/*
 * Copyright (c) 2003 Fabrice Bellard
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 /**
  * @file
  * libavformat API example.
  *
  * Output a media file in any supported libavformat format. The default
  * codecs are used.
  * @example muxing.c
  */
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <cmath>

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavutil/avassert.h>
#include <libavutil/channel_layout.h>
#include <libavutil/opt.h>
#include <libavutil/mathematics.h>
#include <libavutil/timestamp.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
}

//#define STREAM_DURATION   60.0
#define STREAM_FRAME_RATE 50
#define STREAM_PIX_FMT    AV_PIX_FMT_YUV420P /* default pix_fmt */
#define SCALE_FLAGS SWS_POINT

// a wrapper around a single output AVStream
typedef struct OutputStream {
	AVStream *st;
	AVCodecContext *enc;
	/* pts of the next frame that will be generated */
	int64_t next_pts;
	int samples_count;
	AVFrame *frame;
	AVFrame *tmp_frame;
	float t, tincr, tincr2;
	struct SwsContext *sws_ctx;
	struct SwrContext *swr_ctx;
} OutputStream;


OutputStream video_st, audio_st;
AVFormatContext *oc;
AVPixelFormat source_format = AV_PIX_FMT_RGB24;
uint8_t *picture_source;
int source_width = 0, source_height = 0;
int have_video = 0, have_audio = 0;
int encode_video = 0, encode_audio = 0;

char *_av_err2str(int errnum) {
	/* C++ friendly alternate to av_err2str */
	thread_local char buf[AV_ERROR_MAX_STRING_SIZE] = {};
	return av_make_error_string(buf, AV_ERROR_MAX_STRING_SIZE, errnum);
}

static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt)
{
	char buf[AV_TS_MAX_STRING_SIZE] = { 0 };

	AVRational *time_base = &fmt_ctx->streams[pkt->stream_index]->time_base;

	printf("pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
		av_ts_make_string(buf, pkt->pts), av_ts_make_time_string(buf, pkt->pts, time_base),
		av_ts_make_string(buf, pkt->dts), av_ts_make_time_string(buf, pkt->dts, time_base),
		av_ts_make_string(buf, pkt->duration), av_ts_make_time_string(buf, pkt->duration, time_base),
		pkt->stream_index);
}

static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)
{
	/* rescale output packet timestamp values from codec to stream timebase */
	av_packet_rescale_ts(pkt, *time_base, st->time_base);
	pkt->stream_index = st->index;
	/* Write the compressed frame to the media file. */
	log_packet(fmt_ctx, pkt);
	return av_interleaved_write_frame(fmt_ctx, pkt);
}

/* Add an output stream. */
static void add_stream(OutputStream *ost, AVFormatContext *oc,
	const AVCodec **codec,
	enum AVCodecID codec_id, int width, int height)
{
	AVCodecContext *c;
	int i;
	/* find the encoder */
	*codec = avcodec_find_encoder(codec_id);
	if (!(*codec)) {
		fprintf(stderr, "Could not find encoder for '%s'\n",
			avcodec_get_name(codec_id));
		exit(1);
	}
	ost->st = avformat_new_stream(oc, NULL);
	if (!ost->st) {
		fprintf(stderr, "Could not allocate stream\n");
		exit(1);
	}
	ost->st->id = oc->nb_streams - 1;
	c = avcodec_alloc_context3(*codec);
	if (!c) {
		fprintf(stderr, "Could not alloc an encoding context\n");
		exit(1);
	}
	ost->enc = c;
	switch ((*codec)->type) {
	case AVMEDIA_TYPE_AUDIO:
		c->sample_fmt = (*codec)->sample_fmts ?
			(*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
		c->bit_rate = 64000;
		c->sample_rate = 44100;
		if ((*codec)->supported_samplerates) {
			c->sample_rate = (*codec)->supported_samplerates[0];
			for (i = 0; (*codec)->supported_samplerates[i]; i++) {
				if ((*codec)->supported_samplerates[i] == 44100)
					c->sample_rate = 44100;
			}
		}

    if ((*codec)->ch_layouts) {
      auto chan_layout = (*codec)->ch_layouts;
      for (;chan_layout; chan_layout++) {
        if(chan_layout->nb_channels == 2) {
          av_channel_layout_copy(&c->ch_layout, chan_layout);
          break;
        }
      }

