/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL$
 * $Id$
 *
 */

#include "sound/mp3.h"

#ifdef USE_MAD

#include "common/file.h"
#include "common/util.h"

#include "sound/audiocd.h"
#include "sound/audiostream.h"

#include <mad.h>


namespace Audio {


#pragma mark -
#pragma mark --- MP3 (MAD) stream ---
#pragma mark -


class MP3InputStream : public AudioStream {
protected:
	enum State {
		MP3_STATE_INIT,	// Need to init the decoder
		MP3_STATE_READY,	// ready for processing data
		MP3_STATE_EOS		// end of data reached (may need to loop)
	};

	Common::SeekableReadStream *_inStream;
	bool _disposeAfterUse;

	uint _numLoops;
	uint _posInFrame;
	State _state;

	const mad_timer_t _startTime;
	const mad_timer_t _endTime;
	mad_timer_t _totalTime;

	int32 _totalPlayTime;

	mad_stream _stream;
	mad_frame _frame;
	mad_synth _synth;

	enum {
		BUFFER_SIZE = 5 * 8192
	};

	// This buffer contains a slab of input data
	byte _buf[BUFFER_SIZE + MAD_BUFFER_GUARD];

public:
	MP3InputStream(Common::SeekableReadStream *inStream,
	               bool dispose,
	               mad_timer_t start = mad_timer_zero,
	               mad_timer_t end = mad_timer_zero,
	               uint numLoops = 1);
	~MP3InputStream();

	int readBuffer(int16 *buffer, const int numSamples);

	bool endOfData() const		{ return _state == MP3_STATE_EOS; }
	bool isStereo() const		{ return MAD_NCHANNELS(&_frame.header) == 2; }
	int getRate() const			{ return _frame.header.samplerate; }
	int32 getTotalPlayTime() const { return _totalPlayTime; }

protected:
	void decodeMP3Data();
	void readMP3Data();
};

MP3InputStream::MP3InputStream(Common::SeekableReadStream *inStream, bool dispose, mad_timer_t start, mad_timer_t end, uint numLoops) :
	_inStream(inStream),
	_disposeAfterUse(dispose),
	_numLoops(numLoops),
	_posInFrame(0),
	_state(MP3_STATE_INIT),
	_startTime(start),
	_endTime(end),
	_totalTime(mad_timer_zero) {

	// Make sure that either start < end, or end is zero (indicating "play until end")
	assert(mad_timer_compare(_startTime, _endTime) < 0 || mad_timer_sign(_endTime) == 0);

	// The MAD_BUFFER_GUARD must always contain zeros (the reason
	// for this is that the Layer III Huffman decoder of libMAD
	// may read a few bytes beyond the end of the input buffer).
	memset(_buf + BUFFER_SIZE, 0, MAD_BUFFER_GUARD);

	// Calculate play time
	mad_timer_t length;

	mad_timer_set(&length, 0, 0, 1000);	
	mad_timer_add(&length, start);
	mad_timer_negate(&length);

	if (mad_timer_sign(end) == 0) {
		mad_timer_add(&length, end);
	} else {
		mad_stream_init(&_stream);
		mad_frame_init(&_frame);

		// Reset the stream data
		_inStream->seek(0, SEEK_SET);

		// Update state
		_state = MP3_STATE_READY;

		// Read the first few sample bytes
		readMP3Data();

		do {
			// If necessary, load more data into the stream decoder
			if (_stream.error == MAD_ERROR_BUFLEN)
				readMP3Data();

			while (_state == MP3_STATE_READY) {
				_stream.error = MAD_ERROR_NONE;

				// Decode the next header. Note: mad_frame_decode would do this for us, too.
				// However, for seeking we don't want to decode the full frame (else it would
				// be far too slow).
				if (mad_header_decode(&_frame.header, &_stream) == -1) {
					if (_stream.error == MAD_ERROR_BUFLEN) {
						break; // Read more data
					} else if (MAD_RECOVERABLE(_stream.error)) {
						debug(6, "MP3InputStream: Recoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
						continue;
					} else {
						warning("MP3InputStream: Unrecoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
						break;
					}
				}

