#include "application.h"

#include <chrono>

void Application::event(const SDL_Event &ev) {
    if (ev.type == SDL_QUIT) {
        running = false;
    }

    scene->event(ev);
}

void Application::update(float delta) {
    scene->update(delta);
}

void Application::render() {
    scene->render();

    SDL_GL_SwapWindow(window);
}

void Application::main_loop() {
    std::chrono::high_resolution_clock::time_point start = std::chrono::high_resolution_clock::now();

    //handle input
    SDL_Event current_event;

    while (SDL_PollEvent(&current_event)) {
        event(current_event);
    }

    //update_world
    update(frame_delta);

    //render
    render();

    std::chrono::high_resolution_clock::time_point end = std::chrono::high_resolution_clock::now();

    std::chrono::duration<double> elapsed_seconds = end - start;

    double t = elapsed_seconds.count();

    double tfps = 1.0 / static_cast<float>(target_fps);
    double remaining = tfps - t;

    if (remaining > 0) {
        Uint32 fms = static_cast<Uint32>(remaining * 1000.0);

        frame_delta = tfps;

        SDL_Delay(fms);
    } else {
        frame_delta = t;
    }
}

Application::Application() {
    _instance = this;

    running = true;
    target_fps = 60;

    scene = NULL;

    frame_delta = 0;

    SDL_SetMainReady();

    int error = SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER);

    if (error) {
        SDL_Log("SDL_Init fail: %s\n", SDL_GetError());

        running = false;
        return;
    }

#if defined(_WIN64) || defined(_WIN32)
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
#else
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
#endif

    window = SDL_CreateWindow("SDL + OpenGL", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);

    if (!window) {
        SDL_Log("SDL_CreateWindow Failed! %s\n", SDL_GetError());

        running = false;

        return;
    }

    context = SDL_GL_CreateContext(window);

    #if defined(_WIN64) || defined(_WIN32)
    gladLoadGLLoader((GLADloadproc)SDL_GL_GetProcAddress);
    #endif // defined

    printf("%s\n", glGetString(GL_VERSION));
}
Application::~Application() {
    SDL_DestroyWindow(window);

    window = NULL;

    SDL_Quit();
}

Application *Application::get_singleton() {
    return _instance;
}

Application * Application::_instance = NULL;