    } else {
      AVChannelLayout stereo_layout = AV_CHANNEL_LAYOUT_STEREO;
      av_channel_layout_copy(&c->ch_layout, &stereo_layout);
    }

		ost->st->time_base = { 1, c->sample_rate };
		break;
	case AVMEDIA_TYPE_VIDEO:
		c->codec_id = codec_id;
		c->bit_rate = 4000000;
		/* Resolution must be a multiple of two. */
		c->width = width;
		c->height = height;
		/* timebase: This is the fundamental unit of time (in seconds) in terms
		 * of which frame timestamps are represented. For fixed-fps content,
		 * timebase should be 1/framerate and timestamp increments should be
		 * identical to 1. */
		ost->st->time_base = { 1, STREAM_FRAME_RATE };
		c->time_base = ost->st->time_base;
		c->gop_size = 12; /* emit one intra frame every twelve frames at most */
		c->pix_fmt = STREAM_PIX_FMT;
		if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
			/* just for testing, we also add B-frames */
			c->max_b_frames = 2;
		}
		if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
			/* Needed to avoid using macroblocks in which some coeffs overflow.
			 * This does not happen with normal video, it just happens here as
			 * the motion of the chroma plane does not match the luma plane. */
			c->mb_decision = 2;
		}
		break;
	default:
		break;
	}
	/* Some formats want stream headers to be separate. */
	if (oc->oformat->flags & AVFMT_GLOBALHEADER)
		c->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
/**************************************************************/
/* audio output */
static AVFrame *alloc_audio_frame(enum AVSampleFormat sample_fmt,
	AVChannelLayout *channel_layout,
	int sample_rate, int nb_samples)
{
	AVFrame *frame = av_frame_alloc();
	int ret;
	if (!frame) {
		fprintf(stderr, "Error allocating an audio frame\n");
		exit(1);
	}
	frame->format = sample_fmt;
	av_channel_layout_copy(&frame->ch_layout, channel_layout);
	frame->sample_rate = sample_rate;
	frame->nb_samples = nb_samples;
	if (nb_samples) {
		ret = av_frame_get_buffer(frame, 0);
		if (ret < 0) {
			fprintf(stderr, "Error allocating an audio buffer\n");
			exit(1);
		}
	}
	return frame;
}
static void open_audio(AVFormatContext *oc, const AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
{
	AVCodecContext *c;
	int nb_samples;
	int ret;
	AVDictionary *opt = NULL;
	c = ost->enc;
	/* open it */
	av_dict_copy(&opt, opt_arg, 0);
	ret = avcodec_open2(c, codec, &opt);
	av_dict_free(&opt);
	if (ret < 0) {
		fprintf(stderr, "Could not open audio codec: %s\n", _av_err2str(ret));
		exit(1);
	}
	/* init signal generator */
	ost->t = 0;
	ost->tincr = 2 * M_PI * 110.0 / c->sample_rate;
	/* increment frequency by 110 Hz per second */
	ost->tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
	if (c->codec->capabilities & AV_CODEC_CAP_VARIABLE_FRAME_SIZE)
		nb_samples = 10000;
	else
		nb_samples = c->frame_size;
	ost->frame = alloc_audio_frame(c->sample_fmt, &c->ch_layout,
		c->sample_rate, nb_samples);
	ost->tmp_frame = alloc_audio_frame(AV_SAMPLE_FMT_S16, &c->ch_layout,
		c->sample_rate, nb_samples);
	/* copy the stream parameters to the muxer */
	ret = avcodec_parameters_from_context(ost->st->codecpar, c);
