#include <common/world.h>

static inline Uint32
_surf_pixel (SDL_Surface *surface, int x, int y)
{
  int bpp = SDL_BYTESPERPIXEL (surface->format);
  Uint8 *p = (Uint8 *) surface->pixels + y * surface->pitch + x * bpp;

  switch (bpp)
    {
    case 1:
      return *p;
    case 2:
      return *(Uint16 *) p;
    case 3:
      if (SDL_BYTEORDER == SDL_BIG_ENDIAN)
	{
	  return p[0] << 16 | p[1] << 8 | p[2];
	}
      else
	{
	  return p[0] | p[1] << 8 | p[2] << 16;
	}
    case 4:
      return *(Uint32 *) p;
    default:
      return 0;			// shouldn't happen
    }
}

World *
World_load_from_file (const char *path)
{
  World *self = g_new0 (World, 1);
  self->buildings = g_array_new (FALSE, FALSE, sizeof (Building *));

  SDL_Surface *surf = IMG_Load (path);

  if (!surf)
    {
      g_warning ("Failed to load map from path %s (returning NULL): %s", path,
		 SDL_GetError ());
      return NULL;
    }

  self->width = surf->w;
  self->height = surf->h;
  self->tiles =
    g_array_sized_new (FALSE, FALSE, sizeof (MapTile *), surf->w * surf->h);

  SDL_LockSurface (surf);
  const SDL_PixelFormatDetails *details =
    SDL_GetPixelFormatDetails (surf->format);

  for (int y = 0; y < surf->h; ++y)
    {
      for (int x = 0; x < surf->w; ++x)
	{
	  MapTile *mt = g_new0 (MapTile, 1);
	  mt->x = x;
	  mt->y = y;

	  Uint32 pixel = _surf_pixel (surf, x, y);
	  Uint8 r, g, b, a;
	  /* NULL is a palette, only used in indexed images. */
	  SDL_GetRGBA (pixel, details, NULL, &r, &g, &b, &a);

	  /* Improved color ranges (handles light blue water better) */
	  if (b > 120 && (b > g || b > r))
	    {
	      /* Water: medium-to-light blues */
	      mt->terrain_type = TERRAIN_WATER;
	    }
	  else if (g > 140 && g >= r && g >= b)
	    {
	      /* Green-dominant = flat/grassland */
	      mt->terrain_type = TERRAIN_FLAT;
	    }
	  else
	    {
	      /* Otherwise: hills/mountains */
	      mt->terrain_type = TERRAIN_HILL;
	    }
	  /* Thanks, ChatGPT! */
	  
	  g_array_append_val (self->tiles, mt);
	}
    }

  SDL_UnlockSurface (surf);
  SDL_DestroySurface (surf);

  return self;
}