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>

8 files changed, 265 insertions, 16 deletions

diff --git a/launcher/minecraft/mod/Mod.cpp b/launcher/minecraft/mod/Mod.cpp
index f28fd32a..ed91d999 100644
--- a/launcher/minecraft/mod/Mod.cpp
+++ b/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) {
diff --git a/launcher/minecraft/mod/Mod.h b/launcher/minecraft/mod/Mod.h
index 313c478c..25ac88c9 100644
--- a/launcher/minecraft/mod/Mod.h
+++ b/launcher/minecraft/mod/Mod.h
@@ -70,6 +70,9 @@ public:
 
     auto enable(bool value) -> bool;
 
+    [[nodiscard]] auto compare(Resource const& other, SortType type) const -> std::pair<int, bool> override;
+    [[nodiscard]] bool applyFilter(QRegularExpression filter) const override;
+
     // Delete all the files of this mod
     auto destroy(QDir& index_dir, bool preserve_metadata = false) -> bool;
 
diff --git a/launcher/minecraft/mod/ModFolderModel.cpp b/launcher/minecraft/mod/ModFolderModel.cpp
index 8ab60413..9b8c58bc 100644
--- a/launcher/minecraft/mod/ModFolderModel.cpp
+++ b/launcher/minecraft/mod/ModFolderModel.cpp
@@ -52,6 +52,7 @@
 ModFolderModel::ModFolderModel(const QString &dir, bool is_indexed) : ResourceFolderModel(dir), m_is_indexed(is_indexed)
 {
     FS::ensureFolderPathExists(m_dir.absolutePath());
+    m_column_sort_keys = { SortType::ENABLED, SortType::NAME, SortType::VERSION, SortType::DATE };
 }
 
 QVariant ModFolderModel::data(const QModelIndex &index, int role) const
@@ -213,16 +214,16 @@ bool ModFolderModel::isValid()
     return m_dir.exists() && m_dir.isReadable();
 }
 
-void ModFolderModel::startWatching()
+bool ModFolderModel::startWatching()
 {
     // Remove orphaned metadata next time
     m_first_folder_load = true;
-    ResourceFolderModel::startWatching({ m_dir.absolutePath(), indexDir().absolutePath() });
+    return ResourceFolderModel::startWatching({ m_dir.absolutePath(), indexDir().absolutePath() });
 }
 
-void ModFolderModel::stopWatching()
+bool ModFolderModel::stopWatching()
 {
-    ResourceFolderModel::stopWatching({ m_dir.absolutePath(), indexDir().absolutePath() });
+    return ResourceFolderModel::stopWatching({ m_dir.absolutePath(), indexDir().absolutePath() });
 }
 
 auto ModFolderModel::selectedMods(QModelIndexList& indexes) -> QList<Mod::Ptr>
diff --git a/launcher/minecraft/mod/ModFolderModel.h b/launcher/minecraft/mod/ModFolderModel.h
index ea9f0000..b1f30710 100644
--- a/launcher/minecraft/mod/ModFolderModel.h
+++ b/launcher/minecraft/mod/ModFolderModel.h
@@ -91,15 +91,13 @@ public:
     /// Deletes all the selected mods
     bool deleteMods(const QModelIndexList &indexes);
 
-    void disableInteraction(bool disabled) { ResourceFolderModel::enableInteraction(!disabled); }
-
     /// Enable or disable listed mods
     bool setModStatus(const QModelIndexList &indexes, ModStatusAction action);
 
     bool isValid();
 
-    void startWatching();
-    void stopWatching();
+    bool startWatching() override;
+    bool stopWatching() override;
 
     QDir indexDir() { return { QString("%1/.index").arg(dir().absolutePath()) }; }
 
diff --git a/launcher/minecraft/mod/Resource.cpp b/launcher/minecraft/mod/Resource.cpp
index 8771a20f..c58df3d8 100644
--- a/launcher/minecraft/mod/Resource.cpp
+++ b/launcher/minecraft/mod/Resource.cpp
@@ -1,5 +1,7 @@
 #include "Resource.h"
 
+#include <QRegularExpression>
+
 #include "FileSystem.h"
 
 Resource::Resource(QObject* parent) : QObject(parent) {}
@@ -46,6 +48,43 @@ void Resource::parseFile()
     m_changed_date_time = m_file_info.lastModified();
 }
 
