/* FAudioGMS - Game Maker FAudio bindings in C
 *
 * Copyright (c) 2021 Evan Hemsley
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from
 * the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software in a
 * product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * Evan "cosmonaut" Hemsley <evan@moonside.games>
 *
 */

#include "SDL.h"

#define DISABLE_XNASONG

#include "FAudioGMS.h"

#include "FAPOBase.h"
#include "FAudioFX.h"
#include "F3DAudio.h"

#include "FAudio.h"

#define DR_WAV_IMPLEMENTATION
#define DRWAV_MALLOC(sz)                   SDL_malloc((sz))
#define DRWAV_REALLOC(p, sz)               SDL_realloc((p), (sz))
#define DRWAV_FREE(p)                      SDL_free((p))
#define DRWAV_COPY_MEMORY(dst, src, sz)    SDL_memcpy((dst), (src), (sz))
#define DRWAV_ZERO_MEMORY(p, sz)           SDL_memset((p), 0, (sz))
#include "../lib/dr_wav.h"

/* stb vorbis defines. this is kind of a mess but oh well */

#include "../lib/FAudio/src/FAudio_internal.h"

#define malloc FAudio_malloc
#define realloc FAudio_realloc
#define free FAudio_free
#ifdef memset /* Thanks, Apple! */
#undef memset
#endif
#define memset SDL_memset
#ifdef memcpy /* Thanks, Apple! */
#undef memcpy
#endif
#define memcpy SDL_memcpy
#define memcmp FAudio_memcmp

#define pow FAudio_pow
#define log(x) FAudio_log(x)
#define sin(x) FAudio_sin(x)
#define cos(x) FAudio_cos(x)
#define floor FAudio_floor
#define abs(x) FAudio_abs(x)
#define ldexp(v, e) FAudio_ldexp((v), (e))
#define exp(x) FAudio_exp(x)

#define qsort FAudio_qsort

#ifdef assert
#undef assert
#endif

#define assert FAudio_assert

#define FILE FAudioIOStream
#ifdef SEEK_SET
#undef SEEK_SET
#endif
#ifdef SEEK_END
#undef SEEK_END
#endif
#ifdef EOF
#undef EOF
#endif
#define SEEK_SET FAUDIO_SEEK_SET
#define SEEK_END FAUDIO_SEEK_END
#define EOF FAUDIO_EOF
#define fopen(path, mode) FAudio_fopen(path)
#define fopen_s(io, path, mode) (!(*io = FAudio_fopen(path)))
#define fclose(io) FAudio_close(io)
#define fread(dst, size, count, io) io->read(io->data, dst, size, count)
#define fseek(io, offset, whence) io->seek(io->data, offset, whence)
#define ftell(io) io->seek(io->data, 0, FAUDIO_SEEK_CUR)

#define STB_VORBIS_NO_PUSHDATA_API 1
#define STB_VORBIS_NO_INTEGER_CONVERSION 1
#include "../lib/FAudio/src/stb_vorbis.h"

#include <stdio.h>

static inline void Log(char *string)
{
    printf("%s\n", string);
    fflush(stdout);
}

typedef struct IdStack
{
    uint32_t* array;
    uint32_t count;
    uint32_t capacity;
} IdStack;

static inline void IdStack_Init(IdStack *stack)
{
    stack->array = NULL;
    stack->capacity = 0;
    stack->count = 0;
}

static inline void IdStack_Push(IdStack *stack, uint32_t id)
{
    if (stack->count >= stack->capacity)
    {
        stack->array = SDL_realloc(stack->array, (stack->capacity + 1) * sizeof(uint32_t));
        stack->capacity += 1;
    }

    stack->array[stack->count] = id;
    stack->count += 1;
}

static inline uint32_t IdStack_Pop(IdStack* stack)
{
    stack->count -= 1;
    return stack->array[stack->count];
}

typedef struct BufferQueue 
{
    uint32_t head;
    uint32_t tail;
    uint32_t size; /* DO NOT MUTATE */
    uint32_t count; /* number of currently enqueued elements */
    uint8_t** buffers;
} BufferQueue;

static inline void BufferQueue_Init(BufferQueue* queue, uint32_t size)
{
    queue->head = 0;
    queue->tail = 0;
    queue->size = size;
    queue->count = 0;
    queue->buffers = SDL_malloc(size * sizeof(uint8_t*));
}

static inline uint8_t* BufferQueue_Dequeue(BufferQueue *queue) 
{
    if (queue->tail == queue->head) 
    {
        return NULL;
    }