				// Sum up the total playback time so far
				mad_timer_add(&length, _frame.header.duration);
			}
		} while (_state != MP3_STATE_EOS);

		mad_synth_finish(&_synth);
		mad_frame_finish(&_frame);

		// Reinit stream
		_state = MP3_STATE_INIT;

		// Reset the stream data
		_inStream->seek(0, SEEK_SET);
	}

	_totalPlayTime = mad_timer_count(length, MAD_UNITS_MILLISECONDS);
	
	if (numLoops && mad_timer_sign(length) >= 0)
		_totalPlayTime *= numLoops;
	else
		_totalPlayTime = kUnknownPlayTime;

	// Decode the first chunk of data. This is necessary so that _frame
	// is setup and isStereo() and getRate() return correct results.
	decodeMP3Data();
}

MP3InputStream::~MP3InputStream() {
	if (_state != MP3_STATE_INIT) {
		// Deinit MAD
		mad_synth_finish(&_synth);
		mad_frame_finish(&_frame);
		mad_stream_finish(&_stream);
	}

	if (_disposeAfterUse)
		delete _inStream;
}

void MP3InputStream::decodeMP3Data() {

	do {
		if (_state == MP3_STATE_INIT) {
			// Init MAD
			mad_stream_init(&_stream);
			mad_frame_init(&_frame);
			mad_synth_init(&_synth);

			// Reset the stream data
			_inStream->seek(0, SEEK_SET);
			_totalTime = mad_timer_zero;
			_posInFrame = 0;

			// Update state
			_state = MP3_STATE_READY;

			// Read the first few sample bytes
			readMP3Data();
		}

		if (_state == MP3_STATE_EOS)
			return;

		// If necessary, load more data into the stream decoder
		if (_stream.error == MAD_ERROR_BUFLEN)
			readMP3Data();

		while (_state == MP3_STATE_READY) {
			_stream.error = MAD_ERROR_NONE;

			// Decode the next header. Note: mad_frame_decode would do this for us, too.
			// However, for seeking we don't want to decode the full frame (else it would
			// be far too slow). Hence we perform this explicitly in a separate step.
			if (mad_header_decode(&_frame.header, &_stream) == -1) {
				if (_stream.error == MAD_ERROR_BUFLEN) {
					break; // Read more data
				} else if (MAD_RECOVERABLE(_stream.error)) {
					debug(6, "MP3InputStream: Recoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
					continue;
				} else {
					warning("MP3InputStream: Unrecoverable error in mad_header_decode (%s)", mad_stream_errorstr(&_stream));
					break;
				}
			}

			// Sum up the total playback time so far
			mad_timer_add(&_totalTime, _frame.header.duration);

			// If we have not yet reached the start point, skip to the next frame
			if (mad_timer_compare(_totalTime, _startTime) < 0)
				continue;

			// If an end time is specified and we are past it, stop
			if (mad_timer_sign(_endTime) > 0 && mad_timer_compare(_totalTime, _endTime) >= 0) {
				_state = MP3_STATE_EOS;
				break;
			}

			// Decode the next frame
			if (mad_frame_decode(&_frame, &_stream) == -1) {
				if (_stream.error == MAD_ERROR_BUFLEN) {
					break; // Read more data
				} else if (MAD_RECOVERABLE(_stream.error)) {
					// Note: we will occasionally see MAD_ERROR_BADDATAPTR errors here.
					// These are normal and expected (caused by our frame skipping (i.e. "seeking")
					// code above).
					debug(6, "MP3InputStream: Recoverable error in mad_frame_decode (%s)", mad_stream_errorstr(&_stream));
					continue;
				} else {
					warning("MP3InputStream: Unrecoverable error in mad_frame_decode (%s)", mad_stream_errorstr(&_stream));
					break;
				}
			}

