#include <asm-generic/errno-base.h>
#include <assert.h>
#include <libavcodec/avcodec.h>
#include <libavcodec/codec.h>
#include <libavcodec/codec_id.h>
#include <libavcodec/codec_par.h>
#include <libavcodec/packet.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libavutil/channel_layout.h>
#include <libavutil/dict.h>
#include <libavutil/error.h>
#include <libavutil/frame.h>
#include <libavutil/log.h>
#include <libavutil/mathematics.h>
#include <libavutil/opt.h>
#include <libavutil/rational.h>
#include <libavutil/samplefmt.h>
#include <libswresample/swresample.h>
#include <pthread.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "audio/muxer.h"
#include "common.h"
#include "transmuxer.h"

#define NANOSEC (uint64_t)1000000000
#define MIN(a, b) ((a < b) ? a : b)

enum PacketType {
	PKT_AUDIO,
	PKT_VIDEO,
};

struct HLSRemuxer {
	enum State     state;
	pthread_cond_t resume;

	/* Input objects */
	AVFormatContext *demuxer;
	const AVStream  *audio_stream;
	const AVStream  *video_stream;
	int              audio_stream_index;
	int              video_stream_index;

	/* Output object pointers */
	long long next_sample;
	AVFormatContext *hls_writer;
	AudioMuxer      *audio_muxer;

	struct timespec start_time;

	/* overhead: The target lenght in nanosecond of the output's stream
	 * buffer.
	 */
	uint64_t overhead;
};

static void hls_nanosleep          (uint64_t t);
static uint64_t hls_nanotime      (void);
static int hls_remuxer_init_input (struct HLSRemuxer *remuxer, const char *file);

static void timespec_add_nano     (struct timespec *ts, uint64_t nanoseconds);
static int  timespec_is_ahead     (const struct timespec *a, const struct timespec *b);
static int  remuxer_send_audio    (HLSRemuxer *remuxer, AVPacket *audio_packet);
static int  remuxer_send_video    (HLSRemuxer *remuxer, AVPacket *audio_packet);
static int  remuxer_wait_target_ts (HLSRemuxer *remuxer);
static int  remuxer_get_overrun   (HLSRemuxer *remuxer, struct timespec *until);

HLSRemuxer *hls_remuxer_init   (const struct StreamerOpt *opts)
{
	AVStream  *stream;
	HLSRemuxer      *remuxer;
	AVFormatContext *hls_muxer;
	AudioMuxer      *audio_muxer;
	AVDictionary    *m;

	if ((remuxer = malloc(sizeof(HLSRemuxer))) == NULL)
		return NULL;

	av_log_set_level(AV_LOG_VERBOSE);

	int err;

	if ((err = avformat_alloc_output_context2(&hls_muxer, NULL, "hls", opts->filename)) < 0) {
		fprintf(stderr, "Failed to allocate output context: %s\n", av_err2str(err));
		return NULL;
	}

	struct AudioMuxerOpt audio_opts = {
		.codec_id      = AV_CODEC_ID_MP3,
		.sample_rate   = 44100,
		.sample_format = AV_SAMPLE_FMT_S16P,
		.opts_encoder  = NULL,
		.opts_muxer    = NULL,
		.ch_layout     = AV_CHANNEL_LAYOUT_STEREO
	};

	if (audiomuxer_init(&audio_muxer, hls_muxer, &audio_opts))
		goto error;

	// TODO: Pass muxer options
	if ((err = avformat_write_header(hls_muxer, NULL)) < 0) {
		fprintf(stderr, "Failed to write output file: %s\n", av_err2str(err));
		goto error;
	}

	clock_gettime(CLOCK_MONOTONIC, &remuxer->start_time);
	remuxer->hls_writer  = hls_muxer;
	remuxer->audio_muxer = audio_muxer;
	remuxer->overhead    = 10 * NANOSEC; // NOTE: hls_time * hls_list_size * NANOSEC
	remuxer->resume      = (pthread_cond_t) PTHREAD_COND_INITIALIZER;
	return remuxer;

error:
	audiomuxer_free(audio_muxer);
	avformat_free_context(hls_muxer);
	free(remuxer);
	return NULL;
}

void hls_remuxer_play(HLSRemuxer *remuxer, const char *file)
{
	int err;
	AVPacket   *pkt;
	uint64_t next_second, next_nanosec;

	pkt = av_packet_alloc();

	if (hls_remuxer_init_input(remuxer, file))
		return;

	int64_t pts;
	while (1) {
		/* Demux packet */
		switch (err = av_read_frame(remuxer->demuxer, pkt)) {
			case 0:
				break;
			default:
				fprintf(stderr, "Error: %s\n", av_err2str(err));
			case AVERROR_EOF:
				fprintf(stderr, "Last packet ts: %f\n", (double)(pts *
						remuxer->audio_stream->time_base.num) /
						(remuxer->audio_stream->time_base.den * 60));
				goto exit;
		}
		pts = pkt->pts;