+static void removeThePrefix(QString& string)
+{
+    QRegularExpression regex(QStringLiteral("^(?:the|teh) +"), QRegularExpression::CaseInsensitiveOption);
+    string.remove(regex);
+    string = string.trimmed();
+}
+
+std::pair<int, bool> Resource::compare(const Resource& other, SortType type) const
+{
+    switch (type) {
+        default:
+        case SortType::NAME: {
+            QString this_name{ name() };
+            QString other_name{ other.name() };
+
+            removeThePrefix(this_name);
+            removeThePrefix(other_name);
+
+            auto compare_result = QString::compare(this_name, other_name, Qt::CaseInsensitive);
+            if (compare_result != 0)
+                return { compare_result, type == SortType::NAME };
+        }
+        case SortType::DATE:
+            if (dateTimeChanged() > other.dateTimeChanged())
+                return { 1, type == SortType::DATE };
+            if (dateTimeChanged() < other.dateTimeChanged())
+                return { -1, type == SortType::DATE };
+    }
+
+    return { 0, false };
+}
+
+bool Resource::applyFilter(QRegularExpression filter) const
+{
+    return filter.match(name()).hasMatch();
+}
+
 bool Resource::destroy()
 {
     m_type = ResourceType::UNKNOWN;
diff --git a/launcher/minecraft/mod/Resource.h b/launcher/minecraft/mod/Resource.h
index c348c7e2..68663ab0 100644
--- a/launcher/minecraft/mod/Resource.h
+++ b/launcher/minecraft/mod/Resource.h
@@ -14,6 +14,13 @@ enum class ResourceType {
     LITEMOD,     //!< The resource is a litemod
 };
 
+enum class SortType {
+    NAME,
+    DATE,
+    VERSION,
+    ENABLED,
+};
+
 /** General class for managed resources. It mirrors a file in disk, with some more info
  *  for display and house-keeping purposes.
  *
@@ -40,6 +47,20 @@ class Resource : public QObject {
     [[nodiscard]] virtual auto name() const -> QString { return m_name; }
     [[nodiscard]] virtual bool valid() const { return m_type != ResourceType::UNKNOWN; }
 
+    /** Compares two Resources, for sorting purposes, considering a ascending order, returning:
+     *  > 0: 'this' comes after 'other'
+     *  = 0: 'this' is equal to 'other'
+     *  < 0: 'this' comes before 'other'
+     *
+     *  The second argument in the pair is true if the sorting type that decided which one is greater was 'type'.
+     */
+    [[nodiscard]] virtual auto compare(Resource const& other, SortType type = SortType::NAME) const -> std::pair<int, bool>;
+
+    /** Returns whether the given filter should filter out 'this' (false),
+     *  or if such filter includes the Resource (true).
+     */
+    [[nodiscard]] virtual bool applyFilter(QRegularExpression filter) const;
+
     [[nodiscard]] auto shouldResolve() const -> bool { return !m_is_resolving && !m_is_resolved; }
     [[nodiscard]] auto isResolving() const -> bool { return m_is_resolving; }
     [[nodiscard]] auto resolutionTicket() const -> int { return m_resolution_ticket; }
diff --git a/launcher/minecraft/mod/ResourceFolderModel.cpp b/launcher/minecraft/mod/ResourceFolderModel.cpp
index 4867a8c2..982915e2 100644
--- a/launcher/minecraft/mod/ResourceFolderModel.cpp
+++ b/launcher/minecraft/mod/ResourceFolderModel.cpp
@@ -170,8 +170,11 @@ bool ResourceFolderModel::update()
     }
 
     m_current_update_task.reset(createUpdateTask());
+    if (!m_current_update_task)
+        return false;
 
-    connect(m_current_update_task.get(), &Task::succeeded, this, &ResourceFolderModel::onUpdateSucceeded, Qt::ConnectionType::QueuedConnection);
+    connect(m_current_update_task.get(), &Task::succeeded, this, &ResourceFolderModel::onUpdateSucceeded,
+            Qt::ConnectionType::QueuedConnection);
     connect(m_current_update_task.get(), &Task::failed, this, &ResourceFolderModel::onUpdateFailed, Qt::ConnectionType::QueuedConnection);
 
     auto* thread_pool = QThreadPool::globalInstance();
@@ -187,6 +190,8 @@ void ResourceFolderModel::resolveResource(Resource::Ptr res)
     }
 
     auto task = createParseTask(*res);
+    if (!task)
+        return;
 
     m_ticket_mutex.lock();
     int ticket = m_next_resolution_ticket;
@@ -196,8 +201,10 @@ void ResourceFolderModel::resolveResource(Resource::Ptr res)
     res->setResolving(true, ticket);
     m_active_parse_tasks.insert(ticket, task);
 
