#include <stdio.h>

#define __STDC_CONSTANT_MACROS

#ifdef _WIN32
// Windows
extern "C" {
#include "SDL/SDL.h"
#include "libavcodec/avcodec.h"
#include "libavdevice/avdevice.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
};
#else
// Linux...
#ifdef __cplusplus
extern "C" {
#endif
#include <SDL2/SDL.h>
#include <libavcodec/avcodec.h>
#include <libavdevice/avdevice.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#ifdef __cplusplus
};
#endif
#endif

// Output YUV420P
#define OUTPUT_YUV420P 0
//'1' Use Dshow
//'0' Use GDIgrab
#define USE_DSHOW 0

// Refresh Event
#define SFM_REFRESH_EVENT (SDL_USEREVENT + 1)

#define SFM_BREAK_EVENT (SDL_USEREVENT + 2)

int thread_exit = 0;

int sfp_refresh_thread(void *opaque) {
  thread_exit = 0;
  while (!thread_exit) {
    SDL_Event event;
    event.type = SFM_REFRESH_EVENT;
    SDL_PushEvent(&event);
    SDL_Delay(40);
  }
  thread_exit = 0;
  // Break
  SDL_Event event;
  event.type = SFM_BREAK_EVENT;
  SDL_PushEvent(&event);

  return 0;
}

// Show AVFoundation Device
void show_avfoundation_device() {
  AVFormatContext *pFormatCtx = avformat_alloc_context();
  AVDictionary *options = NULL;
  av_dict_set(&options, "list_devices", "true", 0);
  AVInputFormat *iformat =
      (AVInputFormat *)av_find_input_format("avfoundation");
  printf("==AVFoundation Device Info===\n");
  avformat_open_input(&pFormatCtx, "", iformat, &options);
  printf("=============================\n");
}

int main(int argc, char *argv[]) {
  AVFormatContext *pFormatCtx;
  int i, videoindex;
  AVCodecContext *pCodecCtx;
  AVCodec *pCodec;

  avformat_network_init();
  pFormatCtx = avformat_alloc_context();

  // Open File
  // char filepath[]="src01_480x272_22.h265";
  // avformat_open_input(&pFormatCtx,filepath,NULL,NULL)

  // Register Device
  avdevice_register_all();
  // Windows
#ifdef _WIN32
#if USE_DSHOW
  // Use dshow
  //
  // Need to Install screen-capture-recorder
  // screen-capture-recorder
  // Website: http://sourceforge.net/projects/screencapturer/
  //
  AVInputFormat *ifmt = av_find_input_format("dshow");
  if (avformat_open_input(&pFormatCtx, "video=screen-capture-recorder", ifmt,
                          NULL) != 0) {
    printf("Couldn't open input stream.\n");
    return -1;
  }
#else
  // Use gdigrab
  AVDictionary *options = NULL;
  // Set some options
  // grabbing frame rate
  // av_dict_set(&options,"framerate","5",0);
  // The distance from the left edge of the screen or desktop
  // av_dict_set(&options,"offset_x","20",0);
  // The distance from the top edge of the screen or desktop
  // av_dict_set(&options,"offset_y","40",0);
  // Video frame size. The default is to capture the full screen
  // av_dict_set(&options,"video_size","640x480",0);
  AVInputFormat *ifmt = av_find_input_format("gdigrab");
  if (avformat_open_input(&pFormatCtx, "desktop", ifmt, &options) != 0) {
    printf("Couldn't open input stream.\n");
    return -1;
  }

#endif
#elif defined linux
  // Linux
  AVDictionary *options = NULL;
  // Set some options
  // grabbing frame rate
  // av_dict_set(&options,"framerate","5",0);
  // Make the grabbed area follow the mouse
  // av_dict_set(&options,"follow_mouse","centered",0);
  // Video frame size. The default is to capture the full screen
  // av_dict_set(&options,"video_size","640x480",0);
  AVInputFormat *ifmt = av_find_input_format("x11grab");
  // Grab at position 10,20
  if (avformat_open_input(&pFormatCtx, ":0.0+10,20", ifmt, &options) != 0) {
    printf("Couldn't open input stream.\n");
    return -1;
  }
#else
  show_avfoundation_device();
  // Mac
  AVInputFormat *ifmt = (AVInputFormat *)av_find_input_format("avfoundation");
  // Avfoundation
  //[video]:[audio]
  if (avformat_open_input(&pFormatCtx, "1", ifmt, NULL) != 0) {
    printf("Couldn't open input stream.\n");
    return -1;
  }
#endif

