#include "encoder.h"
#include <assert.h>

int encoder_init (struct Encoder *encoder, const AVCodecParameters *codecpar, AVDictionary **opts)
{
	/* NOTE: While encoder->time_base "MUST be set by user" when encoding
	 * (quoted from the official FFMPEG documentation), avcodec_open2 actually
	 * discard it's value and set it to '1/sample_rate'.
	 *
	 * NOTE: The assert at the end of this section serves to protect cybd in
	 * case the FFMPEG devs update their code to implement some funny behaviors.
	 */
	int err;
	AVCodecContext *avctx;
	const AVCodec *codec;

	if ((codec = avcodec_find_encoder(codecpar->codec_id)) == NULL) {
		err = AVERROR_ENCODER_NOT_FOUND;
		goto error;
	}

	if ((avctx = avcodec_alloc_context3(codec)) == NULL)
		return AVERROR(ENOMEM);

	if ((err = avcodec_parameters_to_context(avctx, codecpar)) < 0)
		goto error;

	if ((err = avcodec_open2(avctx, codec, opts)))
		goto error;

	/* Because some code rely on avctx's time base to be 1/sample_rate, and
	 * because this behavious currently appears undocumented, I placed some
	 * assert here to catch up if anything changes up with ffmpeg. */
	assert(avctx->time_base.num == 1);
	assert(avctx->time_base.den == avctx->sample_rate);
	encoder->avctx = avctx;
	encoder->pts   = 0;
	return 0;

error:
	avcodec_free_context(&avctx);
	return err;
}

int encoder_init_for_stream (struct Encoder *encoder, const AVStream *stream, AVDictionary **opts)
{
	return encoder_init(encoder, stream->codecpar, opts);
}

int encoder_send (struct Encoder *encoder, const AVFrame *frame)
{
	return avcodec_send_frame(encoder->avctx, frame);
}

int encoder_convert (struct Encoder *encoder, AVPacket *pkt_out)
{
	int err;
	err = avcodec_receive_packet(encoder->avctx, pkt_out);
	if (err < 0) return err;
	// Manually setting pts because FFMPEG doesn't do it consistantly
	//pkt_out->pts = encoder->pts;
	//encoder->pts += pkt_out->duration;
	return 0;
}

void encoder_free (struct Encoder *encoder)
{
	avcodec_free_context(&encoder->avctx);
}