NOISSUE refactor *Download into more, smaller pieces

* Download is now Download.
* Download uses Sink subclasses to process various events.
* Validators can be used to further customize the Sink behaviour.

api/logic/net/FileSink.cpp

@@ -0,0 +1,99 @@
+#include "FileSink.h"
+#include <QFile>
+#include <QFileInfo>
+#include "Env.h"
+#include "FileSystem.h"
+
+namespace Net {
+
+FileSink::FileSink(QString filename)
+	:m_filename(filename)
+{
+	// nil
+};
+
+FileSink::~FileSink()
+{
+	// nil
+};
+
+JobStatus FileSink::init(QNetworkRequest& request)
+{
+	auto result = initCache(request);
+	if(result != Job_InProgress)
+	{
+		return result;
+	}
+	// create a new save file and open it for writing
+	if (!FS::ensureFilePathExists(m_filename))
+	{
+		qCritical() << "Could not create folder for " + m_filename;
+		return Job_Failed;
+	}
+	m_output_file.reset(new QSaveFile(m_filename));
+	if (!m_output_file->open(QIODevice::WriteOnly))
+	{
+		qCritical() << "Could not open " + m_filename + " for writing";
+		return Job_Failed;
+	}
+
+	if(initAllValidators(request))
+		return Job_InProgress;
+	return Job_Failed;
+}
+
+JobStatus FileSink::initCache(QNetworkRequest &)
+{
+	return Job_InProgress;
+}
+
+JobStatus FileSink::write(QByteArray& data)
+{
+	if (!writeAllValidators(data) || m_output_file->write(data) != data.size())
+	{
+		qCritical() << "Failed writing into " + m_filename;
+		m_output_file->cancelWriting();
+		m_output_file.reset();
+		wroteAnyData = false;
+		return Job_Failed;
+	}
+	wroteAnyData = true;
+	return Job_InProgress;
+}
+
+JobStatus FileSink::abort()
+{
+	m_output_file->cancelWriting();
+	failAllValidators();
+	return Job_Failed;
+}
+
+JobStatus FileSink::finalize(QNetworkReply& reply)
+{
+	// if we wrote any data to the save file, we try to commit the data to the real file.
+	if (wroteAnyData)
+	{
+		// ask validators for data consistency
+		// we only do this for actual downloads, not 'your data is still the same' cache hits
+		if(!finalizeAllValidators(reply))
+			return Job_Failed;
+		// nothing went wrong...
+		if (!m_output_file->commit())
+		{
+			qCritical() << "Failed to commit changes to " << m_filename;
+			m_output_file->cancelWriting();
+			return Job_Failed;
+		}
+	}
+	// then get rid of the save file
+	m_output_file.reset();
+
+	return finalizeCache(reply);
+}
+
+JobStatus FileSink::finalizeCache(QNetworkReply &)
+{
+	return Job_Finished;
+}
+
+}