedown_buffer_put(buf, (uint8_t *) input.data(), input.size());
+        }
+        const uint8_t * data() const
+        {
+            return buf->data;
+        }
+        size_t size() const
+        {
+            return buf->size;
+        }
+        hoedown_buffer * buf;
+    } ib, ob;
+    HoeDown()
+    {
+        renderer = hoedown_html_renderer_new((hoedown_html_flags) 0,0);
+        document = hoedown_document_new(renderer, (hoedown_extensions) 0, 8);
+    }
+    ~HoeDown()
+    {
+        hoedown_document_free(document);
+        hoedown_html_renderer_free(renderer);
+    }
+    QString process(QByteArray input)
+    {
+        ib.put(input);
+        hoedown_document_render(document, ob.buf, ib.data(), ib.size());
+        return ob.cstr();
+    }
+private:
+    hoedown_document * document;
+    hoedown_renderer * renderer;
+};

launcher/InstanceCopyTask.cpp

@@ -0,0 +1,60 @@
+#include "InstanceCopyTask.h"
+#include "settings/INISettingsObject.h"
+#include "FileSystem.h"
+#include "NullInstance.h"
+#include "pathmatcher/RegexpMatcher.h"
+#include <QtConcurrentRun>
+
+InstanceCopyTask::InstanceCopyTask(InstancePtr origInstance, bool copySaves, bool keepPlaytime)
+{
+    m_origInstance = origInstance;
+    m_keepPlaytime = keepPlaytime;
+
+    if(!copySaves)
+    {
+        // FIXME: get this from the original instance type...
+        auto matcherReal = new RegexpMatcher("[.]?minecraft/saves");
+        matcherReal->caseSensitive(false);
+        m_matcher.reset(matcherReal);
+    }
+}
+
+void InstanceCopyTask::executeTask()
+{
+    setStatus(tr("Copying instance %1").arg(m_origInstance->name()));
+
+    FS::copy folderCopy(m_origInstance->instanceRoot(), m_stagingPath);
+    folderCopy.followSymlinks(false).blacklist(m_matcher.get());
+
+    m_copyFuture = QtConcurrent::run(QThreadPool::globalInstance(), folderCopy);
+    connect(&m_copyFutureWatcher, &QFutureWatcher<bool>::finished, this, &InstanceCopyTask::copyFinished);
+    connect(&m_copyFutureWatcher, &QFutureWatcher<bool>::canceled, this, &InstanceCopyTask::copyAborted);
+    m_copyFutureWatcher.setFuture(m_copyFuture);
+}
+
+void InstanceCopyTask::copyFinished()
+{
+    auto successful = m_copyFuture.result();
+    if(!successful)
+    {
+        emitFailed(tr("Instance folder copy failed."));
+        return;
+    }
+    // FIXME: shouldn't this be able to report errors?
+    auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(m_stagingPath, "instance.cfg"));
+    instanceSettings->registerSetting("InstanceType", "Legacy");
+
+    InstancePtr inst(new NullInstance(m_globalSettings, instanceSettings, m_stagingPath));
+    inst->setName(m_instName);
+    inst->setIconKey(m_instIcon);
+    if(!m_keepPlaytime) {
+        inst->resetTimePlayed();
+    }
+    emitSucceeded();
+}
+
+void InstanceCopyTask::copyAborted()
+{
+    emitFailed(tr("Instance folder copy has been aborted."));
+    return;
+}

launcher/InstanceCopyTask.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include "tasks/Task.h"
+#include "net/NetJob.h"
+#include <QUrl>
+#include <QFuture>
+#include <QFutureWatcher>
+#include "settings/SettingsObject.h"
+#include "BaseVersion.h"
+#include "BaseInstance.h"
+#include "InstanceTask.h"
+
+class InstanceCopyTask : public InstanceTask
+{
+    Q_OBJECT
+public:
+    explicit InstanceCopyTask(InstancePtr origInstance, bool copySaves, bool keepPlaytime);
+
+protected:
+    //! Entry point for tasks.
+    virtual void executeTask() override;
+    void copyFinished();
+    void copyAborted();
+
+private: /* data */
+    InstancePtr m_origInstance;
+    QFuture<bool> m_copyFuture;
+    QFutureWatcher<bool> m_copyFutureWatcher;
+    std::unique_ptr<IPathMatcher> m_matcher;
+    bool m_keepPlaytime;
+};

launcher/InstanceCreationTask.cpp

@@ -0,0 +1,31 @@
+#include "InstanceCreationTask.h"
+#include "settings/INISettingsObject.h"
+#include "FileSystem.h"
+
+//FIXME: remove this
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/PackProfile.h"
+
+InstanceCreationTask::InstanceCreationTask(BaseVersionPtr version)
+{
+    m_version = version;
+}
+
+void InstanceCreationTask::executeTask()
+{
+    setStatus(tr("Creating instance from version %1").arg(m_version->name()));
+    {
+        auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(m_stagingPath, "instance.cfg"));
+        instanceSettings->suspendSave();
+        instanceSettings->registerSetting("InstanceType", "Legacy");
+        instanceSettings->set("InstanceType", "OneSix");
+        MinecraftInstance inst(m_globalSettings, instanceSettings, m_stagingPath);
+        auto components = inst.getPackProfile();
+        components->buildingFromScratch();
+        components->setComponentVersion("net.minecraft", m_version->descriptor(), true);
+        inst.setName(m_instName);
+        inst.setIconKey(m_instIcon);
+        instanceSettings->resumeSave();
+    }
+    emitSucceeded();
+}

launcher/InstanceCreationTask.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "tasks/Task.h"
+#include "net/NetJob.h"
+#include <QUrl>
+#include "settings/SettingsObject.h"
+#include "BaseVersion.h"
+#include "InstanceTask.h"
+
+class InstanceCreationTask : public InstanceTask
+{
+    Q_OBJECT
+public:
+    explicit InstanceCreationTask(BaseVersionPtr version);
+
+protected:
+    //! Entry point for tasks.
+    virtual void executeTask() override;
+
+private: /* data */
+    BaseVersionPtr m_version;
+};

launcher/InstanceImportTask.cpp

@@ -0,0 +1,456 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "InstanceImportTask.h"
+#include "BaseInstance.h"
+#include "FileSystem.h"
+#include "Env.h"
+#include "MMCZip.h"
+#include "NullInstance.h"
+#include "settings/INISettingsObject.h"
+#include "icons/IIconList.h"
+#include "icons/IconUtils.h"
+#include <QtConcurrentRun>
+
+// FIXME: this does not belong here, it's Minecraft/Flame specific
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/PackProfile.h"
+#include "modplatform/flame/FileResolvingTask.h"
+#include "modplatform/flame/PackManifest.h"
+#include "Json.h"
+#include <quazipdir.h>
+#include "modplatform/technic/TechnicPackProcessor.h"
+
+InstanceImportTask::InstanceImportTask(const QUrl sourceUrl)
+{
+    m_sourceUrl = sourceUrl;
+}
+
+void InstanceImportTask::executeTask()
+{
+    if (m_sourceUrl.isLocalFile())
+    {
+        m_archivePath = m_sourceUrl.toLocalFile();
+        processZipPack();
+    }
+    else
+    {
+        setStatus(tr("Downloading modpack:\n%1").arg(m_sourceUrl.toString()));
+        m_downloadRequired = true;
+
+        const QString path = m_sourceUrl.host() + '/' + m_sourceUrl.path();
+        auto entry = ENV.metacache()->resolveEntry("general", path);
+        entry->setStale(true);
+        m_filesNetJob.reset(new NetJob(tr("Modpack download")));
+        m_filesNetJob->addNetAction(Net::Download::makeCached(m_sourceUrl, entry));
+        m_archivePath = entry->getFullPath();
+        auto job = m_filesNetJob.get();
+        connect(job, &NetJob::succeeded, this, &InstanceImportTask::downloadSucceeded);
+        connect(job, &NetJob::progress, this, &InstanceImportTask::downloadProgressChanged);
+        connect(job, &NetJob::failed, this, &InstanceImportTask::downloadFailed);
+        m_filesNetJob->start();
+    }
+}
+
+void InstanceImportTask::downloadSucceeded()
+{
+    processZipPack();
+    m_filesNetJob.reset();
+}
+
+void InstanceImportTask::downloadFailed(QString reason)
+{
+    emitFailed(reason);
+    m_filesNetJob.reset();
+}
+
+void InstanceImportTask::downloadProgressChanged(qint64 current, qint64 total)
+{
+    setProgress(current / 2, total);
+}
+
+void InstanceImportTask::processZipPack()
+{
+    setStatus(tr("Extracting modpack"));
+    QDir extractDir(m_stagingPath);
+    qDebug() << "Attempting to create instance from" << m_archivePath;
+
+    // open the zip and find relevant files in it
+    m_packZip.reset(new QuaZip(m_archivePath));
+    if (!m_packZip->open(QuaZip::mdUnzip))
+    {
+        emitFailed(tr("Unable to open supplied modpack zip file."));
+        return;
+    }
+
+    QStringList blacklist = {"instance.cfg", "manifest.json"};
+    QString mmcFound = MMCZip::findFolderOfFileInZip(m_packZip.get(), "instance.cfg");
+    bool technicFound = QuaZipDir(m_packZip.get()).exists("/bin/modpack.jar") || QuaZipDir(m_packZip.get()).exists("/bin/version.json");
+    QString flameFound = MMCZip::findFolderOfFileInZip(m_packZip.get(), "manifest.json");
+    QString root;
+    if(!mmcFound.isNull())
+    {
+        // process as MultiMC instance/pack
+        qDebug() << "MultiMC:" << mmcFound;
+        root = mmcFound;
+        m_modpackType = ModpackType::MultiMC;
+    }
+    else if (technicFound)
+    {
+        // process as Technic pack
+        qDebug() << "Technic:" << technicFound;
+        extractDir.mkpath(".minecraft");
+        extractDir.cd(".minecraft");
+        m_modpackType = ModpackType::Technic;
+    }
+    else if(!flameFound.isNull())
+    {
+        // process as Flame pack
+        qDebug() << "Flame:" << flameFound;
+        root = flameFound;
+        m_modpackType = ModpackType::Flame;
+    }
+    if(m_modpackType == ModpackType::Unknown)
+    {
+        emitFailed(tr("Archive does not contain a recognized modpack type."));
+        return;
+    }
+
+    // make sure we extract just the pack
+    m_extractFuture = QtConcurrent::run(QThreadPool::globalInstance(), MMCZip::extractSubDir, m_packZip.get(), root, extractDir.absolutePath());
+    connect(&m_extractFutureWatcher, &QFutureWatcher<QStringList>::finished, this, &InstanceImportTask::extractFinished);
+    connect(&m_extractFutureWatcher, &QFutureWatcher<QStringList>::canceled, this, &InstanceImportTask::extractAborted);
+    m_extractFutureWatcher.setFuture(m_extractFuture);
+}
+
+void InstanceImportTask::extractFinished()
+{
+    m_packZip.reset();
+    if (!m_extractFuture.result())
+    {
+        emitFailed(tr("Failed to extract modpack"));
+        return;
+    }
+    QDir extractDir(m_stagingPath);
+
+    qDebug() << "Fixing permissions for extracted pack files...";
+    QDirIterator it(extractDir, QDirIterator::Subdirectories);
+    while (it.hasNext())
+    {
+        auto filepath = it.next();
+        QFileInfo file(filepath);
+        auto permissions = QFile::permissions(filepath);
+        auto origPermissions = permissions;
+        if(file.isDir())
+        {
+            // Folder +rwx for current user
+            permissions |= QFileDevice::Permission::ReadUser | QFileDevice::Permission::WriteUser | QFileDevice::Permission::ExeUser;
+        }
+        else
+        {
+            // File +rw for current user
+            permissions |= QFileDevice::Permission::ReadUser | QFileDevice::Permission::WriteUser;
+        }
+        if(origPermissions != permissions)
+        {
+            if(!QFile::setPermissions(filepath, permissions))
+            {
+                logWarning(tr("Could not fix permissions for %1").arg(filepath));
+            }
+            else
+            {
+                qDebug() << "Fixed" << filepath;
+            }
+        }
+    }
+
+    switch(m_modpackType)
+    {
+        case ModpackType::Flame:
+            processFlame();
+            return;
+        case ModpackType::MultiMC:
+            processMultiMC();
+            return;
+        case ModpackType::Technic:
+            processTechnic();
+            return;
+        case ModpackType::Unknown:
+            emitFailed(tr("Archive does not contain a recognized modpack type."));
+            return;
+    }
+}
+
+void InstanceImportTask::extractAborted()
+{
+    emitFailed(tr("Instance import has been aborted."));
+    return;
+}
+
+void InstanceImportTask::processFlame()
+{
+    const static QMap<QString,QString> forgemap = {
+        {"1.2.5", "3.4.9.171"},
+        {"1.4.2", "6.0.1.355"},
+        {"1.4.7", "6.6.2.534"},
+        {"1.5.2", "7.8.1.737"}
+    };
+    Flame::Manifest pack;
+    try
+    {
+        QString configPath = FS::PathCombine(m_stagingPath, "manifest.json");
+        Flame::loadManifest(pack, configPath);
+        QFile::remove(configPath);
+    }
+    catch (const JSONValidationError &e)
+    {
+        emitFailed(tr("Could not understand pack manifest:\n") + e.cause());
+        return;
+    }
+    if(!pack.overrides.isEmpty())
+    {
+        QString overridePath = FS::PathCombine(m_stagingPath, pack.overrides);
+        if (QFile::exists(overridePath))
+        {
+            QString mcPath = FS::PathCombine(m_stagingPath, "minecraft");
+            if (!QFile::rename(overridePath, mcPath))
+            {
+                emitFailed(tr("Could not rename the overrides folder:\n") + pack.overrides);
+                return;
+            }
+        }
+        else
+        {
+            logWarning(tr("The specified overrides folder (%1) is missing. Maybe the modpack was already used before?").arg(pack.overrides));
+        }
+    }
+
+    QString forgeVersion;
+    QString fabricVersion;
+    for(auto &loader: pack.minecraft.modLoaders)
+    {
+        auto id = loader.id;
+        if(id.startsWith("forge-"))
+        {
+            id.remove("forge-");
+            forgeVersion = id;
+            continue;
+        }
+        if(id.startsWith("fabric-"))
+        {
+            id.remove("fabric-");
+            fabricVersion = id;
+            continue;
+        }
+        logWarning(tr("Unknown mod loader in manifest: %1").arg(id));
+    }
+
+    QString configPath = FS::PathCombine(m_stagingPath, "instance.cfg");
+    auto instanceSettings = std::make_shared<INISettingsObject>(configPath);
+    instanceSettings->registerSetting("InstanceType", "Legacy");
+    instanceSettings->set("InstanceType", "OneSix");
+    MinecraftInstance instance(m_globalSettings, instanceSettings, m_stagingPath);
+    auto mcVersion = pack.minecraft.version;
+    // Hack to correct some 'special sauce'...
+    if(mcVersion.endsWith('.'))
+    {
+        mcVersion.remove(QRegExp("[.]+$"));
+        logWarning(tr("Mysterious trailing dots removed from Minecraft version while importing pack."));
+    }
+    auto components = instance.getPackProfile();
+    components->buildingFromScratch();
+    components->setComponentVersion("net.minecraft", mcVersion, true);
+    if(!forgeVersion.isEmpty())
+    {
+        // FIXME: dirty, nasty, hack. Proper solution requires dependency resolution and knowledge of the metadata.
+        if(forgeVersion == "recommended")
+        {
+            if(forgemap.contains(mcVersion))
+            {
+                forgeVersion = forgemap[mcVersion];
+            }
+            else
+            {
+                logWarning(tr("Could not map recommended forge version for Minecraft %1").arg(mcVersion));
+            }
+        }
+        components->setComponentVersion("net.minecraftforge", forgeVersion);
+    }
+    if(!fabricVersion.isEmpty())
+    {
+        components->setComponentVersion("net.fabricmc.fabric-loader", fabricVersion);
+    }
+    if (m_instIcon != "default")
+    {
+        instance.setIconKey(m_instIcon);
+    }
+    else
+    {
+        if(pack.name.contains("Direwolf20"))
+        {
+            instance.setIconKey("steve");
+        }
+        else if(pack.name.contains("FTB") || pack.name.contains("Feed The Beast"))
+        {
+            instance.setIconKey("ftb_logo");
+        }
+        else
+        {
+            // default to something other than the MultiMC default to distinguish these
+            instance.setIconKey("flame");
+        }
+    }
+    QString jarmodsPath = FS::PathCombine(m_stagingPath, "minecraft", "jarmods");
+    QFileInfo jarmodsInfo(jarmodsPath);
+    if(jarmodsInfo.isDir())
+    {
+        // install all the jar mods
+        qDebug() << "Found jarmods:";
+        QDir jarmodsDir(jarmodsPath);
+        QStringList jarMods;
+        for (auto info: jarmodsDir.entryInfoList(QDir::NoDotAndDotDot | QDir::Files))
+        {
+            qDebug() << info.fileName();
+            jarMods.push_back(info.absoluteFilePath());
+        }
+        auto profile = instance.getPackProfile();
+        profile->installJarMods(jarMods);
+        // nuke the original files
+        FS::deletePath(jarmodsPath);
+    }
+    instance.setName(m_instName);
+    m_modIdResolver.reset(new Flame::FileResolvingTask(pack));
+    connect(m_modIdResolver.get(), &Flame::FileResolvingTask::succeeded, [&]()
+    {
+        auto results = m_modIdResolver->getResults();
+        m_filesNetJob.reset(new NetJob(tr("Mod download")));
+        for(auto result: results.files)
+        {
+            QString filename = result.fileName;
+            if(!result.required)
+            {
+                filename += ".disabled";
+            }
+
+            auto relpath = FS::PathCombine("minecraft", result.targetFolder, filename);
+            auto path = FS::PathCombine(m_stagingPath , relpath);
+
+            switch(result.type)
+            {
+                case Flame::File::Type::Folder:
+                {
+                    logWarning(tr("This 'Folder' may need extracting: %1").arg(relpath));
+                    // fall-through intentional, we treat these as plain old mods and dump them wherever.
+                }
+                case Flame::File::Type::SingleFile:
+                case Flame::File::Type::Mod:
+                {
+                    qDebug() << "Will download" << result.url << "to" << path;
+                    auto dl = Net::Download::makeFile(result.url, path);
+                    m_filesNetJob->addNetAction(dl);
+                    break;
+                }
+                case Flame::File::Type::Modpack:
+                    logWarning(tr("Nesting modpacks in modpacks is not implemented, nothing was downloaded: %1").arg(relpath));
+                    break;
+                case Flame::File::Type::Cmod2:
+                case Flame::File::Type::Ctoc:
+                case Flame::File::Type::Unknown:
+                    logWarning(tr("Unrecognized/unhandled PackageType for: %1").arg(relpath));
+                    break;
+            }
+        }
+        m_modIdResolver.reset();
+        connect(m_filesNetJob.get(), &NetJob::succeeded, this, [&]()
+        {
+            m_filesNetJob.reset();
+            emitSucceeded();
+        }
+        );
+        connect(m_filesNetJob.get(), &NetJob::failed, [&](QString reason)
+        {
+            m_filesNetJob.reset();
+            emitFailed(reason);
+        });
+        connect(m_filesNetJob.get(), &NetJob::progress, [&](qint64 current, qint64 total)
+        {
+            setProgress(current, total);
+        });
+        setStatus(tr("Downloading mods..."));
+        m_filesNetJob->start();
+    }
+    );
+    connect(m_modIdResolver.get(), &Flame::FileResolvingTask::failed, [&](QString reason)
+    {
+        m_modIdResolver.reset();
+        emitFailed(tr("Unable to resolve mod IDs:\n") + reason);
+    });
+    connect(m_modIdResolver.get(), &Flame::FileResolvingTask::progress, [&](qint64 current, qint64 total)
+    {
+        setProgress(current, total);
+    });
+    connect(m_modIdResolver.get(), &Flame::FileResolvingTask::status, [&](QString status)
+    {
+        setStatus(status);
+    });
+    m_modIdResolver->start();
+}
+
+void InstanceImportTask::processTechnic()
+{
+    shared_qobject_ptr<Technic::TechnicPackProcessor> packProcessor = new Technic::TechnicPackProcessor();
+    connect(packProcessor.get(), &Technic::TechnicPackProcessor::succeeded, this, &InstanceImportTask::emitSucceeded);
+    connect(packProcessor.get(), &Technic::TechnicPackProcessor::failed, this, &InstanceImportTask::emitFailed);
+    packProcessor->run(m_globalSettings, m_instName, m_instIcon, m_stagingPath);
+}
+
+void InstanceImportTask::processMultiMC()
+{
+    // FIXME: copy from FolderInstanceProvider!!! FIX IT!!!
+    QString configPath = FS::PathCombine(m_stagingPath, "instance.cfg");
+    auto instanceSettings = std::make_shared<INISettingsObject>(configPath);
+    instanceSettings->registerSetting("InstanceType", "Legacy");
+
+    NullInstance instance(m_globalSettings, instanceSettings, m_stagingPath);
+
+    // reset time played on import... because packs.
+    instance.resetTimePlayed();
+
+    // set a new nice name
+    instance.setName(m_instName);
+
+    // if the icon was specified by user, use that. otherwise pull icon from the pack
+    if (m_instIcon != "default")
+    {
+        instance.setIconKey(m_instIcon);
+    }
+    else
+    {
+        m_instIcon = instance.iconKey();
+
+        auto importIconPath = IconUtils::findBestIconIn(instance.instanceRoot(), m_instIcon);
+        if (!importIconPath.isNull() && QFile::exists(importIconPath))
+        {
+            // import icon
+            auto iconList = ENV.icons();
+            if (iconList->iconFileExists(m_instIcon))
+            {
+                iconList->deleteIcon(m_instIcon);
+            }
+            iconList->installIcons({importIconPath});
+        }
+    }
+    emitSucceeded();
+}

launcher/InstanceImportTask.h

@@ -0,0 +1,72 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include "InstanceTask.h"
+#include "net/NetJob.h"
+#include <QUrl>
+#include <QFuture>
+#include <QFutureWatcher>
+#include "settings/SettingsObject.h"
+#include "QObjectPtr.h"
+
+#include <nonstd/optional>
+
+class QuaZip;
+namespace Flame
+{
+    class FileResolvingTask;
+}
+
+class InstanceImportTask : public InstanceTask
+{
+    Q_OBJECT
+public:
+    explicit InstanceImportTask(const QUrl sourceUrl);
+
+protected:
+    //! Entry point for tasks.
+    virtual void executeTask() override;
+
+private:
+    void processZipPack();
+    void processMultiMC();
+    void processFlame();
+    void processTechnic();
+
+private slots:
+    void downloadSucceeded();
+    void downloadFailed(QString reason);
+    void downloadProgressChanged(qint64 current, qint64 total);
+    void extractFinished();
+    void extractAborted();
+
+private: /* data */
+    NetJobPtr m_filesNetJob;
+    shared_qobject_ptr<Flame::FileResolvingTask> m_modIdResolver;
+    QUrl m_sourceUrl;
+    QString m_archivePath;
+    bool m_downloadRequired = false;
+    std::unique_ptr<QuaZip> m_packZip;
+    QFuture<nonstd::optional<QStringList>> m_extractFuture;
+    QFutureWatcher<nonstd::optional<QStringList>> m_extractFutureWatcher;
+    enum class ModpackType{
+        Unknown,
+        MultiMC,
+        Flame,
+        Technic
+    } m_modpackType = ModpackType::Unknown;
+};

