refactor: generalize mod models and APIs to resources

Firstly, this abstract away behavior in the mod download models that can
also be applied to other types of resources into a superclass, allowing
other resource types to be implemented without so much code duplication.

For that, this also generalizes the APIs used (currently, ModrinthAPI
and FlameAPI) to be able to make requests to other types of resources.

It also does a general cleanup of both of those. In particular, this
makes use of std::optional instead of invalid values for errors and,
well, optional values :p

This is a squash of some commits that were becoming too interlaced
together to be cleanly separated.

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

19 files changed, 1022 insertions, 735 deletions

diff --git a/launcher/ui/pages/instance/ModFolderPage.cpp b/launcher/ui/pages/instance/ModFolderPage.cpp
index 627e71e5..1bce3c0d 100644
--- a/launcher/ui/pages/instance/ModFolderPage.cpp
+++ b/launcher/ui/pages/instance/ModFolderPage.cpp
@@ -59,7 +59,7 @@
 #include "minecraft/mod/Mod.h"
 #include "minecraft/mod/ModFolderModel.h"
 
-#include "modplatform/ModAPI.h"
+#include "modplatform/ResourceAPI.h"
 
 #include "Version.h"
 #include "tasks/ConcurrentTask.h"
@@ -153,12 +153,12 @@ void ModFolderPage::installMods()
         return;  // this is a null instance or a legacy instance
 
     auto profile = static_cast<MinecraftInstance*>(m_instance)->getPackProfile();
-    if (profile->getModLoaders() == ModAPI::Unspecified) {
+    if (!profile->getModLoaders().has_value()) {
         QMessageBox::critical(this, tr("Error"), tr("Please install a mod loader first!"));
         return;
     }
 
-    ModDownloadDialog mdownload(m_model, this, m_instance);
+    ModDownloadDialog mdownload(this, m_model, m_instance);
     if (mdownload.exec()) {
         ConcurrentTask* tasks = new ConcurrentTask(this);
         connect(tasks, &Task::failed, [this, tasks](QString reason) {
diff --git a/launcher/ui/pages/instance/ResourcePackPage.h b/launcher/ui/pages/instance/ResourcePackPage.h
index 9633e3b4..db8af0c5 100644
--- a/launcher/ui/pages/instance/ResourcePackPage.h
+++ b/launcher/ui/pages/instance/ResourcePackPage.h
@@ -73,3 +73,4 @@ public:
         return true;
     }
 };
+
diff --git a/launcher/ui/pages/modplatform/ModModel.cpp b/launcher/ui/pages/modplatform/ModModel.cpp
index ed58eb32..31aae746 100644
--- a/launcher/ui/pages/modplatform/ModModel.cpp
+++ b/launcher/ui/pages/modplatform/ModModel.cpp
@@ -1,226 +1,81 @@
 #include "ModModel.h"
 
-#include "BuildConfig.h"
 #include "Json.h"
 #include "ModPage.h"
 #include "minecraft/MinecraftInstance.h"
 #include "minecraft/PackProfile.h"
-#include "ui/dialogs/ModDownloadDialog.h"
-
-#include "ui/widgets/ProjectItem.h"
 
 #include <QMessageBox>
 
 namespace ModPlatform {
 
-// HACK: We need this to prevent callbacks from calling the ListModel after it has already been deleted.
-// This leaks a tiny bit of memory per time the user has opened the mod dialog. How to make this better?
-static QHash<ListModel*, bool> s_running;
-
-ListModel::ListModel(ModPage* parent) : QAbstractListModel(parent), m_parent(parent) { s_running.insert(this, true); }
-
-ListModel::~ListModel()
-{
-    s_running.find(this).value() = false;
-}
-
-auto ListModel::debugName() const -> QString
-{
-    return m_parent->debugName();
-}
+ListModel::ListModel(ModPage* parent, ResourceAPI* api) : ResourceModel(parent, api) {}
 
