#include <stdio.h>
#include <GL/gl3w.h>
#include <SDL2/SDL.h>

int main()
{
    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        fprintf(stderr, "Unable to initialize SDL");
        return EXIT_FAILURE;
    }

    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
    SDL_GL_SetAttribute(SDL_GL_FRAMEBUFFER_SRGB_CAPABLE, 1);

    auto window = SDL_CreateWindow("GL",
                                   SDL_WINDOWPOS_CENTERED,
                                   SDL_WINDOWPOS_CENTERED,
                                   640, 480,
                                   SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
    if (!window) {
        fprintf(stderr, "Couldn't create window: %s\n", SDL_GetError());
        SDL_Quit();
        return EXIT_FAILURE;
    }

    auto gl_context = SDL_GL_CreateContext(window);
    if (gl3wInit()) {
        fprintf(stderr, "Failed to initialize OpenGL\n");
        return EXIT_FAILURE;
    }
    printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION),
       glGetString(GL_SHADING_LANGUAGE_VERSION));

    SDL_GL_SetSwapInterval(1);  //Vsync

    glClearColor(0.5f, 0.5f, 0.5f, 1.0f);

    auto quit = false;
    SDL_Event event;
    while (!quit) {
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                quit = true;
            }
        }

        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        SDL_GL_SwapWindow(window);
    }

    return EXIT_SUCCESS;
}