launcher/InstanceList.cpp

@@ -0,0 +1,867 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QDir>
+#include <QDirIterator>
+#include <QSet>
+#include <QFile>
+#include <QThread>
+#include <QTextStream>
+#include <QXmlStreamReader>
+#include <QTimer>
+#include <QDebug>
+#include <QFileSystemWatcher>
+#include <QUuid>
+#include <QJsonArray>
+#include <QJsonDocument>
+
+#include "InstanceList.h"
+#include "BaseInstance.h"
+#include "InstanceTask.h"
+#include "settings/INISettingsObject.h"
+#include "minecraft/legacy/LegacyInstance.h"
+#include "NullInstance.h"
+#include "minecraft/MinecraftInstance.h"
+#include "FileSystem.h"
+#include "ExponentialSeries.h"
+#include "WatchLock.h"
+
+const static int GROUP_FILE_FORMAT_VERSION = 1;
+
+InstanceList::InstanceList(SettingsObjectPtr settings, const QString & instDir, QObject *parent)
+    : QAbstractListModel(parent), m_globalSettings(settings)
+{
+    resumeWatch();
+    // Create aand normalize path
+    if (!QDir::current().exists(instDir))
+    {
+        QDir::current().mkpath(instDir);
+    }
+
+    connect(this, &InstanceList::instancesChanged, this, &InstanceList::providerUpdated);
+
+    // NOTE: canonicalPath requires the path to exist. Do not move this above the creation block!
+    m_instDir = QDir(instDir).canonicalPath();
+    m_watcher = new QFileSystemWatcher(this);
+    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &InstanceList::instanceDirContentsChanged);
+    m_watcher->addPath(m_instDir);
+}
+
+InstanceList::~InstanceList()
+{
+}
+
+int InstanceList::rowCount(const QModelIndex &parent) const
+{
+    Q_UNUSED(parent);
+    return m_instances.count();
+}
+
+QModelIndex InstanceList::index(int row, int column, const QModelIndex &parent) const
+{
+    Q_UNUSED(parent);
+    if (row < 0 || row >= m_instances.size())
+        return QModelIndex();
+    return createIndex(row, column, (void *)m_instances.at(row).get());
+}
+
+QVariant InstanceList::data(const QModelIndex &index, int role) const
+{
+    if (!index.isValid())
+    {
+        return QVariant();
+    }
+    BaseInstance *pdata = static_cast<BaseInstance *>(index.internalPointer());
+    switch (role)
+    {
+    case InstancePointerRole:
+    {
+        QVariant v = qVariantFromValue((void *)pdata);
+        return v;
+    }
+    case InstanceIDRole:
+    {
+        return pdata->id();
+    }
+    case Qt::EditRole:
+    case Qt::DisplayRole:
+    {
+        return pdata->name();
+    }
+    case Qt::AccessibleTextRole:
+    {
+        return tr("%1 Instance").arg(pdata->name());
+    }
+    case Qt::ToolTipRole:
+    {
+        return pdata->instanceRoot();
+    }
+    case Qt::DecorationRole:
+    {
+        return pdata->iconKey();
+    }
+    // HACK: see GroupView.h in gui!
+    case GroupRole:
+    {
+        return getInstanceGroup(pdata->id());
+    }
+    default:
+        break;
+    }
+    return QVariant();
+}
+
+bool InstanceList::setData(const QModelIndex& index, const QVariant& value, int role)
+{
+    if (!index.isValid())
+    {
+        return false;
+    }
+    if(role != Qt::EditRole)
+    {
+        return false;
+    }
+    BaseInstance *pdata = static_cast<BaseInstance *>(index.internalPointer());
+    auto newName = value.toString();
+    if(pdata->name() == newName)
+    {
+        return true;
+    }
+    pdata->setName(newName);
+    return true;
+}
+
+Qt::ItemFlags InstanceList::flags(const QModelIndex &index) const
+{
+    Qt::ItemFlags f;
+    if (index.isValid())
+    {
+        f |= (Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsEditable);
+    }
+    return f;
+}
+
+GroupId InstanceList::getInstanceGroup(const InstanceId& id) const
+{
+    auto inst = getInstanceById(id);
+    if(!inst)
+    {
+        return GroupId();
+    }
+    auto iter = m_instanceGroupIndex.find(inst->id());
+    if(iter != m_instanceGroupIndex.end())
+    {
+        return *iter;
+    }
+    return GroupId();
+}
+
+void InstanceList::setInstanceGroup(const InstanceId& id, const GroupId& name)
+{
+    auto inst = getInstanceById(id);
+    if(!inst)
+    {
+        qDebug() << "Attempt to set a null instance's group";
+        return;
+    }
+
+    bool changed = false;
+    auto iter = m_instanceGroupIndex.find(inst->id());
+    if(iter != m_instanceGroupIndex.end())
+    {
+        if(*iter != name)
+        {
+            *iter = name;
+            changed = true;
+        }
+    }
+    else
+    {
+        changed = true;
+        m_instanceGroupIndex[id] = name;
+    }
+
+    if(changed)
+    {
+        m_groupNameCache.insert(name);
+        auto idx = getInstIndex(inst.get());
+        emit dataChanged(index(idx), index(idx), {GroupRole});
+        saveGroupList();
+    }
+}
+
+QStringList InstanceList::getGroups()
+{
+    return m_groupNameCache.toList();
+}
+
+void InstanceList::deleteGroup(const QString& name)
+{
+    bool removed = false;
+    qDebug() << "Delete group" << name;
+    for(auto & instance: m_instances)
+    {
+        const auto & instID = instance->id();
+        auto instGroupName = getInstanceGroup(instID);
+        if(instGroupName == name)
+        {
+            m_instanceGroupIndex.remove(instID);
+            qDebug() << "Remove" << instID << "from group" << name;
+            removed = true;
+            auto idx = getInstIndex(instance.get());
+            if(idx > 0)
+            {
+                emit dataChanged(index(idx), index(idx), {GroupRole});
+            }
+        }
+    }
+    if(removed)
+    {
+        saveGroupList();
+    }
+}
+
+bool InstanceList::isGroupCollapsed(const QString& group)
+{
+    return m_collapsedGroups.contains(group);
+}
+
+void InstanceList::deleteInstance(const InstanceId& id)
+{
+    auto inst = getInstanceById(id);
+    if(!inst)
+    {
+        qDebug() << "Cannot delete instance" << id << ". No such instance is present (deleted externally?).";
+        return;
+    }
+
+    if(m_instanceGroupIndex.remove(id))
+    {
+        saveGroupList();
+    }
+
+    qDebug() << "Will delete instance" << id;
+    if(!FS::deletePath(inst->instanceRoot()))
+    {
+        qWarning() << "Deletion of instance" << id << "has not been completely successful ...";
+        return;
+    }
+
+    qDebug() << "Instance" << id << "has been deleted by MultiMC.";
+}
+
+static QMap<InstanceId, InstanceLocator> getIdMapping(const QList<InstancePtr> &list)
+{
+    QMap<InstanceId, InstanceLocator> out;
+    int i = 0;
+    for(auto & item: list)
+    {
+        auto id = item->id();
+        if(out.contains(id))
+        {
+            qWarning() << "Duplicate ID" << id << "in instance list";
+        }
+        out[id] = std::make_pair(item, i);
+        i++;
+    }
+    return out;
+}
+
+QList< InstanceId > InstanceList::discoverInstances()
+{
+    qDebug() << "Discovering instances in" << m_instDir;
+    QList<InstanceId> out;
+    QDirIterator iter(m_instDir, QDir::Dirs | QDir::NoDot | QDir::NoDotDot | QDir::Readable | QDir::Hidden, QDirIterator::FollowSymlinks);
+    while (iter.hasNext())
+    {
+        QString subDir = iter.next();
+        QFileInfo dirInfo(subDir);
+        if (!QFileInfo(FS::PathCombine(subDir, "instance.cfg")).exists())
+            continue;
+        // if it is a symlink, ignore it if it goes to the instance folder
+        if(dirInfo.isSymLink())
+        {
+            QFileInfo targetInfo(dirInfo.symLinkTarget());
+            QFileInfo instDirInfo(m_instDir);
+            if(targetInfo.canonicalPath() == instDirInfo.canonicalFilePath())
+            {
+                qDebug() << "Ignoring symlink" << subDir << "that leads into the instances folder";
+                continue;
+            }
+        }
+        auto id = dirInfo.fileName();
+        out.append(id);
+        qDebug() << "Found instance ID" << id;
+    }
+    instanceSet = out.toSet();
+    m_instancesProbed = true;
+    return out;
+}
+
+InstanceList::InstListError InstanceList::loadList()
+{
+    auto existingIds = getIdMapping(m_instances);
+
+    QList<InstancePtr> newList;
+
+    for(auto & id: discoverInstances())
+    {
+        if(existingIds.contains(id))
+        {
+            auto instPair = existingIds[id];
+            existingIds.remove(id);
+            qDebug() << "Should keep and soft-reload" << id;
+        }
+        else
+        {
+            InstancePtr instPtr = loadInstance(id);
+            if(instPtr)
+            {
+                newList.append(instPtr);
+            }
+        }
+    }
+
+    // TODO: looks like a general algorithm with a few specifics inserted. Do something about it.
+    if(!existingIds.isEmpty())
+    {
+        // get the list of removed instances and sort it by their original index, from last to first
+        auto deadList = existingIds.values();
+        auto orderSortPredicate = [](const InstanceLocator & a, const InstanceLocator & b) -> bool
+        {
+            return a.second > b.second;
+        };
+        std::sort(deadList.begin(), deadList.end(), orderSortPredicate);
+        // remove the contiguous ranges of rows
+        int front_bookmark = -1;
+        int back_bookmark = -1;
+        int currentItem = -1;
+        auto removeNow = [&]()
+        {
+            beginRemoveRows(QModelIndex(), front_bookmark, back_bookmark);
+            m_instances.erase(m_instances.begin() + front_bookmark, m_instances.begin() + back_bookmark + 1);
+            endRemoveRows();
+            front_bookmark = -1;
+            back_bookmark = currentItem;
+        };
+        for(auto & removedItem: deadList)
+        {
+            auto instPtr = removedItem.first;
+            instPtr->invalidate();
+            currentItem = removedItem.second;
+            if(back_bookmark == -1)
+            {
+                // no bookmark yet
+                back_bookmark = currentItem;
+            }
+            else if(currentItem == front_bookmark - 1)
+            {
+                // part of contiguous sequence, continue
+            }
+            else
+            {
+                // seam between previous and current item
+                removeNow();
+            }
+            front_bookmark = currentItem;
+        }
+        if(back_bookmark != -1)
+        {
+            removeNow();
+        }
+    }
+    if(newList.size())
+    {
+        add(newList);
+    }
+    m_dirty = false;
+    updateTotalPlayTime();
+    return NoError;
+}
+
+void InstanceList::updateTotalPlayTime()
+{
+    totalPlayTime = 0;
+    for(auto const& itr : m_instances)
+    {
+        totalPlayTime += itr.get()->totalTimePlayed();
+    }
+}
+
+void InstanceList::saveNow()
+{
+    for(auto & item: m_instances)
+    {
+        item->saveNow();
+    }
+}
+
+void InstanceList::add(const QList<InstancePtr> &t)
+{
+    beginInsertRows(QModelIndex(), m_instances.count(), m_instances.count() + t.size() - 1);
+    m_instances.append(t);
+    for(auto & ptr : t)
+    {
+        connect(ptr.get(), &BaseInstance::propertiesChanged, this, &InstanceList::propertiesChanged);
+    }
+    endInsertRows();
+}
+
+void InstanceList::resumeWatch()
+{
+    if(m_watchLevel > 0)
+    {
+        qWarning() << "Bad suspend level resume in instance list";
+        return;
+    }
+    m_watchLevel++;
+    if(m_watchLevel > 0 && m_dirty)
+    {
+        loadList();
+    }
+}
+
+void InstanceList::suspendWatch()
+{
+    m_watchLevel --;
+}
+
+void InstanceList::providerUpdated()
+{
+    m_dirty = true;
+    if(m_watchLevel == 1)
+    {
+        loadList();
+    }
+}
+
+InstancePtr InstanceList::getInstanceById(QString instId) const
+{
+    if(instId.isEmpty())
+        return InstancePtr();
+    for(auto & inst: m_instances)
+    {
+        if (inst->id() == instId)
+        {
+            return inst;
+        }
+    }
+    return InstancePtr();
+}
+
+QModelIndex InstanceList::getInstanceIndexById(const QString &id) const
+{
+    return index(getInstIndex(getInstanceById(id).get()));
+}
+
+int InstanceList::getInstIndex(BaseInstance *inst) const
+{
+    int count = m_instances.count();
+    for (int i = 0; i < count; i++)
+    {
+        if (inst == m_instances[i].get())
+        {
+            return i;
+        }
+    }
+    return -1;
+}
+
+void InstanceList::propertiesChanged(BaseInstance *inst)
+{
+    int i = getInstIndex(inst);
+    if (i != -1)
+    {
+        emit dataChanged(index(i), index(i));
+        updateTotalPlayTime();
+    }
+}
+
+InstancePtr InstanceList::loadInstance(const InstanceId& id)
+{
+    if(!m_groupsLoaded)
+    {
+        loadGroupList();
+    }
+
+    auto instanceRoot = FS::PathCombine(m_instDir, id);
+    auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instanceRoot, "instance.cfg"));
+    InstancePtr inst;
+
+    instanceSettings->registerSetting("InstanceType", "Legacy");
+
+    QString inst_type = instanceSettings->get("InstanceType").toString();
+
+    if (inst_type == "OneSix" || inst_type == "Nostalgia")
+    {
+        inst.reset(new MinecraftInstance(m_globalSettings, instanceSettings, instanceRoot));
+    }
+    else if (inst_type == "Legacy")
+    {
+        inst.reset(new LegacyInstance(m_globalSettings, instanceSettings, instanceRoot));
+    }
+    else
+    {
+        inst.reset(new NullInstance(m_globalSettings, instanceSettings, instanceRoot));
+    }
+    qDebug() << "Loaded instance " << inst->name() << " from " << inst->instanceRoot();
+    return inst;
+}
+
+void InstanceList::saveGroupList()
+{
+    qDebug() << "Will save group list now.";
+    if(!m_instancesProbed)
+    {
+        qDebug() << "Group saving prevented because we don't know the full list of instances yet.";
+        return;
+    }
+    WatchLock foo(m_watcher, m_instDir);
+    QString groupFileName = m_instDir + "/instgroups.json";
+    QMap<QString, QSet<QString>> reverseGroupMap;
+    for (auto iter = m_instanceGroupIndex.begin(); iter != m_instanceGroupIndex.end(); iter++)
+    {
+        QString id = iter.key();
+        QString group = iter.value();
+        if (group.isEmpty())
+            continue;
+        if(!instanceSet.contains(id))
+        {
+            qDebug() << "Skipping saving missing instance" << id << "to groups list.";
+            continue;
+        }
+
+        if (!reverseGroupMap.count(group))
+        {
+            QSet<QString> set;
+            set.insert(id);
+            reverseGroupMap[group] = set;
+        }
+        else
+        {
+            QSet<QString> &set = reverseGroupMap[group];
+            set.insert(id);
+        }
+    }
+    QJsonObject toplevel;
+    toplevel.insert("formatVersion", QJsonValue(QString("1")));
+    QJsonObject groupsArr;
+    for (auto iter = reverseGroupMap.begin(); iter != reverseGroupMap.end(); iter++)
+    {
+        auto list = iter.value();
+        auto name = iter.key();
+        QJsonObject groupObj;
+        QJsonArray instanceArr;
+        groupObj.insert("hidden", QJsonValue(m_collapsedGroups.contains(name)));
+        for (auto item : list)
+        {
+            instanceArr.append(QJsonValue(item));
+        }
+        groupObj.insert("instances", instanceArr);
+        groupsArr.insert(name, groupObj);
+    }
+    toplevel.insert("groups", groupsArr);
+    QJsonDocument doc(toplevel);
+    try
+    {
+        FS::write(groupFileName, doc.toJson());
+        qDebug() << "Group list saved.";
+    }
+    catch (const FS::FileSystemException &e)
+    {
+        qCritical() << "Failed to write instance group file :" << e.cause();
+    }
+}
+
+void InstanceList::loadGroupList()
+{
+    qDebug() << "Will load group list now.";
+
+    QString groupFileName = m_instDir + "/instgroups.json";
+
+    // if there's no group file, fail
+    if (!QFileInfo(groupFileName).exists())
+        return;
+
+    QByteArray jsonData;
+    try
+    {
+        jsonData = FS::read(groupFileName);
+    }
+    catch (const FS::FileSystemException &e)
+    {
+        qCritical() << "Failed to read instance group file :" << e.cause();
+        return;
+    }
+
+    QJsonParseError error;
+    QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &error);
+
+    // if the json was bad, fail
+    if (error.error != QJsonParseError::NoError)
+    {
+        qCritical() << QString("Failed to parse instance group file: %1 at offset %2")
+                            .arg(error.errorString(), QString::number(error.offset))
+                            .toUtf8();
+        return;
+    }
+
+    // if the root of the json wasn't an object, fail
+    if (!jsonDoc.isObject())
+    {
+        qWarning() << "Invalid group file. Root entry should be an object.";
+        return;
+    }
+
+    QJsonObject rootObj = jsonDoc.object();
+
+    // Make sure the format version matches, otherwise fail.
+    if (rootObj.value("formatVersion").toVariant().toInt() != GROUP_FILE_FORMAT_VERSION)
+        return;
+
+    // Get the groups. if it's not an object, fail
+    if (!rootObj.value("groups").isObject())
+    {
+        qWarning() << "Invalid group list JSON: 'groups' should be an object.";
+        return;
+    }
+
+    QSet<QString> groupSet;
+    m_instanceGroupIndex.clear();
+
+    // Iterate through all the groups.
+    QJsonObject groupMapping = rootObj.value("groups").toObject();
+    for (QJsonObject::iterator iter = groupMapping.begin(); iter != groupMapping.end(); iter++)
+    {
+        QString groupName = iter.key();
+
+        // If not an object, complain and skip to the next one.
+        if (!iter.value().isObject())
+        {
+            qWarning() << QString("Group '%1' in the group list should be an object.").arg(groupName).toUtf8();
+            continue;
+        }
+
+        QJsonObject groupObj = iter.value().toObject();
+        if (!groupObj.value("instances").isArray())
+        {
+            qWarning() << QString("Group '%1' in the group list is invalid. It should contain an array called 'instances'.").arg(groupName).toUtf8();
+            continue;
+        }
+
+        // keep a list/set of groups for choosing
+        groupSet.insert(groupName);
+
+        auto hidden = groupObj.value("hidden").toBool(false);
+        if(hidden) {
+            m_collapsedGroups.insert(groupName);
+        }
+
+        // Iterate through the list of instances in the group.
+        QJsonArray instancesArray = groupObj.value("instances").toArray();
+
+        for (QJsonArray::iterator iter2 = instancesArray.begin(); iter2 != instancesArray.end(); iter2++)
+        {
+            m_instanceGroupIndex[(*iter2).toString()] = groupName;
+        }
+    }
+    m_groupsLoaded = true;
+    m_groupNameCache.unite(groupSet);
+    qDebug() << "Group list loaded.";
+}
+
+void InstanceList::instanceDirContentsChanged(const QString& path)
+{
+    Q_UNUSED(path);
+    emit instancesChanged();
+}
+
+void InstanceList::on_InstFolderChanged(const Setting &setting, QVariant value)
+{
+    QString newInstDir = QDir(value.toString()).canonicalPath();
+    if(newInstDir != m_instDir)
+    {
+        if(m_groupsLoaded)
+        {
+            saveGroupList();
+        }
+        m_instDir = newInstDir;
+        m_groupsLoaded = false;
+        emit instancesChanged();
+    }
+}
+
+void InstanceList::on_GroupStateChanged(const QString& group, bool collapsed)
+{
+    qDebug() << "Group" << group << (collapsed ? "collapsed" : "expanded");
+    if(collapsed) {
+        m_collapsedGroups.insert(group);
+    } else {
+        m_collapsedGroups.remove(group);
+    }
+    saveGroupList();
+}
+
+class InstanceStaging : public Task
+{
+Q_OBJECT
+    const unsigned minBackoff = 1;
+    const unsigned maxBackoff = 16;
+public:
+    InstanceStaging (
+        InstanceList * parent,
+        Task * child,
+        const QString & stagingPath,
+        const QString& instanceName,
+        const QString& groupName )
+    : backoff(minBackoff, maxBackoff)
+    {
+        m_parent = parent;
+        m_child.reset(child);
+        connect(child, &Task::succeeded, this, &InstanceStaging::childSucceded);
+        connect(child, &Task::failed, this, &InstanceStaging::childFailed);
+        connect(child, &Task::status, this, &InstanceStaging::setStatus);
+        connect(child, &Task::progress, this, &InstanceStaging::setProgress);
+        m_instanceName = instanceName;
+        m_groupName = groupName;
+        m_stagingPath = stagingPath;
+        m_backoffTimer.setSingleShot(true);
+        connect(&m_backoffTimer, &QTimer::timeout, this, &InstanceStaging::childSucceded);
+    }
+
+    virtual ~InstanceStaging() {};
+
+
+    // FIXME/TODO: add ability to abort during instance commit retries
+    bool abort() override
+    {
+        if(m_child && m_child->canAbort())
+        {
+            return m_child->abort();
+        }
+        return false;
+    }
+    bool canAbort() const override
+    {
+        if(m_child && m_child->canAbort())
+        {
+            return true;
+        }
+        return false;
+    }
+
+protected:
+    virtual void executeTask() override
+    {
+        m_child->start();
+    }
+    QStringList warnings() const override
+    {
+        return m_child->warnings();
+    }
+
+private slots:
+    void childSucceded()
+    {
+        unsigned sleepTime = backoff();
+        if(m_parent->commitStagedInstance(m_stagingPath, m_instanceName, m_groupName))
+        {
+            emitSucceeded();
+            return;
+        }
+        // we actually failed, retry?
+        if(sleepTime == maxBackoff)
+        {
+            emitFailed(tr("Failed to commit instance, even after multiple retries. It is being blocked by something."));
+            return;
+        }
+        qDebug() << "Failed to commit instance" << m_instanceName << "Initiating backoff:" << sleepTime;
+        m_backoffTimer.start(sleepTime * 500);
+    }
+    void childFailed(const QString & reason)
+    {
+        m_parent->destroyStagingPath(m_stagingPath);
+        emitFailed(reason);
+    }
+
+private:
+    /*
+     * WHY: the whole reason why this uses an exponential backoff retry scheme is antivirus on Windows.
+     * Basically, it starts messing things up while MultiMC is extracting/creating instances
+     * and causes that horrible failure that is NTFS to lock files in place because they are open.
+     */
+    ExponentialSeries backoff;
+    QString m_stagingPath;
+    InstanceList * m_parent;
+    unique_qobject_ptr<Task> m_child;
+    QString m_instanceName;
+    QString m_groupName;
+    QTimer m_backoffTimer;
+};
+
+Task * InstanceList::wrapInstanceTask(InstanceTask * task)
+{
+    auto stagingPath = getStagedInstancePath();
+    task->setStagingPath(stagingPath);
+    task->setParentSettings(m_globalSettings);
+    return new InstanceStaging(this, task, stagingPath, task->name(), task->group());
+}
+
+QString InstanceList::getStagedInstancePath()
+{
+    QString key = QUuid::createUuid().toString();
+    QString relPath = FS::PathCombine("_MMC_TEMP/" , key);
+    QDir rootPath(m_instDir);
+    auto path = FS::PathCombine(m_instDir, relPath);
+    if(!rootPath.mkpath(relPath))
+    {
+        return QString();
+    }
+    return path;
+}
+
+bool InstanceList::commitStagedInstance(const QString& path, const QString& instanceName, const QString& groupName)
+{
+    QDir dir;
+    QString instID = FS::DirNameFromString(instanceName, m_instDir);
+    {
+        WatchLock lock(m_watcher, m_instDir);
+        QString destination = FS::PathCombine(m_instDir, instID);
+        if(!dir.rename(path, destination))
+        {
+            qWarning() << "Failed to move" << path << "to" << destination;
+            return false;
+        }
+        m_instanceGroupIndex[instID] = groupName;
+        instanceSet.insert(instID);
+        m_groupNameCache.insert(groupName);
+        emit instancesChanged();
+        emit instanceSelectRequest(instID);
+    }
+    saveGroupList();
+    return true;
+}
+
+bool InstanceList::destroyStagingPath(const QString& keyPath)
+{
+    return FS::deletePath(keyPath);
+}
+
+int InstanceList::getTotalPlayTime() {
+    updateTotalPlayTime();
+    return totalPlayTime;
+}
+
+#include "InstanceList.moc"

launcher/InstanceList.h

@@ -0,0 +1,173 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QObject>
+#include <QAbstractListModel>
+#include <QSet>
+#include <QList>
+
+#include "BaseInstance.h"
+
+#include "QObjectPtr.h"
+
+class QFileSystemWatcher;
+class InstanceTask;
+using InstanceId = QString;
+using GroupId = QString;
+using InstanceLocator = std::pair<InstancePtr, int>;
+
+enum class InstCreateError
+{
+    NoCreateError = 0,
+    NoSuchVersion,
+    UnknownCreateError,
+    InstExists,
+    CantCreateDir
+};
+
+enum class GroupsState
+{
+    NotLoaded,
+    Steady,
+    Dirty
+};
+
+
+class InstanceList : public QAbstractListModel
+{
+    Q_OBJECT
+
+public:
+    explicit InstanceList(SettingsObjectPtr settings, const QString & instDir, QObject *parent = 0);
+    virtual ~InstanceList();
+
+public:
+    QModelIndex index(int row, int column = 0, const QModelIndex &parent = QModelIndex()) const override;
+    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
+    Qt::ItemFlags flags(const QModelIndex &index) const override;
+
+    bool setData(const QModelIndex & index, const QVariant & value, int role) override;
+
+    enum AdditionalRoles
+    {
+        GroupRole = Qt::UserRole,
+        InstancePointerRole = 0x34B1CB48, ///< Return pointer to real instance
+        InstanceIDRole = 0x34B1CB49 ///< Return id if the instance
+    };
+    /*!
+     * \brief Error codes returned by functions in the InstanceList class.
+     * NoError Indicates that no error occurred.
+     * UnknownError indicates that an unspecified error occurred.
+     */
+    enum InstListError
+    {
+        NoError = 0,
+        UnknownError
+    };
+
+    InstancePtr at(int i) const
+    {
+        return m_instances.at(i);
+    }
+
+    int count() const
+    {
+        return m_instances.count();
+    }
+
+    InstListError loadList();
+    void saveNow();
+
+
+    InstancePtr getInstanceById(QString id) const;
+    QModelIndex getInstanceIndexById(const QString &id) const;
+    QStringList getGroups();
+    bool isGroupCollapsed(const QString &groupName);
+
+    GroupId getInstanceGroup(const InstanceId & id) const;
+    void setInstanceGroup(const InstanceId & id, const GroupId& name);
+
+    void deleteGroup(const GroupId & name);
+    void deleteInstance(const InstanceId & id);
+
+    // Wrap an instance creation task in some more task machinery and make it ready to be used
+    Task * wrapInstanceTask(InstanceTask * task);
+
+    /**
+     * Create a new empty staging area for instance creation and @return a path/key top commit it later.
+     * Used by instance manipulation tasks.
+     */
+    QString getStagedInstancePath();
+
+    /**
+     * Commit the staging area given by @keyPath to the provider - used when creation succeeds.
+     * Used by instance manipulation tasks.
+     */
+    bool commitStagedInstance(const QString & keyPath, const QString& instanceName, const QString & groupName);
+
+    /**
+     * Destroy a previously created staging area given by @keyPath - used when creation fails.
+     * Used by instance manipulation tasks.
+     */
+    bool destroyStagingPath(const QString & keyPath);
+
+    int getTotalPlayTime();
+
+signals:
+    void dataIsInvalid();
+    void instancesChanged();
+    void instanceSelectRequest(QString instanceId);
+    void groupsChanged(QSet<QString> groups);
+
+public slots:
+    void on_InstFolderChanged(const Setting &setting, QVariant value);
+    void on_GroupStateChanged(const QString &group, bool collapsed);
+
+private slots:
+    void propertiesChanged(BaseInstance *inst);
+    void providerUpdated();
+    void instanceDirContentsChanged(const QString &path);
+
+private:
+    int getInstIndex(BaseInstance *inst) const;
+    void updateTotalPlayTime();
+    void suspendWatch();
+    void resumeWatch();
+    void add(const QList<InstancePtr> &list);
+    void loadGroupList();
+    void saveGroupList();
+    QList<InstanceId> discoverInstances();
+    InstancePtr loadInstance(const InstanceId& id);
+
+private:
+    int m_watchLevel = 0;
+    int totalPlayTime = 0;
+    bool m_dirty = false;
+    QList<InstancePtr> m_instances;
+    QSet<QString> m_groupNameCache;
+
+    SettingsObjectPtr m_globalSettings;
+    QString m_instDir;
+    QFileSystemWatcher * m_watcher;
+    // FIXME: this is so inefficient that looking at it is almost painful.
+    QSet<QString> m_collapsedGroups;
+    QMap<InstanceId, GroupId> m_instanceGroupIndex;
+    QSet<InstanceId> instanceSet;
+    bool m_groupsLoaded = false;
+    bool m_instancesProbed = false;
+};

launcher/InstancePageProvider.h

@@ -0,0 +1,76 @@
+#pragma once
+#include "minecraft/MinecraftInstance.h"
+#include "minecraft/legacy/LegacyInstance.h"
+#include <FileSystem.h>
+#include "pages/BasePage.h"
+#include "pages/BasePageProvider.h"
+#include "pages/instance/LogPage.h"
+#include "pages/instance/VersionPage.h"
+#include "pages/instance/ModFolderPage.h"
+#include "pages/instance/ResourcePackPage.h"
+#include "pages/instance/TexturePackPage.h"
+#include "pages/instance/NotesPage.h"
+#include "pages/instance/ScreenshotsPage.h"
+#include "pages/instance/InstanceSettingsPage.h"
+#include "pages/instance/OtherLogsPage.h"
+#include "pages/instance/LegacyUpgradePage.h"
+#include "pages/instance/WorldListPage.h"
+#include "pages/instance/ServersPage.h"
+#include "pages/instance/GameOptionsPage.h"
+
+#include "Env.h"
+
+class InstancePageProvider : public QObject, public BasePageProvider
+{
+    Q_OBJECT
+public:
+    explicit InstancePageProvider(InstancePtr parent)
+    {
+        inst = parent;
+    }
+
+    virtual ~InstancePageProvider() {};
+    virtual QList<BasePage *> getPages() override
+    {
+        QList<BasePage *> values;
+        values.append(new LogPage(inst));
+        std::shared_ptr<MinecraftInstance> onesix = std::dynamic_pointer_cast<MinecraftInstance>(inst);
+        if(onesix)
+        {
+            values.append(new VersionPage(onesix.get()));
+            auto modsPage = new ModFolderPage(onesix.get(), onesix->loaderModList(), "mods", "loadermods", tr("Loader mods"), "Loader-mods");
+            modsPage->setFilter("%1 (*.zip *.jar *.litemod)");
+            values.append(modsPage);
+            values.append(new CoreModFolderPage(onesix.get(), onesix->coreModList(), "coremods", "coremods", tr("Core mods"), "Core-mods"));
+            values.append(new ResourcePackPage(onesix.get()));
+            values.append(new TexturePackPage(onesix.get()));
+            values.append(new NotesPage(onesix.get()));
+            values.append(new WorldListPage(onesix.get(), onesix->worldList()));
+            values.append(new ServersPage(onesix));
+            // values.append(new GameOptionsPage(onesix.get()));
+            values.append(new ScreenshotsPage(FS::PathCombine(onesix->gameRoot(), "screenshots")));
+            values.append(new InstanceSettingsPage(onesix.get()));
+        }
+        std::shared_ptr<LegacyInstance> legacy = std::dynamic_pointer_cast<LegacyInstance>(inst);
+        if(legacy)
+        {
+            values.append(new LegacyUpgradePage(legacy));
+            values.append(new NotesPage(legacy.get()));
+            values.append(new WorldListPage(legacy.get(), legacy->worldList()));
+            values.append(new ScreenshotsPage(FS::PathCombine(legacy->gameRoot(), "screenshots")));
+        }
+        auto logMatcher = inst->getLogFileMatcher();
+        if(logMatcher)
+        {
+            values.append(new OtherLogsPage(inst->getLogFileRoot(), logMatcher));
+        }
+        return values;
+    }
+
+    virtual QString dialogTitle() override
+    {
+        return tr("Edit Instance (%1)").arg(inst->name());
+    }
+protected:
+    InstancePtr inst;
+};

launcher/InstanceProxyModel.cpp

@@ -0,0 +1,34 @@
+#include "InstanceProxyModel.h"
+#include "MultiMC.h"
+#include <BaseInstance.h>
+#include <icons/IconList.h>
+
+InstanceProxyModel::InstanceProxyModel(QObject *parent) : GroupedProxyModel(parent)
+{
+}
+
+QVariant InstanceProxyModel::data(const QModelIndex & index, int role) const
+{
+    QVariant data = QSortFilterProxyModel::data(index, role);
+    if(role == Qt::DecorationRole)
+    {
+        return QVariant(MMC->icons()->getIcon(data.toString()));
+    }
+    return data;
+}
+
+bool InstanceProxyModel::subSortLessThan(const QModelIndex &left,
+                                         const QModelIndex &right) const
+{
+    BaseInstance *pdataLeft = static_cast<BaseInstance *>(left.internalPointer());
+    BaseInstance *pdataRight = static_cast<BaseInstance *>(right.internalPointer());
+    QString sortMode = MMC->settings()->get("InstSortMode").toString();
+    if (sortMode == "LastLaunch")
+    {
+        return pdataLeft->lastLaunch() > pdataRight->lastLaunch();
+    }
+    else
+    {
+        return QString::localeAwareCompare(pdataLeft->name(), pdataRight->name()) < 0;
+    }
+}

launcher/InstanceProxyModel.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "groupview/GroupedProxyModel.h"
+
+/**
+ * A proxy model that is responsible for sorting instances into groups
+ */
+class InstanceProxyModel : public GroupedProxyModel
+{
+public:
+    explicit InstanceProxyModel(QObject *parent = 0);
+    QVariant data(const QModelIndex & index, int role) const override;
+
+protected:
+    virtual bool subSortLessThan(const QModelIndex &left, const QModelIndex &right) const override;
+};

launcher/InstanceTask.cpp

@@ -0,0 +1,9 @@
+#include "InstanceTask.h"
+
+InstanceTask::InstanceTask()
+{
+}
+
+InstanceTask::~InstanceTask()
+{
+}

launcher/InstanceTask.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include "tasks/Task.h"
+#include "settings/SettingsObject.h"
+
+class InstanceTask : public Task
+{
+    Q_OBJECT
+public:
+    explicit InstanceTask();
+    virtual ~InstanceTask();
+
+    void setParentSettings(SettingsObjectPtr settings)
+    {
+        m_globalSettings = settings;
+    }
+
+    void setStagingPath(const QString &stagingPath)
+    {
+        m_stagingPath = stagingPath;
+    }
+
+    void setName(const QString &name)
+    {
+        m_instName = name;
+    }
+    QString name() const
+    {
+        return m_instName;
+    }
+
+    void setIcon(const QString &icon)
+    {
+        m_instIcon = icon;
+    }
+
+    void setGroup(const QString &group)
+    {
+        m_instGroup = group;
+    }
+    QString group() const
+    {
+        return m_instGroup;
+    }
+
+protected: /* data */
+    SettingsObjectPtr m_globalSettings;
+    QString m_instName;
+    QString m_instIcon;
+    QString m_instGroup;
+    QString m_stagingPath;
+};