-    connect(task, &Task::succeeded, this, [=] { onParseSucceeded(ticket, res->internal_id()); }, Qt::ConnectionType::QueuedConnection);
-    connect(task, &Task::failed, this, [=] { onParseFailed(ticket, res->internal_id()); }, Qt::ConnectionType::QueuedConnection);
+    connect(
+        task, &Task::succeeded, this, [=] { onParseSucceeded(ticket, res->internal_id()); }, Qt::ConnectionType::QueuedConnection);
+    connect(
+        task, &Task::failed, this, [=] { onParseFailed(ticket, res->internal_id()); }, Qt::ConnectionType::QueuedConnection);
 
     auto* thread_pool = QThreadPool::globalInstance();
     thread_pool->start(task);
@@ -325,6 +332,71 @@ bool ResourceFolderModel::validateIndex(const QModelIndex& index) const
     return true;
 }
 
+QVariant ResourceFolderModel::data(const QModelIndex& index, int role) const
+{
+    if (!validateIndex(index))
+        return {};
+
+    int row = index.row();
+    int column = index.column();
+
+    switch (role) {
+        case Qt::DisplayRole:
+            switch (column) {
+                case NAME_COLUMN:
+                    return m_resources[row]->name();
+                case DATE_COLUMN:
+                    return m_resources[row]->dateTimeChanged();
+                default:
+                    return {};
+            }
+        case Qt::ToolTipRole:
+            return m_resources[row]->internal_id();
+        default:
+            return {};
+    }
+}
+
+QVariant ResourceFolderModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    switch (role) {
+        case Qt::DisplayRole:
+            switch (section) {
+                case NAME_COLUMN:
+                    return tr("Name");
+                case DATE_COLUMN:
+                    return tr("Last modified");
+                default:
+                    return {};
+            }
+        case Qt::ToolTipRole: {
+            switch (section) {
+                case NAME_COLUMN:
+                    return tr("The name of the resource.");
+                case DATE_COLUMN:
+                    return tr("The date and time this resource was last changed (or added).");
+                default:
+                    return {};
+            }
+        }
+        default:
+            break;
+    }
+
+    return {};
+}
+
+QSortFilterProxyModel* ResourceFolderModel::createFilterProxyModel(QObject* parent)
+{
+    return new ProxyModel(parent);
+}
+
+SortType ResourceFolderModel::columnToSortKey(size_t column) const
+{
+    Q_ASSERT(m_column_sort_keys.size() == columnCount());
+    return m_column_sort_keys.at(column);
+}
+
 void ResourceFolderModel::enableInteraction(bool enabled)
 {
     if (m_can_interact == enabled)
@@ -334,3 +406,39 @@ void ResourceFolderModel::enableInteraction(bool enabled)
     if (size())
         emit dataChanged(index(0), index(size() - 1));
 }
+
+/* Standard Proxy Model for createFilterProxyModel */
+[[nodiscard]] bool ResourceFolderModel::ProxyModel::filterAcceptsRow(int source_row, const QModelIndex& source_parent) const
+{
+    auto* model = qobject_cast<ResourceFolderModel*>(sourceModel());
+    if (!model)
+        return true;
+
+    const auto& resource = model->at(source_row);
+
+    return resource.applyFilter(filterRegularExpression());
+}
+
+[[nodiscard]] bool ResourceFolderModel::ProxyModel::lessThan(const QModelIndex& source_left, const QModelIndex& source_right) const
+{
+    auto* model = qobject_cast<ResourceFolderModel*>(sourceModel());
+    if (!model || !source_left.isValid() || !source_right.isValid() || source_left.column() != source_right.column()) {
+        return QSortFilterProxyModel::lessThan(source_left, source_right);
+    }
+
+    // we are now guaranteed to have two valid indexes in the same column... we love the provided invariants unconditionally and
+    // proceed.
+
+    auto column_sort_key = model->columnToSortKey(source_left.column());
+    auto const& resource_left = model->at(source_left.row());
+    auto const& resource_right = model->at(source_right.row());
+
+    auto compare_result = resource_left.compare(resource_right, column_sort_key);
+    if (compare_result.first == 0)
+        return QSortFilterProxyModel::lessThan(source_left, source_right);
+
+    if (compare_result.second || sortOrder() != Qt::DescendingOrder)
+        return (compare_result.first < 0);
+    return (compare_result.first > 0);
+}
+
diff --git a/launcher/minecraft/mod/ResourceFolderModel.h b/launcher/minecraft/mod/ResourceFolderModel.h
index 31fd7414..2ccf14f0 100644
--- a/launcher/minecraft/mod/ResourceFolderModel.h
+++ b/launcher/minecraft/mod/ResourceFolderModel.h
@@ -5,12 +5,13 @@
 #include <QFileSystemWatcher>
 #include <QMutex>
 #include <QSet>
+#include <QSortFilterProxyModel>
 