			// Synthesize PCM data
			mad_synth_frame(&_synth, &_frame);
			_posInFrame = 0;
			break;
		}

		if (_state == MP3_STATE_EOS && _numLoops != 1) {
			// If looping is on and there are loops left, rewind to the start
			if (_numLoops != 0)
				_numLoops--;

			// Deinit MAD
			mad_synth_finish(&_synth);
			mad_frame_finish(&_frame);
			mad_stream_finish(&_stream);

			// Reset the decoder state to indicate we should start over
			_state = MP3_STATE_INIT;
		}

	} while (_state != MP3_STATE_EOS && _stream.error == MAD_ERROR_BUFLEN);

	if (_stream.error != MAD_ERROR_NONE)
		_state = MP3_STATE_EOS;
}

void MP3InputStream::readMP3Data() {
	uint32 remaining = 0;

	// Give up immediately if we already used up all data in the stream
	if (_inStream->eos()) {
		_state = MP3_STATE_EOS;
		return;
	}

	if (_stream.next_frame) {
		// If there is still data in the MAD stream, we need to preserve it.
		// Note that we use memmove, as we are reusing the same buffer,
		// and hence the data regions we copy from and to may overlap.
		remaining = _stream.bufend - _stream.next_frame;
		assert(remaining < BUFFER_SIZE);	// Paranoia check
		memmove(_buf, _stream.next_frame, remaining);
	}

	// Try to read the next block
	uint32 size = _inStream->read(_buf + remaining, BUFFER_SIZE - remaining);
	if (size <= 0) {
		_state = MP3_STATE_EOS;
		return;
	}

	// Feed the data we just read into the stream decoder
	_stream.error = MAD_ERROR_NONE;
	mad_stream_buffer(&_stream, _buf, size + remaining);
}


static inline int scale_sample(mad_fixed_t sample) {
	// round
	sample += (1L << (MAD_F_FRACBITS - 16));

	// clip
	if (sample > MAD_F_ONE - 1)
		sample = MAD_F_ONE - 1;
	else if (sample < -MAD_F_ONE)
		sample = -MAD_F_ONE;

	// quantize and scale to not saturate when mixing a lot of channels
	return sample >> (MAD_F_FRACBITS + 1 - 16);
}

int MP3InputStream::readBuffer(int16 *buffer, const int numSamples) {
	int samples = 0;
	// Keep going as long as we have input available
	while (samples < numSamples && _state != MP3_STATE_EOS) {
		const int len = MIN(numSamples, samples + (int)(_synth.pcm.length - _posInFrame) * MAD_NCHANNELS(&_frame.header));
		while (samples < len) {
			*buffer++ = (int16)scale_sample(_synth.pcm.samples[0][_posInFrame]);
			samples++;
			if (MAD_NCHANNELS(&_frame.header) == 2) {
				*buffer++ = (int16)scale_sample(_synth.pcm.samples[1][_posInFrame]);
				samples++;
			}
			_posInFrame++;
		}
		if (_posInFrame >= _synth.pcm.length) {
			// We used up all PCM data in the current frame -- read & decode more
			decodeMP3Data();
		}
	}
	return samples;
}


#pragma mark -
#pragma mark --- MP3 factory functions ---
#pragma mark -


AudioStream *makeMP3Stream(
	Common::SeekableReadStream *stream,
	bool disposeAfterUse,
	uint32 startTime,
	uint32 duration,
	uint numLoops) {

	mad_timer_t start;
	mad_timer_t end;

	// Both startTime and duration are given in milliseconds.
	// Calculate the appropriate mad_timer_t values from them.
	mad_timer_set(&start, startTime / 1000, startTime % 1000, 1000);
	if (duration == 0) {
		end = mad_timer_zero;
	} else {
		int endTime = startTime + duration;
		mad_timer_set(&end, endTime / 1000, endTime % 1000, 1000);
	}

	return new MP3InputStream(stream, disposeAfterUse, start, end, numLoops);
}

} // End of namespace Audio

#endif // #ifdef USE_MAD