launcher/InstanceWindow.cpp

@@ -0,0 +1,236 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "InstanceWindow.h"
+#include "MultiMC.h"
+
+#include <QScrollBar>
+#include <QMessageBox>
+#include <QHBoxLayout>
+#include <QPushButton>
+#include <qlayoutitem.h>
+#include <QCloseEvent>
+
+#include <dialogs/CustomMessageBox.h>
+#include <dialogs/ProgressDialog.h>
+#include "widgets/PageContainer.h"
+#include "InstancePageProvider.h"
+
+#include "icons/IconList.h"
+
+InstanceWindow::InstanceWindow(InstancePtr instance, QWidget *parent)
+    : QMainWindow(parent), m_instance(instance)
+{
+    setAttribute(Qt::WA_DeleteOnClose);
+
+    auto icon = MMC->icons()->getIcon(m_instance->iconKey());
+    QString windowTitle = tr("Console window for ") + m_instance->name();
+
+    // Set window properties
+    {
+        setWindowIcon(icon);
+        setWindowTitle(windowTitle);
+    }
+
+    // Add page container
+    {
+        auto provider = std::make_shared<InstancePageProvider>(m_instance);
+        m_container = new PageContainer(provider.get(), "console", this);
+        m_container->setParentContainer(this);
+        setCentralWidget(m_container);
+        setContentsMargins(0, 0, 0, 0);
+    }
+
+    // Add custom buttons to the page container layout.
+    {
+        auto horizontalLayout = new QHBoxLayout();
+        horizontalLayout->setObjectName(QStringLiteral("horizontalLayout"));
+        horizontalLayout->setContentsMargins(6, -1, 6, -1);
+
+        auto btnHelp = new QPushButton();
+        btnHelp->setText(tr("Help"));
+        horizontalLayout->addWidget(btnHelp);
+        connect(btnHelp, SIGNAL(clicked(bool)), m_container, SLOT(help()));
+
+        auto spacer = new QSpacerItem(40, 20, QSizePolicy::Expanding, QSizePolicy::Minimum);
+        horizontalLayout->addSpacerItem(spacer);
+
+        m_killButton = new QPushButton();
+        horizontalLayout->addWidget(m_killButton);
+        connect(m_killButton, SIGNAL(clicked(bool)), SLOT(on_btnKillMinecraft_clicked()));
+
+        m_launchOfflineButton = new QPushButton();
+        horizontalLayout->addWidget(m_launchOfflineButton);
+        m_launchOfflineButton->setText(tr("Launch Offline"));
+        updateLaunchButtons();
+        connect(m_launchOfflineButton, SIGNAL(clicked(bool)), SLOT(on_btnLaunchMinecraftOffline_clicked()));
+
+        m_closeButton = new QPushButton();
+        m_closeButton->setText(tr("Close"));
+        horizontalLayout->addWidget(m_closeButton);
+        connect(m_closeButton, SIGNAL(clicked(bool)), SLOT(on_closeButton_clicked()));
+
+        m_container->addButtons(horizontalLayout);
+    }
+
+    // restore window state
+    {
+        auto base64State = MMC->settings()->get("ConsoleWindowState").toByteArray();
+        restoreState(QByteArray::fromBase64(base64State));
+        auto base64Geometry = MMC->settings()->get("ConsoleWindowGeometry").toByteArray();
+        restoreGeometry(QByteArray::fromBase64(base64Geometry));
+    }
+
+    // set up instance and launch process recognition
+    {
+        auto launchTask = m_instance->getLaunchTask();
+        on_InstanceLaunchTask_changed(launchTask);
+        connect(m_instance.get(), &BaseInstance::launchTaskChanged, this, &InstanceWindow::on_InstanceLaunchTask_changed);
+        connect(m_instance.get(), &BaseInstance::runningStatusChanged, this, &InstanceWindow::on_RunningState_changed);
+    }
+
+    // set up instance destruction detection
+    {
+        connect(m_instance.get(), &BaseInstance::statusChanged, this, &InstanceWindow::on_instanceStatusChanged);
+    }
+    show();
+}
+
+void InstanceWindow::on_instanceStatusChanged(BaseInstance::Status, BaseInstance::Status newStatus)
+{
+    if(newStatus == BaseInstance::Status::Gone)
+    {
+        m_doNotSave = true;
+        close();
+    }
+}
+
+void InstanceWindow::updateLaunchButtons()
+{
+    if(m_instance->isRunning())
+    {
+        m_launchOfflineButton->setEnabled(false);
+        m_killButton->setText(tr("Kill"));
+        m_killButton->setObjectName("killButton");
+        m_killButton->setToolTip(tr("Kill the running instance"));
+    }
+    else if(!m_instance->canLaunch())
+    {
+        m_launchOfflineButton->setEnabled(false);
+        m_killButton->setText(tr("Launch"));
+        m_killButton->setObjectName("launchButton");
+        m_killButton->setToolTip(tr("Launch the instance"));
+        m_killButton->setEnabled(false);
+    }
+    else
+    {
+        m_launchOfflineButton->setEnabled(true);
+        m_killButton->setText(tr("Launch"));
+        m_killButton->setObjectName("launchButton");
+        m_killButton->setToolTip(tr("Launch the instance"));
+    }
+    // NOTE: this is a hack to force the button to recalculate its style
+    m_killButton->setStyleSheet("/* */");
+    m_killButton->setStyleSheet(QString());
+}
+
+void InstanceWindow::on_btnLaunchMinecraftOffline_clicked()
+{
+    MMC->launch(m_instance, false, nullptr);
+}
+
+void InstanceWindow::on_InstanceLaunchTask_changed(shared_qobject_ptr<LaunchTask> proc)
+{
+    m_proc = proc;
+}
+
+void InstanceWindow::on_RunningState_changed(bool running)
+{
+    updateLaunchButtons();
+    m_container->refreshContainer();
+    if(running) {
+        selectPage("log");
+    }
+}
+
+void InstanceWindow::on_closeButton_clicked()
+{
+    close();
+}
+
+void InstanceWindow::closeEvent(QCloseEvent *event)
+{
+    bool proceed = true;
+    if(!m_doNotSave)
+    {
+        proceed &= m_container->prepareToClose();
+    }
+
+    if(!proceed)
+    {
+        return;
+    }
+
+    MMC->settings()->set("ConsoleWindowState", saveState().toBase64());
+    MMC->settings()->set("ConsoleWindowGeometry", saveGeometry().toBase64());
+    emit isClosing();
+    event->accept();
+}
+
+bool InstanceWindow::saveAll()
+{
+    return m_container->saveAll();
+}
+
+void InstanceWindow::on_btnKillMinecraft_clicked()
+{
+    if(m_instance->isRunning())
+    {
+        MMC->kill(m_instance);
+    }
+    else
+    {
+        MMC->launch(m_instance, true, nullptr);
+    }
+}
+
+QString InstanceWindow::instanceId()
+{
+    return m_instance->id();
+}
+
+bool InstanceWindow::selectPage(QString pageId)
+{
+    return m_container->selectPage(pageId);
+}
+
+void InstanceWindow::refreshContainer()
+{
+    m_container->refreshContainer();
+}
+
+InstanceWindow::~InstanceWindow()
+{
+}
+
+bool InstanceWindow::requestClose()
+{
+    if(m_container->prepareToClose())
+    {
+        close();
+        return true;
+    }
+    return false;
+}

launcher/InstanceWindow.h

@@ -0,0 +1,73 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QMainWindow>
+#include "LaunchController.h"
+#include <QObjectPtr.h>
+#include <QSystemTrayIcon>
+#include "launch/LaunchTask.h"
+#include "pages/BasePageContainer.h"
+
+class QPushButton;
+class PageContainer;
+class InstanceWindow : public QMainWindow, public BasePageContainer
+{
+    Q_OBJECT
+
+public:
+    explicit InstanceWindow(InstancePtr proc, QWidget *parent = 0);
+    virtual ~InstanceWindow();
+
+    bool selectPage(QString pageId) override;
+    void refreshContainer() override;
+
+    QString instanceId();
+
+    // save all settings and changes (prepare for launch)
+    bool saveAll();
+
+    // request closing the window (from a page)
+    bool requestClose() override;
+
+signals:
+    void isClosing();
+
+private
+slots:
+    void on_closeButton_clicked();
+    void on_btnKillMinecraft_clicked();
+    void on_btnLaunchMinecraftOffline_clicked();
+
+    void on_InstanceLaunchTask_changed(shared_qobject_ptr<LaunchTask> proc);
+    void on_RunningState_changed(bool running);
+    void on_instanceStatusChanged(BaseInstance::Status, BaseInstance::Status newStatus);
+
+protected:
+    void closeEvent(QCloseEvent *) override;
+
+private:
+    void updateLaunchButtons();
+
+private:
+    shared_qobject_ptr<LaunchTask> m_proc;
+    InstancePtr m_instance;
+    bool m_doNotSave = false;
+    PageContainer *m_container = nullptr;
+    QPushButton *m_closeButton = nullptr;
+    QPushButton *m_killButton = nullptr;
+    QPushButton *m_launchOfflineButton = nullptr;
+};

launcher/JavaCommon.cpp

@@ -0,0 +1,104 @@
+#include "JavaCommon.h"
+#include "dialogs/CustomMessageBox.h"
+#include <MMCStrings.h>
+
+bool JavaCommon::checkJVMArgs(QString jvmargs, QWidget *parent)
+{
+    if (jvmargs.contains("-XX:PermSize=") || jvmargs.contains(QRegExp("-Xm[sx]"))
+        || jvmargs.contains("-XX-MaxHeapSize") || jvmargs.contains("-XX:InitialHeapSize"))
+    {
+        auto warnStr = QObject::tr(
+            "You tried to manually set a JVM memory option (using \"-XX:PermSize\", \"-XX-MaxHeapSize\", \"-XX:InitialHeapSize\",  \"-Xmx\" or \"-Xms\").\n"
+            "There are dedicated boxes for these in the settings (Java tab, in the Memory group at the top).\n"
+            "This message will be displayed until you remove them from the JVM arguments.");
+        CustomMessageBox::selectable(
+            parent, QObject::tr("JVM arguments warning"),
+            warnStr,
+            QMessageBox::Warning)->exec();
+        return false;
+    }
+    return true;
+}
+
+void JavaCommon::javaWasOk(QWidget *parent, JavaCheckResult result)
+{
+    QString text;
+    text += QObject::tr("Java test succeeded!<br />Platform reported: %1<br />Java version "
+        "reported: %2<br />Java vendor "
+        "reported: %3<br />").arg(result.realPlatform, result.javaVersion.toString(), result.javaVendor);
+    if (result.errorLog.size())
+    {
+        auto htmlError = result.errorLog;
+        htmlError.replace('\n', "<br />");
+        text += QObject::tr("<br />Warnings:<br /><font color=\"orange\">%1</font>").arg(htmlError);
+    }
+    CustomMessageBox::selectable(parent, QObject::tr("Java test success"), text, QMessageBox::Information)->show();
+}
+
+void JavaCommon::javaArgsWereBad(QWidget *parent, JavaCheckResult result)
+{
+    auto htmlError = result.errorLog;
+    QString text;
+    htmlError.replace('\n', "<br />");
+    text += QObject::tr("The specified java binary didn't work with the arguments you provided:<br />");
+    text += QString("<font color=\"red\">%1</font>").arg(htmlError);
+    CustomMessageBox::selectable(parent, QObject::tr("Java test failure"), text, QMessageBox::Warning)->show();
+}
+
+void JavaCommon::javaBinaryWasBad(QWidget *parent, JavaCheckResult result)
+{
+    QString text;
+    text += QObject::tr(
+        "The specified java binary didn't work.<br />You should use the auto-detect feature, "
+        "or set the path to the java executable.<br />");
+    CustomMessageBox::selectable(parent, QObject::tr("Java test failure"), text, QMessageBox::Warning)->show();
+}
+
+void JavaCommon::TestCheck::run()
+{
+    if (!JavaCommon::checkJVMArgs(m_args, m_parent))
+    {
+        emit finished();
+        return;
+    }
+    checker.reset(new JavaChecker());
+    connect(checker.get(), SIGNAL(checkFinished(JavaCheckResult)), this,
+            SLOT(checkFinished(JavaCheckResult)));
+    checker->m_path = m_path;
+    checker->performCheck();
+}
+
+void JavaCommon::TestCheck::checkFinished(JavaCheckResult result)
+{
+    if (result.validity != JavaCheckResult::Validity::Valid)
+    {
+        javaBinaryWasBad(m_parent, result);
+        emit finished();
+        return;
+    }
+    checker.reset(new JavaChecker());
+    connect(checker.get(), SIGNAL(checkFinished(JavaCheckResult)), this,
+            SLOT(checkFinishedWithArgs(JavaCheckResult)));
+    checker->m_path = m_path;
+    checker->m_args = m_args;
+    checker->m_minMem = m_minMem;
+    checker->m_maxMem = m_maxMem;
+    if (result.javaVersion.requiresPermGen())
+    {
+        checker->m_permGen = m_permGen;
+    }
+    checker->performCheck();
+}
+
+void JavaCommon::TestCheck::checkFinishedWithArgs(JavaCheckResult result)
+{
+    if (result.validity == JavaCheckResult::Validity::Valid)
+    {
+        javaWasOk(m_parent, result);
+        emit finished();
+        return;
+    }
+    javaArgsWereBad(m_parent, result);
+    emit finished();
+}
+

launcher/JavaCommon.h

@@ -0,0 +1,48 @@
+#pragma once
+#include <java/JavaChecker.h>
+
+class QWidget;
+
+/**
+ * Common UI bits for the java pages to use.
+ */
+namespace JavaCommon
+{
+    bool checkJVMArgs(QString args, QWidget *parent);
+
+    // Show a dialog saying that the Java binary was not usable
+    void javaBinaryWasBad(QWidget *parent, JavaCheckResult result);
+    // Show a dialog saying that the Java binary was not usable because of bad options
+    void javaArgsWereBad(QWidget *parent, JavaCheckResult result);
+    // Show a dialog saying that the Java binary was usable
+    void javaWasOk(QWidget *parent, JavaCheckResult result);
+
+    class TestCheck : public QObject
+    {
+        Q_OBJECT
+    public:
+        TestCheck(QWidget *parent, QString path, QString args, int minMem, int maxMem, int permGen)
+            :m_parent(parent), m_path(path), m_args(args), m_minMem(minMem), m_maxMem(maxMem), m_permGen(permGen)
+        {
+        }
+        virtual ~TestCheck() {};
+
+        void run();
+
+    signals:
+        void finished();
+
+    private slots:
+        void checkFinished(JavaCheckResult result);
+        void checkFinishedWithArgs(JavaCheckResult result);
+
+    private:
+        std::shared_ptr<JavaChecker> checker;
+        QWidget *m_parent = nullptr;
+        QString m_path;
+        QString m_args;
+        int m_minMem = 0;
+        int m_maxMem = 0;
+        int m_permGen = 64;
+    };
+}

launcher/Json.cpp

@@ -0,0 +1,272 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#include "Json.h"
+
+#include <QFile>
+
+#include "FileSystem.h"
+#include <math.h>
+
+namespace Json
+{
+void write(const QJsonDocument &doc, const QString &filename)
+{
+    FS::write(filename, doc.toJson());
+}
+void write(const QJsonObject &object, const QString &filename)
+{
+    write(QJsonDocument(object), filename);
+}
+void write(const QJsonArray &array, const QString &filename)
+{
+    write(QJsonDocument(array), filename);
+}
+
+QByteArray toBinary(const QJsonObject &obj)
+{
+    return QJsonDocument(obj).toBinaryData();
+}
+QByteArray toBinary(const QJsonArray &array)
+{
+    return QJsonDocument(array).toBinaryData();
+}
+QByteArray toText(const QJsonObject &obj)
+{
+    return QJsonDocument(obj).toJson(QJsonDocument::Compact);
+}
+QByteArray toText(const QJsonArray &array)
+{
+    return QJsonDocument(array).toJson(QJsonDocument::Compact);
+}
+
+static bool isBinaryJson(const QByteArray &data)
+{
+    decltype(QJsonDocument::BinaryFormatTag) tag = QJsonDocument::BinaryFormatTag;
+    return memcmp(data.constData(), &tag, sizeof(QJsonDocument::BinaryFormatTag)) == 0;
+}
+QJsonDocument requireDocument(const QByteArray &data, const QString &what)
+{
+    if (isBinaryJson(data))
+    {
+        QJsonDocument doc = QJsonDocument::fromBinaryData(data);
+        if (doc.isNull())
+        {
+            throw JsonException(what + ": Invalid JSON (binary JSON detected)");
+        }
+        return doc;
+    }
+    else
+    {
+        QJsonParseError error;
+        QJsonDocument doc = QJsonDocument::fromJson(data, &error);
+        if (error.error != QJsonParseError::NoError)
+        {
+            throw JsonException(what + ": Error parsing JSON: " + error.errorString());
+        }
+        return doc;
+    }
+}
+QJsonDocument requireDocument(const QString &filename, const QString &what)
+{
+    return requireDocument(FS::read(filename), what);
+}
+QJsonObject requireObject(const QJsonDocument &doc, const QString &what)
+{
+    if (!doc.isObject())
+    {
+        throw JsonException(what + " is not an object");
+    }
+    return doc.object();
+}
+QJsonArray requireArray(const QJsonDocument &doc, const QString &what)
+{
+    if (!doc.isArray())
+    {
+        throw JsonException(what + " is not an array");
+    }
+    return doc.array();
+}
+
+void writeString(QJsonObject &to, const QString &key, const QString &value)
+{
+    if (!value.isEmpty())
+    {
+        to.insert(key, value);
+    }
+}
+
+void writeStringList(QJsonObject &to, const QString &key, const QStringList &values)
+{
+    if (!values.isEmpty())
+    {
+        QJsonArray array;
+        for(auto value: values)
+        {
+            array.append(value);
+        }
+        to.insert(key, array);
+    }
+}
+
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url)
+{
+    return QJsonValue(url.toString(QUrl::FullyEncoded));
+}
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data)
+{
+    return QJsonValue(QString::fromLatin1(data.toHex()));
+}
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime)
+{
+    return QJsonValue(datetime.toString(Qt::ISODate));
+}
+template<>
+QJsonValue toJson<QDir>(const QDir &dir)
+{
+    return QDir::current().relativeFilePath(dir.absolutePath());
+}
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid)
+{
+    return uuid.toString();
+}
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant)
+{
+    return QJsonValue::fromVariant(variant);
+}
+
+
+template<> QByteArray requireIsType<QByteArray>(const QJsonValue &value, const QString &what)
+{
+    const QString string = ensureIsType<QString>(value, what);
+    // ensure that the string can be safely cast to Latin1
+    if (string != QString::fromLatin1(string.toLatin1()))
+    {
+        throw JsonException(what + " is not encodable as Latin1");
+    }
+    return QByteArray::fromHex(string.toLatin1());
+}
+
+template<> QJsonArray requireIsType<QJsonArray>(const QJsonValue &value, const QString &what)
+{
+    if (!value.isArray())
+    {
+        throw JsonException(what + " is not an array");
+    }
+    return value.toArray();
+}
+
+
+template<> QString requireIsType<QString>(const QJsonValue &value, const QString &what)
+{
+    if (!value.isString())
+    {
+        throw JsonException(what + " is not a string");
+    }
+    return value.toString();
+}
+
+template<> bool requireIsType<bool>(const QJsonValue &value, const QString &what)
+{
+    if (!value.isBool())
+    {
+        throw JsonException(what + " is not a bool");
+    }
+    return value.toBool();
+}
+
+template<> double requireIsType<double>(const QJsonValue &value, const QString &what)
+{
+    if (!value.isDouble())
+    {
+        throw JsonException(what + " is not a double");
+    }
+    return value.toDouble();
+}
+
+template<> int requireIsType<int>(const QJsonValue &value, const QString &what)
+{
+    const double doubl = requireIsType<double>(value, what);
+    if (fmod(doubl, 1) != 0)
+    {
+        throw JsonException(what + " is not an integer");
+    }
+    return int(doubl);
+}
+
+template<> QDateTime requireIsType<QDateTime>(const QJsonValue &value, const QString &what)
+{
+    const QString string = requireIsType<QString>(value, what);
+    const QDateTime datetime = QDateTime::fromString(string, Qt::ISODate);
+    if (!datetime.isValid())
+    {
+        throw JsonException(what + " is not a ISO formatted date/time value");
+    }
+    return datetime;
+}
+
+template<> QUrl requireIsType<QUrl>(const QJsonValue &value, const QString &what)
+{
+    const QString string = ensureIsType<QString>(value, what);
+    if (string.isEmpty())
+    {
+        return QUrl();
+    }
+    const QUrl url = QUrl(string, QUrl::StrictMode);
+    if (!url.isValid())
+    {
+        throw JsonException(what + " is not a correctly formatted URL");
+    }
+    return url;
+}
+
+template<> QDir requireIsType<QDir>(const QJsonValue &value, const QString &what)
+{
+    const QString string = requireIsType<QString>(value, what);
+    // FIXME: does not handle invalid characters!
+    return QDir::current().absoluteFilePath(string);
+}
+
+template<> QUuid requireIsType<QUuid>(const QJsonValue &value, const QString &what)
+{
+    const QString string = requireIsType<QString>(value, what);
+    const QUuid uuid = QUuid(string);
+    if (uuid.toString() != string) // converts back => valid
+    {
+        throw JsonException(what + " is not a valid UUID");
+    }
+    return uuid;
+}
+
+template<> QJsonObject requireIsType<QJsonObject>(const QJsonValue &value, const QString &what)
+{
+    if (!value.isObject())
+    {
+        throw JsonException(what + " is not an object");
+    }
+    return value.toObject();
+}
+
+template<> QVariant requireIsType<QVariant>(const QJsonValue &value, const QString &what)
+{
+    if (value.isNull() || value.isUndefined())
+    {
+        throw JsonException(what + " is null or undefined");
+    }
+    return value.toVariant();
+}
+
+template<> QJsonValue requireIsType<QJsonValue>(const QJsonValue &value, const QString &what)
+{
+    if (value.isNull() || value.isUndefined())
+    {
+        throw JsonException(what + " is null or undefined");
+    }
+    return value;
+}
+
+}

launcher/Json.h

@@ -0,0 +1,249 @@
+// Licensed under the Apache-2.0 license. See README.md for details.
+
+#pragma once
+
+#include <QJsonDocument>
+#include <QJsonArray>
+#include <QJsonObject>
+#include <QDateTime>
+#include <QUrl>
+#include <QDir>
+#include <QUuid>
+#include <QVariant>
+#include <memory>
+
+#include "Exception.h"
+
+namespace Json
+{
+class JsonException : public ::Exception
+{
+public:
+    JsonException(const QString &message) : Exception(message) {}
+};
+
+/// @throw FileSystemException
+void write(const QJsonDocument &doc, const QString &filename);
+/// @throw FileSystemException
+void write(const QJsonObject &object, const QString &filename);
+/// @throw FileSystemException
+void write(const QJsonArray &array, const QString &filename);
+
+QByteArray toBinary(const QJsonObject &obj);
+QByteArray toBinary(const QJsonArray &array);
+QByteArray toText(const QJsonObject &obj);
+QByteArray toText(const QJsonArray &array);
+
+/// @throw JsonException
+QJsonDocument requireDocument(const QByteArray &data, const QString &what = "Document");
+/// @throw JsonException
+QJsonDocument requireDocument(const QString &filename, const QString &what = "Document");
+/// @throw JsonException
+QJsonObject requireObject(const QJsonDocument &doc, const QString &what = "Document");
+/// @throw JsonException
+QJsonArray requireArray(const QJsonDocument &doc, const QString &what = "Document");
+
+/////////////////// WRITING ////////////////////
+
+void writeString(QJsonObject & to, const QString &key, const QString &value);
+void writeStringList(QJsonObject & to, const QString &key, const QStringList &values);
+
+template<typename T>
+QJsonValue toJson(const T &t)
+{
+    return QJsonValue(t);
+}
+template<>
+QJsonValue toJson<QUrl>(const QUrl &url);
+template<>
+QJsonValue toJson<QByteArray>(const QByteArray &data);
+template<>
+QJsonValue toJson<QDateTime>(const QDateTime &datetime);
+template<>
+QJsonValue toJson<QDir>(const QDir &dir);
+template<>
+QJsonValue toJson<QUuid>(const QUuid &uuid);
+template<>
+QJsonValue toJson<QVariant>(const QVariant &variant);
+
+template<typename T>
+QJsonArray toJsonArray(const QList<T> &container)
+{
+    QJsonArray array;
+    for (const T item : container)
+    {
+        array.append(toJson<T>(item));
+    }
+    return array;
+}
+
+////////////////// READING ////////////////////
+
+/// @throw JsonException
+template <typename T>
+T requireIsType(const QJsonValue &value, const QString &what = "Value");
+
+/// @throw JsonException
+template<> double requireIsType<double>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> bool requireIsType<bool>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> int requireIsType<int>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QJsonObject requireIsType<QJsonObject>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QJsonArray requireIsType<QJsonArray>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QJsonValue requireIsType<QJsonValue>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QByteArray requireIsType<QByteArray>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QDateTime requireIsType<QDateTime>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QVariant requireIsType<QVariant>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QString requireIsType<QString>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QUuid requireIsType<QUuid>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QDir requireIsType<QDir>(const QJsonValue &value, const QString &what);
+/// @throw JsonException
+template<> QUrl requireIsType<QUrl>(const QJsonValue &value, const QString &what);
+
+// the following functions are higher level functions, that make use of the above functions for
+// type conversion
+template <typename T>
+T ensureIsType(const QJsonValue &value, const T default_ = T(), const QString &what = "Value")
+{
+    if (value.isUndefined() || value.isNull())
+    {
+        return default_;
+    }
+    try
+    {
+        return requireIsType<T>(value, what);
+    }
+    catch (const JsonException &)
+    {
+        return default_;
+    }
+}
+
+/// @throw JsonException
+template <typename T>
+T requireIsType(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__")
+{
+    const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+    if (!parent.contains(key))
+    {
+        throw JsonException(localWhat + "s parent does not contain " + localWhat);
+    }
+    return requireIsType<T>(parent.value(key), localWhat);
+}
+
+template <typename T>
+T ensureIsType(const QJsonObject &parent, const QString &key, const T default_ = T(), const QString &what = "__placeholder__")
+{
+    const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+    if (!parent.contains(key))
+    {
+        return default_;
+    }
+    return ensureIsType<T>(parent.value(key), default_, localWhat);
+}
+
+template <typename T>
+QVector<T> requireIsArrayOf(const QJsonDocument &doc)
+{
+    const QJsonArray array = requireArray(doc);
+    QVector<T> out;
+    for (const QJsonValue val : array)
+    {
+        out.append(requireIsType<T>(val, "Document"));
+    }
+    return out;
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonValue &value, const QString &what = "Value")
+{
+    const QJsonArray array = ensureIsType<QJsonArray>(value, QJsonArray(), what);
+    QVector<T> out;
+    for (const QJsonValue val : array)
+    {
+        out.append(requireIsType<T>(val, what));
+    }
+    return out;
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonValue &value, const QVector<T> default_, const QString &what = "Value")
+{
+    if (value.isUndefined())
+    {
+        return default_;
+    }
+    return ensureIsArrayOf<T>(value, what);
+}
+
+/// @throw JsonException
+template <typename T>
+QVector<T> requireIsArrayOf(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__")
+{
+    const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+    if (!parent.contains(key))
+    {
+        throw JsonException(localWhat + "s parent does not contain " + localWhat);
+    }
+    return ensureIsArrayOf<T>(parent.value(key), localWhat);
+}
+
+template <typename T>
+QVector<T> ensureIsArrayOf(const QJsonObject &parent, const QString &key,
+                         const QVector<T> &default_ = QVector<T>(), const QString &what = "__placeholder__")
+{
+    const QString localWhat = QString(what).replace("__placeholder__", '\'' + key + '\'');
+    if (!parent.contains(key))
+    {
+        return default_;
+    }
+    return ensureIsArrayOf<T>(parent.value(key), default_, localWhat);
+}
+
+// this macro part could be replaced by variadic functions that just pass on their arguments, but that wouldn't work well with IDE helpers
+#define JSON_HELPERFUNCTIONS(NAME, TYPE) \
+    inline TYPE require##NAME(const QJsonValue &value, const QString &what = "Value") \
+    { \
+        return requireIsType<TYPE>(value, what); \
+    } \
+    inline TYPE ensure##NAME(const QJsonValue &value, const TYPE default_ = TYPE(), const QString &what = "Value") \
+    { \
+        return ensureIsType<TYPE>(value, default_, what); \
+    } \
+    inline TYPE require##NAME(const QJsonObject &parent, const QString &key, const QString &what = "__placeholder__") \
+    { \
+        return requireIsType<TYPE>(parent, key, what); \
+    } \
+    inline TYPE ensure##NAME(const QJsonObject &parent, const QString &key, const TYPE default_ = TYPE(), const QString &what = "__placeholder") \
+    { \
+        return ensureIsType<TYPE>(parent, key, default_, what); \
+    }
+
+JSON_HELPERFUNCTIONS(Array, QJsonArray)
+JSON_HELPERFUNCTIONS(Object, QJsonObject)
+JSON_HELPERFUNCTIONS(JsonValue, QJsonValue)
+JSON_HELPERFUNCTIONS(String, QString)
+JSON_HELPERFUNCTIONS(Boolean, bool)
+JSON_HELPERFUNCTIONS(Double, double)
+JSON_HELPERFUNCTIONS(Integer, int)
+JSON_HELPERFUNCTIONS(DateTime, QDateTime)
+JSON_HELPERFUNCTIONS(Url, QUrl)
+JSON_HELPERFUNCTIONS(ByteArray, QByteArray)
+JSON_HELPERFUNCTIONS(Dir, QDir)
+JSON_HELPERFUNCTIONS(Uuid, QUuid)
+JSON_HELPERFUNCTIONS(Variant, QVariant)
+
+#undef JSON_HELPERFUNCTIONS
+
+}
+using JSONValidationError = Json::JsonException;

launcher/KonamiCode.cpp

@@ -0,0 +1,44 @@
+#include "KonamiCode.h"
+
+#include <array>
+#include <QDebug>
+
+namespace {
+const std::array<Qt::Key, 10> konamiCode =
+{
+    {
+        Qt::Key_Up, Qt::Key_Up,
+        Qt::Key_Down, Qt::Key_Down,
+        Qt::Key_Left, Qt::Key_Right,
+        Qt::Key_Left, Qt::Key_Right,
+        Qt::Key_B, Qt::Key_A
+    }
+};
+}
+
+KonamiCode::KonamiCode(QObject* parent) : QObject(parent)
+{
+}
+
+
+void KonamiCode::input(QEvent* event)
+{
+    if( event->type() == QEvent::KeyPress )
+    {
+        QKeyEvent *keyEvent = static_cast<QKeyEvent*>( event );
+        auto key = Qt::Key(keyEvent->key());
+        if(key == konamiCode[m_progress])
+        {
+            m_progress ++;
+        }
+        else
+        {
+            m_progress = 0;
+        }
+        if(m_progress == static_cast<int>(konamiCode.size()))
+        {
+            m_progress = 0;
+            emit triggered();
+        }
+    }
+}

launcher/KonamiCode.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <QKeyEvent>
+
+class KonamiCode : public QObject
+{
+    Q_OBJECT
+public:
+    KonamiCode(QObject *parent = 0);
+    void input(QEvent *event);
+
+signals:
+    void triggered();
+
+private:
+    int m_progress = 0;
+};

