/*
    Copyright (C) 2012 Carl Hetherington <cth@carlh.net>

    This program 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 2 of the License, or
    (at your option) any later version.

    This program 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 this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

/** @file  src/ffmpeg_decoder.cc
 *  @brief A decoder using FFmpeg to decode content.
 */

#include <stdexcept>
#include <vector>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <stdint.h>
#include <boost/lexical_cast.hpp>
#include <sndfile.h>
extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
}
#include "film.h"
#include "filter.h"
#include "exceptions.h"
#include "image.h"
#include "util.h"
#include "log.h"
#include "ffmpeg_decoder.h"
#include "filter_graph.h"
#include "subtitle.h"
#include "audio_buffers.h"

#include "i18n.h"

using std::cout;
using std::string;
using std::vector;
using std::stringstream;
using std::list;
using std::min;
using boost::shared_ptr;
using boost::optional;
using boost::dynamic_pointer_cast;
using libdcp::Size;

FFmpegDecoder::FFmpegDecoder (shared_ptr<const Film> f, shared_ptr<const FFmpegContent> c, bool video, bool audio)
	: Decoder (f)
	, VideoDecoder (f)
	, AudioDecoder (f)
	, FFmpeg (c)
	, _subtitle_codec_context (0)
	, _subtitle_codec (0)
	, _decode_video (video)
	, _decode_audio (audio)
	, _pts_offset (0)
	, _just_sought (false)
{
	setup_subtitle ();

	if (video && audio && c->audio_stream() && c->first_video() && c->audio_stream()->first_audio) {
		_pts_offset = compute_pts_offset (c->first_video().get(), c->audio_stream()->first_audio.get(), c->video_frame_rate());
	}
}

double
FFmpegDecoder::compute_pts_offset (double first_video, double first_audio, float video_frame_rate)
{
	double const old_first_video = first_video;
	
	/* Round the first video to a frame boundary */
	if (fabs (rint (first_video * video_frame_rate) - first_video * video_frame_rate) > 1e-6) {
		first_video = ceil (first_video * video_frame_rate) / video_frame_rate;
	}

	/* Compute the required offset (also removing any common start delay) */
	return first_video - old_first_video - min (first_video, first_audio);
}

FFmpegDecoder::~FFmpegDecoder ()
{
	boost::mutex::scoped_lock lm (_mutex);

	if (_subtitle_codec_context) {
		avcodec_close (_subtitle_codec_context);
	}
}	

void
FFmpegDecoder::pass ()
{
	int r = av_read_frame (_format_context, &_packet);

	if (r < 0) {
		if (r != AVERROR_EOF) {
			/* Maybe we should fail here, but for now we'll just finish off instead */
			char buf[256];
			av_strerror (r, buf, sizeof(buf));
			shared_ptr<const Film> film = _film.lock ();
			assert (film);
			film->log()->log (String::compose (N_("error on av_read_frame (%1) (%2)"), buf, r));
		}

		/* Get any remaining frames */
		
		_packet.data = 0;
		_packet.size = 0;
		
		/* XXX: should we reset _packet.data and size after each *_decode_* call? */
		
		if (_decode_video) {
			while (decode_video_packet ());
		}

		if (_ffmpeg_content->audio_stream() && _decode_audio) {
			decode_audio_packet ();
		}

		/* Stop us being asked for any more data */
		_video_position = _ffmpeg_content->video_length ();
		_audio_position = _ffmpeg_content->audio_length ();
		return;
	}

	avcodec_get_frame_defaults (_frame);

	if (_packet.stream_index == _video_stream && _decode_video) {
		decode_video_packet ();
	} else if (_ffmpeg_content->audio_stream() && _packet.stream_index == _ffmpeg_content->audio_stream()->id && _decode_audio) {
		decode_audio_packet ();
	} else if (_ffmpeg_content->subtitle_stream() && _packet.stream_index == _ffmpeg_content->subtitle_stream()->id) {
#if 0		

		int got_subtitle;
		AVSubtitle sub;
		if (avcodec_decode_subtitle2 (_subtitle_codec_context, &sub, &got_subtitle, &_packet) && got_subtitle) {
			/* Sometimes we get an empty AVSubtitle, which is used by some codecs to
			   indicate that the previous subtitle should stop.
			*/
			if (sub.num_rects > 0) {
				shared_ptr<TimedSubtitle> ts;
				try {
					subtitle (shared_ptr<TimedSubtitle> (new TimedSubtitle (sub)));
				} catch (...) {
					/* some problem with the subtitle; we probably didn't understand it */
				}
			} else {
				subtitle (shared_ptr<TimedSubtitle> ());
			}
			avsubtitle_free (&sub);
		}
#endif		
	}

	av_free_packet (&_packet);
}

/** @param data pointer to array of pointers to buffers.
 *  Only the first buffer will be used for non-planar data, otherwise there will be one per channel.
 */
shared_ptr<AudioBuffers>
FFmpegDecoder::deinterleave_audio (uint8_t** data, int size)
{
	assert (_ffmpeg_content->audio_channels());
	assert (bytes_per_audio_sample());

