/* 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

#include "awe/sfx_player.h"
#include "awe/resource.h"
#include "awe/sound.h"
#include "awe/system_stub.h"

namespace Awe {

void SfxInstrument::clear() {
	data = nullptr;
	volume = 0;
}

void SfxModule::clear() {
	data = nullptr;
	curPos = 0;
	curOrder = 0;
	numOrder = 0;
	orderTable = nullptr;

	clearSamples();
}

void SfxModule::clearSamples() {
	for (int i = 0; i < 15; ++i)
		samples[i].clear();
}

SfxPlayer::SfxPlayer(Resource *res)
	: _res(res), _delay(0) {
	_playing = false;
}

void SfxPlayer::setEventsDelay(uint16 delay) {
	debugC(kDebugSound, "SfxPlayer::setEventsDelay(%d)", delay);
	_delay = delay;
}

void SfxPlayer::loadSfxModule(uint16 resNum, uint16 delay, uint8 pos) {
	debugC(kDebugSound, "SfxPlayer::loadSfxModule(0x%X, %d, %d)", resNum, delay, pos);
	MemEntry *me = &_res->_memList[resNum];
	if (me->status == Resource::STATUS_LOADED && me->type == Resource::RT_MUSIC) {
		_sfxMod.clear();

		_sfxMod.curOrder = pos;
		_sfxMod.numOrder = me->bufPtr[0x3F];
		debugC(kDebugSound, "SfxPlayer::loadSfxModule() curOrder = 0x%X numOrder = 0x%X", _sfxMod.curOrder, _sfxMod.numOrder);
		_sfxMod.orderTable = me->bufPtr + 0x40;
		if (delay == 0) {
			_delay = READ_BE_UINT16(me->bufPtr);
		} else {
			_delay = delay;
		}
		_sfxMod.data = me->bufPtr + 0xC0;
		debugC(kDebugSound, "SfxPlayer::loadSfxModule() eventDelay = %d ms", _delay);
		prepareInstruments(me->bufPtr + 2);
	} else {
		warning("SfxPlayer::loadSfxModule() ec=0x%X", 0xF8);
	}
}

void SfxPlayer::prepareInstruments(const uint8 *p) {
	_sfxMod.clearSamples();

	for (int i = 0; i < 15; ++i) {
		SfxInstrument *ins = &_sfxMod.samples[i];
		const uint16 resNum = READ_BE_UINT16(p); p += 2;
		if (resNum != 0) {
			ins->volume = READ_BE_UINT16(p);
			MemEntry *me = &_res->_memList[resNum];
			if (me->status == Resource::STATUS_LOADED && me->type == Resource::RT_SOUND) {
				ins->data = me->bufPtr;
				debugC(kDebugSound, "Loaded instrument 0x%X n=%d volume=%d", resNum, i, ins->volume);
			} else {
				error("Error loading instrument 0x%X", resNum);
			}
		}
		p += 2; // skip volume
	}
}

void SfxPlayer::play(int rate) {
	_playing = true;
	_rate = rate;
	_samplesLeft = 0;

	for (int i = 0; i < NUM_CHANNELS; i++) {
		_channels[i].sampleData = nullptr;
		_channels[i].sampleLen = 0;
		_channels[i].sampleLoopPos = 0;
		_channels[i].sampleLoopLen = 0;
		_channels[i].volume = 0;
		_channels[i].pos.inc = 0;
		_channels[i].pos.offset = 0;
	}
}

static int16 toS16(int a) {
	if (a <= -128) {
		return -32768;
	} else if (a >= 127) {
		return 32767;
	} else {
		const uint8 u8 = (a ^ 0x80);
		return ((u8 << 8) | u8) - 32768;
	}
}

static void mixChannel(int16 &s, SfxChannel *ch) {
	if (ch->sampleLen == 0) {
		return;
	}
	const int pos1 = ch->pos.offset >> Frac::BITS;
	ch->pos.offset += ch->pos.inc;
	int pos2 = pos1 + 1;
	if (ch->sampleLoopLen != 0) {
		if (pos1 >= ch->sampleLoopPos + ch->sampleLoopLen - 1) {
			pos2 = ch->sampleLoopPos;
			ch->pos.offset = pos2 << Frac::BITS;
		}
	} else {
		if (pos1 >= ch->sampleLen - 1) {
			ch->sampleLen = 0;
			return;
		}
	}
	int sample = ch->pos.interpolate((int8)ch->sampleData[pos1], (int8)ch->sampleData[pos2]);
	sample = s + toS16(sample * ch->volume / 64);
	s = (sample < -32768 ? -32768 : (sample > 32767 ? 32767 : sample));
}