launcher/LaunchController.cpp

@@ -0,0 +1,353 @@
+#include "LaunchController.h"
+#include "MainWindow.h"
+#include <minecraft/auth/MojangAccountList.h>
+#include "MultiMC.h"
+#include "dialogs/CustomMessageBox.h"
+#include "dialogs/ProfileSelectDialog.h"
+#include "dialogs/ProgressDialog.h"
+#include "dialogs/EditAccountDialog.h"
+#include "InstanceWindow.h"
+#include "BuildConfig.h"
+#include "JavaCommon.h"
+#include <QLineEdit>
+#include <QInputDialog>
+#include <tasks/Task.h>
+#include <minecraft/auth/YggdrasilTask.h>
+#include <launch/steps/TextPrint.h>
+#include <QStringList>
+#include <QHostInfo>
+#include <QList>
+#include <QHostAddress>
+
+LaunchController::LaunchController(QObject *parent) : Task(parent)
+{
+}
+
+void LaunchController::executeTask()
+{
+    if (!m_instance)
+    {
+        emitFailed(tr("No instance specified!"));
+        return;
+    }
+
+    login();
+}
+
+// FIXME: minecraft specific
+void LaunchController::login()
+{
+    JavaCommon::checkJVMArgs(m_instance->settings()->get("JvmArgs").toString(), m_parentWidget);
+
+    // Find an account to use.
+    std::shared_ptr<MojangAccountList> accounts = MMC->accounts();
+    MojangAccountPtr account = accounts->activeAccount();
+    if (accounts->count() <= 0)
+    {
+        // Tell the user they need to log in at least one account in order to play.
+        auto reply = CustomMessageBox::selectable(
+            m_parentWidget, tr("No Accounts"),
+            tr("In order to play Minecraft, you must have at least one Mojang or Minecraft "
+               "account logged in to MultiMC."
+               "Would you like to open the account manager to add an account now?"),
+            QMessageBox::Information, QMessageBox::Yes | QMessageBox::No)->exec();
+
+        if (reply == QMessageBox::Yes)
+        {
+            // Open the account manager.
+            MMC->ShowGlobalSettings(m_parentWidget, "accounts");
+        }
+    }
+    else if (account.get() == nullptr)
+    {
+        // If no default account is set, ask the user which one to use.
+        ProfileSelectDialog selectDialog(tr("Which profile would you like to use?"),
+                                         ProfileSelectDialog::GlobalDefaultCheckbox, m_parentWidget);
+
+        selectDialog.exec();
+
+        // Launch the instance with the selected account.
+        account = selectDialog.selectedAccount();
+
+        // If the user said to use the account as default, do that.
+        if (selectDialog.useAsGlobalDefault() && account.get() != nullptr)
+            accounts->setActiveAccount(account->username());
+    }
+
+    // if no account is selected, we bail
+    if (!account.get())
+    {
+        emitFailed(tr("No account selected for launch."));
+        return;
+    }
+
+    // we try empty password first :)
+    QString password;
+    // we loop until the user succeeds in logging in or gives up
+    bool tryagain = true;
+    // the failure. the default failure.
+    const QString needLoginAgain = tr("Your account is currently not logged in. Please enter your password to log in again. <br /> <br /> This could be caused by a password change.");
+    QString failReason = needLoginAgain;
+
+    while (tryagain)
+    {
+        m_session = std::make_shared<AuthSession>();
+        m_session->wants_online = m_online;
+        auto task = account->login(m_session, password);
+        if (task)
+        {
+            // We'll need to validate the access token to make sure the account
+            // is still logged in.
+            ProgressDialog progDialog(m_parentWidget);
+            if (m_online)
+            {
+                progDialog.setSkipButton(true, tr("Play Offline"));
+            }
+            progDialog.execWithTask(task.get());
+            if (!task->wasSuccessful())
+            {
+                auto failReasonNew = task->failReason();
+                if(failReasonNew == "Invalid token.")
+                {
+                    account->invalidateClientToken();
+                    failReason = needLoginAgain;
+                }
+                else failReason = failReasonNew;
+            }
+        }
+        switch (m_session->status)
+        {
+        case AuthSession::Undetermined:
+        {
+            qCritical() << "Received undetermined session status during login. Bye.";
+            tryagain = false;
+            emitFailed(tr("Received undetermined session status during login."));
+            break;
+        }
+        case AuthSession::RequiresPassword:
+        {
+            EditAccountDialog passDialog(failReason, m_parentWidget, EditAccountDialog::PasswordField);
+            auto username = m_session->username;
+            auto chopN = [](QString toChop, int N) -> QString
+            {
+                if(toChop.size() > N)
+                {
+                    auto left = toChop.left(N);
+                    left += QString("\u25CF").repeated(toChop.size() - N);
+                    return left;
+                }
+                return toChop;
+            };
+
+            if(username.contains('@'))
+            {
+                auto parts = username.split('@');
+                auto mailbox = chopN(parts[0],3);
+                QString domain = chopN(parts[1], 3);
+                username = mailbox + '@' + domain;
+            }
+            passDialog.setUsername(username);
+            if (passDialog.exec() == QDialog::Accepted)
+            {
+                password = passDialog.password();
+            }
+            else
+            {
+                tryagain = false;
+            }
+            break;
+        }
+        case AuthSession::PlayableOffline:
+        {
+            // we ask the user for a player name
+            bool ok = false;
+            QString usedname = m_session->player_name;
+            QString name = QInputDialog::getText(m_parentWidget, tr("Player name"),
+                                                 tr("Choose your offline mode player name."),
+                                                 QLineEdit::Normal, m_session->player_name, &ok);
+            if (!ok)
+            {
+                tryagain = false;
+                break;
+            }
+            if (name.length())
+            {
+                usedname = name;
+            }
+            m_session->MakeOffline(usedname);
+            // offline flavored game from here :3
+        }
+        case AuthSession::PlayableOnline:
+        {
+            launchInstance();
+            tryagain = false;
+            return;
+        }
+        }
+    }
+    emitFailed(tr("Failed to launch."));
+}
+
+void LaunchController::launchInstance()
+{
+    Q_ASSERT_X(m_instance != NULL, "launchInstance", "instance is NULL");
+    Q_ASSERT_X(m_session.get() != nullptr, "launchInstance", "session is NULL");
+
+    if(!m_instance->reloadSettings())
+    {
+        QMessageBox::critical(m_parentWidget, tr("Error!"), tr("Couldn't load the instance profile."));
+        emitFailed(tr("Couldn't load the instance profile."));
+        return;
+    }
+
+    m_launcher = m_instance->createLaunchTask(m_session, m_serverToJoin);
+    if (!m_launcher)
+    {
+        emitFailed(tr("Couldn't instantiate a launcher."));
+        return;
+    }
+
+    auto console = qobject_cast<InstanceWindow *>(m_parentWidget);
+    auto showConsole = m_instance->settings()->get("ShowConsole").toBool();
+    if(!console && showConsole)
+    {
+        MMC->showInstanceWindow(m_instance);
+    }
+    connect(m_launcher.get(), &LaunchTask::readyForLaunch, this, &LaunchController::readyForLaunch);
+    connect(m_launcher.get(), &LaunchTask::succeeded, this, &LaunchController::onSucceeded);
+    connect(m_launcher.get(), &LaunchTask::failed, this,  &LaunchController::onFailed);
+    connect(m_launcher.get(), &LaunchTask::requestProgress, this, &LaunchController::onProgressRequested);
+
+    // Prepend Online and Auth Status
+    QString online_mode;
+    if(m_session->wants_online) {
+        online_mode = "online";
+
+        // Prepend Server Status
+        QStringList servers = {"authserver.mojang.com", "session.minecraft.net", "textures.minecraft.net", "api.mojang.com"};
+        QString resolved_servers = "";
+        QHostInfo host_info;
+
+        for(QString server : servers) {
+            host_info = QHostInfo::fromName(server);
+            resolved_servers = resolved_servers + server + " resolves to:\n    [";
+            if(!host_info.addresses().isEmpty()) {
+                for(QHostAddress address : host_info.addresses()) {
+                    resolved_servers = resolved_servers + address.toString();
+                    if(!host_info.addresses().endsWith(address)) {
+                        resolved_servers = resolved_servers + ", ";
+                    }
+                }
+            } else {
+                resolved_servers = resolved_servers + "N/A";
+            }
+            resolved_servers = resolved_servers + "]\n\n";
+        }
+        m_launcher->prependStep(new TextPrint(m_launcher.get(), resolved_servers, MessageLevel::MultiMC));
+    } else {
+        online_mode = "offline";
+    }
+
+    QString auth_server_status;
+    if(m_session->auth_server_online) {
+        auth_server_status = "online";
+    } else {
+        auth_server_status = "offline";
+    }
+
+    m_launcher->prependStep(new TextPrint(m_launcher.get(), "Launched instance in " + online_mode + " mode\nAuthentication server is " + auth_server_status + "\n", MessageLevel::MultiMC));
+
+    // Prepend Version
+    m_launcher->prependStep(new TextPrint(m_launcher.get(), "MultiMC version: " + BuildConfig.printableVersionString() + "\n\n", MessageLevel::MultiMC));
+    m_launcher->start();
+}
+
+void LaunchController::readyForLaunch()
+{
+    if (!m_profiler)
+    {
+        m_launcher->proceed();
+        return;
+    }
+
+    QString error;
+    if (!m_profiler->check(&error))
+    {
+        m_launcher->abort();
+        QMessageBox::critical(m_parentWidget, tr("Error!"), tr("Couldn't start profiler: %1").arg(error));
+        emitFailed("Profiler startup failed!");
+        return;
+    }
+    BaseProfiler *profilerInstance = m_profiler->createProfiler(m_launcher->instance(), this);
+
+    connect(profilerInstance, &BaseProfiler::readyToLaunch, [this](const QString & message)
+    {
+        QMessageBox msg;
+        msg.setText(tr("The game launch is delayed until you press the "
+                        "button. This is the right time to setup the profiler, as the "
+                        "profiler server is running now.\n\n%1").arg(message));
+        msg.setWindowTitle(tr("Waiting."));
+        msg.setIcon(QMessageBox::Information);
+        msg.addButton(tr("Launch"), QMessageBox::AcceptRole);
+        msg.setModal(true);
+        msg.exec();
+        m_launcher->proceed();
+    });
+    connect(profilerInstance, &BaseProfiler::abortLaunch, [this](const QString & message)
+    {
+        QMessageBox msg;
+        msg.setText(tr("Couldn't start the profiler: %1").arg(message));
+        msg.setWindowTitle(tr("Error"));
+        msg.setIcon(QMessageBox::Critical);
+        msg.addButton(QMessageBox::Ok);
+        msg.setModal(true);
+        msg.exec();
+        m_launcher->abort();
+        emitFailed("Profiler startup failed!");
+    });
+    profilerInstance->beginProfiling(m_launcher);
+}
+
+void LaunchController::onSucceeded()
+{
+    emitSucceeded();
+}
+
+void LaunchController::onFailed(QString reason)
+{
+    if(m_instance->settings()->get("ShowConsoleOnError").toBool())
+    {
+        MMC->showInstanceWindow(m_instance, "console");
+    }
+    emitFailed(reason);
+}
+
+void LaunchController::onProgressRequested(Task* task)
+{
+    ProgressDialog progDialog(m_parentWidget);
+    progDialog.setSkipButton(true, tr("Abort"));
+    m_launcher->proceed();
+    progDialog.execWithTask(task);
+}
+
+bool LaunchController::abort()
+{
+    if(!m_launcher)
+    {
+        return true;
+    }
+    if(!m_launcher->canAbort())
+    {
+        return false;
+    }
+    auto response = CustomMessageBox::selectable(
+            m_parentWidget, tr("Kill Minecraft?"),
+            tr("This can cause the instance to get corrupted and should only be used if Minecraft "
+            "is frozen for some reason"),
+            QMessageBox::Question, QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes)->exec();
+    if (response == QMessageBox::Yes)
+    {
+        return m_launcher->abort();
+    }
+    return false;
+}

launcher/LaunchController.h

@@ -0,0 +1,68 @@
+#pragma once
+#include <QObject>
+#include <BaseInstance.h>
+#include <tools/BaseProfiler.h>
+
+#include "minecraft/launch/MinecraftServerTarget.h"
+
+class InstanceWindow;
+class LaunchController: public Task
+{
+    Q_OBJECT
+public:
+    void executeTask() override;
+
+    LaunchController(QObject * parent = nullptr);
+    virtual ~LaunchController(){};
+
+    void setInstance(InstancePtr instance)
+    {
+        m_instance = instance;
+    }
+    InstancePtr instance()
+    {
+        return m_instance;
+    }
+    void setOnline(bool online)
+    {
+        m_online = online;
+    }
+    void setProfiler(BaseProfilerFactory *profiler)
+    {
+        m_profiler = profiler;
+    }
+    void setParentWidget(QWidget * widget)
+    {
+        m_parentWidget = widget;
+    }
+    void setServerToJoin(MinecraftServerTargetPtr serverToJoin)
+    {
+        m_serverToJoin = std::move(serverToJoin);
+    }
+    QString id()
+    {
+        return m_instance->id();
+    }
+    bool abort() override;
+
+private:
+    void login();
+    void launchInstance();
+
+private slots:
+    void readyForLaunch();
+
+    void onSucceeded();
+    void onFailed(QString reason);
+    void onProgressRequested(Task *task);
+
+private:
+    BaseProfilerFactory *m_profiler = nullptr;
+    bool m_online = true;
+    InstancePtr m_instance;
+    QWidget * m_parentWidget = nullptr;
+    InstanceWindow *m_console = nullptr;
+    AuthSessionPtr m_session;
+    shared_qobject_ptr<LaunchTask> m_launcher;
+    MinecraftServerTargetPtr m_serverToJoin;
+};

launcher/LoggedProcess.cpp

@@ -0,0 +1,176 @@
+#include "LoggedProcess.h"
+#include "MessageLevel.h"
+#include <QDebug>
+
+LoggedProcess::LoggedProcess(QObject *parent) : QProcess(parent)
+{
+    // QProcess has a strange interface... let's map a lot of those into a few.
+    connect(this, &QProcess::readyReadStandardOutput, this, &LoggedProcess::on_stdOut);
+    connect(this, &QProcess::readyReadStandardError, this, &LoggedProcess::on_stdErr);
+    connect(this, SIGNAL(finished(int,QProcess::ExitStatus)), SLOT(on_exit(int,QProcess::ExitStatus)));
+    connect(this, SIGNAL(error(QProcess::ProcessError)), this, SLOT(on_error(QProcess::ProcessError)));
+    connect(this, &QProcess::stateChanged, this, &LoggedProcess::on_stateChange);
+}
+
+LoggedProcess::~LoggedProcess()
+{
+    if(m_is_detachable)
+    {
+        setProcessState(QProcess::NotRunning);
+    }
+}
+
+QStringList reprocess(const QByteArray & data, QString & leftover)
+{
+    QString str = leftover + QString::fromLocal8Bit(data);
+
+    str.remove('\r');
+    QStringList lines = str.split("\n");
+    leftover = lines.takeLast();
+    return lines;
+}
+
+void LoggedProcess::on_stdErr()
+{
+    auto lines = reprocess(readAllStandardError(), m_err_leftover);
+    emit log(lines, MessageLevel::StdErr);
+}
+
+void LoggedProcess::on_stdOut()
+{
+    auto lines = reprocess(readAllStandardOutput(), m_out_leftover);
+    emit log(lines, MessageLevel::StdOut);
+}
+
+void LoggedProcess::on_exit(int exit_code, QProcess::ExitStatus status)
+{
+    // save the exit code
+    m_exit_code = exit_code;
+
+    // Flush console window
+    if (!m_err_leftover.isEmpty())
+    {
+        emit log({m_err_leftover}, MessageLevel::StdErr);
+        m_err_leftover.clear();
+    }
+    if (!m_out_leftover.isEmpty())
+    {
+        emit log({m_err_leftover}, MessageLevel::StdOut);
+        m_out_leftover.clear();
+    }
+
+    // based on state, send signals
+    if (!m_is_aborting)
+    {
+        if (status == QProcess::NormalExit)
+        {
+            //: Message displayed on instance exit
+            emit log({tr("Process exited with code %1.").arg(exit_code)}, MessageLevel::MultiMC);
+            changeState(LoggedProcess::Finished);
+        }
+        else
+        {
+            //: Message displayed on instance crashed
+            if(exit_code == -1)
+                emit log({tr("Process crashed.")}, MessageLevel::MultiMC);
+            else
+                emit log({tr("Process crashed with exitcode %1.").arg(exit_code)}, MessageLevel::MultiMC);
+            changeState(LoggedProcess::Crashed);
+        }
+    }
+    else
+    {
+        //: Message displayed after the instance exits due to kill request
+        emit log({tr("Process was killed by user.")}, MessageLevel::Error);
+        changeState(LoggedProcess::Aborted);
+    }
+}
+
+void LoggedProcess::on_error(QProcess::ProcessError error)
+{
+    switch(error)
+    {
+        case QProcess::FailedToStart:
+        {
+            emit log({tr("The process failed to start.")}, MessageLevel::Fatal);
+            changeState(LoggedProcess::FailedToStart);
+            break;
+        }
+        // we'll just ignore those... never needed them
+        case QProcess::Crashed:
+        case QProcess::ReadError:
+        case QProcess::Timedout:
+        case QProcess::UnknownError:
+        case QProcess::WriteError:
+            break;
+    }
+}
+
+void LoggedProcess::kill()
+{
+    m_is_aborting = true;
+    QProcess::kill();
+}
+
+int LoggedProcess::exitCode() const
+{
+    return m_exit_code;
+}
+
+void LoggedProcess::changeState(LoggedProcess::State state)
+{
+    if(state == m_state)
+        return;
+    m_state = state;
+    emit stateChanged(m_state);
+}
+
+LoggedProcess::State LoggedProcess::state() const
+{
+    return m_state;
+}
+
+void LoggedProcess::on_stateChange(QProcess::ProcessState state)
+{
+    switch(state)
+    {
+        case QProcess::NotRunning:
+            break; // let's not - there are too many that handle this already.
+        case QProcess::Starting:
+        {
+            if(m_state != LoggedProcess::NotRunning)
+            {
+                qWarning() << "Wrong state change for process from state" << m_state << "to" << (int) LoggedProcess::Starting;
+            }
+            changeState(LoggedProcess::Starting);
+            return;
+        }
+        case QProcess::Running:
+        {
+            if(m_state != LoggedProcess::Starting)
+            {
+                qWarning() << "Wrong state change for process from state" << m_state << "to" << (int) LoggedProcess::Running;
+            }
+            changeState(LoggedProcess::Running);
+            return;
+        }
+    }
+}
+
+#if defined Q_OS_WIN32
+#include <windows.h>
+#endif
+
+qint64 LoggedProcess::processId() const
+{
+#ifdef Q_OS_WIN
+    return pid() ? pid()->dwProcessId : 0;
+#else
+    return pid();
+#endif
+}
+
+void LoggedProcess::setDetachable(bool detachable)
+{
+    m_is_detachable = detachable;
+}

launcher/LoggedProcess.h

@@ -0,0 +1,79 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QProcess>
+#include "MessageLevel.h"
+
+/*
+ * This is a basic process.
+ * It has line-based logging support and hides some of the nasty bits.
+ */
+class LoggedProcess : public QProcess
+{
+Q_OBJECT
+public:
+    enum State
+    {
+        NotRunning,
+        Starting,
+        FailedToStart,
+        Running,
+        Finished,
+        Crashed,
+        Aborted
+    };
+
+public:
+    explicit LoggedProcess(QObject* parent = 0);
+    virtual ~LoggedProcess();
+
+    State state() const;
+    int exitCode() const;
+    qint64 processId() const;
+
+    void setDetachable(bool detachable);
+
+signals:
+    void log(QStringList lines, MessageLevel::Enum level);
+    void stateChanged(LoggedProcess::State state);
+
+public slots:
+    /**
+     * @brief kill the process - equivalent to kill -9
+     */
+    void kill();
+
+
+private slots:
+    void on_stdErr();
+    void on_stdOut();
+    void on_exit(int exit_code, QProcess::ExitStatus status);
+    void on_error(QProcess::ProcessError error);
+    void on_stateChange(QProcess::ProcessState);
+
+private:
+    void changeState(LoggedProcess::State state);
+
+private:
+    QString m_err_leftover;
+    QString m_out_leftover;
+    bool m_killed = false;
+    State m_state = NotRunning;
+    int m_exit_code = 0;
+    bool m_is_aborting = false;
+    bool m_is_detachable = false;
+};

launcher/MMCStrings.cpp

@@ -0,0 +1,76 @@
+#include "MMCStrings.h"
+
+/// TAKEN FROM Qt, because it doesn't expose it intelligently
+static inline QChar getNextChar(const QString &s, int location)
+{
+    return (location < s.length()) ? s.at(location) : QChar();
+}
+
+/// TAKEN FROM Qt, because it doesn't expose it intelligently
+int Strings::naturalCompare(const QString &s1, const QString &s2, Qt::CaseSensitivity cs)
+{
+    for (int l1 = 0, l2 = 0; l1 <= s1.count() && l2 <= s2.count(); ++l1, ++l2)
+    {
+        // skip spaces, tabs and 0's
+        QChar c1 = getNextChar(s1, l1);
+        while (c1.isSpace())
+            c1 = getNextChar(s1, ++l1);
+        QChar c2 = getNextChar(s2, l2);
+        while (c2.isSpace())
+            c2 = getNextChar(s2, ++l2);
+
+        if (c1.isDigit() && c2.isDigit())
+        {
+            while (c1.digitValue() == 0)
+                c1 = getNextChar(s1, ++l1);
+            while (c2.digitValue() == 0)
+                c2 = getNextChar(s2, ++l2);
+
+            int lookAheadLocation1 = l1;
+            int lookAheadLocation2 = l2;
+            int currentReturnValue = 0;
+            // find the last digit, setting currentReturnValue as we go if it isn't equal
+            for (QChar lookAhead1 = c1, lookAhead2 = c2;
+                 (lookAheadLocation1 <= s1.length() && lookAheadLocation2 <= s2.length());
+                 lookAhead1 = getNextChar(s1, ++lookAheadLocation1),
+                       lookAhead2 = getNextChar(s2, ++lookAheadLocation2))
+            {
+                bool is1ADigit = !lookAhead1.isNull() && lookAhead1.isDigit();
+                bool is2ADigit = !lookAhead2.isNull() && lookAhead2.isDigit();
+                if (!is1ADigit && !is2ADigit)
+                    break;
+                if (!is1ADigit)
+                    return -1;
+                if (!is2ADigit)
+                    return 1;
+                if (currentReturnValue == 0)
+                {
+                    if (lookAhead1 < lookAhead2)
+                    {
+                        currentReturnValue = -1;
+                    }
+                    else if (lookAhead1 > lookAhead2)
+                    {
+                        currentReturnValue = 1;
+                    }
+                }
+            }
+            if (currentReturnValue != 0)
+                return currentReturnValue;
+        }
+        if (cs == Qt::CaseInsensitive)
+        {
+            if (!c1.isLower())
+                c1 = c1.toLower();
+            if (!c2.isLower())
+                c2 = c2.toLower();
+        }
+        int r = QString::localeAwareCompare(c1, c2);
+        if (r < 0)
+            return -1;
+        if (r > 0)
+            return 1;
+    }
+    // The two strings are the same (02 == 2) so fall back to the normal sort
+    return QString::compare(s1, s2, cs);
+}

launcher/MMCStrings.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <QString>
+
+namespace Strings
+{
+    int naturalCompare(const QString &s1, const QString &s2, Qt::CaseSensitivity cs);
+}

launcher/MMCZip.cpp

@@ -0,0 +1,312 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <quazip.h>
+#include <quazipdir.h>
+#include <quazipfile.h>
+#include <JlCompress.h>
+#include "MMCZip.h"
+#include "FileSystem.h"
+
+#include <QDebug>
+
+// ours
+bool MMCZip::mergeZipFiles(QuaZip *into, QFileInfo from, QSet<QString> &contained, const JlCompress::FilterFunction filter)
+{
+    QuaZip modZip(from.filePath());
+    modZip.open(QuaZip::mdUnzip);
+
+    QuaZipFile fileInsideMod(&modZip);
+    QuaZipFile zipOutFile(into);
+    for (bool more = modZip.goToFirstFile(); more; more = modZip.goToNextFile())
+    {
+        QString filename = modZip.getCurrentFileName();
+        if (filter && !filter(filename))
+        {
+            qDebug() << "Skipping file " << filename << " from "
+                        << from.fileName() << " - filtered";
+            continue;
+        }
+        if (contained.contains(filename))
+        {
+            qDebug() << "Skipping already contained file " << filename << " from "
+                        << from.fileName();
+            continue;
+        }
+        contained.insert(filename);
+
+        if (!fileInsideMod.open(QIODevice::ReadOnly))
+        {
+            qCritical() << "Failed to open " << filename << " from " << from.fileName();
+            return false;
+        }
+
+        QuaZipNewInfo info_out(fileInsideMod.getActualFileName());
+
+        if (!zipOutFile.open(QIODevice::WriteOnly, info_out))
+        {
+            qCritical() << "Failed to open " << filename << " in the jar";
+            fileInsideMod.close();
+            return false;
+        }
+        if (!JlCompress::copyData(fileInsideMod, zipOutFile))
+        {
+            zipOutFile.close();
+            fileInsideMod.close();
+            qCritical() << "Failed to copy data of " << filename << " into the jar";
+            return false;
+        }
+        zipOutFile.close();
+        fileInsideMod.close();
+    }
+    return true;
+}
+
+// ours
+bool MMCZip::createModdedJar(QString sourceJarPath, QString targetJarPath, const QList<Mod>& mods)
+{
+    QuaZip zipOut(targetJarPath);
+    if (!zipOut.open(QuaZip::mdCreate))
+    {
+        QFile::remove(targetJarPath);
+        qCritical() << "Failed to open the minecraft.jar for modding";
+        return false;
+    }
+    // Files already added to the jar.
+    // These files will be skipped.
+    QSet<QString> addedFiles;
+
+    // Modify the jar
+    QListIterator<Mod> i(mods);
+    i.toBack();
+    while (i.hasPrevious())
+    {
+        const Mod &mod = i.previous();
+        // do not merge disabled mods.
+        if (!mod.enabled())
+            continue;
+        if (mod.type() == Mod::MOD_ZIPFILE)
+        {
+            if (!mergeZipFiles(&zipOut, mod.filename(), addedFiles))
+            {
+                zipOut.close();
+                QFile::remove(targetJarPath);
+                qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+                return false;
+            }
+        }
+        else if (mod.type() == Mod::MOD_SINGLEFILE)
+        {
+            // FIXME: buggy - does not work with addedFiles
+            auto filename = mod.filename();
+            if (!JlCompress::compressFile(&zipOut, filename.absoluteFilePath(), filename.fileName()))
+            {
+                zipOut.close();
+                QFile::remove(targetJarPath);
+                qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+                return false;
+            }
+            addedFiles.insert(filename.fileName());
+        }
+        else if (mod.type() == Mod::MOD_FOLDER)
+        {
+            // FIXME: buggy - does not work with addedFiles
+            auto filename = mod.filename();
+            QString what_to_zip = filename.absoluteFilePath();
+            QDir dir(what_to_zip);
+            dir.cdUp();
+            QString parent_dir = dir.absolutePath();
+            if (!JlCompress::compressSubDir(&zipOut, what_to_zip, parent_dir, addedFiles))
+            {
+                zipOut.close();
+                QFile::remove(targetJarPath);
+                qCritical() << "Failed to add" << mod.filename().fileName() << "to the jar.";
+                return false;
+            }
+            qDebug() << "Adding folder " << filename.fileName() << " from "
+                        << filename.absoluteFilePath();
+        }
+        else
+        {
+            // Make sure we do not continue launching when something is missing or undefined...
+            zipOut.close();
+            QFile::remove(targetJarPath);
+            qCritical() << "Failed to add unknown mod type" << mod.filename().fileName() << "to the jar.";
+            return false;
+        }
+    }
+
+    if (!mergeZipFiles(&zipOut, QFileInfo(sourceJarPath), addedFiles, [](const QString key){return !key.contains("META-INF");}))
+    {
+        zipOut.close();
+        QFile::remove(targetJarPath);
+        qCritical() << "Failed to insert minecraft.jar contents.";
+        return false;
+    }
+
+    // Recompress the jar
+    zipOut.close();
+    if (zipOut.getZipError() != 0)
+    {
+        QFile::remove(targetJarPath);
+        qCritical() << "Failed to finalize minecraft.jar!";
+        return false;
+    }
+    return true;
+}
+
+// ours
+QString MMCZip::findFolderOfFileInZip(QuaZip * zip, const QString & what, const QString &root)
+{
+    QuaZipDir rootDir(zip, root);
+    for(auto fileName: rootDir.entryList(QDir::Files))
+    {
+        if(fileName == what)
+            return root;
+    }
+    for(auto fileName: rootDir.entryList(QDir::Dirs))
+    {
+        QString result = findFolderOfFileInZip(zip, what, root + fileName);
+        if(!result.isEmpty())
+        {
+            return result;
+        }
+    }
+    return QString();
+}
+
+// ours
+bool MMCZip::findFilesInZip(QuaZip * zip, const QString & what, QStringList & result, const QString &root)
+{
+    QuaZipDir rootDir(zip, root);
+    for(auto fileName: rootDir.entryList(QDir::Files))
+    {
+        if(fileName == what)
+        {
+            result.append(root);
+            return true;
+        }
+    }
+    for(auto fileName: rootDir.entryList(QDir::Dirs))
+    {
+        findFilesInZip(zip, what, result, root + fileName);
+    }
+    return !result.isEmpty();
+}
+
+
+// ours
+nonstd::optional<QStringList> MMCZip::extractSubDir(QuaZip *zip, const QString & subdir, const QString &target)
+{
+    QDir directory(target);
+    QStringList extracted;
+
+    qDebug() << "Extracting subdir" << subdir << "from" << zip->getZipName() << "to" << target;
+    auto numEntries = zip->getEntriesCount();
+    if(numEntries < 0) {
+        qWarning() << "Failed to enumerate files in archive";
+        return nonstd::nullopt;
+    }
+    else if(numEntries == 0) {
+        qDebug() << "Extracting empty archives seems odd...";
+        return extracted;
+    }
+    else if (!zip->goToFirstFile())
+    {
+        qWarning() << "Failed to seek to first file in zip";
+        return nonstd::nullopt;
+    }
+
+    do
+    {
+        QString name = zip->getCurrentFileName();
+        if(!name.startsWith(subdir))
+        {
+            continue;
+        }
+        name.remove(0, subdir.size());
+        QString absFilePath = directory.absoluteFilePath(name);
+        if(name.isEmpty())
+        {
+            absFilePath += "/";
+        }
+        if (!JlCompress::extractFile(zip, "", absFilePath))
+        {
+            qWarning() << "Failed to extract file" << name << "to" << absFilePath;
+            JlCompress::removeFile(extracted);
+            return nonstd::nullopt;
+        }
+        extracted.append(absFilePath);
+        qDebug() << "Extracted file" << name;
+    } while (zip->goToNextFile());
+    return extracted;
+}
+
+// ours
+bool MMCZip::extractRelFile(QuaZip *zip, const QString &file, const QString &target)
+{
+    return JlCompress::extractFile(zip, file, target);
+}
+
+// ours
+nonstd::optional<QStringList> MMCZip::extractDir(QString fileCompressed, QString dir)
+{
+    QuaZip zip(fileCompressed);
+    if (!zip.open(QuaZip::mdUnzip))
+    {
+        // check if this is a minimum size empty zip file...
+        QFileInfo fileInfo(fileCompressed);
+        if(fileInfo.size() == 22) {
+            return QStringList();
+        }
+        qWarning() << "Could not open archive for unzipping:" << fileCompressed << "Error:" << zip.getZipError();;
+        return nonstd::nullopt;
+    }
+    return MMCZip::extractSubDir(&zip, "", dir);
+}
+
+// ours
+nonstd::optional<QStringList> MMCZip::extractDir(QString fileCompressed, QString subdir, QString dir)
+{
+    QuaZip zip(fileCompressed);
+    if (!zip.open(QuaZip::mdUnzip))
+    {
+        // check if this is a minimum size empty zip file...
+        QFileInfo fileInfo(fileCompressed);
+        if(fileInfo.size() == 22) {
+            return QStringList();
+        }
+        qWarning() << "Could not open archive for unzipping:" << fileCompressed << "Error:" << zip.getZipError();;
+        return nonstd::nullopt;
+    }
+    return MMCZip::extractSubDir(&zip, subdir, dir);
+}
+
+// ours
+bool MMCZip::extractFile(QString fileCompressed, QString file, QString target)
+{
+    QuaZip zip(fileCompressed);
+    if (!zip.open(QuaZip::mdUnzip))
+    {
+        // check if this is a minimum size empty zip file...
+        QFileInfo fileInfo(fileCompressed);
+        if(fileInfo.size() == 22) {
+            return true;
+        }
+        qWarning() << "Could not open archive for unzipping:" << fileCompressed << "Error:" << zip.getZipError();
+        return false;
+    }
+    return MMCZip::extractRelFile(&zip, file, target);
+}