	/* Deinterleave and convert to float */

	assert ((size % (bytes_per_audio_sample() * _ffmpeg_content->audio_channels())) == 0);

	int const total_samples = size / bytes_per_audio_sample();
	int const frames = total_samples / _ffmpeg_content->audio_channels();
	shared_ptr<AudioBuffers> audio (new AudioBuffers (_ffmpeg_content->audio_channels(), frames));

	switch (audio_sample_format()) {
	case AV_SAMPLE_FMT_S16:
	{
		int16_t* p = reinterpret_cast<int16_t *> (data[0]);
		int sample = 0;
		int channel = 0;
		for (int i = 0; i < total_samples; ++i) {
			audio->data(channel)[sample] = float(*p++) / (1 << 15);

			++channel;
			if (channel == _ffmpeg_content->audio_channels()) {
				channel = 0;
				++sample;
			}
		}
	}
	break;

	case AV_SAMPLE_FMT_S16P:
	{
		int16_t** p = reinterpret_cast<int16_t **> (data);
		for (int i = 0; i < _ffmpeg_content->audio_channels(); ++i) {
			for (int j = 0; j < frames; ++j) {
				audio->data(i)[j] = static_cast<float>(p[i][j]) / (1 << 15);
			}
		}
	}
	break;
	
	case AV_SAMPLE_FMT_S32:
	{
		int32_t* p = reinterpret_cast<int32_t *> (data[0]);
		int sample = 0;
		int channel = 0;
		for (int i = 0; i < total_samples; ++i) {
			audio->data(channel)[sample] = static_cast<float>(*p++) / (1 << 31);

			++channel;
			if (channel == _ffmpeg_content->audio_channels()) {
				channel = 0;
				++sample;
			}
		}
	}
	break;

	case AV_SAMPLE_FMT_FLT:
	{
		float* p = reinterpret_cast<float*> (data[0]);
		int sample = 0;
		int channel = 0;
		for (int i = 0; i < total_samples; ++i) {
			audio->data(channel)[sample] = *p++;

			++channel;
			if (channel == _ffmpeg_content->audio_channels()) {
				channel = 0;
				++sample;
			}
		}
	}
	break;
		
	case AV_SAMPLE_FMT_FLTP:
	{
		float** p = reinterpret_cast<float**> (data);
		for (int i = 0; i < _ffmpeg_content->audio_channels(); ++i) {
			memcpy (audio->data(i), p[i], frames * sizeof(float));
		}
	}
	break;

	default:
		throw DecodeError (String::compose (_("Unrecognised audio sample format (%1)"), static_cast<int> (audio_sample_format())));
	}

	return audio;
}

AVSampleFormat
FFmpegDecoder::audio_sample_format () const
{
	if (!_ffmpeg_content->audio_stream()) {
		return (AVSampleFormat) 0;
	}
	
	return audio_codec_context()->sample_fmt;
}

int
FFmpegDecoder::bytes_per_audio_sample () const
{
	return av_get_bytes_per_sample (audio_sample_format ());
}

void
FFmpegDecoder::seek (VideoContent::Frame frame, bool accurate)
{
	double const time_base = av_q2d (_format_context->streams[_video_stream]->time_base);
	int64_t const vt = frame / (_ffmpeg_content->video_frame_rate() * time_base);
	av_seek_frame (_format_context, _video_stream, vt, AVSEEK_FLAG_BACKWARD);

	avcodec_flush_buffers (video_codec_context());
	if (_subtitle_codec_context) {
		avcodec_flush_buffers (_subtitle_codec_context);
	}

	_just_sought = true;

	if (accurate) {
		while (1) {
			int r = av_read_frame (_format_context, &_packet);
			if (r < 0) {
				return;
			}
			
			avcodec_get_frame_defaults (_frame);
			
			if (_packet.stream_index == _video_stream) {
				int finished = 0;
				int const r = avcodec_decode_video2 (video_codec_context(), _frame, &finished, &_packet);
				if (r >= 0 && finished) {
					int64_t const bet = av_frame_get_best_effort_timestamp (_frame);
					if (bet >= vt) {
						_video_position = rint (
							(bet * time_base + _pts_offset)	* _ffmpeg_content->video_frame_rate()
							);
						av_free_packet (&_packet);
						break;
					}
				}
			}
			
			av_free_packet (&_packet);
		}
	}
}

void
FFmpegDecoder::decode_audio_packet ()
{
	/* Audio packets can contain multiple frames, so we may have to call avcodec_decode_audio4
	   several times.
	*/
	