 /******** Make data requests ********/
 
-void ListModel::fetchMore(const QModelIndex& parent)
+ResourceAPI::SearchArgs ListModel::createSearchArguments()
 {
-    if (parent.isValid())
-        return;
-    if (nextSearchOffset == 0) {
-        qWarning() << "fetchMore with 0 offset is wrong...";
-        return;
-    }
-    performPaginatedSearch();
+    auto profile = static_cast<MinecraftInstance&>(m_associated_page->m_base_instance).getPackProfile();
+    return { ModPlatform::ResourceType::MOD, m_next_search_offset,     m_search_term,
+             getSorts()[currentSort],        profile->getModLoaders(), getMineVersions() };
 }
-
-auto ListModel::data(const QModelIndex& index, int role) const -> QVariant
+ResourceAPI::SearchCallbacks ListModel::createSearchCallbacks()
 {
-    int pos = index.row();
-    if (pos >= modpacks.size() || pos < 0 || !index.isValid()) {
-        return QString("INVALID INDEX %1").arg(pos);
-    }
-
-    ModPlatform::IndexedPack pack = modpacks.at(pos);
-    switch (role) {
-        case Qt::ToolTipRole: {
-            if (pack.description.length() > 100) {
-                // some magic to prevent to long tooltips and replace html linebreaks
-                QString edit = pack.description.left(97);
-                edit = edit.left(edit.lastIndexOf("<br>")).left(edit.lastIndexOf(" ")).append("...");
-                return edit;
-            }
-            return pack.description;
-        }
-        case Qt::DecorationRole: {
-            if (m_logoMap.contains(pack.logoName)) {
-                return m_logoMap.value(pack.logoName);
-            }
-            QIcon icon = APPLICATION->getThemedIcon("screenshot-placeholder");
-            // un-const-ify this
-            ((ListModel*)this)->requestLogo(pack.logoName, pack.logoUrl);
-            return icon;
-        }
-        case Qt::SizeHintRole: 
-            return QSize(0, 58);
-        case Qt::UserRole: {
-            QVariant v;
-            v.setValue(pack);
-            return v;
-        }
-    // Custom data
-        case UserDataTypes::TITLE:
-            return pack.name;
-        case UserDataTypes::DESCRIPTION:
-            return pack.description;
-        case UserDataTypes::SELECTED:
-            return m_parent->getDialog()->isModSelected(pack.name);
-        default:
-            break;
-    }
-
-    return {};
+    return { [this](auto& doc) {
+        if (!s_running_models.constFind(this).value())
+            return;
+        searchRequestFinished(doc);
+    } };
 }
 
-bool ListModel::setData(const QModelIndex &index, const QVariant &value, int role)
+ResourceAPI::VersionSearchArgs ListModel::createVersionsArguments(QModelIndex& entry)
 {
-    int pos = index.row();
-    if (pos >= modpacks.size() || pos < 0 || !index.isValid())
-        return false;
+    auto const& pack = m_packs[entry.row()];
+    auto profile = static_cast<MinecraftInstance&>(m_associated_page->m_base_instance).getPackProfile();
 
-    modpacks[pos] = value.value<ModPlatform::IndexedPack>();
-
-    return true;
+    return { pack.addonId.toString(), getMineVersions(), profile->getModLoaders() };
 }
-
-void ListModel::requestModVersions(ModPlatform::IndexedPack const& current, QModelIndex index)
+ResourceAPI::VersionSearchCallbacks ListModel::createVersionsCallbacks(QModelIndex& entry)
 {
-    auto profile = (dynamic_cast<MinecraftInstance*>((dynamic_cast<ModPage*>(parent()))->m_instance))->getPackProfile();
-
-    m_parent->apiProvider()->getVersions({ current.addonId.toString(), getMineVersions(), profile->getModLoaders() },
-                                         [this, current, index](QJsonDocument& doc, QString addonId) {
-                                             if (!s_running.constFind(this).value())
-                                                 return;
-                                             versionRequestSucceeded(doc, addonId, index);
-                                         });
-}
-
-void ListModel::performPaginatedSearch()
-{
-    auto profile = (dynamic_cast<MinecraftInstance*>((dynamic_cast<ModPage*>(parent()))->m_instance))->getPackProfile();
+    auto const& pack = m_packs[entry.row()];
 
