Add basic lua scripting capabilities (#4341)

The scripting capabilities is locked behind a cmake flag, and is not enabled by default.

Co-authored-by: nerix <nerixdev@outlook.de>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/controllers/plugins/PluginController.hpp

@@ -0,0 +1,68 @@
+#pragma once
+
+#ifdef CHATTERINO_HAVE_PLUGINS
+
+#    include "common/Singleton.hpp"
+#    include "controllers/commands/CommandContext.hpp"
+#    include "controllers/plugins/Plugin.hpp"
+
+#    include <QDir>
+#    include <QFileInfo>
+#    include <QJsonArray>
+#    include <QJsonObject>
+#    include <QString>
+
+#    include <algorithm>
+#    include <map>
+#    include <memory>
+#    include <utility>
+#    include <vector>
+
+struct lua_State;
+
+namespace chatterino {
+
+class Paths;
+
+class PluginController : public Singleton
+{
+public:
+    void initialize(Settings &settings, Paths &paths) override;
+
+    QString tryExecPluginCommand(const QString &commandName,
+                                 const CommandContext &ctx);
+
+    // NOTE: this pointer does not own the Plugin, unique_ptr still owns it
+    // This is required to be public because of c functions
+    Plugin *getPluginByStatePtr(lua_State *L);
+
+    const std::map<QString, std::unique_ptr<Plugin>> &plugins() const;
+
+    /**
+     * @brief Reload plugin given by id
+     *
+     * @param id This is the unique identifier of the plugin, the name of the directory it is in
+     */
+    bool reload(const QString &id);
+
+    /**
+     * @brief Checks settings to tell if a plugin named by id is enabled.
+     *
+     * It is the callers responsibility to check Settings::pluginsEnabled
+     */
+    static bool isPluginEnabled(const QString &id);
+
+private:
+    void loadPlugins();
+    void load(const QFileInfo &index, const QDir &pluginDir,
+              const PluginMeta &meta);
+
+    // This function adds lua standard libraries into the state
+    static void openLibrariesFor(lua_State *L, const PluginMeta & /*meta*/);
+    static void loadChatterinoLib(lua_State *l);
+    bool tryLoadFromDir(const QDir &pluginDir);
+    std::map<QString, std::unique_ptr<Plugin>> plugins_;
+};
+
+};  // namespace chatterino
+#endif