	if (ret < 0) {
		fprintf(stderr, "Could not copy the stream parameters\n");
		exit(1);
	}
	/* create resampler context */
	ost->swr_ctx = swr_alloc();
	if (!ost->swr_ctx) {
		fprintf(stderr, "Could not allocate resampler context\n");
		exit(1);
	}
	/* set options */
	av_opt_set_int(ost->swr_ctx, "in_channel_count", c->ch_layout.nb_channels, 0);
	av_opt_set_int(ost->swr_ctx, "in_sample_rate", c->sample_rate, 0);
	av_opt_set_sample_fmt(ost->swr_ctx, "in_sample_fmt", AV_SAMPLE_FMT_S16, 0);
	av_opt_set_int(ost->swr_ctx, "out_channel_count", c->ch_layout.nb_channels, 0);
	av_opt_set_int(ost->swr_ctx, "out_sample_rate", c->sample_rate, 0);
	av_opt_set_sample_fmt(ost->swr_ctx, "out_sample_fmt", c->sample_fmt, 0);
	/* initialize the resampling context */
	if ((ret = swr_init(ost->swr_ctx)) < 0) {
		fprintf(stderr, "Failed to initialize the resampling context\n");
		exit(1);
	}
}
/* Prepare a 16 bit dummy audio frame of 'frame_size' samples and
 * 'nb_channels' channels. */
static AVFrame *get_audio_frame(OutputStream *ost)
{
	AVFrame *frame = ost->tmp_frame;
	int j, i, v;
	int16_t *q = (int16_t*)frame->data[0];
	/* check if we want to generate more frames */
	/*if (av_compare_ts(ost->next_pts, ost->enc->time_base,
		(int64_t)STREAM_DURATION, { 1, 1 }) >= 0)
		return NULL;*/
	for (j = 0; j < frame->nb_samples; j++) {
		v = (int)(sin(ost->t) * 10000);
		for (i = 0; i < ost->enc->ch_layout.nb_channels; i++)
			*q++ = v;
		ost->t += ost->tincr;
		ost->tincr += ost->tincr2;
	}
	frame->pts = ost->next_pts;
	ost->next_pts += frame->nb_samples;
	return frame;
}
/*
 * encode one audio frame and send it to the muxer
 * return 1 when encoding is finished, 0 otherwise
 */
static int write_audio_frame(AVFormatContext *oc, OutputStream *ost)
{
	AVCodecContext *c;
	AVPacket pkt = {}; // data and size must be 0;
	AVFrame *frame;
	int ret;
	//int got_packet;
	int dst_nb_samples;
	av_init_packet(&pkt);
	c = ost->enc;
	frame = get_audio_frame(ost);
	if (frame) {
		/* convert samples from native format to destination codec format, using the resampler */
			/* compute destination number of samples */
		dst_nb_samples = av_rescale_rnd(swr_get_delay(ost->swr_ctx, c->sample_rate) + frame->nb_samples,
			c->sample_rate, c->sample_rate, AV_ROUND_UP);
		av_assert0(dst_nb_samples == frame->nb_samples);
		/* when we pass a frame to the encoder, it may keep a reference to it
		 * internally;
		 * make sure we do not overwrite it here
		 */
		ret = av_frame_make_writable(ost->frame);
		if (ret < 0)
			exit(1);
		/* convert to destination format */
		ret = swr_convert(ost->swr_ctx,
			ost->frame->data, dst_nb_samples,
			(const uint8_t **)frame->data, frame->nb_samples);
		if (ret < 0) {
			fprintf(stderr, "Error while converting: %s\n", _av_err2str(ret));
			exit(1);
		}
		frame = ost->frame;
		frame->pts = av_rescale_q(ost->samples_count, { 1, c->sample_rate }, c->time_base);
		ost->samples_count += dst_nb_samples;
	}
	ret = avcodec_send_frame(c, frame);
	if (ret < 0) {
		fprintf(stderr, "error sending frame for encoding: %s\n", _av_err2str(ret));
		return -1;
	}

