/* 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.
 *
 */

#ifndef SCI_AUDIO32_H
#define SCI_AUDIO32_H
#include "audio/audiostream.h"     // for AudioStream, SeekableAudioStream (...
#include "audio/mixer.h"           // for Mixer, SoundHandle
#include "audio/rate.h"            // for Audio::st_volume_t, RateConverter
#include "common/array.h"          // for Array
#include "common/mutex.h"          // for StackLock, Mutex
#include "common/scummsys.h"       // for int16, uint8, uint32, uint16
#include "sci/resource.h"          // for ResourceId
#include "sci/engine/vm_types.h"   // for reg_t, NULL_REG
#include "sci/video/robot_decoder.h" // for RobotAudioStream

namespace Sci {
class Console;

bool detectSolAudio(Common::SeekableReadStream &stream);
bool detectWaveAudio(Common::SeekableReadStream &stream);

#pragma mark AudioChannel

/**
 * An audio channel used by the software SCI mixer.
 */
struct AudioChannel {
	/**
	 * The ID of the resource loaded into this channel.
	 */
	ResourceId id;

	/**
	 * The resource loaded into this channel. The resource is owned by
	 * ResourceManager.
	 */
	Resource *resource;

	/**
	 * The audio stream loaded into this channel. Can cast to
	 * `SeekableAudioStream` for normal channels and `RobotAudioStream` for
	 * robot channels.
	 */
	Common::ScopedPtr<Audio::AudioStream> stream;

	/**
	 * The converter used to transform and merge the input stream into the
	 * mixer's output buffer.
	 */
	Common::ScopedPtr<Audio::RateConverter> converter;

	/**
	 * Duration of the channel, in ticks.
	 */
	uint32 duration;

	/**
	 * The tick when the channel was started.
	 */
	uint32 startedAtTick;

	/**
	 * The tick when the channel was paused.
	 */
	uint32 pausedAtTick;

	/**
	 * The time, in ticks, that the channel fade began. If 0, the channel is not
	 * being faded.
	 */
	uint32 fadeStartTick;

	/**
	 * The start volume of a fade.
	 */
	int fadeStartVolume;

	/**
	 * The total length of the fade, in ticks.
	 */
	uint32 fadeDuration;

	/**
	 * The end volume of a fade.
	 */
	int fadeTargetVolume;

	/**
	 * Whether or not the channel should be stopped and freed when the fade is
	 * complete.
	 */
	bool stopChannelOnFade;

	/**
	 * Whether or not this channel contains a Robot audio block.
	 */
	bool robot;

	/**
	 * For digital sound effects, the related VM Sound::nodePtr object for the
	 * sound.
	 */
	reg_t soundNode;

	/**
	 * The playback volume, from 1 to 127 inclusive.
	 */
	int volume;

	/**
	 * The amount to pan to the right, from 0 to 100. 50 is centered, -1 is not
	 * panned.
	 */
	int pan;

	AudioChannel &operator=(AudioChannel &other) {
		id = other.id;
		resource = other.resource;
		stream.reset(other.stream.release());
		converter.reset(other.converter.release());
		duration = other.duration;
		startedAtTick = other.startedAtTick;
		pausedAtTick = other.pausedAtTick;
		fadeStartTick = other.fadeStartTick;
		fadeStartVolume = other.fadeStartVolume;
		fadeDuration = other.fadeDuration;
		fadeTargetVolume = other.fadeTargetVolume;
		stopChannelOnFade = other.stopChannelOnFade;
		robot = other.robot;
		soundNode = other.soundNode;
		volume = other.volume;
		pan = other.pan;
		return *this;
	}
};

#pragma mark -

/**
 * Special audio channel indexes used to select a channel for digital audio
 * playback.
 */
enum AudioChannelIndex {
	kRobotChannel = -3,
	kNoExistingChannel = -2,
	kAllChannels = -1
};

/**
 * Audio32 acts as a permanent audio stream into the system mixer and provides
 * digital audio services for the SCI32 engine, since the system mixer does not
 * support all the features of SCI.
 */
class Audio32 : public Audio::AudioStream, public Common::Serializable {
public:
	Audio32(ResourceManager *resMan);
	~Audio32() override;

	void saveLoadWithSerializer(Common::Serializer &s) override;

	enum {
		/**
		 * The maximum channel volume.
		 */
		kMaxVolume = 127,

		kMonitorAudioFlagSci3 = 0x80
	};

private:
	ResourceManager *_resMan;
	Audio::Mixer *_mixer;
	Audio::SoundHandle _handle;
	Common::Mutex _mutex;