void SfxPlayer::mixSamples(int16 *buf, int len) {
	while (len != 0) {
		if (_samplesLeft == 0) {
			handleEvents();
			const int samplesPerTick = _rate * (_delay * 60 * 1000 / kPaulaFreq) / 1000;
			_samplesLeft = samplesPerTick;
		}
		int count = _samplesLeft;
		if (count > len) {
			count = len;
		}
		_samplesLeft -= count;
		len -= count;
		for (int i = 0; i < count; ++i) {
			mixChannel(*buf, &_channels[0]);
			mixChannel(*buf, &_channels[3]);
			++buf;
			mixChannel(*buf, &_channels[1]);
			mixChannel(*buf, &_channels[2]);
			++buf;
		}
	}
}

void SfxPlayer::readSamples(int16 *buf, int len) {
	if (_delay != 0) {
		mixSamples(buf, len / 2);
	}
}

void SfxPlayer::start() {
	debugC(kDebugSound, "SfxPlayer::start()");
	_sfxMod.curPos = 0;
}

void SfxPlayer::stop() {
	debugC(kDebugSound, "SfxPlayer::stop()");
	_playing = false;
}

void SfxPlayer::handleEvents() {
	uint8 order = _sfxMod.orderTable[_sfxMod.curOrder];
	const uint8 *patternData = _sfxMod.data + _sfxMod.curPos + order * 1024;
	for (uint8 ch = 0; ch < 4; ++ch) {
		handlePattern(ch, patternData);
		patternData += 4;
	}
	_sfxMod.curPos += 4 * 4;
	debugC(kDebugSound, "SfxPlayer::handleEvents() order = 0x%X curPos = 0x%X", order, _sfxMod.curPos);
	if (_sfxMod.curPos >= 1024) {
		_sfxMod.curPos = 0;
		order = _sfxMod.curOrder + 1;
		if (order == _sfxMod.numOrder) {
			_playing = false;
		}
		_sfxMod.curOrder = order;
	}
}

void SfxPlayer::handlePattern(uint8 channel, const uint8 *data) {
	SfxPattern pat;
	pat.note_1 = READ_BE_UINT16(data + 0);
	pat.note_2 = READ_BE_UINT16(data + 2);
	if (pat.note_1 != 0xFFFD) {
		const uint16 sample = (pat.note_2 & 0xF000) >> 12;
		if (sample != 0) {
			uint8 *ptr = _sfxMod.samples[sample - 1].data;
			if (ptr != nullptr) {
				debugC(kDebugSound, "SfxPlayer::handlePattern() preparing sample %d", sample);
				pat.sampleVolume = _sfxMod.samples[sample - 1].volume;
				pat.sampleStart = 8;
				pat.sampleBuffer = ptr;
				pat.sampleLen = READ_BE_UINT16(ptr) * 2;
				const uint16 loopLen = READ_BE_UINT16(ptr + 2) * 2;
				if (loopLen != 0) {
					pat.loopPos = pat.sampleLen;
					pat.loopLen = loopLen;
				} else {
					pat.loopPos = 0;
					pat.loopLen = 0;
				}
				int16 m = pat.sampleVolume;
				const uint8 effect = (pat.note_2 & 0x0F00) >> 8;
				if (effect == 5) { // volume up
					const uint8 volume = (pat.note_2 & 0xFF);
					m += volume;
					if (m > 0x3F) {
						m = 0x3F;
					}
				} else if (effect == 6) { // volume down
					const uint8 volume = (pat.note_2 & 0xFF);
					m -= volume;
					if (m < 0) {
						m = 0;
					}
				}
				_channels[channel].volume = m;
				pat.sampleVolume = m;
			}
		}
	}
	if (pat.note_1 == 0xFFFD) {
		debugC(kDebugSound, "SfxPlayer::handlePattern() _syncVar = 0x%X", pat.note_2);
		*_syncVar = pat.note_2;
	} else if (pat.note_1 == 0xFFFE) {
		_channels[channel].sampleLen = 0;
	} else if (pat.note_1 != 0 && pat.sampleBuffer != nullptr) {
		assert(pat.note_1 >= 0x37 && pat.note_1 < 0x1000);
		// convert Amiga period value to hz
		const int freq = kPaulaFreq / (pat.note_1 * 2);
		debugC(kDebugSound, "SfxPlayer::handlePattern() adding sample freq = 0x%X", freq);
		SfxChannel *ch = &_channels[channel];
		ch->sampleData = pat.sampleBuffer + pat.sampleStart;
		ch->sampleLen = pat.sampleLen;
		ch->sampleLoopPos = pat.loopPos;
		ch->sampleLoopLen = pat.loopLen;
		ch->volume = pat.sampleVolume;
		ch->pos.offset = 0;
		ch->pos.inc = (freq << Frac::BITS) / _rate;
	}
}

} // namespace Awe