-    m_parent->apiProvider()->searchMods(
-        this, { nextSearchOffset, currentSearchTerm, getSorts()[currentSort], profile->getModLoaders(), getMineVersions() });
+    return { [this, pack, entry](auto& doc, auto addonId) {
+        if (!s_running_models.constFind(this).value())
+            return;
+        versionRequestSucceeded(doc, addonId, entry);
+    } };
 }
 
-void ListModel::requestModInfo(ModPlatform::IndexedPack& current, QModelIndex index)
+ResourceAPI::ProjectInfoArgs ListModel::createInfoArguments(QModelIndex& entry)
 {
-    m_parent->apiProvider()->getModInfo(current, [this, index](QJsonDocument& doc, ModPlatform::IndexedPack& pack) {
-        if (!s_running.constFind(this).value())
-            return;
-        infoRequestFinished(doc, pack, index);
-    });
+    auto& pack = m_packs[entry.row()];
+    return { pack };
 }
-
-void ListModel::refresh()
+ResourceAPI::ProjectInfoCallbacks ListModel::createInfoCallbacks(QModelIndex& entry)
 {
-    if (jobPtr) {
-        jobPtr->abort();
-        searchState = ResetRequested;
-        return;
-    } else {
-        beginResetModel();
-        modpacks.clear();
-        endResetModel();
-        searchState = None;
-    }
-    nextSearchOffset = 0;
-    performPaginatedSearch();
+    return { [this, entry](auto& doc, auto& pack) {
+        if (!s_running_models.constFind(this).value())
+            return;
+        infoRequestFinished(doc, pack, entry);
+    } };
 }
 
 void ListModel::searchWithTerm(const QString& term, const int sort, const bool filter_changed)
 {
-    if (currentSearchTerm == term && currentSearchTerm.isNull() == term.isNull() && currentSort == sort && !filter_changed) {
+    if (m_search_term == term && m_search_term.isNull() == term.isNull() && currentSort == sort && !filter_changed) {
         return;
     }
 
-    currentSearchTerm = term;
+    setSearchTerm(term);
     currentSort = sort;
 
     refresh();
 }
 
-void ListModel::getLogo(const QString& logo, const QString& logoUrl, LogoCallback callback)
-{
-    if (m_logoMap.contains(logo)) {
-        callback(APPLICATION->metacache()
-                     ->resolveEntry(m_parent->metaEntryBase(), QString("logos/%1").arg(logo.section(".", 0, 0)))
-                     ->getFullPath());
-    } else {
-        requestLogo(logo, logoUrl);
-    }
-}
-
-void ListModel::requestLogo(QString logo, QString url)
-{
-    if (m_loadingLogos.contains(logo) || m_failedLogos.contains(logo) || url.isEmpty()) {
-        return;
-    }
-
-    MetaEntryPtr entry =
-        APPLICATION->metacache()->resolveEntry(m_parent->metaEntryBase(), QString("logos/%1").arg(logo.section(".", 0, 0)));
-    auto job = new NetJob(QString("%1 Icon Download %2").arg(m_parent->debugName()).arg(logo), APPLICATION->network());
-    job->addNetAction(Net::Download::makeCached(QUrl(url), entry));
-
-    auto fullPath = entry->getFullPath();
-    QObject::connect(job, &NetJob::succeeded, this, [this, logo, fullPath, job] {
-        job->deleteLater();
-        emit logoLoaded(logo, QIcon(fullPath));
-        if (waitingCallbacks.contains(logo)) {
-            waitingCallbacks.value(logo)(fullPath);
-        }
-    });
-
-    QObject::connect(job, &NetJob::failed, this, [this, logo, job] {
-        job->deleteLater();
-        emit logoFailed(logo);
-    });
-
-    job->start();
-    m_loadingLogos.append(logo);
-}
-
 /******** Request callbacks ********/
 