launcher/MMCZip.h

@@ -0,0 +1,92 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QString>
+#include <QFileInfo>
+#include <QSet>
+#include "minecraft/mod/Mod.h"
+#include <functional>
+
+#include <JlCompress.h>
+#include <nonstd/optional>
+
+namespace MMCZip
+{
+
+    /**
+     * Merge two zip files, using a filter function
+     */
+    bool mergeZipFiles(QuaZip *into, QFileInfo from, QSet<QString> &contained,
+                                            const JlCompress::FilterFunction filter = nullptr);
+
+    /**
+     * take a source jar, add mods to it, resulting in target jar
+     */
+    bool createModdedJar(QString sourceJarPath, QString targetJarPath, const QList<Mod>& mods);
+
+    /**
+     * Find a single file in archive by file name (not path)
+     *
+     * \return the path prefix where the file is
+     */
+    QString findFolderOfFileInZip(QuaZip * zip, const QString & what, const QString &root = QString(""));
+
+    /**
+     * Find a multiple files of the same name in archive by file name
+     * If a file is found in a path, no deeper paths are searched
+     *
+     * \return true if anything was found
+     */
+    bool findFilesInZip(QuaZip * zip, const QString & what, QStringList & result, const QString &root = QString());
+
+    /**
+     * Extract a subdirectory from an archive
+     */
+    nonstd::optional<QStringList> extractSubDir(QuaZip *zip, const QString & subdir, const QString &target);
+
+    bool extractRelFile(QuaZip *zip, const QString & file, const QString &target);
+
+    /**
+     * Extract a whole archive.
+     *
+     * \param fileCompressed The name of the archive.
+     * \param dir The directory to extract to, the current directory if left empty.
+     * \return The list of the full paths of the files extracted, empty on failure.
+     */
+    nonstd::optional<QStringList> extractDir(QString fileCompressed, QString dir);
+
+    /**
+     * Extract a subdirectory from an archive
+     *
+     * \param fileCompressed The name of the archive.
+     * \param subdir The directory within the archive to extract
+     * \param dir The directory to extract to, the current directory if left empty.
+     * \return The list of the full paths of the files extracted, empty on failure.
+     */
+    nonstd::optional<QStringList> extractDir(QString fileCompressed, QString subdir, QString dir);
+
+    /**
+     * Extract a single file from an archive into a directory
+     *
+     * \param fileCompressed The name of the archive.
+     * \param file The file within the archive to extract
+     * \param dir The directory to extract to, the current directory if left empty.
+     * \return true for success or false for failure
+     */
+    bool extractFile(QString fileCompressed, QString file, QString dir);
+
+}

launcher/MainWindow.h

@@ -0,0 +1,226 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <QMainWindow>
+#include <QProcess>
+#include <QTimer>
+
+#include "BaseInstance.h"
+#include "minecraft/auth/MojangAccount.h"
+#include "net/NetJob.h"
+#include "updater/GoUpdate.h"
+
+class LaunchController;
+class NewsChecker;
+class NotificationChecker;
+class QToolButton;
+class InstanceProxyModel;
+class LabeledToolButton;
+class QLabel;
+class MinecraftLauncher;
+class BaseProfilerFactory;
+class GroupView;
+class ServerStatus;
+class KonamiCode;
+class InstanceTask;
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+
+    class Ui;
+
+public:
+    explicit MainWindow(QWidget *parent = 0);
+    ~MainWindow();
+
+    bool eventFilter(QObject *obj, QEvent *ev) override;
+    void closeEvent(QCloseEvent *event) override;
+    void changeEvent(QEvent * event) override;
+
+    void checkInstancePathForProblems();
+
+    void updatesAllowedChanged(bool allowed);
+
+    void droppedURLs(QList<QUrl> urls);
+signals:
+    void isClosing();
+
+protected:
+    QMenu * createPopupMenu() override;
+
+private slots:
+    void onCatToggled(bool);
+
+    void on_actionAbout_triggered();
+
+    void on_actionAddInstance_triggered();
+
+    void on_actionREDDIT_triggered();
+
+    void on_actionDISCORD_triggered();
+
+    void on_actionCopyInstance_triggered();
+
+    void on_actionChangeInstGroup_triggered();
+
+    void on_actionChangeInstIcon_triggered();
+    void on_changeIconButton_clicked(bool)
+    {
+        on_actionChangeInstIcon_triggered();
+    }
+
+    void on_actionViewInstanceFolder_triggered();
+
+    void on_actionConfig_Folder_triggered();
+
+    void on_actionViewSelectedInstFolder_triggered();
+
+    void on_actionViewSelectedMCFolder_triggered();
+
+    void refreshInstances();
+
+    void on_actionViewCentralModsFolder_triggered();
+
+    void checkForUpdates();
+
+    void on_actionSettings_triggered();
+
+    void on_actionInstanceSettings_triggered();
+
+    void on_actionManageAccounts_triggered();
+
+    void on_actionReportBug_triggered();
+
+    void on_actionPatreon_triggered();
+
+    void on_actionMoreNews_triggered();
+
+    void newsButtonClicked();
+
+    void on_actionLaunchInstance_triggered();
+
+    void on_actionLaunchInstanceOffline_triggered();
+
+    void on_actionDeleteInstance_triggered();
+
+    void deleteGroup();
+
+    void on_actionExportInstance_triggered();
+
+    void on_actionRenameInstance_triggered();
+    void on_renameButton_clicked(bool)
+    {
+        on_actionRenameInstance_triggered();
+    }
+
+    void on_actionEditInstance_triggered();
+
+    void on_actionEditInstNotes_triggered();
+
+    void on_actionWorlds_triggered();
+
+    void on_actionScreenshots_triggered();
+
+    void taskEnd();
+
+    /**
+     * called when an icon is changed in the icon model.
+     */
+    void iconUpdated(QString);
+
+    void showInstanceContextMenu(const QPoint &);
+
+    void updateToolsMenu();
+
+    void skinJobFinished();
+
+    void instanceActivated(QModelIndex);
+
+    void instanceChanged(const QModelIndex &current, const QModelIndex &previous);
+
+    void instanceSelectRequest(QString id);
+
+    void instanceDataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight);
+
+    void selectionBad();
+
+    void startTask(Task *task);
+
+    void updateAvailable(GoUpdate::Status status);
+
+    void updateNotAvailable();
+
+    void notificationsChanged();
+
+    void activeAccountChanged();
+
+    void changeActiveAccount();
+
+    void repopulateAccountsMenu();
+
+    void updateNewsLabel();
+
+    /*!
+     * Runs the DownloadTask and installs updates.
+     */
+    void downloadUpdates(GoUpdate::Status status);
+
+    void konamiTriggered();
+
+    void globalSettingsClosed();
+
+private:
+    void retranslateUi();
+
+    void addInstance(QString url = QString());
+    void activateInstance(InstancePtr instance);
+    void setCatBackground(bool enabled);
+    void updateInstanceToolIcon(QString new_icon);
+    void setSelectedInstanceById(const QString &id);
+    void updateStatusCenter();
+
+    void runModalTask(Task *task);
+    void instanceFromInstanceTask(InstanceTask *task);
+    void finalizeInstance(InstancePtr inst);
+
+private:
+    std::unique_ptr<Ui> ui;
+
+    // these are managed by Qt's memory management model!
+    GroupView *view = nullptr;
+    InstanceProxyModel *proxymodel = nullptr;
+    QToolButton *newsLabel = nullptr;
+    QLabel *m_statusLeft = nullptr;
+    QLabel *m_statusCenter = nullptr;
+    ServerStatus *m_statusRight = nullptr;
+    QMenu *accountMenu = nullptr;
+    QToolButton *accountMenuButton = nullptr;
+    KonamiCode * secretEventFilter = nullptr;
+
+    unique_qobject_ptr<NetJob> skin_download_job;
+    unique_qobject_ptr<NewsChecker> m_newsChecker;
+    unique_qobject_ptr<NotificationChecker> m_notificationChecker;
+
+    InstancePtr m_selectedInstance;
+    QString m_currentInstIcon;
+
+    // managed by the application object
+    Task *m_versionLoadTask = nullptr;
+};

launcher/MessageLevel.cpp

@@ -0,0 +1,36 @@
+#include "MessageLevel.h"
+
+MessageLevel::Enum MessageLevel::getLevel(const QString& levelName)
+{
+    if (levelName == "MultiMC")
+        return MessageLevel::MultiMC;
+    else if (levelName == "Debug")
+        return MessageLevel::Debug;
+    else if (levelName == "Info")
+        return MessageLevel::Info;
+    else if (levelName == "Message")
+        return MessageLevel::Message;
+    else if (levelName == "Warning")
+        return MessageLevel::Warning;
+    else if (levelName == "Error")
+        return MessageLevel::Error;
+    else if (levelName == "Fatal")
+        return MessageLevel::Fatal;
+    // Skip PrePost, it's not exposed to !![]!
+    // Also skip StdErr and StdOut
+    else
+        return MessageLevel::Unknown;
+}
+
+MessageLevel::Enum MessageLevel::fromLine(QString &line)
+{
+    // Level prefix
+    int endmark = line.indexOf("]!");
+    if (line.startsWith("!![") && endmark != -1)
+    {
+        auto level = MessageLevel::getLevel(line.left(endmark).mid(3));
+        line = line.mid(endmark + 2);
+        return level;
+    }
+    return MessageLevel::Unknown;
+}

launcher/MessageLevel.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <QString>
+
+/**
+ * @brief the MessageLevel Enum
+ * defines what level a log message is
+ */
+namespace MessageLevel
+{
+enum Enum
+{
+    Unknown, /**< No idea what this is or where it came from */
+    StdOut,  /**< Undetermined stderr messages */
+    StdErr,  /**< Undetermined stdout messages */
+    MultiMC, /**< MultiMC Messages */
+    Debug,   /**< Debug Messages */
+    Info,    /**< Info Messages */
+    Message, /**< Standard Messages */
+    Warning, /**< Warnings */
+    Error,   /**< Errors */
+    Fatal,   /**< Fatal Errors */
+};
+MessageLevel::Enum getLevel(const QString &levelName);
+
+/* Get message level from a line. Line is modified if it was successful. */
+MessageLevel::Enum fromLine(QString &line);
+}

launcher/MultiMC.h

@@ -0,0 +1,235 @@
+#pragma once
+
+#include <QApplication>
+#include <memory>
+#include <QDebug>
+#include <QFlag>
+#include <QIcon>
+#include <QDateTime>
+#include <QUrl>
+#include <updater/GoUpdate.h>
+
+#include <BaseInstance.h>
+
+#include "minecraft/launch/MinecraftServerTarget.h"
+
+class LaunchController;
+class LocalPeer;
+class InstanceWindow;
+class MainWindow;
+class SetupWizard;
+class FolderInstanceProvider;
+class GenericPageProvider;
+class QFile;
+class HttpMetaCache;
+class SettingsObject;
+class InstanceList;
+class MojangAccountList;
+class IconList;
+class QNetworkAccessManager;
+class JavaInstallList;
+class UpdateChecker;
+class BaseProfilerFactory;
+class BaseDetachedToolFactory;
+class TranslationsModel;
+class ITheme;
+class MCEditTool;
+class GAnalytics;
+
+#if defined(MMC)
+#undef MMC
+#endif
+#define MMC (static_cast<MultiMC *>(QCoreApplication::instance()))
+
+class MultiMC : public QApplication
+{
+    // friends for the purpose of limiting access to deprecated stuff
+    Q_OBJECT
+public:
+    enum Status
+    {
+        StartingUp,
+        Failed,
+        Succeeded,
+        Initialized
+    };
+
+public:
+    MultiMC(int &argc, char **argv);
+    virtual ~MultiMC();
+
+    GAnalytics *analytics() const
+    {
+        return m_analytics;
+    }
+
+    std::shared_ptr<SettingsObject> settings() const
+    {
+        return m_settings;
+    }
+
+    qint64 timeSinceStart() const
+    {
+        return startTime.msecsTo(QDateTime::currentDateTime());
+    }
+
+    QIcon getThemedIcon(const QString& name);
+
+    void setIconTheme(const QString& name);
+
+    std::vector<ITheme *> getValidApplicationThemes();
+
+    void setApplicationTheme(const QString& name, bool initial);
+
+    // DownloadUpdateTask
+    std::shared_ptr<UpdateChecker> updateChecker()
+    {
+        return m_updateChecker;
+    }
+
+    std::shared_ptr<TranslationsModel> translations();
+
+    std::shared_ptr<JavaInstallList> javalist();
+
+    std::shared_ptr<InstanceList> instances() const
+    {
+        return m_instances;
+    }
+
+    FolderInstanceProvider * folderProvider() const
+    {
+        return m_instanceFolder;
+    }
+
+    std::shared_ptr<IconList> icons() const
+    {
+        return m_icons;
+    }
+
+    MCEditTool *mcedit() const
+    {
+        return m_mcedit.get();
+    }
+
+    std::shared_ptr<MojangAccountList> accounts() const
+    {
+        return m_accounts;
+    }
+
+    Status status() const
+    {
+        return m_status;
+    }
+
+    const QMap<QString, std::shared_ptr<BaseProfilerFactory>> &profilers() const
+    {
+        return m_profilers;
+    }
+
+    /// this is the root of the 'installation'. Used for automatic updates
+    const QString &root()
+    {
+        return m_rootPath;
+    }
+
+    /*!
+     * Opens a json file using either a system default editor, or, if not empty, the editor
+     * specified in the settings
+     */
+    bool openJsonEditor(const QString &filename);
+
+    InstanceWindow *showInstanceWindow(InstancePtr instance, QString page = QString());
+    MainWindow *showMainWindow(bool minimized = false);
+
+    void updateIsRunning(bool running);
+    bool updatesAreAllowed();
+
+    void ShowGlobalSettings(class QWidget * parent, QString open_page = QString());
+
+signals:
+    void updateAllowedChanged(bool status);
+    void globalSettingsAboutToOpen();
+    void globalSettingsClosed();
+
+public slots:
+    bool launch(
+            InstancePtr instance,
+            bool online = true,
+            BaseProfilerFactory *profiler = nullptr,
+            MinecraftServerTargetPtr serverToJoin = nullptr
+    );
+    bool kill(InstancePtr instance);
+
+private slots:
+    void on_windowClose();
+    void messageReceived(const QString & message);
+    void controllerSucceeded();
+    void controllerFailed(const QString & error);
+    void analyticsSettingChanged(const Setting &setting, QVariant value);
+    void setupWizardFinished(int status);
+
+private:
+    bool createSetupWizard();
+    void performMainStartupAction();
+
+    // sets the fatal error message and m_status to Failed.
+    void showFatalErrorMessage(const QString & title, const QString & content);
+
+private:
+    void addRunningInstance();
+    void subRunningInstance();
+    bool shouldExitNow() const;
+
+private:
+    QDateTime startTime;
+
+    std::shared_ptr<SettingsObject> m_settings;
+    std::shared_ptr<InstanceList> m_instances;
+    FolderInstanceProvider * m_instanceFolder = nullptr;
+    std::shared_ptr<IconList> m_icons;
+    std::shared_ptr<UpdateChecker> m_updateChecker;
+    std::shared_ptr<MojangAccountList> m_accounts;
+    std::shared_ptr<JavaInstallList> m_javalist;
+    std::shared_ptr<TranslationsModel> m_translations;
+    std::shared_ptr<GenericPageProvider> m_globalSettingsProvider;
+    std::map<QString, std::unique_ptr<ITheme>> m_themes;
+    std::unique_ptr<MCEditTool> m_mcedit;
+
+    QMap<QString, std::shared_ptr<BaseProfilerFactory>> m_profilers;
+
+    QString m_rootPath;
+    Status m_status = MultiMC::StartingUp;
+
+#if defined Q_OS_WIN32
+    // used on Windows to attach the standard IO streams
+    bool consoleAttached = false;
+#endif
+
+    // FIXME: attach to instances instead.
+    struct InstanceXtras
+    {
+        InstanceWindow * window = nullptr;
+        shared_qobject_ptr<LaunchController> controller;
+    };
+    std::map<QString, InstanceXtras> m_instanceExtras;
+
+    // main state variables
+    size_t m_openWindows = 0;
+    size_t m_runningInstances = 0;
+    bool m_updateRunning = false;
+
+    // main window, if any
+    MainWindow * m_mainWindow = nullptr;
+
+    // peer MultiMC instance connector - used to implement single instance MultiMC and signalling
+    LocalPeer * m_peerInstance = nullptr;
+
+    GAnalytics * m_analytics = nullptr;
+    SetupWizard * m_setupWizard = nullptr;
+public:
+    QString m_instanceIdToLaunch;
+    QString m_serverToJoin;
+    bool m_liveCheck = false;
+    QUrl m_zipToImport;
+    std::unique_ptr<QFile> logFile;
+};

launcher/NullInstance.h

@@ -0,0 +1,76 @@
+#pragma once
+#include "BaseInstance.h"
+#include "launch/LaunchTask.h"
+
+class NullInstance: public BaseInstance
+{
+    Q_OBJECT
+public:
+    NullInstance(SettingsObjectPtr globalSettings, SettingsObjectPtr settings, const QString& rootDir)
+    :BaseInstance(globalSettings, settings, rootDir)
+    {
+        setVersionBroken(true);
+    }
+    virtual ~NullInstance() {};
+    void saveNow() override
+    {
+    }
+    QString getStatusbarDescription() override
+    {
+        return tr("Unknown instance type");
+    };
+    QSet< QString > traits() const override
+    {
+        return {};
+    };
+    QString instanceConfigFolder() const override
+    {
+        return instanceRoot();
+    };
+    shared_qobject_ptr<LaunchTask> createLaunchTask(AuthSessionPtr, MinecraftServerTargetPtr) override
+    {
+        return nullptr;
+    }
+    shared_qobject_ptr< Task > createUpdateTask(Net::Mode mode) override
+    {
+        return nullptr;
+    }
+    QProcessEnvironment createEnvironment() override
+    {
+        return QProcessEnvironment();
+    }
+    QMap<QString, QString> getVariables() const override
+    {
+        return QMap<QString, QString>();
+    }
+    IPathMatcher::Ptr getLogFileMatcher() override
+    {
+        return nullptr;
+    }
+    QString getLogFileRoot() override
+    {
+        return instanceRoot();
+    }
+    QString typeName() const override
+    {
+        return "Null";
+    }
+    bool canExport() const override
+    {
+        return false;
+    }
+    bool canEdit() const override
+    {
+        return false;
+    }
+    bool canLaunch() const override
+    {
+        return false;
+    }
+    QStringList verboseDescription(AuthSessionPtr session, MinecraftServerTargetPtr serverToJoin) override
+    {
+        QStringList out;
+        out << "Null instance - placeholder.";
+        return out;
+    }
+};

launcher/ProblemProvider.h

@@ -0,0 +1,47 @@
+#pragma once
+
+enum class ProblemSeverity
+{
+    None,
+    Warning,
+    Error
+};
+
+struct PatchProblem
+{
+    ProblemSeverity m_severity;
+    QString m_description;
+};
+
+class ProblemProvider
+{
+public:
+    virtual ~ProblemProvider() {};
+    virtual const QList<PatchProblem> getProblems() const = 0;
+    virtual ProblemSeverity getProblemSeverity() const = 0;
+};
+
+class ProblemContainer : public ProblemProvider
+{
+public:
+    const QList<PatchProblem> getProblems() const override
+    {
+        return m_problems;
+    }
+    ProblemSeverity getProblemSeverity() const override
+    {
+        return m_problemSeverity;
+    }
+    virtual void addProblem(ProblemSeverity severity, const QString &description)
+    {
+        if(severity > m_problemSeverity)
+        {
+            m_problemSeverity = severity;
+        }
+        m_problems.append({severity, description});
+    }
+
+private:
+    QList<PatchProblem> m_problems;
+    ProblemSeverity m_problemSeverity = ProblemSeverity::None;
+};

launcher/QObjectPtr.h

@@ -0,0 +1,83 @@
+#pragma once
+
+#include <functional>
+#include <memory>
+#include <QObject>
+
+namespace details
+{
+struct DeleteQObjectLater
+{
+    void operator()(QObject *obj) const
+    {
+        obj->deleteLater();
+    }
+};
+}
+/**
+ * A unique pointer class with unique pointer semantics intended for derivates of QObject
+ * Calls deleteLater() instead of destroying the contained object immediately
+ */
+template<typename T> using unique_qobject_ptr = std::unique_ptr<T, details::DeleteQObjectLater>;
+
+/**
+ * A shared pointer class with shared pointer semantics intended for derivates of QObject
+ * Calls deleteLater() instead of destroying the contained object immediately
+ */
+template <typename T>
+class shared_qobject_ptr
+{
+public:
+    shared_qobject_ptr(){}
+    shared_qobject_ptr(T * wrap)
+    {
+        reset(wrap);
+    }
+    shared_qobject_ptr(const shared_qobject_ptr<T>& other)
+    {
+        m_ptr = other.m_ptr;
+    }
+    template<typename Derived>
+    shared_qobject_ptr(const shared_qobject_ptr<Derived> &other)
+    {
+        m_ptr = other.unwrap();
+    }
+
+public:
+    void reset(T * wrap)
+    {
+        using namespace std::placeholders;
+        m_ptr.reset(wrap, std::bind(&QObject::deleteLater, _1));
+    }
+    void reset(const shared_qobject_ptr<T> &other)
+    {
+        m_ptr = other.m_ptr;
+    }
+    void reset()
+    {
+        m_ptr.reset();
+    }
+    T * get() const
+    {
+        return m_ptr.get();
+    }
+    T * operator->() const
+    {
+        return m_ptr.get();
+    }
+    T & operator*() const
+    {
+        return *m_ptr.get();
+    }
+    operator bool() const
+    {
+        return m_ptr.get() != nullptr;
+    }
+    const std::shared_ptr <T> unwrap() const
+    {
+        return m_ptr;
+    }
+
+private:
+    std::shared_ptr <T> m_ptr;
+};

launcher/RWStorage.h

@@ -0,0 +1,66 @@
+#pragma once
+#include <QWriteLocker>
+#include <QReadLocker>
+#include <QMap>
+#include <QSet>
+
+template <typename K, typename V>
+class RWStorage
+{
+public:
+    void add(K key, V value)
+    {
+        QWriteLocker l(&lock);
+        cache[key] = value;
+        stale_entries.remove(key);
+    }
+    V get(K key)
+    {
+        QReadLocker l(&lock);
+        if(cache.contains(key))
+        {
+            return cache[key];
+        }
+        else return V();
+    }
+    bool get(K key, V& value)
+    {
+        QReadLocker l(&lock);
+        if(cache.contains(key))
+        {
+            value = cache[key];
+            return true;
+        }
+        else return false;
+    }
+    bool has(K key)
+    {
+        QReadLocker l(&lock);
+        return cache.contains(key);
+    }
+    bool stale(K key)
+    {
+        QReadLocker l(&lock);
+        if(!cache.contains(key))
+            return true;
+        return stale_entries.contains(key);
+    }
+    void setStale(K key)
+    {
+        QWriteLocker l(&lock);
+        if(cache.contains(key))
+        {
+            stale_entries.insert(key);
+        }
+    }
+    void clear()
+    {
+        QWriteLocker l(&lock);
+        cache.clear();
+        stale_entries.clear();
+    }
+private:
+    QReadWriteLock lock;
+    QMap<K, V> cache;
+    QSet<K> stale_entries;
+};

launcher/RecursiveFileSystemWatcher.cpp

@@ -0,0 +1,111 @@
+#include "RecursiveFileSystemWatcher.h"
+
+#include <QRegularExpression>
+#include <QDebug>
+
+RecursiveFileSystemWatcher::RecursiveFileSystemWatcher(QObject *parent)
+    : QObject(parent), m_watcher(new QFileSystemWatcher(this))
+{
+    connect(m_watcher, &QFileSystemWatcher::fileChanged, this,
+            &RecursiveFileSystemWatcher::fileChange);
+    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this,
+            &RecursiveFileSystemWatcher::directoryChange);
+}
+
+void RecursiveFileSystemWatcher::setRootDir(const QDir &root)
+{
+    bool wasEnabled = m_isEnabled;
+    disable();
+    m_root = root;
+    setFiles(scanRecursive(m_root));
+    if (wasEnabled)
+    {
+        enable();
+    }
+}
+void RecursiveFileSystemWatcher::setWatchFiles(const bool watchFiles)
+{
+    bool wasEnabled = m_isEnabled;
+    disable();
+    m_watchFiles = watchFiles;
+    if (wasEnabled)
+    {
+        enable();
+    }
+}
+
+void RecursiveFileSystemWatcher::enable()
+{
+    if (m_isEnabled)
+    {
+        return;
+    }
+    Q_ASSERT(m_root != QDir::root());
+    addFilesToWatcherRecursive(m_root);
+    m_isEnabled = true;
+}
+void RecursiveFileSystemWatcher::disable()
+{
+    if (!m_isEnabled)
+    {
+        return;
+    }
+    m_isEnabled = false;
+    m_watcher->removePaths(m_watcher->files());
+    m_watcher->removePaths(m_watcher->directories());
+}
+
+void RecursiveFileSystemWatcher::setFiles(const QStringList &files)
+{
+    if (files != m_files)
+    {
+        m_files = files;
+        emit filesChanged();
+    }
+}
+
+void RecursiveFileSystemWatcher::addFilesToWatcherRecursive(const QDir &dir)
+{
+    m_watcher->addPath(dir.absolutePath());
+    for (const QString &directory : dir.entryList(QDir::Dirs | QDir::NoDotAndDotDot))
+    {
+        addFilesToWatcherRecursive(dir.absoluteFilePath(directory));
+    }
+    if (m_watchFiles)
+    {
+        for (const QFileInfo &info : dir.entryInfoList(QDir::Files))
+        {
+            m_watcher->addPath(info.absoluteFilePath());
+        }
+    }
+}
+QStringList RecursiveFileSystemWatcher::scanRecursive(const QDir &directory)
+{
+    QStringList ret;
+    if(!m_matcher)
+    {
+        return {};
+    }
+    for (const QString &dir : directory.entryList(QDir::Dirs | QDir::NoDotAndDotDot | QDir::Hidden))
+    {
+        ret.append(scanRecursive(directory.absoluteFilePath(dir)));
+    }
+    for (const QString &file : directory.entryList(QDir::Files | QDir::Hidden))
+    {
+        auto relPath = m_root.relativeFilePath(directory.absoluteFilePath(file));
+        if (m_matcher->matches(relPath))
+        {
+            ret.append(relPath);
+        }
+    }
+    return ret;
+}
+
+void RecursiveFileSystemWatcher::fileChange(const QString &path)
+{
+    emit fileChanged(path);
+}
+void RecursiveFileSystemWatcher::directoryChange(const QString &path)
+{
+    setFiles(scanRecursive(m_root));
+}

launcher/RecursiveFileSystemWatcher.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <QFileSystemWatcher>
+#include <QDir>
+#include "pathmatcher/IPathMatcher.h"
+
+class RecursiveFileSystemWatcher : public QObject
+{
+    Q_OBJECT
+public:
+    RecursiveFileSystemWatcher(QObject *parent);
+
+    void setRootDir(const QDir &root);
+    QDir rootDir() const
+    {
+        return m_root;
+    }
+
+    // WARNING: setting this to true may be bad for performance
+    void setWatchFiles(const bool watchFiles);
+    bool watchFiles() const
+    {
+        return m_watchFiles;
+    }
+
+    void setMatcher(IPathMatcher::Ptr matcher)
+    {
+        m_matcher = matcher;
+    }
+
+    QStringList files() const
+    {
+        return m_files;
+    }
+
+signals:
+    void filesChanged();
+    void fileChanged(const QString &path);
+
+public slots:
+    void enable();
+    void disable();
+
+private:
+    QDir m_root;
+    bool m_watchFiles = false;
+    bool m_isEnabled = false;
+    IPathMatcher::Ptr m_matcher;
+
+    QFileSystemWatcher *m_watcher;
+
+    QStringList m_files;
+    void setFiles(const QStringList &files);
+
+    void addFilesToWatcherRecursive(const QDir &dir);
+    QStringList scanRecursive(const QDir &dir);
+
+private slots:
+    void fileChange(const QString &path);
+    void directoryChange(const QString &path);
+};

