#include <SDL.h>
#include <SDL_image.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include "kiss.h"

char *title = "SDL 13 - Alpha Blending";
SDL_Window *window;
SDL_Renderer *renderer;
SDL_Texture *sprite_sheet;
SDL_Rect sprite[2] = {
   { 0, 0, 404, 366 },
   { 404, 0, 396, 366 },
};

int
init_sdl(void)
{
   int status = -1;
   int x = SDL_WINDOWPOS_UNDEFINED;
   int y = SDL_WINDOWPOS_UNDEFINED;
   int width = 800;
   int height = 732;
   int flags = 0;       // SDL_WINDOW_FULLSCREEN_DESKTOP

   SDL_INIT(SDL_INIT_VIDEO);
   IMG_INIT(IMG_INIT_PNG);
   window = SDL_CREATEWINDOW(title, x, y, width, height, flags);
   renderer = SDL_CREATERENDERER(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
   status = 0;
error:
   return status;
}

#define INIT_SDL(...) SDL_ZERO(init_sdl, __VA_ARGS__)

SDL_Texture *
load_texture(char *path)
{
   SDL_Texture *ret = NULL;
   SDL_Texture *texture = NULL;
   SDL_Surface *surface = NULL;
   surface = IMG_LOAD(path);
//	SDL_SETCOLORKEY(surface, SDL_TRUE, SDL_MapRGB(surface->format, 0x00, 0xFF, 0xFF));
   texture = SDL_CREATETEXTUREFROMSURFACE(renderer, surface);
   SDL_SETTEXTUREBLENDMODE(texture, SDL_BLENDMODE_ADD);       // SDL_BLENDMODE_BLEND
   ret = texture;
error:
   if (!ret)
     SDL_DestroyTexture(texture);
   SDL_FreeSurface(surface);
   return ret;
}

#define LOAD_TEXTURE(...) SDL_CHK(load_texture, __VA_ARGS__)

int
sprite_draw_ex(SDL_Rect *sprite, int x, int y, double zoom, double angle, SDL_RendererFlip flip, const SDL_Color *c)
{
   int status = -1;
   SDL_Rect target = { x, y, sprite->w * zoom, sprite->h * zoom };
   if (c)
     {
        SDL_SETTEXTURECOLORMOD(sprite_sheet, c->r, c->g, c->b);
        SDL_SETTEXTUREALPHAMOD(sprite_sheet, c->a);
     }
   SDL_RENDERCOPYEX(renderer, sprite_sheet, sprite, &target, angle, NULL, flip);
   if (c)
     {
        SDL_SETTEXTURECOLORMOD(sprite_sheet, 0xFF, 0xFF, 0xFF);
        SDL_SETTEXTUREALPHAMOD(sprite_sheet, 0xFF);
     }
   status = 0;
error:
   return status;
}

#define SPRITE_DRAW_EX(...) SDL_ZERO(sprite_draw_ex, __VA_ARGS__)

void
close_sdl(void)
{
   SDL_DestroyRenderer(renderer);
   SDL_DestroyWindow(window);
   IMG_Quit();
   SDL_Quit();
}

int x = 0;
int y = 0;
double angle = 30;
SDL_Color tint = { 0xFF, 0xFF, 0xFF, 0x7F };

int frame = 0;

int
draw(void)
{
   int status = -1;
   int w, h;
   double zoom = 2;
   SDL_GetWindowSize(window, &w, &h);
   SDL_Color tint2 = tint;

   SDL_SetRenderDrawColor(renderer, 0x00, 0x00, 0x00, 0xFF);
   SDL_RENDERCLEAR(renderer);
   tint2.a = 0xFF - tint.a;
   SPRITE_DRAW_EX(&sprite[0], x, y, zoom, angle, 0, &tint);
   SPRITE_DRAW_EX(&sprite[1], -x, y, zoom, -angle, 0, &tint2);
   SDL_RenderPresent(renderer);
   ++frame;
   status = 0;
error:
   return status;
}

#define DRAW(...) SDL_ZERO(draw, __VA_ARGS__)

void
key_down(SDL_Keycode k)
{
   switch (k)
     {
      case SDLK_LEFT: x -= 1; break;

      case SDLK_RIGHT: x += 1; break;

      case SDLK_UP: y -= 1; break;

      case SDLK_DOWN: y += 1; break;

      case SDLK_q: tint.r += 1; break;

      case SDLK_w: tint.g += 1; break;

      case SDLK_e: tint.b += 1; break;

      case SDLK_r: tint.a += 1; break;

      case SDLK_a: tint.r -= 1; break;

      case SDLK_s: tint.g -= 1; break;

      case SDLK_d: tint.b -= 1; break;

      case SDLK_f: tint.a -= 1; break;

      case SDLK_t: angle += 1; break;

      case SDLK_g: angle -= 1; break;

      default: x = 0; y = 0; break;
     }
}

int
main(void)
{
   int exit_status = EXIT_FAILURE;
   bool quit = 0;
   SDL_Event e;

   INIT_SDL();

   sprite_sheet = LOAD_TEXTURE("logo.png");

   DRAW();
   while (!quit)
     {
        SDL_WAITEVENT(&e);
        if (e.type == SDL_QUIT)
          quit = 1;
        else if (e.type == SDL_KEYDOWN)
          {
             key_down(e.key.keysym.sym);
             DRAW();
          }
     }

   exit_status = EXIT_SUCCESS;
error:
   SDL_DestroyTexture(sprite_sheet);
   close_sdl();
   exit(exit_status);
}