    uint8_t* buffer = queue->buffers[queue->tail];
    queue->buffers[queue->tail] = NULL;
    queue->tail = (queue->tail + 1) % queue->size;

    queue->count -= 1;
    return buffer;
}

static inline void BufferQueue_Enqueue(BufferQueue *queue, uint8_t* buffer) 
{
    if (((queue->head + 1) % queue->size) == queue->tail) 
    {
        return;
    }

    queue->buffers[queue->head] = buffer;
    queue->head = (queue->head + 1) % queue->size;

    queue->count += 1;
}

typedef enum FAudioGMS_SoundState
{
    SoundState_Playing,
    SoundState_Paused,
    SoundState_Stopped
} FAudioGMS_SoundState;

typedef struct FAudioGMS_StaticSound
{
    uint32_t id;
    FAudioBuffer buffer;
    uint32_t channels;
    uint32_t samplesPerSecond;
    uint32_t loopStart;
    uint32_t loopLength;
} FAudioGMS_StaticSound;

typedef struct FAudioGMS_StreamingSound
{
    stb_vorbis* fileHandle;
    stb_vorbis_info info;
    BufferQueue bufferQueue;
} FAudioGMS_StreamingSound;

typedef struct FAudioGMS_SoundInstance
{
    uint32_t id;
    FAudioSourceVoice *handle;
    FAudioWaveFormatEx format;
    uint8_t loop; /* bool */
    FAudioGMS_SoundState soundState;
    F3DAUDIO_DSP_SETTINGS dspSettings;

    float pan;
    float pitch;
    float volume;
    float reverb;
    float lowPassFilter;
    float highPassFilter;
    float bandPassFilter;

    uint8_t reverbAttached;
    FAudioSubmixVoice* reverbVoice;
    FAudioVoiceSends reverbSends;

    uint8_t isStatic;
    uint8_t destroyOnFinish;

    uint8_t is3D;
    F3DAUDIO_EMITTER* emitter; /* must not be NULL if is3D */
    float stereoAzimuth[2];

    union
    {
        FAudioGMS_StaticSound *staticSound; /* static sounds are loaded separately, so they do not belong to the instance */
        FAudioGMS_StreamingSound streamingSound;
    } soundData;
} FAudioGMS_SoundInstance;

static const float SPEED_OF_SOUND = 343.5f;
static const float DOPPLER_SCALE = 1.0f;
static const uint32_t MINIMUM_BUFFER_CHECK = 3;

#define MAX_BUFFER_QUEUE_COUNT 16
#define STREAMING_BUFFER_SIZE 1024 * 128 * sizeof(float) /* FIXME: what should this value be? */

typedef struct FAudioGMS_Device
{
    FAudio* handle;
    F3DAUDIO_HANDLE handle3D;

    FAudioDeviceDetails deviceDetails;
    FAudioMasteringVoice *masteringVoice;

    F3DAUDIO_LISTENER listener;
    float spatialDistanceScale;

    FAudioGMS_StaticSound **staticSounds;
    uint32_t staticSoundCount;
    IdStack staticSoundIndexStack;

    FAudioGMS_SoundInstance **soundInstances;
    uint32_t soundInstanceCount;
    IdStack soundInstanceIndexStack;

    float streamStagingBuffer[STREAMING_BUFFER_SIZE];
} FAudioGMS_Device;

static FAudioGMS_Device* device = NULL;

static inline FAudioGMS_StaticSound* FAudioGMS_INTERNAL_LookupStaticSound(uint32_t id)
{
    if (id >= 0 && id < device->staticSoundCount)
    {
        return device->staticSounds[id];
    }
    else
    {
        Log("Invalid StaticSound ID!");
        return NULL;
    }
}

static inline FAudioGMS_SoundInstance* FAudioGMS_INTERNAL_LookupSoundInstance(uint32_t id)
{
    if (id >= 0 && id < device->soundInstanceCount)
    {
        return device->soundInstances[id];
    }
    else
    {
        Log("Invalid SoundInstance ID!");
        return NULL;
    }
}

void FAudioGMS_Init(double spatialDistanceScale)
{
    device = SDL_malloc(sizeof(FAudioGMS_Device));

    uint32_t result = FAudioCreate(&device->handle, 0, FAUDIO_DEFAULT_PROCESSOR);

    if (result != 0)
    {
        Log("Failed to create device! Bailing!");
        SDL_free(device);
        device = NULL;
        return;
    }