launcher/SeparatorPrefixTree.h

@@ -0,0 +1,298 @@
+#pragma once
+#include <QString>
+#include <QMap>
+#include <QStringList>
+
+template <char Tseparator>
+class SeparatorPrefixTree
+{
+public:
+    SeparatorPrefixTree(QStringList paths)
+    {
+        insert(paths);
+    }
+
+    SeparatorPrefixTree(bool contained = false)
+    {
+        m_contained = contained;
+    }
+
+    void insert(QStringList paths)
+    {
+        for(auto &path: paths)
+        {
+            insert(path);
+        }
+    }
+
+    /// insert an exact path into the tree
+    SeparatorPrefixTree & insert(QString path)
+    {
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            children[path] = SeparatorPrefixTree(true);
+            return children[path];
+        }
+        else
+        {
+            auto prefix = path.left(sepIndex);
+            if(!children.contains(prefix))
+            {
+                children[prefix] = SeparatorPrefixTree(false);
+            }
+            return children[prefix].insert(path.mid(sepIndex + 1));
+        }
+    }
+
+    /// is the path fully contained in the tree?
+    bool contains(QString path) const
+    {
+        auto node = find(path);
+        return node != nullptr;
+    }
+
+    /// does the tree cover a path? That means the prefix of the path is contained in the tree
+    bool covers(QString path) const
+    {
+        // if we found some valid node, it's good enough. the tree covers the path
+        if(m_contained)
+        {
+            return true;
+        }
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            auto found = children.find(path);
+            if(found == children.end())
+            {
+                return false;
+            }
+            return (*found).covers(QString());
+        }
+        else
+        {
+            auto prefix = path.left(sepIndex);
+            auto found = children.find(prefix);
+            if(found == children.end())
+            {
+                return false;
+            }
+            return (*found).covers(path.mid(sepIndex + 1));
+        }
+    }
+
+    /// return the contained path that covers the path specified
+    QString cover(QString path) const
+    {
+        // if we found some valid node, it's good enough. the tree covers the path
+        if(m_contained)
+        {
+            return QString("");
+        }
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            auto found = children.find(path);
+            if(found == children.end())
+            {
+                return QString();
+            }
+            auto nested = (*found).cover(QString());
+            if(nested.isNull())
+            {
+                return nested;
+            }
+            if(nested.isEmpty())
+                return path;
+            return path + Tseparator + nested;
+        }
+        else
+        {
+            auto prefix = path.left(sepIndex);
+            auto found = children.find(prefix);
+            if(found == children.end())
+            {
+                return QString();
+            }
+            auto nested = (*found).cover(path.mid(sepIndex + 1));
+            if(nested.isNull())
+            {
+                return nested;
+            }
+            if(nested.isEmpty())
+                return prefix;
+            return prefix + Tseparator + nested;
+        }
+    }
+
+    /// Does the path-specified node exist in the tree? It does not have to be contained.
+    bool exists(QString path) const
+    {
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            auto found = children.find(path);
+            if(found == children.end())
+            {
+                return false;
+            }
+            return true;
+        }
+        else
+        {
+            auto prefix = path.left(sepIndex);
+            auto found = children.find(prefix);
+            if(found == children.end())
+            {
+                return false;
+            }
+            return (*found).exists(path.mid(sepIndex + 1));
+        }
+    }
+
+    /// find a node in the tree by name
+    const SeparatorPrefixTree * find(QString path) const
+    {
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            auto found = children.find(path);
+            if(found == children.end())
+            {
+                return nullptr;
+            }
+            return &(*found);
+        }
+        else
+        {
+            auto prefix = path.left(sepIndex);
+            auto found = children.find(prefix);
+            if(found == children.end())
+            {
+                return nullptr;
+            }
+            return (*found).find(path.mid(sepIndex + 1));
+        }
+    }
+
+    /// is this a leaf node?
+    bool leaf() const
+    {
+        return children.isEmpty();
+    }
+
+    /// is this node actually contained in the tree, or is it purely structural?
+    bool contained() const
+    {
+        return m_contained;
+    }
+
+    /// Remove a path from the tree
+    bool remove(QString path)
+    {
+        return removeInternal(path) != Failed;
+    }
+
+    /// Clear all children of this node tree node
+    void clear()
+    {
+        children.clear();
+    }
+
+    QStringList toStringList() const
+    {
+        QStringList collected;
+        // collecting these is more expensive.
+        auto iter = children.begin();
+        while(iter != children.end())
+        {
+            QStringList list = iter.value().toStringList();
+            for(int i = 0; i < list.size(); i++)
+            {
+                list[i] = iter.key() + Tseparator + list[i];
+            }
+            collected.append(list);
+            if((*iter).m_contained)
+            {
+                collected.append(iter.key());
+            }
+            iter++;
+        }
+        return collected;
+    }
+private:
+    enum Removal
+    {
+        Failed,
+        Succeeded,
+        HasChildren
+    };
+    Removal removeInternal(QString path = QString())
+    {
+        if(path.isEmpty())
+        {
+            if(!m_contained)
+            {
+                // remove all children - we are removing a prefix
+                clear();
+                return Succeeded;
+            }
+            m_contained = false;
+            if(children.size())
+            {
+                return HasChildren;
+            }
+            return Succeeded;
+        }
+        Removal remStatus = Failed;
+        QString childToRemove;
+        auto sepIndex = path.indexOf(Tseparator);
+        if(sepIndex == -1)
+        {
+            childToRemove = path;
+            auto found = children.find(childToRemove);
+            if(found == children.end())
+            {
+                return Failed;
+            }
+            remStatus = (*found).removeInternal();
+        }
+        else
+        {
+            childToRemove = path.left(sepIndex);
+            auto found = children.find(childToRemove);
+            if(found == children.end())
+            {
+                return Failed;
+            }
+            remStatus = (*found).removeInternal(path.mid(sepIndex + 1));
+        }
+        switch (remStatus)
+        {
+            case Failed:
+            case HasChildren:
+            {
+                return remStatus;
+            }
+            case Succeeded:
+            {
+                children.remove(childToRemove);
+                if(m_contained)
+                {
+                    return HasChildren;
+                }
+                if(children.size())
+                {
+                    return HasChildren;
+                }
+                return Succeeded;
+            }
+        }
+        return Failed;
+    }
+
+private:
+    QMap<QString,SeparatorPrefixTree<Tseparator>> children;
+    bool m_contained = false;
+};

launcher/SkinUtils.cpp

@@ -0,0 +1,52 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "SkinUtils.h"
+#include "net/HttpMetaCache.h"
+#include "Env.h"
+
+#include <QFile>
+#include <QPainter>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonArray>
+
+namespace SkinUtils
+{
+/*
+ * Given a username, return a pixmap of the cached skin (if it exists), QPixmap() otherwise
+ */
+QPixmap getFaceFromCache(QString username, int height, int width)
+{
+    QFile fskin(ENV.metacache()
+                    ->resolveEntry("skins", username + ".png")
+                    ->getFullPath());
+
+    if (fskin.exists())
+    {
+        QPixmap skinTexture(fskin.fileName());
+        if(!skinTexture.isNull())
+        {
+            QPixmap skin = QPixmap(8, 8);
+            QPainter painter(&skin);
+            painter.drawPixmap(0, 0, skinTexture.copy(8, 8, 8, 8));
+            painter.drawPixmap(0, 0, skinTexture.copy(40, 8, 8, 8));
+            return skin.scaled(height, width, Qt::KeepAspectRatio);
+        }
+    }
+
+    return QPixmap();
+}
+}

launcher/SkinUtils.h

@@ -0,0 +1,23 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QPixmap>
+
+namespace SkinUtils
+{
+QPixmap getFaceFromCache(QString id, int height = 64, int width = 64);
+}

launcher/UpdateController.cpp

@@ -0,0 +1,449 @@
+#include <QFile>
+#include <QMessageBox>
+#include <FileSystem.h>
+#include <updater/GoUpdate.h>
+#include "UpdateController.h"
+#include <QApplication>
+#include <thread>
+#include <chrono>
+#include <LocalPeer.h>
+
+// from <sys/stat.h>
+#ifndef S_IRUSR
+#define __S_IREAD 0400         /* Read by owner.  */
+#define __S_IWRITE 0200        /* Write by owner.  */
+#define __S_IEXEC 0100         /* Execute by owner.  */
+#define S_IRUSR __S_IREAD      /* Read by owner.  */
+#define S_IWUSR __S_IWRITE     /* Write by owner.  */
+#define S_IXUSR __S_IEXEC      /* Execute by owner.  */
+
+#define S_IRGRP (S_IRUSR >> 3) /* Read by group.  */
+#define S_IWGRP (S_IWUSR >> 3) /* Write by group.  */
+#define S_IXGRP (S_IXUSR >> 3) /* Execute by group.  */
+
+#define S_IROTH (S_IRGRP >> 3) /* Read by others.  */
+#define S_IWOTH (S_IWGRP >> 3) /* Write by others.  */
+#define S_IXOTH (S_IXGRP >> 3) /* Execute by others.  */
+#endif
+static QFile::Permissions unixModeToPermissions(const int mode)
+{
+    QFile::Permissions perms;
+
+    if (mode & S_IRUSR)
+    {
+        perms |= QFile::ReadUser;
+    }
+    if (mode & S_IWUSR)
+    {
+        perms |= QFile::WriteUser;
+    }
+    if (mode & S_IXUSR)
+    {
+        perms |= QFile::ExeUser;
+    }
+
+    if (mode & S_IRGRP)
+    {
+        perms |= QFile::ReadGroup;
+    }
+    if (mode & S_IWGRP)
+    {
+        perms |= QFile::WriteGroup;
+    }
+    if (mode & S_IXGRP)
+    {
+        perms |= QFile::ExeGroup;
+    }
+
+    if (mode & S_IROTH)
+    {
+        perms |= QFile::ReadOther;
+    }
+    if (mode & S_IWOTH)
+    {
+        perms |= QFile::WriteOther;
+    }
+    if (mode & S_IXOTH)
+    {
+        perms |= QFile::ExeOther;
+    }
+    return perms;
+}
+
+static const QLatin1String liveCheckFile("live.check");
+
+UpdateController::UpdateController(QWidget * parent, const QString& root, const QString updateFilesDir, GoUpdate::OperationList operations)
+{
+    m_parent = parent;
+    m_root = root;
+    m_updateFilesDir = updateFilesDir;
+    m_operations = operations;
+}
+
+
+void UpdateController::installUpdates()
+{
+    qint64 pid = -1;
+    QStringList args;
+    bool started = false;
+
+    qDebug() << "Installing updates.";
+#ifdef Q_OS_WIN
+    QString finishCmd = QApplication::applicationFilePath();
+#elif defined Q_OS_LINUX
+    QString finishCmd = FS::PathCombine(m_root, "MultiMC");
+#elif defined Q_OS_MAC
+    QString finishCmd = QApplication::applicationFilePath();
+#else
+#error Unsupported operating system.
+#endif
+
+    QString backupPath = FS::PathCombine(m_root, "update", "backup");
+    QDir origin(m_root);
+
+    // clean up the backup folder. it should be empty before we start
+    if(!FS::deletePath(backupPath))
+    {
+        qWarning() << "couldn't remove previous backup folder" << backupPath;
+    }
+    // and it should exist.
+    if(!FS::ensureFolderPathExists(backupPath))
+    {
+        qWarning() << "couldn't create folder" << backupPath;
+        return;
+    }
+
+    bool useXPHack = false;
+    QString exePath;
+    QString exeOrigin;
+    QString exeBackup;
+
+    // perform the update operations
+    for(auto op: m_operations)
+    {
+        switch(op.type)
+        {
+            // replace = move original out to backup, if it exists, move the new file in its place
+            case GoUpdate::Operation::OP_REPLACE:
+            {
+#ifdef Q_OS_WIN32
+                // hack for people renaming the .exe because ... reasons :)
+                if(op.destination == "MultiMC.exe")
+                {
+                    op.destination = QFileInfo(QApplication::applicationFilePath()).fileName();
+                }
+#endif
+                QFileInfo destination (FS::PathCombine(m_root, op.destination));
+#ifdef Q_OS_WIN32
+                if(QSysInfo::windowsVersion() < QSysInfo::WV_VISTA)
+                {
+                    if(destination.fileName() == "MultiMC.exe")
+                    {
+                        QDir rootDir(m_root);
+                        exeOrigin = rootDir.relativeFilePath(op.source);
+                        exePath = rootDir.relativeFilePath(op.destination);
+                        exeBackup = rootDir.relativeFilePath(FS::PathCombine(backupPath, destination.fileName()));
+                        useXPHack = true;
+                        continue;
+                    }
+                }
+#endif
+                if(destination.exists())
+                {
+                    QString backupName = op.destination;
+                    backupName.replace('/', '_');
+                    QString backupFilePath = FS::PathCombine(backupPath, backupName);
+                    if(!QFile::rename(destination.absoluteFilePath(), backupFilePath))
+                    {
+                        qWarning() << "Couldn't move:" << destination.absoluteFilePath() << "to" << backupFilePath;
+                        m_failedOperationType = Replace;
+                        m_failedFile = op.destination;
+                        fail();
+                        return;
+                    }
+                    BackupEntry be;
+                    be.original = destination.absoluteFilePath();
+                    be.backup = backupFilePath;
+                    be.update = op.source;
+                    m_replace_backups.append(be);
+                }
+                // make sure the folder we are putting this into exists
+                if(!FS::ensureFilePathExists(destination.absoluteFilePath()))
+                {
+                    qWarning() << "REPLACE: Couldn't create folder:" << destination.absoluteFilePath();
+                    m_failedOperationType = Replace;
+                    m_failedFile = op.destination;
+                    fail();
+                    return;
+                }
+                // now move the new file in
+                if(!QFile::rename(op.source, destination.absoluteFilePath()))
+                {
+                    qWarning() << "REPLACE: Couldn't move:" << op.source << "to" << destination.absoluteFilePath();
+                    m_failedOperationType = Replace;
+                    m_failedFile = op.destination;
+                    fail();
+                    return;
+                }
+                QFile::setPermissions(destination.absoluteFilePath(), unixModeToPermissions(op.destinationMode));
+            }
+            break;
+            // delete = move original to backup
+            case GoUpdate::Operation::OP_DELETE:
+            {
+                QString destFilePath = FS::PathCombine(m_root, op.destination);
+                if(QFile::exists(destFilePath))
+                {
+                    QString backupName = op.destination;
+                    backupName.replace('/', '_');
+                    QString trashFilePath = FS::PathCombine(backupPath, backupName);
+
+                    if(!QFile::rename(destFilePath, trashFilePath))
+                    {
+                        qWarning() << "DELETE: Couldn't move:" << op.destination << "to" << trashFilePath;
+                        m_failedFile = op.destination;
+                        m_failedOperationType = Delete;
+                        fail();
+                        return;
+                    }
+                    BackupEntry be;
+                    be.original = destFilePath;
+                    be.backup = trashFilePath;
+                    m_delete_backups.append(be);
+                }
+            }
+            break;
+        }
+    }
+
+    // try to start the new binary
+    args = qApp->arguments();
+    args.removeFirst();
+
+    // on old Windows, do insane things... no error checking here, this is just to have something.
+    if(useXPHack)
+    {
+        QString script;
+        auto nativePath = QDir::toNativeSeparators(exePath);
+        auto nativeOriginPath = QDir::toNativeSeparators(exeOrigin);
+        auto nativeBackupPath = QDir::toNativeSeparators(exeBackup);
+
+        // so we write this vbscript thing...
+        QTextStream out(&script);
+        out << "WScript.Sleep 1000\n";
+        out << "Set fso=CreateObject(\"Scripting.FileSystemObject\")\n";
+        out << "Set shell=CreateObject(\"WScript.Shell\")\n";
+        out << "fso.MoveFile \"" << nativePath << "\", \"" << nativeBackupPath << "\"\n";
+        out << "fso.MoveFile \"" << nativeOriginPath << "\", \"" << nativePath << "\"\n";
+        out << "shell.Run \"" << nativePath << "\"\n";
+
+        QString scriptPath = FS::PathCombine(m_root, "update", "update.vbs");
+
+        // we save it
+        QFile scriptFile(scriptPath);
+        scriptFile.open(QIODevice::WriteOnly);
+        scriptFile.write(script.toLocal8Bit().replace("\n", "\r\n"));
+        scriptFile.close();
+
+        // we run it
+        started = QProcess::startDetached("wscript", {scriptPath}, m_root);
+
+        // and we quit. conscious thought.
+        qApp->quit();
+        return;
+    }
+    bool doLiveCheck = true;
+    bool startFailed = false;
+
+    // remove live check file, if any
+    if(QFile::exists(liveCheckFile))
+    {
+        if(!QFile::remove(liveCheckFile))
+        {
+            qWarning() << "Couldn't remove the" << liveCheckFile << "file! We will proceed without :(";
+            doLiveCheck = false;
+        }
+    }
+
+    if(doLiveCheck)
+    {
+        if(!args.contains("--alive"))
+        {
+            args.append("--alive");
+        }
+    }
+
+    // FIXME: reparse args and construct a safe variant from scratch. This is a workaround for GH-1874:
+    QStringList realargs;
+    int skip = 0;
+    for(auto & arg: args)
+    {
+        if(skip)
+        {
+            skip--;
+            continue;
+        }
+        if(arg == "-l")
+        {
+            skip = 1;
+            continue;
+        }
+        realargs.append(arg);
+    }
+
+    // start the updated application
+    started = QProcess::startDetached(finishCmd, realargs, QDir::currentPath(), &pid);
+    // much dumber check - just find out if the call
+    if(!started || pid == -1)
+    {
+        qWarning() << "Couldn't start new process properly!";
+        startFailed = true;
+    }
+    if(!startFailed && doLiveCheck)
+    {
+        int attempts = 0;
+        while(attempts < 10)
+        {
+            attempts++;
+            QString key;
+            std::this_thread::sleep_for(std::chrono::milliseconds(250));
+            if(!QFile::exists(liveCheckFile))
+            {
+                qWarning() << "Couldn't find the" << liveCheckFile << "file!";
+                startFailed = true;
+                continue;
+            }
+            try
+            {
+                key = QString::fromUtf8(FS::read(liveCheckFile));
+                auto id = ApplicationId::fromRawString(key);
+                LocalPeer peer(nullptr, id);
+                if(peer.isClient())
+                {
+                    startFailed = false;
+                    qDebug() << "Found process started with key " << key;
+                    break;
+                }
+                else
+                {
+                    startFailed = true;
+                    qDebug() << "Process started with key " << key << "apparently died or is not reponding...";
+                    break;
+                }
+            }
+            catch (const Exception &e)
+            {
+                qWarning() << "Couldn't read the" << liveCheckFile << "file!";
+                startFailed = true;
+                continue;
+            }
+        }
+    }
+    if(startFailed)
+    {
+        m_failedOperationType = Start;
+        fail();
+        return;
+    }
+    else
+    {
+        origin.rmdir(m_updateFilesDir);
+        qApp->quit();
+        return;
+    }
+}
+
+void UpdateController::fail()
+{
+    qWarning() << "Update failed!";
+
+    QString msg;
+    bool doRollback = false;
+    QString failTitle = QObject::tr("Update failed!");
+    QString rollFailTitle = QObject::tr("Rollback failed!");
+    switch (m_failedOperationType)
+    {
+        case Replace:
+        {
+            msg = QObject::tr("Couldn't replace file %1. Changes will be reverted.\n"
+                "See the MultiMC log file for details.").arg(m_failedFile);
+            doRollback = true;
+            QMessageBox::critical(m_parent, failTitle, msg);
+            break;
+        }
+        case Delete:
+        {
+            msg = QObject::tr("Couldn't remove file %1. Changes will be reverted.\n"
+                "See the MultiMC log file for details.").arg(m_failedFile);
+            doRollback = true;
+            QMessageBox::critical(m_parent, failTitle, msg);
+            break;
+        }
+        case Start:
+        {
+            msg = QObject::tr("The new version didn't start or is too old and doesn't respond to startup checks.\n"
+                "\n"
+                "Roll back to previous version?");
+            auto result = QMessageBox::critical(
+                m_parent,
+                failTitle,
+                msg,
+                QMessageBox::Yes | QMessageBox::No,
+                QMessageBox::Yes
+            );
+            doRollback = (result == QMessageBox::Yes);
+            break;
+        }
+        case Nothing:
+        default:
+            return;
+    }
+    if(doRollback)
+    {
+        auto rollbackOK = rollback();
+        if(!rollbackOK)
+        {
+            msg = QObject::tr("The rollback failed too.\n"
+                "You will have to repair MultiMC manually.\n"
+                "Please let us know why and how this happened.").arg(m_failedFile);
+            QMessageBox::critical(m_parent, rollFailTitle, msg);
+            qApp->quit();
+        }
+    }
+    else
+    {
+        qApp->quit();
+    }
+}
+
+bool UpdateController::rollback()
+{
+    bool revertOK = true;
+    // if the above failed, roll back changes
+    for(auto backup:m_replace_backups)
+    {
+        qWarning() << "restoring" << backup.original << "from" << backup.backup;
+        if(!QFile::rename(backup.original, backup.update))
+        {
+            revertOK = false;
+            qWarning() << "moving new" << backup.original << "back to" << backup.update << "failed!";
+            continue;
+        }
+
+        if(!QFile::rename(backup.backup, backup.original))
+        {
+            revertOK = false;
+            qWarning() << "restoring" << backup.original << "failed!";
+        }
+    }
+    for(auto backup:m_delete_backups)
+    {
+        qWarning() << "restoring" << backup.original << "from" << backup.backup;
+        if(!QFile::rename(backup.backup, backup.original))
+        {
+            revertOK = false;
+            qWarning() << "restoring" << backup.original << "failed!";
+        }
+    }
+    return revertOK;
+}

launcher/UpdateController.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <QString>
+#include <QList>
+#include <updater/GoUpdate.h>
+
+class QWidget;
+
+class UpdateController
+{
+public:
+    UpdateController(QWidget * parent, const QString &root, const QString updateFilesDir, GoUpdate::OperationList operations);
+    void installUpdates();
+
+private:
+    void fail();
+    bool rollback();
+
+private:
+    QString m_root;
+    QString m_updateFilesDir;
+    GoUpdate::OperationList m_operations;
+    QWidget * m_parent;
+
+    struct BackupEntry
+    {
+        // path where we got the new file from
+        QString update;
+        // path of what is being actually updated
+        QString original;
+        // path where the backup of the updated file was placed
+        QString backup;
+    };
+    QList <BackupEntry> m_replace_backups;
+    QList <BackupEntry> m_delete_backups;
+    enum Failure
+    {
+        Replace,
+        Delete,
+        Start,
+        Nothing
+    } m_failedOperationType = Nothing;
+    QString m_failedFile;
+};

launcher/Usable.h

@@ -0,0 +1,58 @@
+#pragma once
+
+#include <cstddef>
+#include <memory>
+
+class Usable;
+
+/**
+ * Base class for things that can be used by multiple other things and we want to track the use count.
+ *
+ * @see UseLock
+ */
+class Usable
+{
+    friend class UseLock;
+public:
+    std::size_t useCount()
+    {
+        return m_useCount;
+    }
+    bool isInUse()
+    {
+        return m_useCount > 0;
+    }
+protected:
+    virtual void decrementUses()
+    {
+        m_useCount--;
+    }
+    virtual void incrementUses()
+    {
+        m_useCount++;
+    }
+private:
+    std::size_t m_useCount = 0;
+};
+
+/**
+ * Lock class to use for keeping track of uses of other things derived from Usable
+ *
+ * @see Usable
+ */
+class UseLock
+{
+public:
+    UseLock(std::shared_ptr<Usable> usable)
+        : m_usable(usable)
+    {
+        // this doesn't use shared pointer use count, because that wouldn't be correct. this count is separate.
+        m_usable->incrementUses();
+    }
+    ~UseLock()
+    {
+        m_usable->decrementUses();
+    }
+private:
+    std::shared_ptr<Usable> m_usable;
+};

launcher/Version.cpp

@@ -0,0 +1,85 @@
+#include "Version.h"
+
+#include <QStringList>
+#include <QUrl>
+#include <QRegularExpression>
+#include <QRegularExpressionMatch>
+
+Version::Version(const QString &str) : m_string(str)
+{
+    parse();
+}
+
+bool Version::operator<(const Version &other) const
+{
+    const int size = qMax(m_sections.size(), other.m_sections.size());
+    for (int i = 0; i < size; ++i)
+    {
+        const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+        const Section sec2 =
+            (i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+        if (sec1 != sec2)
+        {
+            return sec1 < sec2;
+        }
+    }
+
+    return false;
+}
+bool Version::operator<=(const Version &other) const
+{
+    return *this < other || *this == other;
+}
+bool Version::operator>(const Version &other) const
+{
+    const int size = qMax(m_sections.size(), other.m_sections.size());
+    for (int i = 0; i < size; ++i)
+    {
+        const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+        const Section sec2 =
+            (i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+        if (sec1 != sec2)
+        {
+            return sec1 > sec2;
+        }
+    }
+
+    return false;
+}
+bool Version::operator>=(const Version &other) const
+{
+    return *this > other || *this == other;
+}
+bool Version::operator==(const Version &other) const
+{
+    const int size = qMax(m_sections.size(), other.m_sections.size());
+    for (int i = 0; i < size; ++i)
+    {
+        const Section sec1 = (i >= m_sections.size()) ? Section("0") : m_sections.at(i);
+        const Section sec2 =
+            (i >= other.m_sections.size()) ? Section("0") : other.m_sections.at(i);
+        if (sec1 != sec2)
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+bool Version::operator!=(const Version &other) const
+{
+    return !operator==(other);
+}
+
+void Version::parse()
+{
+    m_sections.clear();
+
+    // FIXME: this is bad. versions can contain a lot more separators...
+    QStringList parts = m_string.split('.');
+
+    for (const auto &part : parts)
+    {
+        m_sections.append(Section(part));
+    }
+}

launcher/Version.h

@@ -0,0 +1,105 @@
+#pragma once
+
+#include <QString>
+#include <QList>
+
+class QUrl;
+
+class Version
+{
+public:
+    Version(const QString &str);
+    Version() {}
+
+    bool operator<(const Version &other) const;
+    bool operator<=(const Version &other) const;
+    bool operator>(const Version &other) const;
+    bool operator>=(const Version &other) const;
+    bool operator==(const Version &other) const;
+    bool operator!=(const Version &other) const;
+
+    QString toString() const
+    {
+        return m_string;
+    }
+
+private:
+    QString m_string;
+    struct Section
+    {
+        explicit Section(const QString &fullString)
+        {
+            m_fullString = fullString;
+            int cutoff = m_fullString.size();
+            for(int i = 0; i < m_fullString.size(); i++)
+            {
+                if(!m_fullString[i].isDigit())
+                {
+                    cutoff = i;
+                    break;
+                }
+            }
+            auto numPart = m_fullString.leftRef(cutoff);
+            if(numPart.size())
+            {
+                numValid = true;
+                m_numPart = numPart.toInt();
+            }
+            auto stringPart = m_fullString.midRef(cutoff);
+            if(stringPart.size())
+            {
+                m_stringPart = stringPart.toString();
+            }
+        }
+        explicit Section() {}
+        bool numValid = false;
+        int m_numPart = 0;
+        QString m_stringPart;
+        QString m_fullString;
+
+        inline bool operator!=(const Section &other) const
+        {
+            if(numValid && other.numValid)
+            {
+                return m_numPart != other.m_numPart || m_stringPart != other.m_stringPart;
+            }
+            else
+            {
+                return m_fullString != other.m_fullString;
+            }
+        }
+        inline bool operator<(const Section &other) const
+        {
+            if(numValid && other.numValid)
+            {
+                if(m_numPart < other.m_numPart)
+                    return true;
+                if(m_numPart == other.m_numPart && m_stringPart < other.m_stringPart)
+                    return true;
+                return false;
+            }
+            else
+            {
+                return m_fullString < other.m_fullString;
+            }
+        }
+        inline bool operator>(const Section &other) const
+        {
+            if(numValid && other.numValid)
+            {
+                if(m_numPart > other.m_numPart)
+                    return true;
+                if(m_numPart == other.m_numPart && m_stringPart > other.m_stringPart)
+                    return true;
+                return false;
+            }
+            else
+            {
+                return m_fullString > other.m_fullString;
+            }
+        }
+    };
+    QList<Section> m_sections;
+
+    void parse();
+};