-void ListModel::logoLoaded(QString logo, QIcon out)
-{
-    m_loadingLogos.removeAll(logo);
-    m_logoMap.insert(logo, out);
-    for (int i = 0; i < modpacks.size(); i++) {
-        if (modpacks[i].logoName == logo) {
-            emit dataChanged(createIndex(i, 0), createIndex(i, 0), { Qt::DecorationRole });
-        }
-    }
-}
-
-void ListModel::logoFailed(QString logo)
-{
-    m_failedLogos.append(logo);
-    m_loadingLogos.removeAll(logo);
-}
-
 void ListModel::searchRequestFinished(QJsonDocument& doc)
 {
-    jobPtr.reset();
-
     QList<ModPlatform::IndexedPack> newList;
     auto packs = documentToArray(doc);
 
@@ -232,62 +87,27 @@ void ListModel::searchRequestFinished(QJsonDocument& doc)
             loadIndexedPack(pack, packObj);
             newList.append(pack);
         } catch (const JSONValidationError& e) {
-            qWarning() << "Error while loading mod from " << m_parent->debugName() << ": " << e.cause();
+            qWarning() << "Error while loading mod from " << m_associated_page->debugName() << ": " << e.cause();
             continue;
         }
     }
 
     if (packs.size() < 25) {
-        searchState = Finished;
+        m_search_state = SearchState::Finished;
     } else {
-        nextSearchOffset += 25;
-        searchState = CanPossiblyFetchMore;
+        m_next_search_offset += 25;
+        m_search_state = SearchState::CanFetchMore;
     }
 
     // When you have a Qt build with assertions turned on, proceeding here will abort the application
     if (newList.size() == 0)
         return;
 
-    beginInsertRows(QModelIndex(), modpacks.size(), modpacks.size() + newList.size() - 1);
-    modpacks.append(newList);
+    beginInsertRows(QModelIndex(), m_packs.size(), m_packs.size() + newList.size() - 1);
+    m_packs.append(newList);
     endInsertRows();
 }
 
-void ListModel::searchRequestFailed(QString reason)
-{
-    auto failed_action = jobPtr->getFailedActions().at(0);
-    if (!failed_action->m_reply) {
-        // Network error
-        QMessageBox::critical(nullptr, tr("Error"), tr("A network error occurred. Could not load mods."));
-    } else if (failed_action->m_reply && failed_action->m_reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt() == 409) {
-        // 409 Gone, notify user to update
-        QMessageBox::critical(nullptr, tr("Error"),
-                              //: %1 refers to the launcher itself
-                              QString("%1 %2")
-                                  .arg(m_parent->displayName())
-                                  .arg(tr("API version too old!\nPlease update %1!").arg(BuildConfig.LAUNCHER_DISPLAYNAME)));
-    }
-
-    jobPtr.reset();
-    searchState = Finished;
-}
-
-void ListModel::searchRequestAborted()
-{
-    if (searchState != ResetRequested)
-        qCritical() << "Search task in ModModel aborted by an unknown reason!";
-
-    // Retry fetching
-    jobPtr.reset();
-
-    beginResetModel();
-    modpacks.clear();
-    endResetModel();
-
-    nextSearchOffset = 0;
-    performPaginatedSearch();
-}
-
 void ListModel::infoRequestFinished(QJsonDocument& doc, ModPlatform::IndexedPack& pack, const QModelIndex& index)
 {
     qDebug() << "Loading mod info";
@@ -310,12 +130,12 @@ void ListModel::infoRequestFinished(QJsonDocument& doc, ModPlatform::IndexedPack
         }
     }
 
-    m_parent->updateUi();
+    m_associated_page->updateUi();
 }
 
 void ListModel::versionRequestSucceeded(QJsonDocument doc, QString addonId, const QModelIndex& index)
 {
-    auto& current = m_parent->getCurrent();
+    auto current = m_associated_page->getCurrentPack();
     if (addonId != current.addonId) {
         return;
     }
@@ -336,15 +156,19 @@ void ListModel::versionRequestSucceeded(QJsonDocument doc, QString addonId, cons
         qWarning() << "Failed to cache mod versions!";
     }
 
-
-    m_parent->updateModVersions();
+    m_associated_page->updateVersionList();
 }
 