    /* Find a suitable device */

    uint32_t deviceCount;
    FAudio_GetDeviceCount(device->handle, &deviceCount);

    if (deviceCount == 0)
    {
        Log("No audio devices found! Bailing!");
        FAudio_Release(device->handle);
        SDL_free(device);
        device = NULL;
        return;
    }

    FAudioDeviceDetails deviceDetails;

    uint32_t i = 0;
    for (i = 0; i < deviceCount; i += 1)
    {
        FAudio_GetDeviceDetails(
            device->handle,
            i,
            &deviceDetails);

        if ((deviceDetails.Role & FAudioDefaultGameDevice) == FAudioDefaultGameDevice)
        {
            device->deviceDetails = deviceDetails;
            break;
        }
    }

    if (i == deviceCount)
    {
        i = 0; /* whatever we'll just use the first one i guess */
        FAudio_GetDeviceDetails(
            device->handle,
            i,
            &deviceDetails);

        device->deviceDetails = deviceDetails;
    }

    if (FAudio_CreateMasteringVoice(
        device->handle,
        &device->masteringVoice,
        FAUDIO_DEFAULT_CHANNELS,
        FAUDIO_DEFAULT_SAMPLERATE,
        0,
        i,
        NULL
    ) != 0)
    {
        Log("No mastering voice found! Bailing!");
        FAudio_Release(device->handle);
        SDL_free(device);
        device = NULL;
        return;
    }

    device->spatialDistanceScale = spatialDistanceScale;

    F3DAudioInitialize(
        device->deviceDetails.OutputFormat.dwChannelMask,
        SPEED_OF_SOUND,
        device->handle3D
    );

    device->listener.OrientFront.x = 0;
    device->listener.OrientFront.y = 0;
    device->listener.OrientFront.z = -1;
    device->listener.OrientTop.x = 0;
    device->listener.OrientTop.y = 1;
    device->listener.OrientTop.z = 0;
    device->listener.Position.x = 0;
    device->listener.Position.y = 0;
    device->listener.Position.z = 0;
    device->listener.Velocity.x = 0;
    device->listener.Velocity.y = 0;
    device->listener.Velocity.z = 0;
    device->listener.pCone = NULL;

    device->staticSounds = NULL;
    device->staticSoundCount = 0;
    IdStack_Init(&device->staticSoundIndexStack);

    device->soundInstances = NULL;
    device->soundInstanceCount = 0;
    IdStack_Init(&device->soundInstanceIndexStack);

    Log("FAudio initialized successfully!");
    printf("Device: %ls", device->deviceDetails.DisplayName);
    fflush(stdout);
}

/* Taken from https://github.com/FNA-XNA/FNA/blob/master/src/Audio/SoundEffectInstance.cs */
static void SetPanMatrixCoefficients(FAudioGMS_SoundInstance *instance)
{
    /* Two major things to notice:
    * 1. The spec assumes any speaker count >= 2 has Front Left/Right.
    * 2. Stereo panning is WAY more complicated than you think.
    *    The main thing is that hard panning does NOT eliminate an
    *    entire channel; the two channels are blended on each side.
    * -flibit
    */

    float* outputMatrix = (float*) instance->dspSettings.pMatrixCoefficients;
    if (instance->dspSettings.SrcChannelCount == 1)
    {
        if (instance->dspSettings.DstChannelCount == 1)
        {
            outputMatrix[0] = 1.0f;
        }
        else
        {
            outputMatrix[0] = (instance->pan > 0.0f) ? (1.0f - instance->pan) : 1.0f;
            outputMatrix[1] = (instance->pan < 0.0f) ? (1.0f  + instance->pan) : 1.0f;
        }
    }
    else
    {
        if (instance->dspSettings.DstChannelCount == 1)
        {
            outputMatrix[0] = 1.0f;
            outputMatrix[1] = 1.0f;
        }
        else
        {
            if (instance->pan <= 0.0f)
            {
                // Left speaker blends left/right channels
                outputMatrix[0] = 0.5f * instance->pan + 1.0f;
                outputMatrix[1] = 0.5f * -instance->pan;
                // Right speaker gets less of the right channel
                outputMatrix[2] = 0.0f;
                outputMatrix[3] = instance->pan + 1.0f;
            }
            else
            {
                // Left speaker gets less of the left channel
                outputMatrix[0] = -instance->pan + 1.0f;
                outputMatrix[1] = 0.0f;
                // Right speaker blends right/left channels
                outputMatrix[2] = 0.5f * instance->pan;
                outputMatrix[3] = 0.5f * -instance->pan + 1.0f;
            }
        }
    }
}

double FAudioGMS_StaticSound_LoadWAV(char *filePath)
{
    drwav_uint64 frameCount;

