fix: sorting by pack format

Signed-off-by: flow <flowlnlnln@gmail.com>

launcher/minecraft/mod/ResourcePack.cpp

@@ -41,8 +41,31 @@ std::pair<Version, Version> ResourcePack::compatibleVersions() const
         // but if we did and we still don't have a valid pack format, that's a bit concerning.
         Q_ASSERT(!isResolved());
 
-        return {{}, {}};
+        return { {}, {} };
     }
 
     return s_pack_format_versions.constFind(m_pack_format).value();
 }
+
+std::pair<int, bool> ResourcePack::compare(const Resource& other, SortType type) const
+{
+    auto const& cast_other = static_cast<ResourcePack const&>(other);
+
+    switch (type) {
+        default: {
+            auto res = Resource::compare(other, type);
+            if (res.first != 0)
+                return res;
+        }
+        case SortType::PACK_FORMAT: {
+            auto this_ver = packFormat();
+            auto other_ver = cast_other.packFormat();
+
+            if (this_ver > other_ver)
+                return { 1, type == SortType::PACK_FORMAT };
+            if (this_ver < other_ver)
+                return { -1, type == SortType::PACK_FORMAT };
+        }
+    }
+    return { 0, false };
+}