 }  // namespace ModPlatform
 
 /******** Helpers ********/
 
-auto ModPlatform::ListModel::getMineVersions() const -> std::list<Version>
+#define MOD_PAGE(x) static_cast<ModPage*>(x)
+
+auto ModPlatform::ListModel::getMineVersions() const -> std::optional<std::list<Version>>
 {
-    return m_parent->getFilter()->versions;
+    auto versions = MOD_PAGE(m_associated_page)->getFilter()->versions;
+    if (!versions.empty())
+        return versions;
+    return {};
 }
diff --git a/launcher/ui/pages/modplatform/ModModel.h b/launcher/ui/pages/modplatform/ModModel.h
index 36840649..7c735d90 100644
--- a/launcher/ui/pages/modplatform/ModModel.h
+++ b/launcher/ui/pages/modplatform/ModModel.h
@@ -3,90 +3,52 @@
 #include <QAbstractListModel>
 
 #include "modplatform/ModIndex.h"
-#include "net/NetJob.h"
+#include "modplatform/ResourceAPI.h"
+
+#include "ui/pages/modplatform/ResourceModel.h"
 
 class ModPage;
 class Version;
 
 namespace ModPlatform {
 
-using LogoMap = QMap<QString, QIcon>;
-using LogoCallback = std::function<void (QString)>;
-
-class ListModel : public QAbstractListModel {
+class ListModel : public ResourceModel {
     Q_OBJECT
 
    public:
-    ListModel(ModPage* parent);
-    ~ListModel() override;
-
-    inline auto rowCount(const QModelIndex& parent) const -> int override { return parent.isValid() ? 0 : modpacks.size(); };
-    inline auto columnCount(const QModelIndex& parent) const -> int override { return parent.isValid() ? 0 : 1; };
-    inline auto flags(const QModelIndex& index) const -> Qt::ItemFlags override { return QAbstractListModel::flags(index); };
-
-    auto debugName() const -> QString;
-
-    /* Retrieve information from the model at a given index with the given role */
-    auto data(const QModelIndex& index, int role) const -> QVariant override;
-    bool setData(const QModelIndex &index, const QVariant &value, int role) override;
-
-    inline void setActiveJob(NetJob::Ptr ptr) { jobPtr = ptr; }
-    inline NetJob* activeJob() { return jobPtr.get(); }
+    ListModel(ModPage* parent, ResourceAPI* api);
 
     /* Ask the API for more information */
-    void fetchMore(const QModelIndex& parent) override;
-    void refresh();
     void searchWithTerm(const QString& term, const int sort, const bool filter_changed);
-    void requestModInfo(ModPlatform::IndexedPack& current, QModelIndex index);
-    void requestModVersions(const ModPlatform::IndexedPack& current, QModelIndex index);
 
     virtual void loadIndexedPack(ModPlatform::IndexedPack& m, QJsonObject& obj) = 0;
     virtual void loadExtraPackInfo(ModPlatform::IndexedPack& m, QJsonObject& obj) = 0;
     virtual void loadIndexedPackVersions(ModPlatform::IndexedPack& m, QJsonArray& arr) = 0;
 
-    void getLogo(const QString& logo, const QString& logoUrl, LogoCallback callback);
-
-    inline auto canFetchMore(const QModelIndex& parent) const -> bool override { return parent.isValid() ? false : searchState == CanPossiblyFetchMore; };
-
    public slots:
     void searchRequestFinished(QJsonDocument& doc);
-    void searchRequestFailed(QString reason);
-    void searchRequestAborted();
 
     void infoRequestFinished(QJsonDocument& doc, ModPlatform::IndexedPack& pack, const QModelIndex& index);
 
     void versionRequestSucceeded(QJsonDocument doc, QString addonId, const QModelIndex& index);
 
-   protected slots:
+   public slots:
+    ResourceAPI::SearchArgs createSearchArguments() override;
+    ResourceAPI::SearchCallbacks createSearchCallbacks() override;
 
-    void logoFailed(QString logo);
-    void logoLoaded(QString logo, QIcon out);
+    ResourceAPI::VersionSearchArgs createVersionsArguments(QModelIndex&) override;
+    ResourceAPI::VersionSearchCallbacks createVersionsCallbacks(QModelIndex&) override;
 