    FAudioGMS_StaticSound *sound = SDL_malloc(sizeof(FAudioGMS_StaticSound));
    float *pSampleData = drwav_open_file_and_read_pcm_frames_f32(filePath, &sound->channels, &sound->samplesPerSecond, &frameCount, NULL);
    if (pSampleData == NULL)
    {
        Log("Error opening WAV file: ");
        Log(filePath);
        SDL_free(sound);
        return -1;
    }

    sound->buffer.AudioBytes = (uint32_t)(frameCount * sound->channels * sizeof(float));
    sound->buffer.Flags = FAUDIO_END_OF_STREAM;
    sound->buffer.LoopBegin = 0;
    sound->buffer.LoopCount = 0;
    sound->buffer.LoopLength = 0;
    sound->buffer.pAudioData = (uint8_t*) pSampleData;
    sound->buffer.pContext = NULL;
    sound->buffer.PlayBegin = 0;
    sound->buffer.PlayLength = 0;

    sound->loopStart = 0;
    sound->loopLength = 0;

    if (device->staticSoundIndexStack.count > 0)
    {
        sound->id = IdStack_Pop(&device->staticSoundIndexStack);
    }
    else
    {
        sound->id = device->staticSoundCount;

        device->staticSounds = SDL_realloc(device->staticSounds, (device->staticSoundCount + 1) * sizeof(FAudioGMS_StaticSound*));
        device->staticSoundCount += 1;
    }

    device->staticSounds[sound->id] = sound;

    return (double)sound->id;
}

static void FAudioGMS_INTERNAL_SoundInstance_AttachReverb(FAudioGMS_SoundInstance* instance)
{
    if (!instance->reverbAttached)
    {
        /* Init reverb */

        FAPO* reverb;
        FAudioCreateReverb(&reverb, 0);

        FAudioEffectChain* reverbChain = SDL_malloc(sizeof(FAudioEffectChain));

        reverbChain->EffectCount = 1;
        reverbChain->pEffectDescriptors = SDL_malloc(sizeof(FAudioEffectDescriptor));

        FAudioEffectDescriptor* reverbDescriptor = reverbChain->pEffectDescriptors;

        reverbDescriptor->InitialState = 1;
        reverbDescriptor->OutputChannels = device->deviceDetails.OutputFormat.Format.nChannels == 6 ? 6 : 1;
        reverbDescriptor->pEffect = reverb;

        FAudio_CreateSubmixVoice(
            device->handle,
            &instance->reverbVoice,
            1, /* omnidirectional reverb */
            device->deviceDetails.OutputFormat.Format.nSamplesPerSec,
            0,
            0,
            NULL,
            reverbChain);

        FAPOBase_Release((FAPOBase*)reverb);
        SDL_free(reverbChain->pEffectDescriptors);
        SDL_free(reverbChain);

        FAudioFXReverbParameters* reverbParams = SDL_malloc(sizeof(FAudioFXReverbParameters));

        reverbParams->WetDryMix = 100.0f;
        reverbParams->ReflectionsDelay = 7;
        reverbParams->ReverbDelay = 11;
        reverbParams->RearDelay = FAUDIOFX_REVERB_DEFAULT_REAR_DELAY;
        reverbParams->PositionLeft = FAUDIOFX_REVERB_DEFAULT_POSITION;
        reverbParams->PositionRight = FAUDIOFX_REVERB_DEFAULT_POSITION;
        reverbParams->PositionMatrixLeft = FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX;
        reverbParams->PositionMatrixRight = FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX;
        reverbParams->EarlyDiffusion = 15;
        reverbParams->LateDiffusion = 15;
        reverbParams->LowEQGain = 8;
        reverbParams->LowEQCutoff = 4;
        reverbParams->HighEQGain = 8;
        reverbParams->HighEQCutoff = 6;
        reverbParams->RoomFilterFreq = 5000.0f;
        reverbParams->RoomFilterMain = -10.0f;
        reverbParams->RoomFilterHF = -1.0f;
        reverbParams->ReflectionsGain = -26.0200005f;
        reverbParams->ReverbGain = 10.0f;
        reverbParams->DecayTime = 1.49000001f;
        reverbParams->Density = 100.0f;
        reverbParams->RoomSize = FAUDIOFX_REVERB_DEFAULT_ROOM_SIZE;