launcher/VersionProxyModel.cpp

@@ -0,0 +1,447 @@
+#include "VersionProxyModel.h"
+#include "MultiMC.h"
+#include <QSortFilterProxyModel>
+#include <QPixmapCache>
+#include <Version.h>
+#include <meta/VersionList.h>
+
+class VersionFilterModel : public QSortFilterProxyModel
+{
+    Q_OBJECT
+public:
+    VersionFilterModel(VersionProxyModel *parent) : QSortFilterProxyModel(parent)
+    {
+        m_parent = parent;
+        setSortRole(BaseVersionList::SortRole);
+        sort(0, Qt::DescendingOrder);
+    }
+
+    bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const
+    {
+        const auto &filters = m_parent->filters();
+        for (auto it = filters.begin(); it != filters.end(); ++it)
+        {
+            auto idx = sourceModel()->index(source_row, 0, source_parent);
+            auto data = sourceModel()->data(idx, it.key());
+            auto match = data.toString();
+            if(!it.value()->accepts(match))
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    void filterChanged()
+    {
+        invalidateFilter();
+    }
+private:
+    VersionProxyModel *m_parent;
+};
+
+VersionProxyModel::VersionProxyModel(QObject *parent) : QAbstractProxyModel(parent)
+{
+    filterModel = new VersionFilterModel(this);
+    connect(filterModel, &QAbstractItemModel::dataChanged, this, &VersionProxyModel::sourceDataChanged);
+    connect(filterModel, &QAbstractItemModel::rowsAboutToBeInserted, this, &VersionProxyModel::sourceRowsAboutToBeInserted);
+    connect(filterModel, &QAbstractItemModel::rowsInserted, this, &VersionProxyModel::sourceRowsInserted);
+    connect(filterModel, &QAbstractItemModel::rowsAboutToBeRemoved, this, &VersionProxyModel::sourceRowsAboutToBeRemoved);
+    connect(filterModel, &QAbstractItemModel::rowsRemoved, this, &VersionProxyModel::sourceRowsRemoved);
+    // FIXME: implement when needed
+    /*
+    connect(replacing, &QAbstractItemModel::rowsAboutToBeMoved, this, &VersionProxyModel::sourceRowsAboutToBeMoved);
+    connect(replacing, &QAbstractItemModel::rowsMoved, this, &VersionProxyModel::sourceRowsMoved);
+    connect(replacing, &QAbstractItemModel::layoutAboutToBeChanged, this, &VersionProxyModel::sourceLayoutAboutToBeChanged);
+    connect(replacing, &QAbstractItemModel::layoutChanged, this, &VersionProxyModel::sourceLayoutChanged);
+    */
+    connect(filterModel, &QAbstractItemModel::modelAboutToBeReset, this, &VersionProxyModel::sourceAboutToBeReset);
+    connect(filterModel, &QAbstractItemModel::modelReset, this, &VersionProxyModel::sourceReset);
+
+    QAbstractProxyModel::setSourceModel(filterModel);
+}
+
+QVariant VersionProxyModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    if(section < 0 || section >= m_columns.size())
+        return QVariant();
+    if(orientation != Qt::Horizontal)
+        return QVariant();
+    auto column = m_columns[section];
+    if(role == Qt::DisplayRole)
+    {
+        switch(column)
+        {
+            case Name:
+                return tr("Version");
+            case ParentVersion:
+                return tr("Minecraft"); //FIXME: this should come from metadata
+            case Branch:
+                return tr("Branch");
+            case Type:
+                return tr("Type");
+            case Architecture:
+                return tr("Architecture");
+            case Path:
+                return tr("Path");
+            case Time:
+                return tr("Released");
+        }
+    }
+    else if(role == Qt::ToolTipRole)
+    {
+        switch(column)
+        {
+            case Name:
+                return tr("The name of the version.");
+            case ParentVersion:
+                return tr("Minecraft version"); //FIXME: this should come from metadata
+            case Branch:
+                return tr("The version's branch");
+            case Type:
+                return tr("The version's type");
+            case Architecture:
+                return tr("CPU Architecture");
+            case Path:
+                return tr("Filesystem path to this version");
+            case Time:
+                return tr("Release date of this version");
+        }
+    }
+    return QVariant();
+}
+
+QVariant VersionProxyModel::data(const QModelIndex &index, int role) const
+{
+    if(!index.isValid())
+    {
+        return QVariant();
+    }
+    auto column = m_columns[index.column()];
+    auto parentIndex = mapToSource(index);
+    switch(role)
+    {
+        case Qt::DisplayRole:
+        {
+            switch(column)
+            {
+                case Name:
+                {
+                    QString version = sourceModel()->data(parentIndex, BaseVersionList::VersionRole).toString();
+                    if(version == m_currentVersion)
+                    {
+                        return tr("%1 (installed)").arg(version);
+                    }
+                    return version;
+                }
+                case ParentVersion:
+                    return sourceModel()->data(parentIndex, BaseVersionList::ParentVersionRole);
+                case Branch:
+                    return sourceModel()->data(parentIndex, BaseVersionList::BranchRole);
+                case Type:
+                    return sourceModel()->data(parentIndex, BaseVersionList::TypeRole);
+                case Architecture:
+                    return sourceModel()->data(parentIndex, BaseVersionList::ArchitectureRole);
+                case Path:
+                    return sourceModel()->data(parentIndex, BaseVersionList::PathRole);
+                case Time:
+                    return sourceModel()->data(parentIndex, Meta::VersionList::TimeRole).toDate();
+                default:
+                    return QVariant();
+            }
+        }
+        case Qt::ToolTipRole:
+        {
+            switch(column)
+            {
+                case Name:
+                {
+                    if(hasRecommended)
+                    {
+                        auto value = sourceModel()->data(parentIndex, BaseVersionList::RecommendedRole);
+                        if(value.toBool())
+                        {
+                            return tr("Recommended");
+                        }
+                        else if(hasLatest)
+                        {
+                            auto value = sourceModel()->data(parentIndex, BaseVersionList::LatestRole);
+                            if(value.toBool())
+                            {
+                                return tr("Latest");
+                            }
+                        }
+                        else if(index.row() == 0)
+                        {
+                            return tr("Latest");
+                        }
+                    }
+                }
+                default:
+                {
+                    return sourceModel()->data(parentIndex, BaseVersionList::VersionIdRole);
+                }
+            }
+        }
+        case Qt::DecorationRole:
+        {
+            switch(column)
+            {
+                case Name:
+                {
+                    if(hasRecommended)
+                    {
+                        auto value = sourceModel()->data(parentIndex, BaseVersionList::RecommendedRole);
+                        if(value.toBool())
+                        {
+                            return MMC->getThemedIcon("star");
+                        }
+                        else if(hasLatest)
+                        {
+                            auto value = sourceModel()->data(parentIndex, BaseVersionList::LatestRole);
+                            if(value.toBool())
+                            {
+                                return MMC->getThemedIcon("bug");
+                            }
+                        }
+                        else if(index.row() == 0)
+                        {
+                            return MMC->getThemedIcon("bug");
+                        }
+                        auto pixmap = QPixmapCache::find("placeholder");
+                        if(!pixmap)
+                        {
+                            QPixmap px(16,16);
+                            px.fill(Qt::transparent);
+                            QPixmapCache::insert("placeholder", px);
+                            return px;
+                        }
+                        return *pixmap;
+                    }
+                }
+                default:
+                {
+                    return QVariant();
+                }
+            }
+        }
+        default:
+        {
+            if(roles.contains((BaseVersionList::ModelRoles)role))
+            {
+                return sourceModel()->data(parentIndex, role);
+            }
+            return QVariant();
+        }
+    }
+}
+
+QModelIndex VersionProxyModel::parent(const QModelIndex &child) const
+{
+    return QModelIndex();
+}
+
+QModelIndex VersionProxyModel::mapFromSource(const QModelIndex &sourceIndex) const
+{
+    if(sourceIndex.isValid())
+    {
+        return index(sourceIndex.row(), 0);
+    }
+    return QModelIndex();
+}
+
+QModelIndex VersionProxyModel::mapToSource(const QModelIndex &proxyIndex) const
+{
+    if(proxyIndex.isValid())
+    {
+        return sourceModel()->index(proxyIndex.row(), 0);
+    }
+    return QModelIndex();
+}
+
+QModelIndex VersionProxyModel::index(int row, int column, const QModelIndex &parent) const
+{
+    // no trees here... shoo
+    if(parent.isValid())
+    {
+        return QModelIndex();
+    }
+    if(row < 0 || row >= sourceModel()->rowCount())
+        return QModelIndex();
+    if(column < 0 || column >= columnCount())
+        return QModelIndex();
+    return QAbstractItemModel::createIndex(row, column);
+}
+
+int VersionProxyModel::columnCount(const QModelIndex &parent) const
+{
+    return m_columns.size();
+}
+
+int VersionProxyModel::rowCount(const QModelIndex &parent) const
+{
+    if(sourceModel())
+    {
+        return sourceModel()->rowCount();
+    }
+    return 0;
+}
+
+void VersionProxyModel::sourceDataChanged(const QModelIndex &source_top_left,
+                                          const QModelIndex &source_bottom_right)
+{
+    if(source_top_left.parent() != source_bottom_right.parent())
+        return;
+
+    // whole row is getting changed
+    auto topLeft = createIndex(source_top_left.row(), 0);
+    auto bottomRight = createIndex(source_bottom_right.row(), columnCount() - 1);
+    emit dataChanged(topLeft, bottomRight);
+}
+
+void VersionProxyModel::setSourceModel(QAbstractItemModel *replacingRaw)
+{
+    auto replacing = dynamic_cast<BaseVersionList *>(replacingRaw);
+    beginResetModel();
+
+    m_columns.clear();
+    if(!replacing)
+    {
+        roles.clear();
+        filterModel->setSourceModel(replacing);
+        return;
+    }
+
+    roles = replacing->providesRoles();
+    if(roles.contains(BaseVersionList::VersionRole))
+    {
+        m_columns.push_back(Name);
+    }
+    /*
+    if(roles.contains(BaseVersionList::ParentVersionRole))
+    {
+        m_columns.push_back(ParentVersion);
+    }
+    */
+    if(roles.contains(BaseVersionList::ArchitectureRole))
+    {
+        m_columns.push_back(Architecture);
+    }
+    if(roles.contains(BaseVersionList::PathRole))
+    {
+        m_columns.push_back(Path);
+    }
+    if(roles.contains(Meta::VersionList::TimeRole))
+    {
+        m_columns.push_back(Time);
+    }
+    if(roles.contains(BaseVersionList::BranchRole))
+    {
+        m_columns.push_back(Branch);
+    }
+    if(roles.contains(BaseVersionList::TypeRole))
+    {
+        m_columns.push_back(Type);
+    }
+    if(roles.contains(BaseVersionList::RecommendedRole))
+    {
+        hasRecommended = true;
+    }
+    if(roles.contains(BaseVersionList::LatestRole))
+    {
+        hasLatest = true;
+    }
+    filterModel->setSourceModel(replacing);
+
+    endResetModel();
+}
+
+QModelIndex VersionProxyModel::getRecommended() const
+{
+    if(!roles.contains(BaseVersionList::RecommendedRole))
+    {
+        return index(0, 0);
+    }
+    int recommended = 0;
+    for (int i = 0; i < rowCount(); i++)
+    {
+        auto value = sourceModel()->data(mapToSource(index(i, 0)), BaseVersionList::RecommendedRole);
+        if (value.toBool())
+        {
+            recommended = i;
+        }
+    }
+    return index(recommended, 0);
+}
+
+QModelIndex VersionProxyModel::getVersion(const QString& version) const
+{
+    int found = -1;
+    for (int i = 0; i < rowCount(); i++)
+    {
+        auto value = sourceModel()->data(mapToSource(index(i, 0)), BaseVersionList::VersionRole);
+        if (value.toString() == version)
+        {
+            found = i;
+        }
+    }
+    if(found == -1)
+    {
+        return QModelIndex();
+    }
+    return index(found, 0);
+}
+
+void VersionProxyModel::clearFilters()
+{
+    m_filters.clear();
+    filterModel->filterChanged();
+}
+
+void VersionProxyModel::setFilter(const BaseVersionList::ModelRoles column, Filter * f)
+{
+    m_filters[column].reset(f);
+    filterModel->filterChanged();
+}
+
+const VersionProxyModel::FilterMap &VersionProxyModel::filters() const
+{
+    return m_filters;
+}
+
+void VersionProxyModel::sourceAboutToBeReset()
+{
+    beginResetModel();
+}
+
+void VersionProxyModel::sourceReset()
+{
+    endResetModel();
+}
+
+void VersionProxyModel::sourceRowsAboutToBeInserted(const QModelIndex& parent, int first, int last)
+{
+    beginInsertRows(parent, first, last);
+}
+
+void VersionProxyModel::sourceRowsInserted(const QModelIndex& parent, int first, int last)
+{
+    endInsertRows();
+}
+
+void VersionProxyModel::sourceRowsAboutToBeRemoved(const QModelIndex& parent, int first, int last)
+{
+    beginRemoveRows(parent, first, last);
+}
+
+void VersionProxyModel::sourceRowsRemoved(const QModelIndex& parent, int first, int last)
+{
+    endRemoveRows();
+}
+
+void VersionProxyModel::setCurrentVersion(const QString &version)
+{
+    m_currentVersion = version;
+}
+
+#include "VersionProxyModel.moc"

launcher/VersionProxyModel.h

@@ -0,0 +1,67 @@
+#pragma once
+#include <QAbstractProxyModel>
+#include "BaseVersionList.h"
+
+#include <Filter.h>
+
+class VersionFilterModel;
+
+class VersionProxyModel: public QAbstractProxyModel
+{
+    Q_OBJECT
+public:
+
+    enum Column
+    {
+        Name,
+        ParentVersion,
+        Branch,
+        Type,
+        Architecture,
+        Path,
+        Time
+    };
+    typedef QHash<BaseVersionList::ModelRoles, std::shared_ptr<Filter>> FilterMap;
+
+public:
+    VersionProxyModel ( QObject* parent = 0 );
+    virtual ~VersionProxyModel() {};
+
+    virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override;
+    virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+    virtual QModelIndex mapFromSource(const QModelIndex &sourceIndex) const override;
+    virtual QModelIndex mapToSource(const QModelIndex &proxyIndex) const override;
+    virtual QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
+    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+    virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+    virtual QModelIndex parent(const QModelIndex &child) const override;
+    virtual void setSourceModel(QAbstractItemModel *sourceModel) override;
+
+    const FilterMap &filters() const;
+    void setFilter(const BaseVersionList::ModelRoles column, Filter * filter);
+    void clearFilters();
+    QModelIndex getRecommended() const;
+    QModelIndex getVersion(const QString & version) const;
+    void setCurrentVersion(const QString &version);
+private slots:
+
+    void sourceDataChanged(const QModelIndex &source_top_left,const QModelIndex &source_bottom_right);
+
+    void sourceAboutToBeReset();
+    void sourceReset();
+
+    void sourceRowsAboutToBeInserted(const QModelIndex &parent, int first, int last);
+    void sourceRowsInserted(const QModelIndex &parent, int first, int last);
+
+    void sourceRowsAboutToBeRemoved(const QModelIndex &parent, int first, int last);
+    void sourceRowsRemoved(const QModelIndex &parent, int first, int last);
+
+private:
+    QList<Column> m_columns;
+    FilterMap m_filters;
+    BaseVersionList::RoleList roles;
+    VersionFilterModel * filterModel;
+    bool hasRecommended = false;
+    bool hasLatest = false;
+    QString m_currentVersion;
+};

launcher/Version_test.cpp

@@ -0,0 +1,85 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QTest>
+
+#include "TestUtil.h"
+#include <Version.h>
+
+class ModUtilsTest : public QObject
+{
+    Q_OBJECT
+    void setupVersions()
+    {
+        QTest::addColumn<QString>("first");
+        QTest::addColumn<QString>("second");
+        QTest::addColumn<bool>("lessThan");
+        QTest::addColumn<bool>("equal");
+
+        QTest::newRow("equal, explicit") << "1.2.0" << "1.2.0" << false << true;
+        QTest::newRow("equal, implicit 1") << "1.2" << "1.2.0" << false << true;
+        QTest::newRow("equal, implicit 2") << "1.2.0" << "1.2" << false << true;
+        QTest::newRow("equal, two-digit") << "1.42" << "1.42" << false << true;
+
+        QTest::newRow("lessThan, explicit 1") << "1.2.0" << "1.2.1" << true << false;
+        QTest::newRow("lessThan, explicit 2") << "1.2.0" << "1.3.0" << true << false;
+        QTest::newRow("lessThan, explicit 3") << "1.2.0" << "2.2.0" << true << false;
+        QTest::newRow("lessThan, implicit 1") << "1.2" << "1.2.1" << true << false;
+        QTest::newRow("lessThan, implicit 2") << "1.2" << "1.3.0" << true << false;
+        QTest::newRow("lessThan, implicit 3") << "1.2" << "2.2.0" << true << false;
+        QTest::newRow("lessThan, two-digit") << "1.41" << "1.42" << true << false;
+
+        QTest::newRow("greaterThan, explicit 1") << "1.2.1" << "1.2.0" << false << false;
+        QTest::newRow("greaterThan, explicit 2") << "1.3.0" << "1.2.0" << false << false;
+        QTest::newRow("greaterThan, explicit 3") << "2.2.0" << "1.2.0" << false << false;
+        QTest::newRow("greaterThan, implicit 1") << "1.2.1" << "1.2" << false << false;
+        QTest::newRow("greaterThan, implicit 2") << "1.3.0" << "1.2" << false << false;
+        QTest::newRow("greaterThan, implicit 3") << "2.2.0" << "1.2" << false << false;
+        QTest::newRow("greaterThan, two-digit") << "1.42" << "1.41" << false << false;
+    }
+
+private slots:
+    void initTestCase()
+    {
+
+    }
+    void cleanupTestCase()
+    {
+
+    }
+
+    void test_versionCompare_data()
+    {
+        setupVersions();
+    }
+    void test_versionCompare()
+    {
+        QFETCH(QString, first);
+        QFETCH(QString, second);
+        QFETCH(bool, lessThan);
+        QFETCH(bool, equal);
+
+        const auto v1 = Version(first);
+        const auto v2 = Version(second);
+
+        QCOMPARE(v1 < v2, lessThan);
+        QCOMPARE(v1 > v2, !lessThan && !equal);
+        QCOMPARE(v1 == v2, equal);
+    }
+};
+
+QTEST_GUILESS_MAIN(ModUtilsTest)
+
+#include "Version_test.moc"

launcher/WatchLock.h

@@ -0,0 +1,20 @@
+
+#pragma once
+
+#include <QString>
+#include <QFileSystemWatcher>
+
+struct WatchLock
+{
+    WatchLock(QFileSystemWatcher * watcher, const QString& directory)
+        : m_watcher(watcher), m_directory(directory)
+    {
+        m_watcher->removePath(m_directory);
+    }
+    ~WatchLock()
+    {
+        m_watcher->addPath(m_directory);
+    }
+    QFileSystemWatcher * m_watcher;
+    QString m_directory;
+};

launcher/dialogs/AboutDialog.cpp

@@ -0,0 +1,138 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "AboutDialog.h"
+#include "ui_AboutDialog.h"
+#include <QIcon>
+#include "MultiMC.h"
+#include "BuildConfig.h"
+
+#include <net/NetJob.h>
+
+#include "HoeDown.h"
+
+namespace {
+// Credits
+// This is a hack, but I can't think of a better way to do this easily without screwing with QTextDocument...
+QString getCreditsHtml(QStringList patrons)
+{
+    QString patronsHeading = QObject::tr("Patrons", "About Credits");
+    QString output;
+    QTextStream stream(&output);
+    stream << "<center>\n";
+    // TODO: possibly retrieve from git history at build time?
+    stream << "<h3>" << QObject::tr("MultiMC Developers", "About Credits") << "</h3>\n";
+    stream << "<p>Andrew Okin &lt;<a href='mailto:forkk@forkk.net'>forkk@forkk.net</a>&gt;</p>\n";
+    stream << "<p>Petr Mrázek &lt;<a href='mailto:peterix@gmail.com'>peterix@gmail.com</a>&gt;</p>\n";
+    stream << "<p>Sky Welch &lt;<a href='mailto:multimc@bunnies.io'>multimc@bunnies.io</a>&gt;</p>\n";
+    stream << "<p>Jan (02JanDal) &lt;<a href='mailto:02jandal@gmail.com'>02jandal@gmail.com</a>&gt;</p>\n";
+    stream << "<p>RoboSky &lt;<a href='https://twitter.com/RoboSky_'>@RoboSky_</a>&gt;</p>\n";
+    stream << "<br />\n";
+
+    stream << "<h3>" << QObject::tr("With thanks to", "About Credits") << "</h3>\n";
+    stream << "<p>Orochimarufan &lt;<a href='mailto:orochimarufan.x3@gmail.com'>orochimarufan.x3@gmail.com</a>&gt;</p>\n";
+    stream << "<p>TakSuyu &lt;<a href='mailto:taksuyu@gmail.com'>taksuyu@gmail.com</a>&gt;</p>\n";
+    stream << "<p>Kilobyte &lt;<a href='mailto:stiepen22@gmx.de'>stiepen22@gmx.de</a>&gt;</p>\n";
+    stream << "<p>Rootbear75 &lt;<a href='https://twitter.com/rootbear75'>@rootbear75</a>&gt;</p>\n";
+    stream << "<p>Zeker Zhayard &lt;<a href='https://twitter.com/zeker_zhayard'>@Zeker_Zhayard</a>&gt;</p>\n";
+    stream << "<br />\n";
+
+    if(!patrons.isEmpty()) {
+        stream << "<h3>" << QObject::tr("Patrons", "About Credits") << "</h3>\n";
+        for (QString patron : patrons)
+        {
+            stream << "<p>" << patron << "</p>\n";
+        }
+    }
+    stream << "</center>\n";
+    return output;
+}
+
+QString getLicenseHtml()
+{
+    HoeDown hoedown;
+    QFile dataFile(":/documents/COPYING.md");
+    dataFile.open(QIODevice::ReadOnly);
+    QString output = hoedown.process(dataFile.readAll());
+    return output;
+}
+
+}
+
+AboutDialog::AboutDialog(QWidget *parent) : QDialog(parent), ui(new Ui::AboutDialog)
+{
+    ui->setupUi(this);
+
+    QString chtml = getCreditsHtml(QStringList());
+    ui->creditsText->setHtml(chtml);
+
+    QString lhtml = getLicenseHtml();
+    ui->licenseText->setHtml(lhtml);
+
+    ui->urlLabel->setOpenExternalLinks(true);
+
+    ui->icon->setPixmap(MMC->getThemedIcon("logo").pixmap(64));
+    ui->title->setText("MultiMC 5");
+
+    ui->versionLabel->setText(tr("Version") +": " + BuildConfig.printableVersionString());
+    ui->platformLabel->setText(tr("Platform") +": " + BuildConfig.BUILD_PLATFORM);
+
+    if (BuildConfig.VERSION_BUILD >= 0)
+        ui->buildNumLabel->setText(tr("Build Number") +": " + QString::number(BuildConfig.VERSION_BUILD));
+    else
+        ui->buildNumLabel->setVisible(false);
+
+    if (!BuildConfig.VERSION_CHANNEL.isEmpty())
+        ui->channelLabel->setText(tr("Channel") +": " + BuildConfig.VERSION_CHANNEL);
+    else
+        ui->channelLabel->setVisible(false);
+
+    ui->redistributionText->setHtml(tr(
+"<p>We keep MultiMC open source because we think it's important to be able to see the source code for a project like this, and we do so using the Apache license.</p>\n"
+"<p>Part of the reason for using the Apache license is we don't want people using the &quot;MultiMC&quot; name when redistributing the project. "
+"This means people must take the time to go through the source code and remove all references to &quot;MultiMC&quot;, including but not limited to the project "
+"icon and the title of windows, (no <b>MultiMC-fork</b> in the title).</p>\n"
+"<p>The Apache license covers reasonable use for the name - a mention of the project's origins in the About dialog and the license is acceptable. "
+"However, it should be abundantly clear that the project is a fork <b>without</b> implying that you have our blessing.</p>"
+    ));
+
+    connect(ui->closeButton, SIGNAL(clicked()), SLOT(close()));
+
+    connect(ui->aboutQt, &QPushButton::clicked, &QApplication::aboutQt);
+
+    loadPatronList();
+}
+
+AboutDialog::~AboutDialog()
+{
+    delete ui;
+}
+
+void AboutDialog::loadPatronList()
+{
+    netJob.reset(new NetJob("Patreon Patron List"));
+    netJob->addNetAction(Net::Download::makeByteArray(QUrl("https://files.multimc.org/patrons.txt"), &dataSink));
+    connect(netJob.get(), &NetJob::succeeded, this, &AboutDialog::patronListLoaded);
+    netJob->start();
+}
+
+void AboutDialog::patronListLoaded()
+{
+    QString patronListStr(dataSink);
+    dataSink.clear();
+    QString html = getCreditsHtml(patronListStr.split("\n", QString::SkipEmptyParts));
+    ui->creditsText->setHtml(html);
+}
+

launcher/dialogs/AboutDialog.h

@@ -0,0 +1,47 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QDialog>
+#include <net/NetJob.h>
+
+namespace Ui
+{
+class AboutDialog;
+}
+
+class AboutDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit AboutDialog(QWidget *parent = 0);
+    ~AboutDialog();
+
+public
+slots:
+    /// Starts loading a list of Patreon patrons.
+    void loadPatronList();
+    
+    /// Slot for when the patron list loads successfully.
+    void patronListLoaded();
+
+private:
+    Ui::AboutDialog *ui;
+
+    NetJobPtr netJob;
+    QByteArray dataSink;
+};

launcher/dialogs/AboutDialog.ui

@@ -0,0 +1,312 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>AboutDialog</class>
+ <widget class="QDialog" name="AboutDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>783</width>
+    <height>843</height>
+   </rect>
+  </property>
+  <property name="minimumSize">
+   <size>
+    <width>450</width>
+    <height>400</height>
+   </size>
+  </property>
+  <property name="windowTitle">
+   <string>About MultiMC</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
+     <item>
+      <spacer name="horizontalSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QLabel" name="icon">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+       <property name="minimumSize">
+        <size>
+         <width>64</width>
+         <height>64</height>
+        </size>
+       </property>
+       <property name="baseSize">
+        <size>
+         <width>64</width>
+         <height>64</height>
+        </size>
+       </property>
+       <property name="text">
+        <string/>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QLabel" name="title">
+     <property name="font">
+      <font>
+       <pointsize>15</pointsize>
+      </font>
+     </property>
+     <property name="text">
+      <string notr="true">MultiMC 5</string>
+     </property>
+     <property name="alignment">
+      <set>Qt::AlignCenter</set>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QTabWidget" name="tabWidget">
+     <property name="currentIndex">
+      <number>0</number>
+     </property>
+     <widget class="QWidget" name="aboutTab">
+      <attribute name="title">
+       <string>About</string>
+      </attribute>
+      <layout class="QVBoxLayout" name="verticalLayout_5">
+       <item>
+        <widget class="QLabel" name="versionLabel">
+         <property name="text">
+          <string>Version:</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="platformLabel">
+         <property name="text">
+          <string>Platform:</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="buildNumLabel">
+         <property name="text">
+          <string>Build Number:</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="channelLabel">
+         <property name="text">
+          <string>Channel:</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="aboutLabel">
+         <property name="enabled">
+          <bool>true</bool>
+         </property>
+         <property name="text">
+          <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;MultiMC is a custom launcher that makes managing Minecraft easier by allowing you to have multiple instances of Minecraft at once.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+         <property name="wordWrap">
+          <bool>true</bool>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="copyLabel">
+         <property name="font">
+          <font>
+           <pointsize>8</pointsize>
+           <kerning>true</kerning>
+          </font>
+         </property>
+         <property name="text">
+          <string>© 2012-2021 MultiMC Contributors</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="urlLabel">
+         <property name="font">
+          <font>
+           <pointsize>10</pointsize>
+          </font>
+         </property>
+         <property name="text">
+          <string notr="true">&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;&lt;a href=&quot;https://github.com/MultiMC/MultiMC5&quot;&gt;https://github.com/MultiMC/MultiMC5&lt;/a&gt;&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <spacer name="verticalSpacer">
+         <property name="orientation">
+          <enum>Qt::Vertical</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>20</width>
+           <height>212</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+      </layout>
+     </widget>
+     <widget class="QWidget" name="creditsTab">
+      <attribute name="title">
+       <string>Credits</string>
+      </attribute>
+      <layout class="QVBoxLayout" name="verticalLayout_2">
+       <item>
+        <widget class="QTextEdit" name="creditsText">
+         <property name="readOnly">
+          <bool>true</bool>
+         </property>
+         <property name="textInteractionFlags">
+          <set>Qt::TextBrowserInteraction</set>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+     <widget class="QWidget" name="licenseTab">
+      <attribute name="title">
+       <string>License</string>
+      </attribute>
+      <layout class="QVBoxLayout" name="verticalLayout_3">
+       <item>
+        <widget class="QTextEdit" name="licenseText">
+         <property name="minimumSize">
+          <size>
+           <width>0</width>
+           <height>0</height>
+          </size>
+         </property>
+         <property name="font">
+          <font>
+           <family>DejaVu Sans Mono</family>
+          </font>
+         </property>
+         <property name="readOnly">
+          <bool>true</bool>
+         </property>
+         <property name="textInteractionFlags">
+          <set>Qt::TextBrowserInteraction</set>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+     <widget class="QWidget" name="forkingTab">
+      <attribute name="title">
+       <string>Forking/Redistribution</string>
+      </attribute>
+      <layout class="QVBoxLayout" name="verticalLayout_4">
+       <item>
+        <widget class="QTextEdit" name="redistributionText">
+         <property name="textInteractionFlags">
+          <set>Qt::LinksAccessibleByKeyboard|Qt::LinksAccessibleByMouse|Qt::TextBrowserInteraction|Qt::TextSelectableByKeyboard|Qt::TextSelectableByMouse</set>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </widget>
+    </widget>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout_2">
+     <item>
+      <widget class="QPushButton" name="aboutQt">
+       <property name="autoFillBackground">
+        <bool>false</bool>
+       </property>
+       <property name="text">
+        <string>About Qt</string>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer_3">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QPushButton" name="closeButton">
+       <property name="text">
+        <string>Close</string>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+  </layout>
+ </widget>
+ <tabstops>
+  <tabstop>tabWidget</tabstop>
+  <tabstop>creditsText</tabstop>
+  <tabstop>licenseText</tabstop>
+  <tabstop>redistributionText</tabstop>
+  <tabstop>aboutQt</tabstop>
+  <tabstop>closeButton</tabstop>
+ </tabstops>
+ <resources/>
+ <connections/>
+</ui>

launcher/dialogs/CopyInstanceDialog.cpp

@@ -0,0 +1,144 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QLayout>
+#include <QPushButton>
+
+#include "MultiMC.h"
+#include "CopyInstanceDialog.h"
+#include "ui_CopyInstanceDialog.h"
+
+#include "dialogs/IconPickerDialog.h"
+
+#include "BaseVersion.h"
+#include "icons/IconList.h"
+#include "tasks/Task.h"
+#include "BaseInstance.h"
+#include "InstanceList.h"
+
+CopyInstanceDialog::CopyInstanceDialog(InstancePtr original, QWidget *parent)
+    :QDialog(parent), ui(new Ui::CopyInstanceDialog), m_original(original)
+{
+    ui->setupUi(this);
+    resize(minimumSizeHint());
+    layout()->setSizeConstraint(QLayout::SetFixedSize);
+
+    InstIconKey = original->iconKey();
+    ui->iconButton->setIcon(MMC->icons()->getIcon(InstIconKey));
+    ui->instNameTextBox->setText(original->name());
+    ui->instNameTextBox->setFocus();
+    auto groups = MMC->instances()->getGroups().toSet();
+    auto groupList = QStringList(groups.toList());
+    groupList.sort(Qt::CaseInsensitive);
+    groupList.removeOne("");
+    groupList.push_front("");
+    ui->groupBox->addItems(groupList);
+    int index = groupList.indexOf(MMC->instances()->getInstanceGroup(m_original->id()));
+    if(index == -1)
+    {
+        index = 0;
+    }
+    ui->groupBox->setCurrentIndex(index);
+    ui->groupBox->lineEdit()->setPlaceholderText(tr("No group"));
+    ui->copySavesCheckbox->setChecked(m_copySaves);
+    ui->keepPlaytimeCheckbox->setChecked(m_keepPlaytime);
+}
+
+CopyInstanceDialog::~CopyInstanceDialog()
+{
+    delete ui;
+}
+
+void CopyInstanceDialog::updateDialogState()
+{
+    auto allowOK = !instName().isEmpty();
+    auto OkButton = ui->buttonBox->button(QDialogButtonBox::Ok);
+    if(OkButton->isEnabled() != allowOK)
+    {
+        OkButton->setEnabled(allowOK);
+    }
+}
+
+QString CopyInstanceDialog::instName() const
+{
+    auto result = ui->instNameTextBox->text().trimmed();
+    if(result.size())
+    {
+        return result;
+    }
+    return QString();
+}
+
+QString CopyInstanceDialog::iconKey() const
+{
+    return InstIconKey;
+}
+
+QString CopyInstanceDialog::instGroup() const
+{
+    return ui->groupBox->currentText();
+}
+
+void CopyInstanceDialog::on_iconButton_clicked()
+{
+    IconPickerDialog dlg(this);
+    dlg.execWithSelection(InstIconKey);
+
+    if (dlg.result() == QDialog::Accepted)
+    {
+        InstIconKey = dlg.selectedIconKey;
+        ui->iconButton->setIcon(MMC->icons()->getIcon(InstIconKey));
+    }
+}
+
+void CopyInstanceDialog::on_instNameTextBox_textChanged(const QString &arg1)
+{
+    updateDialogState();
+}
+
+bool CopyInstanceDialog::shouldCopySaves() const
+{
+    return m_copySaves;
+}
+
+void CopyInstanceDialog::on_copySavesCheckbox_stateChanged(int state)
+{
+    if(state == Qt::Unchecked)
+    {
+        m_copySaves = false;
+    }
+    else if(state == Qt::Checked)
+    {
+        m_copySaves = true;
+    }
+}
+
+bool CopyInstanceDialog::shouldKeepPlaytime() const
+{
+    return m_keepPlaytime;
+}
+
+
+void CopyInstanceDialog::on_keepPlaytimeCheckbox_stateChanged(int state)
+{
+    if(state == Qt::Unchecked)
+    {
+        m_keepPlaytime = false;
+    }
+    else if(state == Qt::Checked)
+    {
+        m_keepPlaytime = true;
+    }
+}

