#include <sdl\SDL.h>
#include <sdl\SDL_opengl.h>
#include <GL\GLU.h>
#include <iostream>
#include <ctime>
#include <chrono>
#include <windows.h>

SDL_Window* window;
int window_width = 800;
int window_height = 480;


LARGE_INTEGER li;
double ticks_per_second;
__int64 last_time = 0;
double get_delta() {
    QueryPerformanceCounter(&li);
    __int64 now = li.QuadPart;
    int diff = now - last_time;
    last_time = now;
    return double(diff) / ticks_per_second;
}

int main(int argc, char* argv[]) {
    QueryPerformanceFrequency(&li);
    ticks_per_second = double(li.QuadPart);



    SDL_Init(SDL_INIT_EVERYTHING);
    window = SDL_CreateWindow("SDL Game Loop", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, window_width, window_height, SDL_WINDOW_OPENGL);
    //SDL_SetWindowFullscreen(window, SDL_WINDOW_FULLSCREEN_DESKTOP);
    SDL_GL_CreateContext(window);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetSwapInterval(0);
    glClearColor(.2,.2,.2,1);

    double dt = get_delta();
    while (true) {
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            switch (event.type) {
            case SDL_QUIT:
                return 0;
                break;
            }
        }


        glClearDepth(1);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        get_delta();
        SDL_GL_SwapWindow(window);
        dt = get_delta();

        if (dt >= 0.001) std::cout << "SDL_GL_SwapWindow(window) took " << dt << "ms" << std::endl;
        if (dt >= 0.016) std::cout << "huge dt warning: " << dt << std::endl;

        //double freetime = (1.0 / 60.0) - dt - 0.001;
        //if (freetime > 0.001) SDL_Delay(freetime * 1000);
    }

    return 0;
}