#ifndef SRC_ENGINE_H_
#define SRC_ENGINE_H_

#include <string>
#include <memory>
#include <vector>
#include <stdexcept>
#include <filesystem>
#include "typedefs.h"
#include "settings.h"

#include "assets/Assets.h"
#include "content/Content.h"
#include "content/ContentPack.h"
#include "files/engine_paths.h"

class Level;
class Screen;
class EnginePaths;
class ResPaths;

namespace fs = std::filesystem;

namespace gui {
    class GUI;
}

class initialize_error : public std::runtime_error {
public:
    initialize_error(const std::string& message) : std::runtime_error(message) {}
};

class Engine {
    std::unique_ptr<Assets> assets = nullptr;
    std::shared_ptr<Screen> screen = nullptr;
    std::vector<ContentPack> contentPacks;
    EngineSettings& settings;
    std::unique_ptr<Content> content = nullptr;
    EnginePaths* paths;
    std::unique_ptr<ResPaths> resPaths = nullptr;

    uint64_t frame = 0;
    double lastTime = 0.0;
    double delta = 0.0;

    std::unique_ptr<gui::GUI> gui;
    
    void updateTimers();
    void updateHotkeys();
public:
    Engine(EngineSettings& settings, EnginePaths* paths);
    ~Engine();
 
    /// @brief Start main engine input/update/render loop. 
    /// Automatically sets MenuScreen
    void mainloop();

    
    /// @brief Set screen (scene).
    /// nullptr may be used to delete previous screen before creating new one,
    /// not-null value must be set before next frame
    /// @param screen nullable screen
    void setScreen(std::shared_ptr<Screen> screen);
    
    /// @brief Change locale to specified
    /// @param locale isolanguage_ISOCOUNTRY (example: en_US)
    void setLanguage(std::string locale);

    /// @brief Load all selected content-packs and reload assets
    void loadContent();
    
    /// @brief Collect world content-packs and load content
    /// @see loadContent
    /// @param folder world folder
    void loadWorldContent(const fs::path& folder);

    /// @brief Collect all available content-packs from res/content
    void loadAllPacks();

    /// @brief Get current frame delta-time
    double getDelta() const;

    /// @brief Get active assets storage instance
    Assets* getAssets();
    
    /// @brief Get main UI controller
    gui::GUI* getGUI();

    /// @brief Get writeable engine settings structure instance
    EngineSettings& getSettings();

    /// @brief Get engine filesystem paths source
    EnginePaths* getPaths();

    /// @brief Get engine resource paths controller
    ResPaths* getResPaths();

    /// @brief Get current Content instance
    const Content* getContent() const;

    /// @brief Get selected content packs
    std::vector<ContentPack>& getContentPacks();

    /// @brief Get current screen
    std::shared_ptr<Screen> getScreen();
};

#endif // SRC_ENGINE_H_