#include <SDL2/SDL.h>
#include "demo.h"

void update_demo(struct demo* demo) {
  int width, height;
  int pixel_width, pixel_height;

  SDL_GetWindowSize(demo->win, &width, &height);
  SDL_GetRendererOutputSize(demo->ren, &pixel_width, &pixel_height);

  demo->display_scale_x = pixel_width / width;
  demo->display_scale_y = pixel_height / height;
}

void demo_rendercopy(struct demo* demo,
                     SDL_Texture* texture,
                     SDL_Rect* s_rect,
                     SDL_Rect* d_rect) {
  const float scale_x = demo->display_scale_x;
  const float scale_y = demo->display_scale_y;

  SDL_Rect new_srect;
  SDL_Rect new_drect;

  if(s_rect) {
    new_srect = (SDL_Rect){
      .x = s_rect->x * scale_x,
      .y = s_rect->y * scale_y,
      .w = s_rect->w * scale_x,
      .h = s_rect->h * scale_y
    };
  }

  if(d_rect) {
    new_drect = (SDL_Rect){
      .x = d_rect->x * scale_x,
      .y = d_rect->y * scale_y,
      .w = d_rect->w * scale_x,
      .h = d_rect->h * scale_y
    };
  }

  //Handle edge case where s_rect or d_rect are NULL
  SDL_RenderCopy(demo->ren, texture,
                 s_rect ? &new_srect : NULL,
                 d_rect ?&new_drect : NULL);
}