/*
 * This file is part of Moonlight Embedded.
 *
 * Based on Moonlight Pc implementation
 *
 * Moonlight is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Moonlight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Moonlight; if not, see <http://www.gnu.org/licenses/>.
 */

#include "ffmpeg.h"

#ifdef HAVE_VDPAU
#include "ffmpeg_vdpau.h"
#endif

#include <Limelight.h>

#include <stdlib.h>
#include <libswscale/swscale.h>
#include <pthread.h>
#include <stdio.h>
#include <stdbool.h>

// General decoder and renderer state
static AVPacket pkt;
static AVCodec* decoder;
static AVCodecContext* decoder_ctx;
static AVFrame** dec_frames;

static int dec_frames_cnt;
static int current_frame, next_frame;

enum decoders {SOFTWARE, VDPAU};
enum decoders decoder_system;

#define BYTES_PER_PIXEL 4

// This function must be called before
// any other decoding functions
int ffmpeg_init(int videoFormat, int width, int height, int perf_lvl, int buffer_count, int thread_count) {
  // Initialize the avcodec library and register codecs
  av_log_set_level(AV_LOG_QUIET);
  avcodec_register_all();

  av_init_packet(&pkt);

  #ifdef HAVE_VDPAU
  if (perf_lvl & HARDWARE_ACCELERATION) {
    switch (videoFormat) {
      case VIDEO_FORMAT_H264:
        decoder = avcodec_find_decoder_by_name("h264_vdpau");
        break;
      case VIDEO_FORMAT_H265:
        decoder = avcodec_find_decoder_by_name("hevc_vdpau");
        break;
    }

    if (decoder != NULL)
      decoder_system = VDPAU;
  }
  #endif

  if (decoder == NULL) {
    decoder_system = SOFTWARE;
    switch (videoFormat) {
      case VIDEO_FORMAT_H264:
        decoder = avcodec_find_decoder_by_name("h264");
        break;
      case VIDEO_FORMAT_H265:
        decoder = avcodec_find_decoder_by_name("hevc");
        break;
    }
    if (decoder == NULL) {
      printf("Couldn't find decoder\n");
      return -1;
    }
  }

  decoder_ctx = avcodec_alloc_context3(decoder);
  if (decoder_ctx == NULL) {
    printf("Couldn't allocate context");
    return -1;
  }

  if (perf_lvl & DISABLE_LOOP_FILTER)
    // Skip the loop filter for performance reasons
    decoder_ctx->skip_loop_filter = AVDISCARD_ALL;

  if (perf_lvl & LOW_LATENCY_DECODE)
    // Use low delay single threaded encoding
    decoder_ctx->flags |= CODEC_FLAG_LOW_DELAY;

  if (perf_lvl & SLICE_THREADING)
    decoder_ctx->thread_type = FF_THREAD_SLICE;
  else
    decoder_ctx->thread_type = FF_THREAD_FRAME;

  decoder_ctx->thread_count = thread_count;

  decoder_ctx->width = width;
  decoder_ctx->height = height;
  decoder_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

  int err = avcodec_open2(decoder_ctx, decoder, NULL);
  if (err < 0) {
    printf("Couldn't open codec");
    return err;
  }

  dec_frames_cnt = buffer_count;
  dec_frames = malloc(buffer_count * sizeof(AVFrame*));
  if (dec_frames == NULL) {
    fprintf(stderr, "Couldn't allocate frames");
    return -1;
  }

  for (int i = 0; i < buffer_count; i++) {
    dec_frames[i] = av_frame_alloc();
    if (dec_frames[i] == NULL) {
      fprintf(stderr, "Couldn't allocate frame");
      return -1;
    }
  }

  #ifdef HAVE_VDPAU
  if (decoder_system == VDPAU)
    vdpau_init(decoder_ctx, width, height);
  #endif

  return 0;
}

// This function must be called after
// decoding is finished
void ffmpeg_destroy(void) {
  if (decoder_ctx) {
    avcodec_close(decoder_ctx);
    av_free(decoder_ctx);
    decoder_ctx = NULL;
  }
  if (dec_frames) {
    for (int i = 0; i < dec_frames_cnt; i++) {
      if (dec_frames[i])
        av_frame_free(&dec_frames[i]);
    }
  }
}

AVFrame* ffmpeg_get_frame() {
  int err = avcodec_receive_frame(decoder_ctx, dec_frames[next_frame]);
  if (err == 0) {
    current_frame = next_frame;
    next_frame = (current_frame+1) % dec_frames_cnt;

    if (decoder_system == SOFTWARE)
      return dec_frames[current_frame];
    #ifdef HAVE_VDPAU
    else if (decoder_system == VDPAU)
      return vdpau_get_frame(dec_frames[current_frame]);
    #endif
  } else if (err != AVERROR(EAGAIN)) {
    char errorstring[512];
    av_strerror(err, errorstring, sizeof(errorstring));
    fprintf(stderr, "Receive failed - %d/%s\n", err, errorstring);
  }
  return NULL;
}

// packets must be decoded in order
// indata must be inlen + FF_INPUT_BUFFER_PADDING_SIZE in length
int ffmpeg_decode(unsigned char* indata, int inlen) {
  int err;

  pkt.data = indata;
  pkt.size = inlen;

  err = avcodec_send_packet(decoder_ctx, &pkt);
  if (err < 0) {
    char errorstring[512];
    av_strerror(err, errorstring, sizeof(errorstring));
    fprintf(stderr, "Decode failed - %s\n", errorstring);
  }
  
  return err < 0 ? err : 0;
}