	AVPacket copy_packet = _packet;

	while (copy_packet.size > 0) {

		int frame_finished;
		int const decode_result = avcodec_decode_audio4 (audio_codec_context(), _frame, &frame_finished, &copy_packet);
		if (decode_result >= 0) {
			if (frame_finished) {

				if (_audio_position == 0) {
					/* Where we are in the source, in seconds */
					double const pts = av_q2d (_format_context->streams[copy_packet.stream_index]->time_base)
						* av_frame_get_best_effort_timestamp(_frame) - _pts_offset;

					if (pts > 0) {
						/* Emit some silence */
						shared_ptr<AudioBuffers> silence (
							new AudioBuffers (
								_ffmpeg_content->audio_channels(),
								pts * _ffmpeg_content->content_audio_frame_rate()
								)
							);
						
						silence->make_silent ();
						audio (silence, _audio_position);
					}
				}
					
				copy_packet.data += decode_result;
				copy_packet.size -= decode_result;
			}
		}
	}
}

bool
FFmpegDecoder::decode_video_packet ()
{
	int frame_finished;
	if (avcodec_decode_video2 (video_codec_context(), _frame, &frame_finished, &_packet) < 0 || !frame_finished) {
		return false;
	}
		
	boost::mutex::scoped_lock lm (_filter_graphs_mutex);

	shared_ptr<FilterGraph> graph;
	
	list<shared_ptr<FilterGraph> >::iterator i = _filter_graphs.begin();
	while (i != _filter_graphs.end() && !(*i)->can_process (libdcp::Size (_frame->width, _frame->height), (AVPixelFormat) _frame->format)) {
		++i;
	}

	if (i == _filter_graphs.end ()) {
		shared_ptr<const Film> film = _film.lock ();
		assert (film);

		graph.reset (new FilterGraph (_ffmpeg_content, libdcp::Size (_frame->width, _frame->height), (AVPixelFormat) _frame->format));
		_filter_graphs.push_back (graph);

		film->log()->log (String::compose (N_("New graph for %1x%2, pixel format %3"), _frame->width, _frame->height, _frame->format));
	} else {
		graph = *i;
	}

	list<shared_ptr<Image> > images = graph->process (_frame);

	string post_process = Filter::ffmpeg_strings (_ffmpeg_content->filters()).second;
	
	for (list<shared_ptr<Image> >::iterator i = images.begin(); i != images.end(); ++i) {

		shared_ptr<Image> image = *i;
		if (!post_process.empty ()) {
			image = image->post_process (post_process, true);
		}
		
		int64_t const bet = av_frame_get_best_effort_timestamp (_frame);
		if (bet != AV_NOPTS_VALUE) {

			double const pts = bet * av_q2d (_format_context->streams[_video_stream]->time_base) - _pts_offset;

			if (_just_sought) {
				/* We just did a seek, so disable any attempts to correct for where we
				   are / should be.
				*/
				_video_position = rint (pts * _ffmpeg_content->video_frame_rate ());
				_just_sought = false;
			}

			double const next = _video_position / _ffmpeg_content->video_frame_rate();
			double const one_frame = 1 / _ffmpeg_content->video_frame_rate ();
			double delta = pts - next;

			while (delta > one_frame) {
				/* This PTS is more than one frame forward in time of where we think we should be; emit
				   a black frame.
				*/
				boost::shared_ptr<Image> black (
					new SimpleImage (
						static_cast<AVPixelFormat> (_frame->format),
						libdcp::Size (video_codec_context()->width, video_codec_context()->height),
						true
						)
					);
				
				black->make_black ();
				video (image, false, _video_position);
				delta -= one_frame;
			}

			if (delta > -one_frame) {
				/* This PTS is within a frame of being right; emit this (otherwise it will be dropped) */
				video (image, false, _video_position);
			}
				
		} else {
			shared_ptr<const Film> film = _film.lock ();
			assert (film);
			film->log()->log ("Dropping frame without PTS");
		}
	}

	return true;
}

	
void
FFmpegDecoder::setup_subtitle ()
{
	boost::mutex::scoped_lock lm (_mutex);
	
	if (!_ffmpeg_content->subtitle_stream() || _ffmpeg_content->subtitle_stream()->id >= int (_format_context->nb_streams)) {
		return;
	}

	_subtitle_codec_context = _format_context->streams[_ffmpeg_content->subtitle_stream()->id]->codec;
	_subtitle_codec = avcodec_find_decoder (_subtitle_codec_context->codec_id);

	if (_subtitle_codec == 0) {
		throw DecodeError (_("could not find subtitle decoder"));
	}
	
	if (avcodec_open2 (_subtitle_codec_context, _subtitle_codec, 0) < 0) {
		throw DecodeError (N_("could not open subtitle decoder"));
	}
}

bool
FFmpegDecoder::done () const
{
	bool const vd = !_decode_video || (_video_position >= _ffmpeg_content->video_length());
	bool const ad = !_decode_audio || !_ffmpeg_content->audio_stream() || (_audio_position >= _ffmpeg_content->audio_length());
	return vd && ad;
}