 #include "Resource.h"
 
 #include "tasks/Task.h"
 
-class QRunnable;
+class QSortFilterProxyModel;
 
 /** A basic model for external resources.
  *
@@ -38,6 +39,10 @@ class ResourceFolderModel : public QAbstractListModel {
      */
     bool stopWatching(const QStringList paths);
 
+    /* Helper methods for subclasses, using a predetermined list of paths. */
+    virtual bool startWatching() { return startWatching({ m_dir.absolutePath() }); };
+    virtual bool stopWatching() { return stopWatching({ m_dir.absolutePath() }); };
+
     /** Given a path in the system, install that resource, moving it to its place in the
      *  instance file hierarchy.
      *
@@ -61,13 +66,18 @@ class ResourceFolderModel : public QAbstractListModel {
 
     [[nodiscard]] size_t size() const { return m_resources.size(); };
     [[nodiscard]] bool empty() const { return size() == 0; }
+    [[nodiscard]] Resource const& at(int index) const { return *m_resources.at(index); }
+    [[nodiscard]] QList<Resource::Ptr> const& all() const { return m_resources; }
 
     [[nodiscard]] QDir const& dir() const { return m_dir; }
 
     /* Qt behavior */
 
-    [[nodiscard]] int rowCount(const QModelIndex&) const override { return size(); }
-    [[nodiscard]] int columnCount(const QModelIndex&) const override = 0;
+    /* Basic columns */
+    enum Columns { NAME_COLUMN = 0, DATE_COLUMN, NUM_COLUMNS };
+
+    [[nodiscard]] int rowCount(const QModelIndex& = {}) const override { return size(); }
+    [[nodiscard]] int columnCount(const QModelIndex& = {}) const override { return NUM_COLUMNS; };
 
     [[nodiscard]] Qt::DropActions supportedDropActions() const override;
 
@@ -78,13 +88,31 @@ class ResourceFolderModel : public QAbstractListModel {
 
     [[nodiscard]] bool validateIndex(const QModelIndex& index) const;
 
-    [[nodiscard]] QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override = 0;
+    [[nodiscard]] QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
     bool setData(const QModelIndex& index, const QVariant& value, int role = Qt::EditRole) override { return false; };
 
-    [[nodiscard]] QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override = 0;
+    [[nodiscard]] QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+
+    /** This creates a proxy model to filter / sort the model for a UI.
+     *
+     *  The actual comparisons and filtering are done directly by the Resource, so to modify behavior go there instead!
+     */
+    QSortFilterProxyModel* createFilterProxyModel(QObject* parent = nullptr);
+
+    [[nodiscard]] SortType columnToSortKey(size_t column) const;
+
+    class ProxyModel : public QSortFilterProxyModel {
+       public:
+        explicit ProxyModel(QObject* parent = nullptr) : QSortFilterProxyModel(parent) {}
+
+       protected:
+        [[nodiscard]] bool filterAcceptsRow(int source_row, const QModelIndex& source_parent) const override;
+        [[nodiscard]] bool lessThan(const QModelIndex& source_left, const QModelIndex& source_right) const override;
+    };
 
    public slots:
     void enableInteraction(bool enabled);
+    void disableInteraction(bool disabled) { enableInteraction(!disabled); }
 
    signals:
     void updateFinished();
@@ -137,6 +165,10 @@ class ResourceFolderModel : public QAbstractListModel {
     virtual void onParseFailed(int ticket, QString resource_id) {}
 
    protected:
+    // Represents the relationship between a column's index (represented by the list index), and it's sorting key.
+    // As such, the order in with they appear is very important!
+    QList<SortType> m_column_sort_keys = { SortType::NAME, SortType::DATE };
+
     bool m_can_interact = true;
 
     QDir m_dir;