////////////////////////////////////////////////////////////////////////////////
//            Copyright (C) 2004-2011 by The Allacrost Project
//            Copyright (C) 2012-2016 by Bertram (Valyria Tear)
//                         All Rights Reserved
//
// This code is licensed under the GNU GPL version 2. It is free software
// and you may modify it and/or redistribute it under the terms of this license.
// See http://www.gnu.org/copyleft/gpl.html for details.
////////////////////////////////////////////////////////////////////////////////

/** ****************************************************************************
*** \file   audio_descriptor.h
*** \author Mois�s Ferrer Serra, byaku@allacrost.org
*** \author Tyler Olsen, roots@allacrost.org
*** \author Yohann Ferreira, yohann ferreira orange fr
*** \brief  Header file for audio descriptors, sources and buffers
***
*** This code provides the interface for the sound and music descriptors, that
*** are the units for load and manage sounds in the engine.
***
*** \note This code uses the OpenAL audio library. See http://www.openal.com/
*** ***************************************************************************/

#ifndef __AUDIO_DESCRIPTOR_HEADER__
#define __AUDIO_DESCRIPTOR_HEADER__

#include "audio_input.h"
#include "audio_stream.h"
#include "audio_effects.h"

// OpenAL includes
#ifdef __APPLE__
#include <OpenAL/al.h>
#include <OpenAL/alc.h>
#else
#include "al.h"
#include "alc.h"
#endif

#include <vector>

namespace vt_mode_manager {
class GameMode;
}

namespace vt_audio
{

class AudioDescriptor;

//! \brief The set of states that AudioDescriptor class objects may be in
enum AUDIO_STATE {
    //! Audio data is not loaded
    AUDIO_STATE_UNLOADED   = 0,
    //! Audio is loaded, but is stopped
    AUDIO_STATE_STOPPED    = 1,
    //! Audio is loaded and is presently playing
    AUDIO_STATE_PLAYING    = 2,
    //! Audio is loaded and was playing, but is now paused
    AUDIO_STATE_PAUSED     = 3,
    //! Audio is fading out
    AUDIO_STATE_FADE_OUT   = 4,
    //! Audio is fading in
    AUDIO_STATE_FADE_IN    = 5,
};

//! \brief The possible ways for that a piece of audio data may be loaded
enum AUDIO_LOAD {
    //! \brief Load audio statically by placing the entire contents of the audio into a single OpenAL buffer
    AUDIO_LOAD_STATIC         = 0,
    //! \brief Stream the audio data from a file into a pair of OpenAL buffers
    AUDIO_LOAD_STREAM_FILE    = 1,
    //! \brief Stream the audio data from memory into a pair of OpenAL buffers
    AUDIO_LOAD_STREAM_MEMORY  = 2
};

//! \brief ALfloat per 3D OpenAL sound vectors (position, direction, velocity)
const uint32_t ALFLOAT3D = 3;
typedef ALfloat ALfloatArray[ALFLOAT3D];

namespace private_audio
{

class AudioEffect;

//! \brief The default buffer size (in bytes) for streaming buffers
const uint32_t DEFAULT_BUFFER_SIZE = 8192;

//! \brief The number of buffers to use for streaming audio descriptors
const uint32_t NUMBER_STREAMING_BUFFERS = 4;

/** ****************************************************************************
*** \brief Represents an OpenAL buffer
***
*** A buffer in OpenAL is simply a structure which contains raw audio data.
*** Buffers must be attached to an OpenAL source in order to play. OpenAL
*** suppports an infinte number of buffers (as long as there is enough memory).
*** ***************************************************************************/
class AudioBuffer
{
    friend class AudioEngine;

public:
    AudioBuffer();

    ~AudioBuffer();