#pragma mark -
#pragma mark AudioStream implementation
public:
	int readBuffer(Audio::st_sample_t *buffer, const int numSamples) override;
	bool isStereo() const override { return true; }
	int getRate() const override { return _mixer->getOutputRate(); }
	bool endOfData() const override { return _numActiveChannels == 0; }
	bool endOfStream() const override { return false; }

private:
	/**
	 * Determines the number of channels that will be mixed together during a
	 * call to readBuffer.
	 */
	int16 getNumChannelsToMix() const;

	/**
	 * Determines whether or not the given audio channel will be mixed into the
	 * output stream.
	 */
	bool channelShouldMix(const AudioChannel &channel) const;

	/**
	 * Mixes audio from the given source stream into the target buffer using the
	 * given rate converter.
	 */
	int writeAudioInternal(Audio::AudioStream &sourceStream, Audio::RateConverter &converter, Audio::st_sample_t *targetBuffer, const int numSamples, const Audio::st_volume_t leftVolume, const Audio::st_volume_t rightVolume);

#pragma mark -
#pragma mark Channel management
public:
	/**
	 * Gets the number of currently active channels.
	 */
	inline uint8 getNumActiveChannels() const {
		Common::StackLock lock(_mutex);
		return _numActiveChannels;
	}

	/**
	 * Gets the number of currently active channels that are playing from
	 * unlocked resources.
	 *
	 * @note In SSCI, this function would actually return the number of channels
	 * whose audio data were not loaded into memory. In practice, the signal for
	 * placing audio data into memory was a call to kLock, so since we do not
	 * follow how SSCI works when it comes to resource management, the lock
	 * state is used as an (apparently) successful proxy for this information
	 * instead.
	 */
	uint8 getNumUnlockedChannels() const;

	/**
	 * Finds a channel that is already configured for the given audio sample.
	 *
	 * @param startIndex The location of the audio resource information in the
	 * arguments list.
	 */
	int16 findChannelByArgs(int argc, const reg_t *argv, const int startIndex, const reg_t soundNode) const;

	/**
	 * Finds a channel that is already configured for the given audio sample.
	 */
	int16 findChannelById(const ResourceId resourceId, const reg_t soundNode = NULL_REG) const;

	/**
	 * Sets or clears a lock on the given resource ID.
	 */
	void lockResource(const ResourceId resourceId, const bool lock);

private:
	typedef Common::Array<ResourceId> LockList;
	typedef Common::Array<Resource *> UnlockList;

	/**
	 * The audio channels.
	 */
	Common::Array<AudioChannel> _channels;

	/**
	 * The number of active audio channels in the mixer. Being active is not the
	 * same as playing; active channels may be paused.
	 */
	uint8 _numActiveChannels;

	/**
	 * Whether or not we are in the audio thread.
	 *
	 * This flag is used instead of passing a parameter to `freeUnusedChannels`
	 * because a parameter would require forwarding through the public method
	 * `stop`, and there is not currently any reason for this implementation
	 * detail to be exposed.
	 */
	bool _inAudioThread;

	/**
	 * The list of resources from freed channels that need to be unlocked from
	 * the main thread.
	 */
	UnlockList _resourcesToUnlock;

	/**
	 * The list of resource IDs that have been locked by game scripts.
	 */
	LockList _lockedResourceIds;

	/**
	 * Gets the audio channel at the given index.
	 */
	inline AudioChannel &getChannel(const int16 channelIndex) {
		Common::StackLock lock(_mutex);
		assert(channelIndex >= 0 && channelIndex < _numActiveChannels);
		return _channels[channelIndex];
	}

	/**
	 * Gets the audio channel at the given index.
	 */
	inline const AudioChannel &getChannel(const int16 channelIndex) const {
		Common::StackLock lock(_mutex);
		assert(channelIndex >= 0 && channelIndex < _numActiveChannels);
		return _channels[channelIndex];
	}

	/**
	 * Frees all non-looping channels that have reached the end of their stream.
	 */
	void freeUnusedChannels();

	/**
	 * Frees resources allocated to the given channel.
	 */
	void freeChannel(const int16 channelIndex);

	/**
	 * Unlocks all resources that were freed by the audio thread.
	 */
	void unlockResources();

#pragma mark -
#pragma mark Script compatibility
public:
	/**
	 * Gets the (fake) sample rate of the hardware DAC. For script compatibility
	 * only.
	 */
	inline uint16 getSampleRate() const {
		return _globalSampleRate;
	}

	/**
	 * Sets the (fake) sample rate of the hardware DAC. For script compatibility
	 * only.
	 */
	void setSampleRate(uint16 rate);

	/**
	 * Gets the (fake) bit depth of the hardware DAC. For script compatibility
	 * only.
	 */
	inline uint8 getBitDepth() const {
		return _globalBitDepth;
	}