	while (ret >= 0) {
		ret = avcodec_receive_packet(c, &pkt);
		if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
			return 0;
		}
		else if (ret < 0) {
			fprintf(stderr, "Error during encoding: %s\n", _av_err2str(ret));
			return ret;
		}

		printf("Encoded frame %3" PRId64 " (size=%5d)\n", pkt.pts, pkt.size);
		ret = write_frame(oc, &c->time_base, ost->st, &pkt);
		if (ret != 0) {
			fprintf(stderr, "Error writing frame: %s\n", _av_err2str(ret));
		}
		av_packet_unref(&pkt);
	}

	return 1;
}
/**************************************************************/
/* video output */
static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
{
	AVFrame *picture;
	int ret;
	picture = av_frame_alloc();
	if (!picture)
		return NULL;
	picture->format = pix_fmt;
	picture->width = width;
	picture->height = height;
	/* allocate the buffers for the frame data */
	ret = av_frame_get_buffer(picture, 32);
	if (ret < 0) {
		fprintf(stderr, "Could not allocate frame data: %s\n", _av_err2str(ret));
		exit(1);
	}
	return picture;
}
static void open_video(AVFormatContext *oc, const AVCodec *codec, OutputStream *ost, AVDictionary *opt_arg)
{
	int ret;
	AVCodecContext *c = ost->enc;
	AVDictionary *opt = NULL;
	av_dict_copy(&opt, opt_arg, 0);
	/* open the codec */
	ret = avcodec_open2(c, codec, &opt);
	av_dict_free(&opt);
	if (ret < 0) {
		fprintf(stderr, "Could not open video codec: %s\n", _av_err2str(ret));
		exit(1);
	}
	/* allocate and init a re-usable frame */
	ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);
	if (!ost->frame) {
		fprintf(stderr, "Could not allocate video frame\n");
		exit(1);
	}
	/* If the output format is not YUV420P, then a temporary YUV420P
	 * picture is needed too. It is then converted to the required
	 * output format. */
	ost->tmp_frame = NULL;
	if (c->pix_fmt != source_format) {
		//ost->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);
		ost->tmp_frame = alloc_picture(source_format, source_width, source_height);
		if (!ost->tmp_frame) {
			fprintf(stderr, "Could not allocate temporary picture\n");
			exit(1);
		}
	}
	/* copy the stream parameters to the muxer */
	ret = avcodec_parameters_from_context(ost->st->codecpar, c);
	if (ret < 0) {
		fprintf(stderr, "Could not copy the stream parameters\n");
		exit(1);
	}
}

static void fill_from_source(AVFrame *pict, int frame_index, int width, int height) {
  int bpp = 3;

  for(int y = 0; y < height; y++) {
    for(int i = 0; i < width * bpp; i++) {
      pict->data[0][y * pict->linesize[0] + i] = picture_source[y * width * bpp + i];
    }
  }
}

static AVFrame *get_video_frame(OutputStream *ost)
{
	AVCodecContext *c = ost->enc;
	/* when we pass a frame to the encoder, it may keep a reference to it
	 * internally; make sure we do not overwrite it here */
	if (av_frame_make_writable(ost->frame) < 0)
		exit(1);

	ost->sws_ctx = sws_getCachedContext(ost->sws_ctx, ost->tmp_frame->width, ost->tmp_frame->height,
		source_format,
		c->width, c->height,
		c->pix_fmt,
		SCALE_FLAGS, NULL, NULL, NULL);
	if (!ost->sws_ctx) {
		fprintf(stderr,
			"Could not initialize the conversion context\n");
		exit(1);
	}

	fill_from_source(ost->tmp_frame, (int)ost->next_pts, ost->tmp_frame->width, ost->tmp_frame->height);
	sws_scale(ost->sws_ctx, (const uint8_t * const *)ost->tmp_frame->data,
		ost->tmp_frame->linesize, 0, ost->tmp_frame->height, ost->frame->data,
		ost->frame->linesize);

	ost->frame->pts = ost->next_pts++;
	return ost->frame;
}
/*
 * encode one video frame and send it to the muxer
 * return 1 when encoding is finished, 0 otherwise
 */
static int write_video_frame(AVFormatContext *oc, OutputStream *ost)
{
	int ret;
	AVCodecContext *c;
	AVFrame *frame;
	AVPacket pkt = {};
	c = ost->enc;
	frame = get_video_frame(ost);
	av_init_packet(&pkt);
	/* encode the image */
	ret = avcodec_send_frame(c, frame);
	if (ret < 0) {
		fprintf(stderr, "error sending frame for encoding!\n");
		return -1;
	}

	while (ret >= 0) {
		ret = avcodec_receive_packet(c, &pkt);
		if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
			return 0;
		}
		else if (ret < 0) {
			fprintf(stderr, "Error during encoding: %d\n", ret);
			return ret;
		}
		printf("Encoded frame %3" PRId64 " (size=%5d)\n", pkt.pts, pkt.size);
		ret = write_frame(oc, &c->time_base, ost->st, &pkt);
		if (ret != 0) {
			fprintf(stderr, "Error writing frame!\n");
		}
		av_packet_unref(&pkt);
	}

	return 1;
}
static void close_stream(AVFormatContext *oc, OutputStream *ost)
{
	avcodec_free_context(&ost->enc);
	av_frame_free(&ost->frame);
	av_frame_free(&ost->tmp_frame);
	sws_freeContext(ost->sws_ctx);
	swr_free(&ost->swr_ctx);
}
/**************************************************************/
/* media file output */