    /** \brief Fills an OpenAL buffer with raw audio data
    *** \param data A pointer to the raw data to fill the buffer with
    *** \param format The format of the buffer data (mono/stereo, 8/16 bits per sample)
    *** \param size The size of the data in number of bytes
    *** \param frequency The audio frequency of the data in samples per second
    **/
    void FillBuffer(uint8_t *data, ALenum format, uint32_t size, uint32_t frequency) {
        alBufferData(buffer, format, data, size, frequency);
    }

    //! \brief Returns true if this class object holds a reference to a valid OpenAL buffer
    bool IsValid() const {
        return (buffer != 0 && alIsBuffer(buffer) == AL_TRUE);
    }

    //! \brief The ID of the OpenAL buffer
    ALuint buffer;
}; // class AudioBuffer


/** ****************************************************************************
*** \brief Represents an OpenAL source
***
*** OpenAL is designed to take care of the complexity of panning sound to
*** different speakers; it does this by storing the locations in 3d space of
*** both the physical sources that a sound might originate from (for example,
*** the point in space where two swords clang together), and also the 3d
*** location of the listener's "ears". A source in OpenAL is simply metadata
*** about the position of the sound; the actual sound itself comes from audio
*** data which is loaded into a buffer, and then played back through one of
*** these sources.
***
*** This metadata includes properties like position, velocity,
*** etc. None of these are actually altered by OpenAL; OpenAL does not use
*** velocity to move the sound sources for us each game tick; rather, it simply
*** uses these to calculate sound itself (velocity is actually used for
*** calculating doppler effects). We are expected to fill these values with
*** appropriate position/velocity data to keep them in sync with the game
*** objects they represent.
***
*** Those properties are not managed by this class, but rather by the
*** AudioDescriptor to which the source is attached. OpenAL (or rather, the
*** audio hardware) only allows a limited number of audio sources to exist at
*** one time, so we can't create a source for every piece of audio that is
*** loaded by the game. Therefore, we create as many sources as we can (up to
*** MAX_DEFAULT_AUDIO_SOURCES) and have the audio descriptors share between
*** sources as they need them.
***
*** \note OpenAL sources are created and by the AudioEngine class, not within the
*** AudioSource constructor. The sources are, however, deleted by the destructor.
***
*** \note You should never really need to call the IsValid() function when
*** retrieving a new AudioSource to use. This is because all AudioSource objects
*** created by AudioEngine are guaranteed to have a valid OpenAL source contained
*** by the object.
*** ***************************************************************************/
class AudioSource
{
public:
    //! \param al_source A valid OpenAL source that has been generated
    explicit AudioSource(ALuint al_source) :
        source(al_source), owner(nullptr) {}

    ~AudioSource();

    //! \brief Returns true if this class object holds a reference to a valid OpenAL source
    bool IsValid() const {
        return (alIsSource(source) == AL_TRUE);
    }

    //! \brief Resets the default properties of the OpenAL sources and removes the owner
    void Reset();

    //! \brief The ID of the OpenAL source
    ALuint source;

    //! \brief Pointer to the descriptor associated to this source.
    AudioDescriptor *owner;
}; // class AudioSource

} // namespace private_audio

/** ****************************************************************************
*** \brief An abstract class for representing a piece of audio
***
*** This class takes the OpenAL buffer and source concepts and ties them
*** together. This class enables playback, streaming, 3D source positioning,
*** and many other features for manipulating a piece of audio. Sounds and
*** music are defined by classes which derive from this class.
***
*** \note Some features of this class are only available if the audio is loaded
*** in a streaming manner.
***
*** \note You should <b>never</b> trust the value of _state when it is set to
*** AUDIO_STATE_PLAYING. This is because the audio may stop playing on its own
*** after the play state has been set. Instead, you should call the GetState()
*** method, which guarantees that the correct state value is set.
***
*** \todo This class either needs to have its copy assignment operator defined
*** or it should be made private.
*** ***************************************************************************/
class AudioDescriptor
{
    friend class AudioEngine;

public:
    AudioDescriptor();

    virtual ~AudioDescriptor() {
        FreeAudio();
    }

    AudioDescriptor(const AudioDescriptor &copy);