		/* Dispatch packet muxer */
		if (pkt->stream_index == remuxer->audio_stream_index)
			err = audiomuxer_send_packet(remuxer->audio_muxer, pkt);
		else
			continue;

		if (err) {
			fprintf(stderr, "Failed to send packet: %s\n", av_err2str(err));
			break;
		}

		/* Prevent overrun */
		remuxer_wait_target_ts(remuxer);
	}

exit:
	av_packet_free(&pkt);
	return;
}

void hls_remuxer_pause(HLSRemuxer *remuxer)
{
	// TODO: mutex?
	remuxer->state = STATE_PAUSED;
}

void hls_remuxer_resume(HLSRemuxer *remuxer)
{
	pthread_cond_broadcast(&remuxer->resume);
}

void hls_remuxer_halt(HLSRemuxer *remuxer)
{
	// TODO: mutex?
	remuxer->state = STATE_STANDBY;
}

void hls_remuxer_free(HLSRemuxer *remuxer)
{
	if (remuxer == NULL) return;
	av_write_trailer(remuxer->hls_writer);
	audiomuxer_free(remuxer->audio_muxer);
	free(remuxer);
}

static int hls_remuxer_init_input(struct HLSRemuxer *remuxer, const char *file)
{
	int err;
	int audio_stream_index;
	int video_stream_index;
	const AVStream          *audio_stream;
	const AVStream          *video_stream;
	AVFormatContext         *demuxer;

	demuxer = NULL;

	if ((err = avformat_open_input(&demuxer, file, NULL, NULL))) { // TODO: Options
		fprintf(stderr, "Failed to open '%s': %s\n", file, av_err2str(err));
		goto error;
	}

	if ((err = avformat_find_stream_info(demuxer, NULL)) < 0) { // TODO: Options
		fprintf(stderr, "Failed to find stream info of '%s': %s\n", file, av_err2str(err));
		goto error;
	}

	audio_stream_index = av_find_best_stream(demuxer, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0);
	video_stream_index = av_find_best_stream(demuxer, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);

	audio_stream = audio_stream_index >= 0 ? demuxer->streams[audio_stream_index] : NULL;
	video_stream = video_stream_index >= 0 ? demuxer->streams[video_stream_index] : NULL;
	if (audio_stream == NULL && video_stream == NULL) {
		fprintf(stderr, "Failed to find audio stream index of '%s'\n", file);
		err = AVERROR_STREAM_NOT_FOUND;
		goto error;
	}

	if ((err = audiomuxer_conf(remuxer->audio_muxer, audio_stream)))
		goto error;

	remuxer->demuxer            = demuxer;
	remuxer->audio_stream       = audio_stream;
	remuxer->video_stream       = video_stream;
	remuxer->audio_stream_index = audio_stream_index;
	remuxer->video_stream_index = video_stream_index;
	return 0;

error:
	avformat_close_input(&demuxer);
	return err;
}

static void timespec_add_nano(struct timespec *ts, uint64_t nanoseconds)
{
	uint64_t new_nano;

	new_nano = ts->tv_nsec + nanoseconds;
	ts->tv_nsec = new_nano % NANOSEC;
	ts->tv_sec += new_nano / NANOSEC;
}


/**
 * Block the thread if the remuxer is getting close to overruning (writing HLS
 * segments and discarding previous ones faster than clients can read them).
 * This is done by checking if all stream[1] have more data ready than needed to
 * fill the buffer delay (2 seconds by default) and calling clock_nanosleep to
 * wait off the overrun[2].
 *
 * - [1] We only have an audio stream right now.
 * - [2] TODO: Implement instead of waiting 2 seconds
 */
static int remuxer_wait_target_ts (HLSRemuxer *remuxer)
{
	uint64_t video_runtime, audio_runtime, min_runtime;
	struct timespec target_ts;

	audio_runtime = audiomuxer_get_runtime(remuxer->audio_muxer);
	video_runtime = INT64_MAX;
	min_runtime = MIN(audio_runtime, video_runtime);
	assert(min_runtime == audio_runtime);
	if (min_runtime < remuxer->overhead)
		return 0;
	min_runtime -= remuxer->overhead;

	target_ts = remuxer->start_time;
	timespec_add_nano(&target_ts, min_runtime);

	return clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &target_ts, NULL);
}