//int main(int argc, char **argv)
int ffmpeg_open_stream(const char *filename, int width, int height, uint8_t *pic_src) {

	const AVOutputFormat *fmt;
	const AVCodec *audio_codec = NULL, *video_codec = NULL;
	int ret;
	AVDictionary *opt = NULL;
	AVPixelFormat src_fmt = AV_PIX_FMT_RGB24;

	source_format = src_fmt;
	picture_source = pic_src;
	source_width = width;
	source_height = height;

	/* allocate the output media context */
	avformat_alloc_output_context2(&oc, NULL, NULL, filename);
	if (!oc) {
		printf("Could not deduce output format from file extension: using MPEG.\n");
		avformat_alloc_output_context2(&oc, NULL, "mpeg", filename);
	}
	if (!oc)
		return 1;
	fmt = oc->oformat;
	/* Add the audio and video streams using the default format codecs
	 * and initialize the codecs. */
	if (fmt->video_codec != AV_CODEC_ID_NONE) {
		add_stream(&video_st, oc, &video_codec, fmt->video_codec, width * 2, height * 2);
		have_video = 1;
		encode_video = 1;
	}
	/*if (fmt->audio_codec != AV_CODEC_ID_NONE) {
		add_stream(&audio_st, oc, &audio_codec, fmt->audio_codec, 0, 0);
		have_audio = 1;
		encode_audio = 1;
	}*/
	/* Now that all the parameters are set, we can open the audio and
	 * video codecs and allocate the necessary encode buffers. */
	if (have_video)
		open_video(oc, video_codec, &video_st, opt);

	if (have_audio)
		open_audio(oc, audio_codec, &audio_st, opt);

	av_dump_format(oc, 0, filename, 1);
	/* open the output file, if needed */
	if (!(fmt->flags & AVFMT_NOFILE)) {
		ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
		if (ret < 0) {
			fprintf(stderr, "Could not open '%s': %s\n", filename,
				_av_err2str(ret));
			return 1;
		}
	}
	/* Write the stream header, if any. */
	ret = avformat_write_header(oc, &opt);
	if (ret < 0) {
		fprintf(stderr, "Error occurred when opening output file: %s\n",
			_av_err2str(ret));
		return 1;
	}

	return 0;
}

int ffmpeg_capture(void)
{
	if (encode_video || encode_audio) {
		/* select the stream to encode */
		if (encode_video &&
			(!encode_audio || av_compare_ts(video_st.next_pts, video_st.enc->time_base,
				audio_st.next_pts, audio_st.enc->time_base) <= 0)) {
			encode_video = !write_video_frame(oc, &video_st);
		}
		else {
			encode_audio = !write_audio_frame(oc, &audio_st);
		}
	}

	return 0;
}

int ffmpeg_close_stream(void) {
	/* Write the trailer, if any. The trailer must be written before you
	 * close the CodecContexts open when you wrote the header; otherwise
	 * av_write_trailer() may try to use memory that was freed on
	 * av_codec_close(). */
	av_write_trailer(oc);
	/* Close each codec. */
	if (have_video) {
		close_stream(oc, &video_st);
		video_st.next_pts = 0;
		video_st.samples_count = 0;
	}
	if (have_audio) {
		close_stream(oc, &audio_st);
		audio_st.next_pts = 0;
		audio_st.samples_count = 0;
	}
	if (!(oc->oformat->flags & AVFMT_NOFILE)) {
		/* Close the output file. */
		avio_closep(&oc->pb);
	}

	audio_st = OutputStream();
	video_st = OutputStream();

	/* free the stream */
	avformat_free_context(oc);
	return 0;
}