	/**
	 * Sets the (fake) sample rate of the hardware DAC. For script compatibility
	 * only.
	 */
	void setBitDepth(uint8 depth);

	/**
	 * Gets the (fake) number of output (speaker) channels of the hardware DAC.
	 * For script compatibility only.
	 */
	inline uint8 getNumOutputChannels() const {
		return _globalNumOutputChannels;
	}

	/**
	 * Sets the (fake) number of output (speaker) channels of the hardware DAC.
	 * For script compatibility only.
	 */
	void setNumOutputChannels(int16 numChannels);

	/**
	 * Gets the (fake) number of preloaded channels. For script compatibility
	 * only.
	 */
	inline uint8 getPreload() const {
		return _preload;
	}

	/**
	 * Sets the (fake) number of preloaded channels. For script compatibility
	 * only.
	 */
	inline void setPreload(uint8 preload) {
		_preload = preload;
	}

private:
	/**
	 * The hardware DAC sample rate. Stored only for script compatibility.
	 */
	uint16 _globalSampleRate;

	/**
	 * The maximum allowed sample rate of the system mixer. Stored only for
	 * script compatibility.
	 */
	uint16 _maxAllowedSampleRate;

	/**
	 * The hardware DAC bit depth. Stored only for script compatibility.
	 */
	uint8 _globalBitDepth;

	/**
	 * The maximum allowed bit depth of the system mixer. Stored only for script
	 * compatibility.
	 */
	uint8 _maxAllowedBitDepth;

	/**
	 * The hardware DAC output (speaker) channel configuration. Stored only for
	 * script compatibility.
	 */
	uint8 _globalNumOutputChannels;

	/**
	 * The maximum allowed number of output (speaker) channels of the system
	 * mixer. Stored only for script compatibility.
	 */
	uint8 _maxAllowedOutputChannels;

	/**
	 * The number of audio channels that should have their data preloaded into
	 * memory instead of streaming from disk. 1 = all channels, 2 = 2nd active
	 * channel and above, etc. Stored only for script compatibility.
	 */
	uint8 _preload;

#pragma mark -
#pragma mark Robot
public:
	bool playRobotAudio(const RobotAudioStream::RobotAudioPacket &packet);
	bool queryRobotAudio(RobotAudioStream::StreamState &outStatus) const;
	bool finishRobotAudio();
	bool stopRobotAudio();

private:
	/**
	 * Finds a channel that is configured for robot playback.
	 */
	int16 findRobotChannel() const;

	/**
	 * When true, channels marked as robot audio will not be played.
	 */
	bool _robotAudioPaused;

#pragma mark -
#pragma mark Playback
public:
	/**
	 * Starts or resumes playback of an audio channel.
	 */
	uint16 play(int16 channelIndex, const ResourceId resourceId, const bool autoPlay, const bool loop, const int16 volume, const reg_t soundNode, const bool monitor);

	/**
	 * Resumes playback of a paused audio channel, or of the entire audio
	 * player.
	 */
	bool resume(const int16 channelIndex);
	bool resume(const ResourceId resourceId, const reg_t soundNode = NULL_REG) {
		Common::StackLock lock(_mutex);
		return resume(findChannelById(resourceId, soundNode));
	}

	/**
	 * Pauses an audio channel, or the entire audio player.
	 */
	bool pause(const int16 channelIndex);
	bool pause(const ResourceId resourceId, const reg_t soundNode = NULL_REG) {
		Common::StackLock lock(_mutex);
		return pause(findChannelById(resourceId, soundNode));
	}

	/**
	 * Stops and unloads an audio channel, or the entire audio player.
	 */
	int16 stop(const int16 channelIndex);
	int16 stop(const ResourceId resourceId, const reg_t soundNode = NULL_REG) {
		Common::StackLock lock(_mutex);
		return stop(findChannelById(resourceId, soundNode));
	}

	/**
	 * Restarts playback of the given audio resource.
	 */
	uint16 restart(const ResourceId resourceId, const bool autoPlay, const bool loop, const int16 volume, const reg_t soundNode, const bool monitor);

	/**
	 * Returns the playback position for the given channel number, in ticks.
	 */
	int16 getPosition(const int16 channelIndex) const;
	int16 getPosition(const ResourceId resourceId, const reg_t soundNode = NULL_REG) {
		Common::StackLock lock(_mutex);
		return getPosition(findChannelById(resourceId, soundNode));
	}

	/**
	 * Sets whether or not the given channel should loop.
	 */
	void setLoop(const int16 channelIndex, const bool loop);
	void setLoop(const ResourceId resourceId, const reg_t soundNode, const bool loop) {
		Common::StackLock lock(_mutex);
		setLoop(findChannelById(resourceId, soundNode), loop);
	}