    /** \brief Loads a new piece of audio data from a file
    *** \param filename The name of the file that contains the new audio data (should have a .wav or .ogg file extension)
    *** \param load_type The type of loading to perform (default == AUDIO_LOAD_STATIC)
    *** \param stream_buffer_size If the loading type is streaming, the buffer size to use (default == DEFAULT_BUFFER_SIZE)
    *** \return True if the audio was successfully loaded, false if there was an error
    ***
    *** The action taken by this function depends on the load type selected. For static sounds, a single OpenAL buffer is
    *** filled. For streaming, the file/memory is prepared.
    **/
    virtual bool LoadAudio(const std::string &filename, AUDIO_LOAD load_type = AUDIO_LOAD_STATIC, uint32_t stream_buffer_size = private_audio::DEFAULT_BUFFER_SIZE);

    /** \brief Frees all data resources and resets class parameters
    ***
    *** It resets the _state and _offset class members, as well as deleting _data, _stream, _input, _buffer, and resets _source.
    **/
    void FreeAudio();

    const std::string GetFilename() const {
        if(_input == nullptr) return std::string();
        else return _input->GetFilename();
    }

    //! \brief Returns true if this audio represents a sound, false if the audio represents a music piece
    virtual bool IsSound() const = 0;

    //! \brief Returns the state of the audio.
    AUDIO_STATE GetState() {
        return _state;
    }

    /** \name Audio State Manipulation Functions
    *** \brief Performs specified operation on the audio
    ***
    *** These functions will only take effect when the audio is in the state(s) specified below:
    *** - PlayAudio()     <==>   all states but the playing state
    *** - PauseAudio()    <==>   playing state
    *** - ResumeAudio()   <==>   paused state
    *** - StopAudio()     <==>   all states but the stopped state
    *** - RewindAudio()   <==>   all states
    **/
    //@{
    virtual bool Play();
    virtual void Stop();
    virtual void Pause();
    virtual void Resume();
    void Rewind();
    //@}

    bool IsLooping() const {
        return _looping;
    }

    /** \brief Enables/disables looping for this audio
    *** \param loop True to enable looping, false to disable it.
    **/
    void SetLooping(bool loop);

    /** \brief Sets the starting loop point, used for customized looping
    *** \param loop_start The sample position for the start loop point
    *** \note This function is only valid if the audio has been loaded with streaming support
    **/
    void SetLoopStart(uint32_t loop_start);

    /** \brief Sets the ending loop point, used for customized looping
    *** \param loop_start The sample position for the end loop point
    *** \note This function is only valid if the audio has been loaded with streaming support
    **/
    void SetLoopEnd(uint32_t loop_end);

    /** \brief Seeks to the requested sample position
    *** \param sample The sample position to seek to
    **/
    void SeekSample(uint32_t sample);

    /** \brief Seeks to the requested playback time
    *** \param second The time to seek to, in seconds (e.g. 4.5f == 4.5 second mark)
    *** \note The position is aligned with a proper sample position, so the seek is not fully
    *** accurate.
    **/
    void SeekSecond(float second);

    //! \brief Gets the current sample number (track offset)
    uint32_t GetCurrentSampleNumber() const;

    //! \brief Returns the volume level for this audio
    float GetVolume() const {
        return _volume;
    }

    /** \brief Sets the volume for this particular audio piece
    *** \param volume The volume level to set, ranging from [0.0f, 1.0f]
    **/
    virtual void SetVolume(float volume) = 0;

    /** \name Functions for 3D Spatial Audio
    *** These functions manipulate and retrieve the 3d properties of the audio. Note that only audio which
    *** are mono channel will be affected by these methods. Stereo channel audio will see no difference.
    **/
    //@{
    void SetPosition(const ALfloat position[ALFLOAT3D]);
    void SetVelocity(const ALfloat velocity[ALFLOAT3D]);
    void SetDirection(const ALfloat direction[ALFLOAT3D]);

