#include "VideoTools.h"
#include "logger.hpp"

extern "C" {
   	#include <libavcodec/avcodec.h> 
	#include <libavdevice/avdevice.h> 
	#include <libavformat/avformat.h> 
	#include <libavfilter/avfilter.h> 
	#include <libavutil/avutil.h> 
    #include <libavutil/pixdesc.h> 
	#include <libswscale/swscale.h>
    #include <libavutil/imgutils.h>
}

namespace VideoTools {

FFImgInfo* snapshot(const string& uri){
    if (uri.empty()){
        return nullptr;
    }
 
    AVFormatContext* ifmt_ctx = nullptr;
	AVCodecContext* codec_ctx = nullptr;
	AVCodec* codec = nullptr;
	AVPacket* pkt = nullptr;
	AVFrame *frame = nullptr;
	AVFrame *pFrameRGB = nullptr;	
	int video_index = -1;
	AVStream* st = nullptr;
	SwsContext *img_convert_ctx = nullptr;
	uint8_t *buffer = nullptr;
    int numBytes = 0;
	int index = 0;

	FFImgInfo* imgInfo = nullptr;
 
 	//av_register_all();
	avformat_network_init();

	// 参数设置
	AVDictionary *options = nullptr;
	av_dict_set( &options, "bufsize", "655360", 0 );
	av_dict_set( &options, "rtsp_transport", "tcp", 0 );
	av_dict_set( &options, "stimeout", "30000000", 0 ); // 单位为 百万分之一秒
	
	///打开输入的流
	int ret = avformat_open_input(&ifmt_ctx, uri.c_str(), nullptr, &options);
	if (ret != 0){
		printf("Couldn't open input stream.\n");
		goto end_flag ;
	}
 
	//查找流信息
	if (avformat_find_stream_info(ifmt_ctx, nullptr) < 0){
		printf("Couldn't find stream information.\n");
		goto end_flag ;
	}
 
	//找到视频流索引
    video_index = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, nullptr, 0);
 
    st = ifmt_ctx->streams[video_index];
    
    //找到解码器
    codec = avcodec_find_decoder(st->codecpar->codec_id);
    if (!codec){
        fprintf(stderr, "Codec not found\n");
        goto end_flag ;
    }
 
    //申请AVCodecContext
    codec_ctx = avcodec_alloc_context3(codec);
    if (!codec_ctx){
        goto end_flag ;
    }
 
	avcodec_parameters_to_context(codec_ctx, ifmt_ctx->streams[video_index]->codecpar);
 
    //打开解码器
    if ((ret = avcodec_open2(codec_ctx, codec, nullptr) < 0)){
        goto end_flag ;
    }
	
    // 计算解码后原始数据所需缓冲区大小，并分配内存空间 Determine required buffer size and allocate buffer
    numBytes = av_image_get_buffer_size(AV_PIX_FMT_BGR24, codec_ctx->width, codec_ctx->height, 1);
    buffer = (uint8_t *)av_malloc(numBytes * sizeof(uint8_t));
    
	pFrameRGB = av_frame_alloc();
    av_image_fill_arrays(pFrameRGB->data, pFrameRGB->linesize, buffer, AV_PIX_FMT_BGR24, codec_ctx->width, codec_ctx->height, 1);

	img_convert_ctx = sws_getContext(codec_ctx->width, codec_ctx->height,codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height, AV_PIX_FMT_BGR24, 
		   SWS_BICUBIC, nullptr, nullptr, nullptr);
 
	pkt = av_packet_alloc();
	frame = av_frame_alloc();
	while (av_read_frame(ifmt_ctx, pkt) >= 0){
		if (pkt->stream_index == video_index){
			int ret = avcodec_send_packet(codec_ctx, pkt);
			if (ret >= 0){
				ret = avcodec_receive_frame(codec_ctx, frame);
				if ((ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) || ret < 0){
					LOG_ERROR("Failed to receive frame: {}",ret);
					continue;
				}

				index ++ ;

				if (index >= 5){
					// 取解码出来的第三帧，应该可以一定程度优化花屏问题
					sws_scale(img_convert_ctx, (const unsigned char* const*)frame->data, frame->linesize, 0, codec_ctx->height, pFrameRGB->data, pFrameRGB->linesize);

					imgInfo = new FFImgInfo();
					imgInfo->pData = buffer;
					imgInfo->height = codec_ctx->height;
					imgInfo->width = codec_ctx->width;

					break;
				}
			}
		}
		av_packet_unref(pkt);
	}

end_flag:
	if (codec_ctx != nullptr){
		avcodec_close(codec_ctx);
		avcodec_free_context(&codec_ctx);
	}
	
	if (ifmt_ctx != nullptr){
		avformat_close_input(&ifmt_ctx);
	}
	
	if (frame != nullptr){
		av_frame_free(&frame);
	}

	if (pFrameRGB != nullptr){
		av_frame_free(&pFrameRGB);
	}

	if (pkt != nullptr){
		av_packet_free(&pkt);
	}

	return imgInfo;
}

void releaseFFImgInfo(FFImgInfo* info) {
	if(nullptr != info){
		if(info->pData != nullptr){
			av_free(info->pData);
			info->pData = nullptr;
		}
		delete info;
		info = nullptr;
	}
}

}  // namespace