-    void performPaginatedSearch();
+    ResourceAPI::ProjectInfoArgs createInfoArguments(QModelIndex&) override;
+    ResourceAPI::ProjectInfoCallbacks createInfoCallbacks(QModelIndex&) override;
 
    protected:
     virtual auto documentToArray(QJsonDocument& obj) const -> QJsonArray = 0;
     virtual auto getSorts() const -> const char** = 0;
 
-    void requestLogo(QString file, QString url);
-
-    inline auto getMineVersions() const -> std::list<Version>;
+    inline auto getMineVersions() const -> std::optional<std::list<Version>>;
 
    protected:
-    ModPage* m_parent;
-
-    QList<ModPlatform::IndexedPack> modpacks;
-
-    LogoMap m_logoMap;
-    QMap<QString, LogoCallback> waitingCallbacks;
-    QStringList m_failedLogos;
-    QStringList m_loadingLogos;
-
-    QString currentSearchTerm;
     int currentSort = 0;
-    int nextSearchOffset = 0;
-    enum SearchState { None, CanPossiblyFetchMore, ResetRequested, Finished } searchState = None;
-
-    NetJob::Ptr jobPtr;
 };
 }  // namespace ModPlatform
diff --git a/launcher/ui/pages/modplatform/ModPage.cpp b/launcher/ui/pages/modplatform/ModPage.cpp
index 0f30689e..853f2c54 100644
--- a/launcher/ui/pages/modplatform/ModPage.cpp
+++ b/launcher/ui/pages/modplatform/ModPage.cpp
@@ -35,59 +35,30 @@
  */
 
 #include "ModPage.h"
-#include "Application.h"
-#include "ui_ModPage.h"
+#include "ui_ResourcePage.h"
 
 #include <QDesktopServices>
 #include <QKeyEvent>
 #include <QRegularExpression>
+
 #include <memory>
 
+#include "Application.h"
+#include "ResourceDownloadTask.h"
+
 #include "minecraft/MinecraftInstance.h"
 #include "minecraft/PackProfile.h"
-#include "ui/dialogs/ModDownloadDialog.h"
-#include "ui/widgets/ProjectItem.h"
-#include "Markdown.h"
-
-ModPage::ModPage(ModDownloadDialog* dialog, BaseInstance* instance, ModAPI* api)
-    : QWidget(dialog)
-    , m_instance(instance)
-    , ui(new Ui::ModPage)
-    , dialog(dialog)
-    , m_fetch_progress(this, false)
-    , api(api)
-{
-    ui->setupUi(this);
-
-    connect(ui->searchButton, &QPushButton::clicked, this, &ModPage::triggerSearch);
-    connect(ui->modFilterButton, &QPushButton::clicked, this, &ModPage::filterMods);
-    connect(ui->packView, &QListView::doubleClicked, this, &ModPage::onModSelected);
-
-    m_search_timer.setTimerType(Qt::TimerType::CoarseTimer);
-    m_search_timer.setSingleShot(true);
-
-    connect(&m_search_timer, &QTimer::timeout, this, &ModPage::triggerSearch);
-
-    ui->searchEdit->installEventFilter(this);
-
-    ui->versionSelectionBox->view()->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
-    ui->versionSelectionBox->view()->parentWidget()->setMaximumHeight(300);
-
-    m_fetch_progress.hideIfInactive(true);
-    m_fetch_progress.setFixedHeight(24);
-    m_fetch_progress.progressFormat("");
-
-    ui->gridLayout_3->addWidget(&m_fetch_progress, 0, 0, 1, ui->gridLayout_3->columnCount());
 
-    ui->packView->setItemDelegate(new ProjectItemDelegate(this));
-    ui->packView->installEventFilter(this);
+#include "ui/dialogs/ModDownloadDialog.h"
 
-    connect(ui->packDescription, &QTextBrowser::anchorClicked, this, &ModPage::openUrl);
-}
+#include "ui/pages/modplatform/ModModel.h"
 
