refactor: move more tied logic to model and move logic to the resources

This moves the QSortFilterProxyModel to the resource model files,
acessible via a factory method, and moves the sorting and filtering to
the objects themselves, decoupling the code a bit.

This also adds a basic implementation of methods in the
ResourceFolderModel, simplifying the process of constructing a new model
from it.

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

launcher/minecraft/mod/Mod.cpp

@@ -39,8 +39,10 @@
 #include <QDebug>
 #include <QDir>
 #include <QString>
+#include <QRegularExpression>
 
 #include "MetadataHandler.h"
+#include "Version.h"
 
 namespace {
 
@@ -111,6 +113,51 @@ void Mod::setMetadata(const Metadata::ModStruct& metadata)
     }
 }
 
+std::pair<int, bool> Mod::compare(const Resource& other, SortType type) const
+{
+    auto cast_other = dynamic_cast<Mod const*>(&other);
+    if (!cast_other)
+        return Resource::compare(other, type);
+
+    switch (type) {
+        default:
+        case SortType::ENABLED:
+            if (enabled() && !cast_other->enabled())
+                return { 1, type == SortType::ENABLED };
+            if (!enabled() && cast_other->enabled())
+                return { -1, type == SortType::ENABLED };
+        case SortType::NAME:
+        case SortType::DATE: {
+            auto res = Resource::compare(other, type);
+            if (res.first != 0)
+                return res;
+        }
+        case SortType::VERSION: {
+            auto this_ver = Version(version());
+            auto other_ver = Version(cast_other->version());
+            if (this_ver > other_ver)
+                return { 1, type == SortType::VERSION };
+            if (this_ver < other_ver)
+                return { -1, type == SortType::VERSION };
+        }
+    }
+    return { 0, false };
+}
+
+bool Mod::applyFilter(QRegularExpression filter) const
+{
+    if (filter.match(description()).hasMatch())
+        return true;
+
+    for (auto& author : authors()) {
+        if (filter.match(author).hasMatch()) {
+            return true;
+        }
+    }
+
+    return Resource::applyFilter(filter);
+}
+
 auto Mod::destroy(QDir& index_dir, bool preserve_metadata) -> bool
 {
     if (!preserve_metadata) {