#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <stdio.h>
#include <math.h>

SDL_Window *window;
SDL_Renderer *render;
SDL_Surface *image;
SDL_Texture *texture;
Sint64 interval;
Sint64 nowTick;
int framecounter;

void my_ending(void)
{
  if (texture != NULL)
    SDL_DestroyTexture(texture);

  if (render != NULL)
    SDL_DestroyRenderer(render);

  if (window != NULL)
    SDL_DestroyWindow(window);

  SDL_Quit();
}

void my_startup(void)
{
  if (SDL_Init(SDL_INIT_EVERYTHING) < 0)
    my_ending();

  window = SDL_CreateWindow("SDL2 Window",
                            100, 100,
                            640, 480, 0);
  if (window == NULL)
  {
    SDL_Log("Could not create window\n");
    my_ending();
  }

  render = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
  if (render == NULL)
  {
    SDL_Log("Could not create renderer\n");
    my_ending();
  }

  // image = SDL_LoadBMP("sample.bmp");
  image = IMG_Load("sample.png");
  if (image == NULL)
  {
    SDL_Log("Could not load image\n");
    my_ending();
  }

  texture = SDL_CreateTextureFromSurface(render, image);
  SDL_FreeSurface(image);
}

int quits(void)
{
  SDL_Event events;
  if (SDL_PollEvent(&events))
  {
    switch (events.type)
    {
    case SDL_QUIT:
      return 0;
      break;

    case SDL_KEYDOWN:
      if (events.key.keysym.sym == SDLK_ESCAPE ||
          events.key.keysym.sym == SDLK_q)
        return 0;
      break;

    default:
      break;
    }
  }
  return 1;
}

void draw(void)
{
  // clear with background color
  SDL_SetRenderDrawColor(render, 0, 64, 136, 255);
  SDL_RenderClear(render);

  SDL_Rect src, dst;
  src.x = 0;
  src.y = 0;
  src.w = 256;
  src.h = 256;
  dst.w = src.w;
  dst.h = src.h;
  double pi = 3.14159;

  for (int i = 0; i < 16; i++)
  {
    double x_rad = (framecounter * 3.8 + i * 12) * pi / 180.0;
    double y_rad = (framecounter * 2.0 + i * 12) * pi / 180.0;
    int x = (int)(320.0 + 160 * sin(x_rad));
    int y = (int)(240.0 + 120 * sin(y_rad));
    dst.x = x - dst.w / 2;
    dst.y = y - dst.h / 2;
    SDL_RenderCopy(render, texture, &src, &dst);
  }

  SDL_RenderPresent(render);
}

void my_wait_init(void)
{
  interval = (Sint64)SDL_GetPerformanceFrequency() / 60;
  nowTick = 0;
}

void my_wait(void)
{
  while (SDL_TRUE)
  {
    if (((Sint64)SDL_GetPerformanceCounter() - nowTick) >= interval)
    {
      break;
    }
    SDL_Delay(0);
  }
  nowTick = SDL_GetPerformanceCounter();
}

int main(int argc, char *args[])
{
  my_startup();

  my_wait_init();
  framecounter = 0;

  while (quits() != 0)
  {
    draw();

    my_wait();
    framecounter++;
  }

  my_ending();
  return 0;
}