launcher/dialogs/CopyInstanceDialog.h

@@ -0,0 +1,58 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QDialog>
+#include "BaseVersion.h"
+#include <BaseInstance.h>
+
+class BaseInstance;
+
+namespace Ui
+{
+class CopyInstanceDialog;
+}
+
+class CopyInstanceDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit CopyInstanceDialog(InstancePtr original, QWidget *parent = 0);
+    ~CopyInstanceDialog();
+
+    void updateDialogState();
+
+    QString instName() const;
+    QString instGroup() const;
+    QString iconKey() const;
+    bool shouldCopySaves() const;
+    bool shouldKeepPlaytime() const;
+
+private
+slots:
+    void on_iconButton_clicked();
+    void on_instNameTextBox_textChanged(const QString &arg1);
+    void on_copySavesCheckbox_stateChanged(int state);
+    void on_keepPlaytimeCheckbox_stateChanged(int state);
+
+private:
+    Ui::CopyInstanceDialog *ui;
+    QString InstIconKey;
+    InstancePtr m_original;
+    bool m_copySaves = true;
+    bool m_keepPlaytime = true;
+};

launcher/dialogs/CopyInstanceDialog.ui

@@ -0,0 +1,182 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>CopyInstanceDialog</class>
+ <widget class="QDialog" name="CopyInstanceDialog">
+  <property name="windowModality">
+   <enum>Qt::ApplicationModal</enum>
+  </property>
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>345</width>
+    <height>323</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Copy Instance</string>
+  </property>
+  <property name="windowIcon">
+   <iconset>
+    <normaloff>:/icons/toolbar/copy</normaloff>:/icons/toolbar/copy</iconset>
+  </property>
+  <property name="modal">
+   <bool>true</bool>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <layout class="QHBoxLayout" name="iconBtnLayout">
+     <item>
+      <spacer name="iconBtnLeftSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+     <item>
+      <widget class="QToolButton" name="iconButton">
+       <property name="icon">
+        <iconset>
+         <normaloff>:/icons/instances/infinity</normaloff>:/icons/instances/infinity</iconset>
+       </property>
+       <property name="iconSize">
+        <size>
+         <width>80</width>
+         <height>80</height>
+        </size>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="iconBtnRightSpacer">
+       <property name="orientation">
+        <enum>Qt::Horizontal</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QLineEdit" name="instNameTextBox">
+     <property name="placeholderText">
+      <string>Name</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="Line" name="line">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <layout class="QGridLayout" name="gridLayout">
+     <item row="0" column="0">
+      <widget class="QLabel" name="labelVersion_3">
+       <property name="text">
+        <string>&amp;Group</string>
+       </property>
+       <property name="buddy">
+        <cstring>groupBox</cstring>
+       </property>
+      </widget>
+     </item>
+     <item row="0" column="1" colspan="2">
+      <widget class="QComboBox" name="groupBox">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+       <property name="editable">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item>
+    <widget class="QCheckBox" name="copySavesCheckbox">
+     <property name="text">
+      <string>Copy saves</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QCheckBox" name="keepPlaytimeCheckbox">
+     <property name="text">
+      <string>Keep play time</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <tabstops>
+  <tabstop>iconButton</tabstop>
+  <tabstop>instNameTextBox</tabstop>
+  <tabstop>groupBox</tabstop>
+  <tabstop>copySavesCheckbox</tabstop>
+  <tabstop>keepPlaytimeCheckbox</tabstop>
+ </tabstops>
+ <resources>
+  <include location="../../graphics.qrc"/>
+ </resources>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>CopyInstanceDialog</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>CopyInstanceDialog</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>

launcher/dialogs/CustomMessageBox.cpp

@@ -0,0 +1,35 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "CustomMessageBox.h"
+
+namespace CustomMessageBox
+{
+QMessageBox *selectable(QWidget *parent, const QString &title, const QString &text,
+                        QMessageBox::Icon icon, QMessageBox::StandardButtons buttons,
+                        QMessageBox::StandardButton defaultButton)
+{
+    QMessageBox *messageBox = new QMessageBox(parent);
+    messageBox->setWindowTitle(title);
+    messageBox->setText(text);
+    messageBox->setStandardButtons(buttons);
+    messageBox->setDefaultButton(defaultButton);
+    messageBox->setTextInteractionFlags(Qt::TextSelectableByMouse);
+    messageBox->setIcon(icon);
+    messageBox->setTextInteractionFlags(Qt::TextBrowserInteraction);
+
+    return messageBox;
+}
+}

launcher/dialogs/CustomMessageBox.h

@@ -0,0 +1,26 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QMessageBox>
+
+namespace CustomMessageBox
+{
+QMessageBox *selectable(QWidget *parent, const QString &title, const QString &text,
+                        QMessageBox::Icon icon = QMessageBox::NoIcon,
+                        QMessageBox::StandardButtons buttons = QMessageBox::Ok,
+                        QMessageBox::StandardButton defaultButton = QMessageBox::NoButton);
+}

launcher/dialogs/EditAccountDialog.cpp

@@ -0,0 +1,61 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "EditAccountDialog.h"
+#include "ui_EditAccountDialog.h"
+#include <DesktopServices.h>
+#include <QUrl>
+
+EditAccountDialog::EditAccountDialog(const QString &text, QWidget *parent, int flags)
+    : QDialog(parent), ui(new Ui::EditAccountDialog)
+{
+    ui->setupUi(this);
+
+    ui->label->setText(text);
+    ui->label->setVisible(!text.isEmpty());
+
+    ui->userTextBox->setEnabled(flags & UsernameField);
+    ui->passTextBox->setEnabled(flags & PasswordField);
+}
+
+EditAccountDialog::~EditAccountDialog()
+{
+    delete ui;
+}
+
+void EditAccountDialog::on_label_linkActivated(const QString &link)
+{
+    DesktopServices::openUrl(QUrl(link));
+}
+
+void EditAccountDialog::setUsername(const QString & user) const
+{
+    ui->userTextBox->setText(user);
+}
+
+QString EditAccountDialog::username() const
+{
+    return ui->userTextBox->text();
+}
+
+void EditAccountDialog::setPassword(const QString & pass) const
+{
+    ui->passTextBox->setText(pass);
+}
+
+QString EditAccountDialog::password() const
+{
+    return ui->passTextBox->text();
+}

launcher/dialogs/EditAccountDialog.h

@@ -0,0 +1,56 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QDialog>
+
+namespace Ui
+{
+class EditAccountDialog;
+}
+
+class EditAccountDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit EditAccountDialog(const QString &text = "", QWidget *parent = 0,
+                               int flags = UsernameField | PasswordField);
+    ~EditAccountDialog();
+
+    void setUsername(const QString & user) const;
+    void setPassword(const QString & pass) const;
+
+    QString username() const;
+    QString password() const;
+
+    enum Flags
+    {
+        NoFlags = 0,
+
+        //! Specifies that the dialog should have a username field.
+        UsernameField,
+
+        //! Specifies that the dialog should have a password field.
+        PasswordField,
+    };
+
+private slots:
+  void on_label_linkActivated(const QString &link);
+
+private:
+    Ui::EditAccountDialog *ui;
+};

launcher/dialogs/EditAccountDialog.ui

@@ -0,0 +1,94 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>EditAccountDialog</class>
+ <widget class="QDialog" name="EditAccountDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>400</width>
+    <height>148</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Login</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <widget class="QLabel" name="label">
+     <property name="text">
+      <string notr="true">Message label placeholder.</string>
+     </property>
+     <property name="textFormat">
+      <enum>Qt::RichText</enum>
+     </property>
+     <property name="textInteractionFlags">
+      <set>Qt::LinksAccessibleByKeyboard|Qt::LinksAccessibleByMouse|Qt::TextBrowserInteraction|Qt::TextSelectableByKeyboard|Qt::TextSelectableByMouse</set>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QLineEdit" name="userTextBox">
+     <property name="placeholderText">
+      <string>Email</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QLineEdit" name="passTextBox">
+     <property name="echoMode">
+      <enum>QLineEdit::Password</enum>
+     </property>
+     <property name="placeholderText">
+      <string>Password</string>
+     </property>
+    </widget>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>EditAccountDialog</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>EditAccountDialog</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>

launcher/dialogs/ExportInstanceDialog.cpp

@@ -0,0 +1,482 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ExportInstanceDialog.h"
+#include "ui_ExportInstanceDialog.h"
+#include <BaseInstance.h>
+#include <MMCZip.h>
+#include <QFileDialog>
+#include <QMessageBox>
+#include <qfilesystemmodel.h>
+
+#include <QSortFilterProxyModel>
+#include <QDebug>
+#include <qstack.h>
+#include <QSaveFile>
+#include "MMCStrings.h"
+#include "SeparatorPrefixTree.h"
+#include "MultiMC.h"
+#include <icons/IconList.h>
+#include <FileSystem.h>
+
+class PackIgnoreProxy : public QSortFilterProxyModel
+{
+    Q_OBJECT
+
+public:
+    PackIgnoreProxy(InstancePtr instance, QObject *parent) : QSortFilterProxyModel(parent)
+    {
+        m_instance = instance;
+    }
+    // NOTE: Sadly, we have to do sorting ourselves.
+    bool lessThan(const QModelIndex &left, const QModelIndex &right) const
+    {
+        QFileSystemModel *fsm = qobject_cast<QFileSystemModel *>(sourceModel());
+        if (!fsm)
+        {
+            return QSortFilterProxyModel::lessThan(left, right);
+        }
+        bool asc = sortOrder() == Qt::AscendingOrder ? true : false;
+
+        QFileInfo leftFileInfo = fsm->fileInfo(left);
+        QFileInfo rightFileInfo = fsm->fileInfo(right);
+
+        if (!leftFileInfo.isDir() && rightFileInfo.isDir())
+        {
+            return !asc;
+        }
+        if (leftFileInfo.isDir() && !rightFileInfo.isDir())
+        {
+            return asc;
+        }
+
+        // sort and proxy model breaks the original model...
+        if (sortColumn() == 0)
+        {
+            return Strings::naturalCompare(leftFileInfo.fileName(), rightFileInfo.fileName(),
+                                           Qt::CaseInsensitive) < 0;
+        }
+        if (sortColumn() == 1)
+        {
+            auto leftSize = leftFileInfo.size();
+            auto rightSize = rightFileInfo.size();
+            if ((leftSize == rightSize) || (leftFileInfo.isDir() && rightFileInfo.isDir()))
+            {
+                return Strings::naturalCompare(leftFileInfo.fileName(),
+                                               rightFileInfo.fileName(),
+                                               Qt::CaseInsensitive) < 0
+                           ? asc
+                           : !asc;
+            }
+            return leftSize < rightSize;
+        }
+        return QSortFilterProxyModel::lessThan(left, right);
+    }
+
+    virtual Qt::ItemFlags flags(const QModelIndex &index) const
+    {
+        if (!index.isValid())
+            return Qt::NoItemFlags;
+
+        auto sourceIndex = mapToSource(index);
+        Qt::ItemFlags flags = sourceIndex.flags();
+        if (index.column() == 0)
+        {
+            flags |= Qt::ItemIsUserCheckable;
+            if (sourceIndex.model()->hasChildren(sourceIndex))
+            {
+                flags |= Qt::ItemIsTristate;
+            }
+        }
+
+        return flags;
+    }
+
+    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const
+    {
+        QModelIndex sourceIndex = mapToSource(index);
+
+        if (index.column() == 0 && role == Qt::CheckStateRole)
+        {
+            QFileSystemModel *fsm = qobject_cast<QFileSystemModel *>(sourceModel());
+            auto blockedPath = relPath(fsm->filePath(sourceIndex));
+            auto cover = blocked.cover(blockedPath);
+            if (!cover.isNull())
+            {
+                return QVariant(Qt::Unchecked);
+            }
+            else if (blocked.exists(blockedPath))
+            {
+                return QVariant(Qt::PartiallyChecked);
+            }
+            else
+            {
+                return QVariant(Qt::Checked);
+            }
+        }
+
+        return sourceIndex.data(role);
+    }
+
+    virtual bool setData(const QModelIndex &index, const QVariant &value,
+                         int role = Qt::EditRole)
+    {
+        if (index.column() == 0 && role == Qt::CheckStateRole)
+        {
+            Qt::CheckState state = static_cast<Qt::CheckState>(value.toInt());
+            return setFilterState(index, state);
+        }
+
+        QModelIndex sourceIndex = mapToSource(index);
+        return QSortFilterProxyModel::sourceModel()->setData(sourceIndex, value, role);
+    }
+
+    QString relPath(const QString &path) const
+    {
+        QString prefix = QDir().absoluteFilePath(m_instance->instanceRoot());
+        prefix += '/';
+        if (!path.startsWith(prefix))
+        {
+            return QString();
+        }
+        return path.mid(prefix.size());
+    }
+
+    bool setFilterState(QModelIndex index, Qt::CheckState state)
+    {
+        QFileSystemModel *fsm = qobject_cast<QFileSystemModel *>(sourceModel());
+
+        if (!fsm)
+        {
+            return false;
+        }
+
+        QModelIndex sourceIndex = mapToSource(index);
+        auto blockedPath = relPath(fsm->filePath(sourceIndex));
+        bool changed = false;
+        if (state == Qt::Unchecked)
+        {
+            // blocking a path
+            auto &node = blocked.insert(blockedPath);
+            // get rid of all blocked nodes below
+            node.clear();
+            changed = true;
+        }
+        else if (state == Qt::Checked || state == Qt::PartiallyChecked)
+        {
+            if (!blocked.remove(blockedPath))
+            {
+                auto cover = blocked.cover(blockedPath);
+                qDebug() << "Blocked by cover" << cover;
+                // uncover
+                blocked.remove(cover);
+                // block all contents, except for any cover
+                QModelIndex rootIndex =
+                    fsm->index(FS::PathCombine(m_instance->instanceRoot(), cover));
+                QModelIndex doing = rootIndex;
+                int row = 0;
+                QStack<QModelIndex> todo;
+                while (1)
+                {
+                    auto node = doing.child(row, 0);
+                    if (!node.isValid())
+                    {
+                        if (!todo.size())
+                        {
+                            break;
+                        }
+                        else
+                        {
+                            doing = todo.pop();
+                            row = 0;
+                            continue;
+                        }
+                    }
+                    auto relpath = relPath(fsm->filePath(node));
+                    if (blockedPath.startsWith(relpath)) // cover found?
+                    {
+                        // continue processing cover later
+                        todo.push(node);
+                    }
+                    else
+                    {
+                        // or just block this one.
+                        blocked.insert(relpath);
+                    }
+                    row++;
+                }
+            }
+            changed = true;
+        }
+        if (changed)
+        {
+            // update the thing
+            emit dataChanged(index, index, {Qt::CheckStateRole});
+            // update everything above index
+            QModelIndex up = index.parent();
+            while (1)
+            {
+                if (!up.isValid())
+                    break;
+                emit dataChanged(up, up, {Qt::CheckStateRole});
+                up = up.parent();
+            }
+            // and everything below the index
+            QModelIndex doing = index;
+            int row = 0;
+            QStack<QModelIndex> todo;
+            while (1)
+            {
+                auto node = doing.child(row, 0);
+                if (!node.isValid())
+                {
+                    if (!todo.size())
+                    {
+                        break;
+                    }
+                    else
+                    {
+                        doing = todo.pop();
+                        row = 0;
+                        continue;
+                    }
+                }
+                emit dataChanged(node, node, {Qt::CheckStateRole});
+                todo.push(node);
+                row++;
+            }
+            // siblings and unrelated nodes are ignored
+        }
+        return true;
+    }
+
+    bool shouldExpand(QModelIndex index)
+    {
+        QModelIndex sourceIndex = mapToSource(index);
+        QFileSystemModel *fsm = qobject_cast<QFileSystemModel *>(sourceModel());
+        if (!fsm)
+        {
+            return false;
+        }
+        auto blockedPath = relPath(fsm->filePath(sourceIndex));
+        auto found = blocked.find(blockedPath);
+        if(found)
+        {
+            return !found->leaf();
+        }
+        return false;
+    }
+
+    void setBlockedPaths(QStringList paths)
+    {
+        beginResetModel();
+        blocked.clear();
+        blocked.insert(paths);
+        endResetModel();
+    }
+
+    const SeparatorPrefixTree<'/'> & blockedPaths() const
+    {
+        return blocked;
+    }
+
+protected:
+    bool filterAcceptsColumn(int source_column, const QModelIndex &source_parent) const
+    {
+        Q_UNUSED(source_parent)
+
+        // adjust the columns you want to filter out here
+        // return false for those that will be hidden
+        if (source_column == 2 || source_column == 3)
+            return false;
+
+        return true;
+    }
+
+private:
+    InstancePtr m_instance;
+    SeparatorPrefixTree<'/'> blocked;
+};
+
+ExportInstanceDialog::ExportInstanceDialog(InstancePtr instance, QWidget *parent)
+    : QDialog(parent), ui(new Ui::ExportInstanceDialog), m_instance(instance)
+{
+    ui->setupUi(this);
+    auto model = new QFileSystemModel(this);
+    proxyModel = new PackIgnoreProxy(m_instance, this);
+    loadPackIgnore();
+    proxyModel->setSourceModel(model);
+    auto root = instance->instanceRoot();
+    ui->treeView->setModel(proxyModel);
+    ui->treeView->setRootIndex(proxyModel->mapFromSource(model->index(root)));
+    ui->treeView->sortByColumn(0, Qt::AscendingOrder);
+
+    connect(proxyModel, SIGNAL(rowsInserted(QModelIndex,int,int)), SLOT(rowsInserted(QModelIndex,int,int)));
+
+    model->setFilter(QDir::AllEntries | QDir::NoDotAndDotDot | QDir::AllDirs | QDir::Hidden);
+    model->setRootPath(root);
+    auto headerView = ui->treeView->header();
+    headerView->setSectionResizeMode(QHeaderView::ResizeToContents);
+    headerView->setSectionResizeMode(0, QHeaderView::Stretch);
+}
+
+ExportInstanceDialog::~ExportInstanceDialog()
+{
+    delete ui;
+}
+
+/// Save icon to instance's folder is needed
+void SaveIcon(InstancePtr m_instance)
+{
+    auto iconKey = m_instance->iconKey();
+    auto iconList = MMC->icons();
+    auto mmcIcon = iconList->icon(iconKey);
+    if(!mmcIcon || mmcIcon->isBuiltIn()) {
+        return;
+    }
+    auto path = mmcIcon->getFilePath();
+    if(!path.isNull()) {
+        QFileInfo inInfo (path);
+        FS::copy(path, FS::PathCombine(m_instance->instanceRoot(), inInfo.fileName())) ();
+        return;
+    }
+    auto & image = mmcIcon->m_images[mmcIcon->type()];
+    auto & icon = image.icon;
+    auto sizes = icon.availableSizes();
+    if(sizes.size() == 0)
+    {
+        return;
+    }
+    auto areaOf = [](QSize size)
+    {
+        return size.width() * size.height();
+    };
+    QSize largest = sizes[0];
+    // find variant with largest area
+    for(auto size: sizes)
+    {
+        if(areaOf(largest) < areaOf(size))
+        {
+            largest = size;
+        }
+    }
+    auto pixmap = icon.pixmap(largest);
+    pixmap.save(FS::PathCombine(m_instance->instanceRoot(), iconKey + ".png"));
+}
+
+bool ExportInstanceDialog::doExport()
+{
+    auto name = FS::RemoveInvalidFilenameChars(m_instance->name());
+
+    const QString output = QFileDialog::getSaveFileName(
+        this, tr("Export %1").arg(m_instance->name()),
+        FS::PathCombine(QDir::homePath(), name + ".zip"), "Zip (*.zip)", nullptr, QFileDialog::DontConfirmOverwrite);
+    if (output.isEmpty())
+    {
+        return false;
+    }
+    if (QFile::exists(output))
+    {
+        int ret =
+            QMessageBox::question(this, tr("Overwrite?"),
+                                  tr("This file already exists. Do you want to overwrite it?"),
+                                  QMessageBox::No, QMessageBox::Yes);
+        if (ret == QMessageBox::No)
+        {
+            return false;
+        }
+    }
+
+    SaveIcon(m_instance);
+
+    auto & blocked = proxyModel->blockedPaths();
+    using std::placeholders::_1;
+    if (!JlCompress::compressDir(output, m_instance->instanceRoot(), name, std::bind(&SeparatorPrefixTree<'/'>::covers, blocked, _1)))
+    {
+        QMessageBox::warning(this, tr("Error"), tr("Unable to export instance"));
+        return false;
+    }
+    return true;
+}
+
+void ExportInstanceDialog::done(int result)
+{
+    savePackIgnore();
+    if (result == QDialog::Accepted)
+    {
+        if (doExport())
+        {
+            QDialog::done(QDialog::Accepted);
+            return;
+        }
+        else
+        {
+            return;
+        }
+    }
+    QDialog::done(result);
+}
+
+void ExportInstanceDialog::rowsInserted(QModelIndex parent, int top, int bottom)
+{
+    //WARNING: possible off-by-one?
+    for(int i = top; i < bottom; i++)
+    {
+        auto node = parent.child(i, 0);
+        if(proxyModel->shouldExpand(node))
+        {
+            auto expNode = node.parent();
+            if(!expNode.isValid())
+            {
+                continue;
+            }
+            ui->treeView->expand(node);
+        }
+    }
+}
+
+QString ExportInstanceDialog::ignoreFileName()
+{
+    return FS::PathCombine(m_instance->instanceRoot(), ".packignore");
+}
+
+void ExportInstanceDialog::loadPackIgnore()
+{
+    auto filename = ignoreFileName();
+    QFile ignoreFile(filename);
+    if(!ignoreFile.open(QIODevice::ReadOnly))
+    {
+        return;
+    }
+    auto data = ignoreFile.readAll();
+    auto string = QString::fromUtf8(data);
+    proxyModel->setBlockedPaths(string.split('\n', QString::SkipEmptyParts));
+}
+
+void ExportInstanceDialog::savePackIgnore()
+{
+    auto data = proxyModel->blockedPaths().toStringList().join('\n').toUtf8();
+    auto filename = ignoreFileName();
+    try
+    {
+        FS::write(filename, data);
+    }
+    catch (const Exception &e)
+    {
+        qWarning() << e.cause();
+    }
+}
+
+#include "ExportInstanceDialog.moc"

launcher/dialogs/ExportInstanceDialog.h

@@ -0,0 +1,54 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <QDialog>
+#include <QModelIndex>
+#include <memory>
+
+class BaseInstance;
+class PackIgnoreProxy;
+typedef std::shared_ptr<BaseInstance> InstancePtr;
+
+namespace Ui
+{
+class ExportInstanceDialog;
+}
+
+class ExportInstanceDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit ExportInstanceDialog(InstancePtr instance, QWidget *parent = 0);
+    ~ExportInstanceDialog();
+
+    virtual void done(int result);
+
+private:
+    bool doExport();
+    void loadPackIgnore();
+    void savePackIgnore();
+    QString ignoreFileName();
+
+private:
+    Ui::ExportInstanceDialog *ui;
+    InstancePtr m_instance;
+    PackIgnoreProxy * proxyModel;
+
+private slots:
+    void rowsInserted(QModelIndex parent, int top, int bottom);
+};

launcher/dialogs/ExportInstanceDialog.ui

@@ -0,0 +1,83 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>ExportInstanceDialog</class>
+ <widget class="QDialog" name="ExportInstanceDialog">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>720</width>
+    <height>625</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Export Instance</string>
+  </property>
+  <layout class="QVBoxLayout" name="verticalLayout">
+   <item>
+    <widget class="QTreeView" name="treeView">
+     <property name="alternatingRowColors">
+      <bool>true</bool>
+     </property>
+     <property name="selectionMode">
+      <enum>QAbstractItemView::ExtendedSelection</enum>
+     </property>
+     <property name="sortingEnabled">
+      <bool>true</bool>
+     </property>
+     <attribute name="headerStretchLastSection">
+      <bool>false</bool>
+     </attribute>
+    </widget>
+   </item>
+   <item>
+    <widget class="QDialogButtonBox" name="buttonBox">
+     <property name="orientation">
+      <enum>Qt::Horizontal</enum>
+     </property>
+     <property name="standardButtons">
+      <set>QDialogButtonBox::Cancel|QDialogButtonBox::Ok</set>
+     </property>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <tabstops>
+  <tabstop>treeView</tabstop>
+ </tabstops>
+ <resources/>
+ <connections>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>accepted()</signal>
+   <receiver>ExportInstanceDialog</receiver>
+   <slot>accept()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>248</x>
+     <y>254</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>157</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>buttonBox</sender>
+   <signal>rejected()</signal>
+   <receiver>ExportInstanceDialog</receiver>
+   <slot>reject()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>316</x>
+     <y>260</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>286</x>
+     <y>274</y>
+    </hint>
+   </hints>
+  </connection>
+ </connections>
+</ui>

launcher/dialogs/IconPickerDialog.cpp

@@ -0,0 +1,163 @@
+/* Copyright 2013-2021 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <QKeyEvent>
+#include <QPushButton>
+#include <QFileDialog>
+
+#include "MultiMC.h"
+
+#include "IconPickerDialog.h"
+#include "ui_IconPickerDialog.h"
+
+#include "groupview/InstanceDelegate.h"
+
+#include "icons/IconList.h"
+#include "icons/IconUtils.h"
+#include <DesktopServices.h>
+
+IconPickerDialog::IconPickerDialog(QWidget *parent)
+    : QDialog(parent), ui(new Ui::IconPickerDialog)
+{
+    ui->setupUi(this);
+    setWindowModality(Qt::WindowModal);
+
+    auto contentsWidget = ui->iconView;
+    contentsWidget->setViewMode(QListView::IconMode);
+    contentsWidget->setFlow(QListView::LeftToRight);
+    contentsWidget->setIconSize(QSize(48, 48));
+    contentsWidget->setMovement(QListView::Static);
+    contentsWidget->setResizeMode(QListView::Adjust);
+    contentsWidget->setSelectionMode(QAbstractItemView::SingleSelection);
+    contentsWidget->setSpacing(5);
+    contentsWidget->setWordWrap(false);
+    contentsWidget->setWrapping(true);
+    contentsWidget->setUniformItemSizes(true);
+    contentsWidget->setTextElideMode(Qt::ElideRight);
+    contentsWidget->setVerticalScrollMode(QAbstractItemView::ScrollPerPixel);
+    contentsWidget->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
+    contentsWidget->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    contentsWidget->setItemDelegate(new ListViewDelegate());
+
+    // contentsWidget->setAcceptDrops(true);
+    contentsWidget->setDropIndicatorShown(true);
+    contentsWidget->viewport()->setAcceptDrops(true);
+    contentsWidget->setDragDropMode(QAbstractItemView::DropOnly);
+    contentsWidget->setDefaultDropAction(Qt::CopyAction);
+
+    contentsWidget->installEventFilter(this);
+
+    contentsWidget->setModel(MMC->icons().get());
+
+    // NOTE: ResetRole forces the button to be on the left, while the OK/Cancel ones are on the right. We win.
+    auto buttonAdd = ui->buttonBox->addButton(tr("Add Icon"), QDialogButtonBox::ResetRole);
+    auto buttonRemove = ui->buttonBox->addButton(tr("Remove Icon"), QDialogButtonBox::ResetRole);
+
+    connect(buttonAdd, SIGNAL(clicked(bool)), SLOT(addNewIcon()));
+    connect(buttonRemove, SIGNAL(clicked(bool)), SLOT(removeSelectedIcon()));
+
+    connect(contentsWidget, SIGNAL(doubleClicked(QModelIndex)), SLOT(activated(QModelIndex)));
+
+    connect(contentsWidget->selectionModel(), SIGNAL(selectionChanged(QItemSelection, QItemSelection)), SLOT(selectionChanged(QItemSelection, QItemSelection)));
+
+    auto buttonFolder = ui->buttonBox->addButton(tr("Open Folder"), QDialogButtonBox::ResetRole);
+    connect(buttonFolder, &QPushButton::clicked, this, &IconPickerDialog::openFolder);
+}
+
+bool IconPickerDialog::eventFilter(QObject *obj, QEvent *evt)
+{
+    if (obj != ui->iconView)
+        return QDialog::eventFilter(obj, evt);
+    if (evt->type() != QEvent::KeyPress)
+    {
+        return QDialog::eventFilter(obj, evt);
+    }
+    QKeyEvent *keyEvent = static_cast<QKeyEvent *>(evt);
+    switch (keyEvent->key())
+    {
+    case Qt::Key_Delete:
+        removeSelectedIcon();
+        return true;
+    case Qt::Key_Plus:
+        addNewIcon();
+        return true;
+    default:
+        break;
+    }
+    return QDialog::eventFilter(obj, evt);
+}
+
+void IconPickerDialog::addNewIcon()
+{
+    //: The title of the select icons open file dialog
+    QString selectIcons = tr("Select Icons");
+    //: The type of icon files
+    auto filter = IconUtils::getIconFilter();
+    QStringList fileNames = QFileDialog::getOpenFileNames(this, selectIcons, QString(), tr("Icons %1").arg(filter));
+    MMC->icons()->installIcons(fileNames);
+}
+
+void IconPickerDialog::removeSelectedIcon()
+{
+    MMC->icons()->deleteIcon(selectedIconKey);
+}
+
+void IconPickerDialog::activated(QModelIndex index)
+{
+    selectedIconKey = index.data(Qt::UserRole).toString();
+    accept();
+}
+
+void IconPickerDialog::selectionChanged(QItemSelection selected, QItemSelection deselected)
+{
+    if (selected.empty())
+        return;
+
+    QString key = selected.first().indexes().first().data(Qt::UserRole).toString();
+    if (!key.isEmpty())
+        selectedIconKey = key;
+}
+
+int IconPickerDialog::execWithSelection(QString selection)
+{
+    auto list = MMC->icons();
+    auto contentsWidget = ui->iconView;
+    selectedIconKey = selection;
+
+    int index_nr = list->getIconIndex(selection);
+    auto model_index = list->index(index_nr);
+    contentsWidget->selectionModel()->select(
+        model_index, QItemSelectionModel::Current | QItemSelectionModel::Select);
+
+    QMetaObject::invokeMethod(this, "delayed_scroll", Qt::QueuedConnection,
+                              Q_ARG(QModelIndex, model_index));
+    return QDialog::exec();
+}
+
+void IconPickerDialog::delayed_scroll(QModelIndex model_index)
+{
+    auto contentsWidget = ui->iconView;
+    contentsWidget->scrollTo(model_index);
+}
+
+IconPickerDialog::~IconPickerDialog()
+{
+    delete ui;
+}
+
+void IconPickerDialog::openFolder()
+{
+    DesktopServices::openDirectory(MMC->icons()->getDirectory(), true);
+}