    //! \brief Returns the pointer to corresponding ALfloat parameter array
    const ALfloatArray& GetPosition() const {
        return _position;
    }
    const ALfloatArray& GetVelocity() const {
        return _velocity;
    }
    const ALfloatArray& GetDirection() const {
        return _direction;
    }
    //@}

    /**
    *** Adds a new game mode owning the audio descriptor.
    *** It is done to permit the engine to automatically free audio files
    *** when the game mode is deleted.
    *** This function won't add nullptr reference and won't permit duplicate owners.
    **/
    void AddGameModeOwner(vt_mode_manager::GameMode *gm);

    /**
    *** Adds multiple owners at once.
    *** @see AddOwner()
    **/
    void AddGameModeOwners(std::vector<vt_mode_manager::GameMode *>& owners);

    /**
    *** Remove a game mode reference from the audio descriptor owners,
    *** and checks whether the file data can be freed.
    *** \returns whether the descriptor should be removed from the cache.
    **/
    bool RemoveGameModeOwner(vt_mode_manager::GameMode *gm);

    /**
    *** Get the list of game mode claiming ownership over the audio descriptor.
    **/
    std::vector<vt_mode_manager::GameMode *>* GetGameModeOwners() {
        return &_game_mode_owners;
    }

    /** \brief Fades a music or sound in as it plays
    *** \param audio A reference to the music or sound to fade in
    *** \param time The amount of time that the fade should last for, in seconds
    **/
    void FadeIn(float time);

    /** \brief Fades a music or sound out as it finisheds
    *** \param audio A referenece to the music or sound to fade out
    *** \param time The amount of time that the fade should last for, in seconds
    **/
    void FadeOut(float time);

    //! Tells whether the audio descriptor is fading out.
    bool IsFadingOut();

    //! \brief Remove effects.
    void RemoveEffects();

    //! \brief Prints various properties about the audio data managed by this class
    void DEBUG_PrintInfo();

protected:
    //! \brief The current state of the audio (playing, stopped, etc.)
    AUDIO_STATE _state;

    //! \brief A pointer to the buffer(s) being used by the audio (1 buffer for static sounds, 2 for streamed ones)
    private_audio::AudioBuffer *_buffer;

    //! \brief A pointer to the source object being used by the audio
    private_audio::AudioSource *_source;

    //! \brief A pointer to the input object that manages the data
    private_audio::AudioInput *_input;

    //! \brief A pointer to the stream object (set to nullptr if the audio was loaded statically)
    private_audio::AudioStream *_stream;

    //! \brief A pointer to where the data is streamed to
    uint8_t *_data;

    //! \brief The format of the audio (mono/stereo, 8/16 bits per second).
    ALenum _format;

    //! \brief Flag for indicating if the audio should loop or not
    bool _looping;

    //! \brief The audio position that was last seeked, in samples.
    uint32_t _offset;

    /** \brief The volume of the audio, ranging from 0.0f to 1.0f
    *** This isn't actually the true volume of the audio, but rather the modulation
    *** value of the global sound or music volume level. For example, if this object
    *** represented a sound and the volume was set to 0.75f, and the global sound
    *** volume in AudioEngine was 0.80f, the true volume would be (0.75 * 0.8 = 0.6).
    *** By default this member is set to 1.0f.
    **/
    float _volume;

    //! \brief Keeps in memory the fade out or in time.
    float _fade_effect_time;

    //! \brief The volume of the audio when the fade effect was registered
    float _original_volume;

    //! \brief Size of the streaming buffer, if the audio was loaded for streaming
    uint32_t _stream_buffer_size;

    //! \brief The 3D orientation properties of the audio
    //@{
    ALfloat _position[ALFLOAT3D];
    ALfloat _velocity[ALFLOAT3D];
    ALfloat _direction[ALFLOAT3D];
    //@}