-ModPage::~ModPage()
+ModPage::ModPage(ModDownloadDialog* dialog, BaseInstance& instance)
+    : ResourcePage(dialog, instance)
 {
-    delete ui;
+    connect(m_ui->searchButton, &QPushButton::clicked, this, &ModPage::triggerSearch);
+    connect(m_ui->resourceFilterButton, &QPushButton::clicked, this, &ModPage::filterMods);
+    connect(m_ui->packView, &QListView::doubleClicked, this, &ModPage::onResourceSelected);
 }
 
 void ModPage::setFilterWidget(unique_qobject_ptr<ModFilterWidget>& widget)
@@ -97,59 +68,19 @@ void ModPage::setFilterWidget(unique_qobject_ptr<ModFilterWidget>& widget)
 
     m_filter_widget.swap(widget);
 
-    ui->gridLayout_3->addWidget(m_filter_widget.get(), 0, 0, 1, ui->gridLayout_3->columnCount());
+    m_ui->gridLayout_3->addWidget(m_filter_widget.get(), 0, 0, 1, m_ui->gridLayout_3->columnCount());
 
-    m_filter_widget->setInstance(static_cast<MinecraftInstance*>(m_instance));
+    m_filter_widget->setInstance(&static_cast<MinecraftInstance&>(m_base_instance));
     m_filter = m_filter_widget->getFilter();
 
     connect(m_filter_widget.get(), &ModFilterWidget::filterChanged, this, [&]{
-        ui->searchButton->setStyleSheet("text-decoration: underline");
+        m_ui->searchButton->setStyleSheet("text-decoration: underline");
     });
     connect(m_filter_widget.get(), &ModFilterWidget::filterUnchanged, this, [&]{
-        ui->searchButton->setStyleSheet("text-decoration: none");
+        m_ui->searchButton->setStyleSheet("text-decoration: none");
     });
 }
 
-
-/******** Qt things ********/
-
-void ModPage::openedImpl()
-{
-    updateSelectionButton();
-    triggerSearch();
-}
-
-auto ModPage::eventFilter(QObject* watched, QEvent* event) -> bool
-{
-    if (watched == ui->searchEdit && event->type() == QEvent::KeyPress) {
-        auto* keyEvent = dynamic_cast<QKeyEvent*>(event);
-        if (keyEvent->key() == Qt::Key_Return) {
-            triggerSearch();
-            keyEvent->accept();
-            return true;
-        } else {
-            if (m_search_timer.isActive())
-                m_search_timer.stop();
-
-            m_search_timer.start(350);
-        }
-    } else if (watched == ui->packView && event->type() == QEvent::KeyPress) {
-        auto* keyEvent = dynamic_cast<QKeyEvent*>(event);
-        if (keyEvent->key() == Qt::Key_Return) {
-            onModSelected();
-
-            // To have the 'select mod' button outlined instead of the 'review and confirm' one
-            ui->modSelectionButton->setFocus(Qt::FocusReason::ShortcutFocusReason);
-            ui->packView->setFocus(Qt::FocusReason::NoFocusReason);
-
-            keyEvent->accept();
-            return true;
-        }
-    }
-    return QWidget::eventFilter(watched, event);
-}
-
-
 /******** Callbacks to events in the UI (set up in the derived classes) ********/
 
 void ModPage::filterMods()
@@ -163,176 +94,37 @@ void ModPage::triggerSearch()
     m_filter = m_filter_widget->getFilter();
 
     if (changed) {
-        ui->packView->clearSelection();
-        ui->packDescription->clear();
-        ui->versionSelectionBox->clear();
+        m_ui->packView->clearSelection();
+        m_ui->packDescription->clear();
+        m_ui->versionSelectionBox->clear();
         updateSelectionButton();
     }
 
-    listModel->searchWithTerm(getSearchTerm(), ui->sortByBox->currentIndex(), changed);
-    m_fetch_progress.watch(listModel->activeJob());
-}
-
-QString ModPage::getSearchTerm() const
-{
-    return ui->searchEdit->text();
-}
-void ModPage::setSearchTerm(QString term)
-{
-    ui->searchEdit->setText(term);
+    static_cast<ModPlatform::ListModel*>(m_model)->searchWithTerm(getSearchTerm(), m_ui->sortByBox->currentIndex(), changed);
+    m_fetch_progress.watch(&m_model->activeJob());
 }
 