  if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
    printf("Couldn't find stream information.\n");
    return -1;
  }
  videoindex = -1;
  for (i = 0; i < pFormatCtx->nb_streams; i++)
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
      videoindex = i;
      break;
    }
  if (videoindex == -1) {
    printf("Didn't find a video stream.\n");
    return -1;
  }
  pCodecCtx = pFormatCtx->streams[videoindex]->codec;
  pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
  if (pCodec == NULL) {
    printf("Codec not found.\n");
    return -1;
  }
  if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
    printf("Could not open codec.\n");
    return -1;
  }
  AVFrame *pFrame, *pFrameYUV;
  pFrame = av_frame_alloc();
  pFrameYUV = av_frame_alloc();
  // unsigned char *out_buffer=(unsigned char
  // *)av_malloc(avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
  // pCodecCtx->height)); avpicture_fill((AVPicture *)pFrameYUV, out_buffer,
  // AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);
  // SDL----------------------------
  if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
    printf("Could not initialize SDL - %s\n", SDL_GetError());
    return -1;
  }
  int screen_w = 640, screen_h = 360;
  const SDL_VideoInfo *vi = SDL_GetVideoInfo();
  // Half of the Desktop's width and height.
  screen_w = vi->current_w / 2;
  screen_h = vi->current_h / 2;
  SDL_Surface *screen;
  screen = SDL_SetVideoMode(screen_w, screen_h, 0, 0);

  if (!screen) {
    printf("SDL: could not set video mode - exiting:%s\n", SDL_GetError());
    return -1;
  }
  SDL_Overlay *bmp;
  bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,
                             SDL_YV12_OVERLAY, screen);
  SDL_Rect rect;
  rect.x = 0;
  rect.y = 0;
  rect.w = screen_w;
  rect.h = screen_h;
  // SDL End------------------------
  int ret, got_picture;

  AVPacket *packet = (AVPacket *)av_malloc(sizeof(AVPacket));

#if OUTPUT_YUV420P
  FILE *fp_yuv = fopen("output.yuv", "wb+");
#endif

  struct SwsContext *img_convert_ctx;
  img_convert_ctx = sws_getContext(
      pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width,
      pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
  //------------------------------
  SDL_Thread *video_tid = SDL_CreateThread(sfp_refresh_thread, NULL);
  //
  SDL_WM_SetCaption("Simplest FFmpeg Grab Desktop", NULL);
  // Event Loop
  SDL_Event event;

  for (;;) {
    // Wait
    SDL_WaitEvent(&event);
    if (event.type == SFM_REFRESH_EVENT) {
      //------------------------------
      if (av_read_frame(pFormatCtx, packet) >= 0) {
        if (packet->stream_index == videoindex) {
          ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
          if (ret < 0) {
            printf("Decode Error.\n");
            return -1;
          }
          if (got_picture) {
            SDL_LockYUVOverlay(bmp);
            pFrameYUV->data[0] = bmp->pixels[0];
            pFrameYUV->data[1] = bmp->pixels[2];
            pFrameYUV->data[2] = bmp->pixels[1];
            pFrameYUV->linesize[0] = bmp->pitches[0];
            pFrameYUV->linesize[1] = bmp->pitches[2];
            pFrameYUV->linesize[2] = bmp->pitches[1];
            sws_scale(img_convert_ctx,
                      (const unsigned char *const *)pFrame->data,
                      pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data,
                      pFrameYUV->linesize);

#if OUTPUT_YUV420P
            int y_size = pCodecCtx->width * pCodecCtx->height;
            fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv);      // Y
            fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv);  // U
            fwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv);  // V
#endif
            SDL_UnlockYUVOverlay(bmp);

            SDL_DisplayYUVOverlay(bmp, &rect);
          }
        }
        av_free_packet(packet);
      } else {
        // Exit Thread
        thread_exit = 1;
      }
    } else if (event.type == SDL_QUIT) {
      thread_exit = 1;
    } else if (event.type == SFM_BREAK_EVENT) {
      break;
    }
  }

  sws_freeContext(img_convert_ctx);

#if OUTPUT_YUV420P
  fclose(fp_yuv);
#endif

  SDL_Quit();

  // av_free(out_buffer);
  av_free(pFrameYUV);
  avcodec_close(pCodecCtx);
  avformat_close_input(&pFormatCtx);

  return 0;
}