    /** \brief The game modes loading the audio file.
    *** On can usually free it whenever no owner is present for a given sound.
    *** Note that data/sounds/musics are only freed when their owners are removed
    *** and were the last in this list.
    *** Musics and sounds that are never owned will have to be freed manually.
    *** @see AddGameModeOwner(), RemoveGameModeOwner()
    **/
    std::vector<vt_mode_manager::GameMode *> _game_mode_owners;

    //! \brief Holds all active audio effects for this descriptor
    std::vector<private_audio::AudioEffect *> _audio_effects;

    /** \brief Sets the local volume control for this particular audio piece
    *** \param volume The volume level to set, ranging from [0.0f, 1.0f]
    *** This should be thought of as a helper function to the SetVolume methods
    *** for the derived classes, which modulate the volume level of the sound/music
    *** by the global sound and music volume controls in the AudioEngine class.
    **/
    void _SetVolumeControl(float volume);

private:
    /** \brief Updates the audio during playback
    *** This function is only useful for streaming audio that is currently in the play state. If either of these two
    *** conditions are not met, the function will return since it has nothing to do.
    **/
    void _Update();

    //! \brief Handles the fading states volumes update.
    void _HandleFadeStates();

    /** \brief Acquires an audio source for playback
    *** This function is called whenever an audio piece is loaded and whenever the Play operation is specified on
    *** the audio, but the audio currently does not have a source. It is not guaranteed that the source acquisition
    *** will be successful, as all other sources may be occupied by other audio.
    **/
    void _AcquireSource();

    /** \brief Sets all of the relevant properties for the OpenAL source
    *** This function should be called whenever a new source is allocated for the audio to use.
    *** It sets all of the necessary properties for the OpenAL source, such as the volume (gain),
    *** enables looping if requested, etc.
    **/
    void _SetSourceProperties();

    /** \brief Prepares streaming buffers when a new source is acquired or after a seeking operation.
    *** This is a special case, since the already queued buffers must be unqueued, and the new
    *** ones must be refilled. This function should only be called for streaming audio.
    **/
    void _PrepareStreamingBuffers();
}; // class AudioDescriptor


/** ****************************************************************************
*** \brief An class for representing a piece of sound audio
***
*** Sounds are almost always in the .wav file format.
*** ***************************************************************************/
class SoundDescriptor : public AudioDescriptor
{
public:
    SoundDescriptor();

    ~SoundDescriptor();

    SoundDescriptor(const SoundDescriptor &copy);

    bool IsSound() const {
        return true;
    }

    /** \brief Sets the volume of the sound
    *** \param volume The volume to set the sound, value between [0.0, 1.0]
    *** This value will be modulated by the global sound volume found in the
    *** AudioEngine class.
    **/
    void SetVolume(float volume);

    //! \brief Plays or restart the currently played sound.
    bool Play();
}; // class SoundDescriptor : public AudioDescriptor


/** ****************************************************************************
*** \brief A class for representing a piece of music audio
***
*** Music is almost always in the .ogg file format.
***
*** \note Looping is enabled for music by default
*** ***************************************************************************/
class MusicDescriptor : public AudioDescriptor
{
public:
    MusicDescriptor();

    ~MusicDescriptor();

    MusicDescriptor(const MusicDescriptor &copy);

    bool LoadAudio(const std::string &filename, AUDIO_LOAD load_type = AUDIO_LOAD_STREAM_FILE, uint32_t stream_buffer_size = private_audio::DEFAULT_BUFFER_SIZE);

    bool IsSound() const {
        return false;
    }

    /** \brief Sets the volume of the music
    *** \param volume The volume to set the music, value between [0.0, 1.0]
    *** This value will be modulated by the global music volume found in the
    *** AudioEngine class.
    **/
    void SetVolume(float volume);

    /** \brief Plays the selected music, after stopping the previous playing music
    *** No two pieces of music are allowed to play simultaneously, meaning that
    *** calling this method on one music also effectively calls stop on another
    *** piece of music that was playing when the call was made
    **/
    bool Play();
}; // class MusicDescriptor : public AudioDescriptor

} // namespace vt_audio

#endif