-void ModPage::onSelectionChanged(QModelIndex curr, QModelIndex prev)
+QMap<QString, QString> ModPage::urlHandlers() const
 {
-    ui->versionSelectionBox->clear();
-
-    if (!curr.isValid()) { return; }
-
-    current = listModel->data(curr, Qt::UserRole).value<ModPlatform::IndexedPack>();
-
-    if (!current.versionsLoaded) {
-        qDebug() << QString("Loading %1 mod versions").arg(debugName());
-
-        ui->modSelectionButton->setText(tr("Loading versions..."));
-        ui->modSelectionButton->setEnabled(false);
-
-        listModel->requestModVersions(current, curr);
-    } else {
-        for (int i = 0; i < current.versions.size(); i++) {
-            ui->versionSelectionBox->addItem(current.versions[i].version, QVariant(i));
-        }
-        if (ui->versionSelectionBox->count() == 0) { ui->versionSelectionBox->addItem(tr("No valid version found."), QVariant(-1)); }
-
-        updateSelectionButton();
-    }
-
-    if(!current.extraDataLoaded){
-        qDebug() << QString("Loading %1 mod info").arg(debugName());
-
-        listModel->requestModInfo(current, curr);
-    }
-
-    updateUi();
-}
-
-void ModPage::onVersionSelectionChanged(QString data)
-{
-    if (data.isNull() || data.isEmpty()) {
-        selectedVersion = -1;
-        return;
-    }
-    selectedVersion = ui->versionSelectionBox->currentData().toInt();
-    updateSelectionButton();
-}
-
-void ModPage::onModSelected()
-{
-    if (selectedVersion < 0)
-        return;
-
-    auto& version = current.versions[selectedVersion];
-    if (dialog->isModSelected(current.name, version.fileName)) {
-        dialog->removeSelectedMod(current.name);
-    } else {
-        bool is_indexed = !APPLICATION->settings()->get("ModMetadataDisabled").toBool();
-        dialog->addSelectedMod(current.name, new ModDownloadTask(current, version, dialog->mods, is_indexed));
-    }
-
-    updateSelectionButton();
-
-    /* Force redraw on the mods list when the selection changes */
-    ui->packView->adjustSize();
-}
-
-static const QRegularExpression modrinth(QRegularExpression::anchoredPattern("(?:www\\.)?modrinth\\.com\\/mod\\/([^\\/]+)\\/?"));
-static const QRegularExpression curseForge(QRegularExpression::anchoredPattern("(?:www\\.)?curseforge\\.com\\/minecraft\\/mc-mods\\/([^\\/]+)\\/?"));
-static const QRegularExpression curseForgeOld(QRegularExpression::anchoredPattern("minecraft\\.curseforge\\.com\\/projects\\/([^\\/]+)\\/?"));
-
-void ModPage::openUrl(const QUrl& url)
-{
-    // do not allow other url schemes for security reasons
-    if (!(url.scheme() == "http" || url.scheme() == "https")) {
-        qWarning() << "Unsupported scheme" << url.scheme();
-        return;
-    }
-
-    // detect mod URLs and search instead
-
-    const QString address = url.host() + url.path();
-    QRegularExpressionMatch match;
-    QString page;
-
-    match = modrinth.match(address);
-    if (match.hasMatch())
-        page = "modrinth";
-    else if (APPLICATION->capabilities() & Application::SupportsFlame) {
-        match = curseForge.match(address);
-        if (!match.hasMatch())
-            match = curseForgeOld.match(address);
-
-        if (match.hasMatch())
-            page = "curseforge";
-    }
-
-    if (!page.isNull()) {
-        const QString slug = match.captured(1);
-
-        // ensure the user isn't opening the same mod
-        if (slug != current.slug) {
-            dialog->selectPage(page);
-
-            ModPage* newPage = dialog->getSelectedPage();
-
-            QLineEdit* searchEdit = newPage->ui->searchEdit;
-            ModPlatform::ListModel* model = newPage->listModel;