	/**
	 * Sets the stereo panning for the given channel.
	 */
	void setPan(const int16 channelIndex, const int16 pan) {
		Common::StackLock lock(_mutex);
		getChannel(channelIndex).pan = pan;
	}

private:
	/**
	 * The tick when audio was globally paused.
	 */
	uint32 _pausedAtTick;

	/**
	 * The tick when audio was globally started.
	 */
	uint32 _startedAtTick;

#pragma mark -
#pragma mark Effects
public:
	/**
	 * Gets the volume for a given channel. Passing `kAllChannels` will get the
	 * global volume.
	 */
	int16 getVolume(const int16 channelIndex) const;
	int16 getVolume(const ResourceId resourceId, const reg_t soundNode) const {
		Common::StackLock lock(_mutex);
		return getVolume(findChannelById(resourceId, soundNode));
	}

	/**
	 * Sets the volume of an audio channel. Passing `kAllChannels` will set the
	 * global volume.
	 */
	void setVolume(const int16 channelIndex, int16 volume);
	void setVolume(const ResourceId resourceId, const reg_t soundNode, const int16 volume) {
		Common::StackLock lock(_mutex);
		setVolume(findChannelById(resourceId, soundNode), volume);
	}

	/**
	 * Sets the master volume for digital audio playback.
	 */
	void setMasterVolume(const int16 volume) {
		_mixer->setVolumeForSoundType(Audio::Mixer::kSFXSoundType, volume * Audio::Mixer::kMaxChannelVolume / kMaxVolume);
	}

	/**
	 * Initiate an immediate fade of the given channel.
	 */
	bool fadeChannel(const int16 channelIndex, const int16 targetVolume, const int16 speed, const int16 steps, const bool stopAfterFade);
	bool fadeChannel(const ResourceId resourceId, const reg_t soundNode, const int16 targetVolume, const int16 speed, const int16 steps, const bool stopAfterFade) {
		Common::StackLock lock(_mutex);
		return fadeChannel(findChannelById(resourceId, soundNode), targetVolume, speed, steps, stopAfterFade);
	}

	/**
	 * Gets whether attenuated mixing mode is active.
	 */
	inline bool getAttenuatedMixing() const {
		return _attenuatedMixing;
	}

	/**
	 * Sets the attenuated mixing mode.
	 */
	void setAttenuatedMixing(bool attenuated) {
		Common::StackLock lock(_mutex);
		_attenuatedMixing = attenuated;
	}

private:
	/**
	 * If true, audio will be mixed by reducing the target buffer by half every
	 * time a new channel is mixed in. The final channel is not attenuated.
	 */
	bool _attenuatedMixing;

	/**
	 * When true, a modified attenuation algorithm is used (`A/4 + B`) instead
	 * of standard linear attenuation (`A/2 + B/2`).
	 */
	bool _useModifiedAttenuation;

	/**
	 * Processes an audio fade for the given channel.
	 *
	 * @returns true if the fade was completed and the channel was stopped.
	 */
	bool processFade(const int16 channelIndex);

#pragma mark -
#pragma mark Signal monitoring
public:
	/**
	 * Returns whether the currently monitored audio channel contains any signal
	 * within the next audio frame.
	 */
	bool hasSignal() const;

private:
	/**
	 * The index of the channel being monitored for signal, or -1 if no channel
	 * is monitored. When a channel is monitored, it also causes the engine to
	 * play only the monitored channel.
	 */
	int16 _monitoredChannelIndex;

	/**
	 * The data buffer holding decompressed audio data for the channel that will
	 * be monitored for an audio signal.
	 */
	Common::Array<Audio::st_sample_t> _monitoredBuffer;

	/**
	 * The number of valid audio samples in the signal monitoring buffer.
	 */
	int _numMonitoredSamples;

#pragma mark -
#pragma mark Kernel
public:
	reg_t kernelPlay(const bool autoPlay, const int argc, const reg_t *const argv);
	reg_t kernelStop(const int argc, const reg_t *const argv);
	reg_t kernelPause(const int argc, const reg_t *const argv);
	reg_t kernelResume(const int argc, const reg_t *const argv);
	reg_t kernelPosition(const int argc, const reg_t *const argv);
	reg_t kernelVolume(const int argc, const reg_t *const argv);
	reg_t kernelMixing(const int argc, const reg_t *const argv);
	reg_t kernelFade(const int argc, const reg_t *const argv);
	void kernelLoop(const int argc, const reg_t *const argv);
	void kernelPan(const int argc, const reg_t *const argv);
	void kernelPanOff(const int argc, const reg_t *const argv);

#pragma mark -
#pragma mark Debugging
public:
	void printAudioList(Console *con) const;
};

} // End of namespace Sci
#endif