// python -m glad --out-path=build --api="gl=2.1" --extensions="" --generator="c"
// g++ example/c++/sdl.cpp build/src/glad.c -Ibuild/include -lSDL2 -ldl

#include <iostream>

#include <glad/glad.h>
#include <SDL2/SDL.h>

int main(int argc, char **argv) {

    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        std::cerr << "SDL2 video subsystem couldn't be initialized. Error: "
                  << SDL_GetError()
                  << std::endl;
        exit(1);
    }

    SDL_Window* window = SDL_CreateWindow("Glad Sample",
                                          SDL_WINDOWPOS_CENTERED,
                                          SDL_WINDOWPOS_CENTERED,
                                          800, 600, SDL_WINDOW_SHOWN |
                                          SDL_WINDOW_OPENGL);

    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1,
                                                SDL_RENDERER_ACCELERATED);

    if (renderer == nullptr) {
        std::cerr << "SDL2 Renderer couldn't be created. Error: "
                  << SDL_GetError()
                  << std::endl;
        exit(1);
    }

    // Create a OpenGL context on SDL2
    SDL_GLContext gl_context = SDL_GL_CreateContext(window);

    // Load GL extensions using glad
    if (!gladLoadGLLoader((GLADloadproc) SDL_GL_GetProcAddress)) {
        std::cerr << "Failed to initialize the OpenGL context." << std::endl;
        exit(1);
    }

    // Loaded OpenGL successfully.
    std::cout << "OpenGL version loaded: " << GLVersion.major << "."
              << GLVersion.minor << std::endl;

    // Create an event handler
    SDL_Event event;
    // Loop condition
    bool running = true;

    while (running) {
        SDL_PollEvent(&event);

        switch(event.type) {
        case SDL_QUIT:
            running = false;
            break;

        case SDL_KEYDOWN:
            switch(event.key.keysym.sym) {
            case SDLK_ESCAPE:
                running = false;
                break;
            }
        }

        glClearColor(0, 0, 0, 1);

        // You'd want to use modern OpenGL here
        glColor3d(0, 1, 0);
        glBegin(GL_TRIANGLES);
            glVertex2f(.2, 0);
            glVertex2f(.01, .2);
            glVertex2f(-.2, 0);
        glEnd();

        SDL_GL_SwapWindow(window);
    }

    // Destroy everything to not leak memory.
    SDL_GL_DeleteContext(gl_context);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);

    SDL_Quit();

    return 0;
}