        FAudioVoice_SetEffectParameters(
            instance->reverbVoice,
            0,
            reverbParams,
            sizeof(FAudioFXReverbParameters),
            0);

        SDL_free(reverbParams);

        /* Init reverb sends */

        instance->reverbSends.SendCount = 2;
        instance->reverbSends.pSends = SDL_malloc(2 * sizeof(FAudioSendDescriptor));

        instance->reverbSends.pSends[0].Flags = 0;
        instance->reverbSends.pSends[0].pOutputVoice = device->masteringVoice;
        instance->reverbSends.pSends[1].Flags = 0;
        instance->reverbSends.pSends[1].pOutputVoice = instance->reverbVoice;

        instance->reverbAttached = 1;
    }

    FAudioVoice_SetOutputVoices(
        instance->handle,
        &instance->reverbSends);
}

static void FAudioGMS_INTERNAL_SoundInstance_SetReverb(FAudioGMS_SoundInstance *instance, float reverb)
{
    if (!instance->reverbAttached)
    {
        FAudioGMS_INTERNAL_SoundInstance_AttachReverb(instance);
    }

    float* outputMatrix = instance->dspSettings.pMatrixCoefficients;

    outputMatrix[0] = reverb;
    if (instance->dspSettings.SrcChannelCount == 2)
    {
        outputMatrix[1] = reverb;
    }

    FAudioVoice_SetOutputMatrix(
        instance->handle, 
        instance->reverbVoice, 
        instance->dspSettings.SrcChannelCount, 
        1, 
        outputMatrix,
        0);

    instance->reverb = reverb;
}

static void FAudioGMS_INTERNAL_SoundInstance_SetLowPassFilter(FAudioGMS_SoundInstance* instance, float lowPassFilter)
{
    FAudioFilterParameters p;
    p.Type = FAudioLowPassFilter;
    p.Frequency = lowPassFilter;
    p.OneOverQ = 1.0f;

    FAudioVoice_SetFilterParameters(instance->handle, &p, 0);

    instance->lowPassFilter = lowPassFilter;
}

static void FAudioGMS_INTERNAL_SoundInstance_SetHighPassFilter(FAudioGMS_SoundInstance* instance, float highPassFilter)
{
    FAudioFilterParameters p;
    p.Type = FAudioHighPassFilter;
    p.Frequency = highPassFilter;
    p.OneOverQ = 1.0f;

    FAudioVoice_SetFilterParameters(instance->handle, &p, 0);

    instance->highPassFilter = highPassFilter;
}

static void FAudioGMS_INTERNAL_SoundInstance_SetBandPassFilter(FAudioGMS_SoundInstance* instance, float bandPassFilter)
{
    FAudioFilterParameters p;
    p.Type = FAudioBandPassFilter;
    p.Frequency = bandPassFilter;
    p.OneOverQ = 1.0f;

    FAudioVoice_SetFilterParameters(instance->handle, &p, 0);

    instance->bandPassFilter = bandPassFilter;
}

static void FAudioGMS_INTERNAL_SoundInstance_SetPan(FAudioGMS_SoundInstance* instance, float pan)
{
    instance->pan = pan;
    SetPanMatrixCoefficients(instance);

    FAudioVoice_SetOutputMatrix(
        instance->handle,
        device->masteringVoice,
        instance->dspSettings.SrcChannelCount,
        instance->dspSettings.DstChannelCount,
        instance->dspSettings.pMatrixCoefficients,
        0
    );
}

static void FAudioGMS_INTERNAL_SoundInstance_UpdatePitch(FAudioGMS_SoundInstance* instance)
{
    float doppler = 1.0f;

    if (!instance->is3D || DOPPLER_SCALE == 0.0f)
    {
        doppler = 1.0f;
    }
    else
    {
        doppler = instance->dspSettings.DopplerFactor * DOPPLER_SCALE;
    }

    FAudioSourceVoice_SetFrequencyRatio(
        instance->handle,
        SDL_powf(2.0f, instance->pitch - 1) * doppler, /* FAudio expects pitch range to be -1.0 to 1.0 while GM uses 0.0 to 2.0 so we adjust here */
        0
    );
}

static void FAudioGMS_INTERNAL_SoundInstance_SetPitch(FAudioGMS_SoundInstance* instance, float pitch)
{
    pitch = SDL_max(0.0, SDL_min(2.0, pitch));
    instance->pitch = pitch;
    FAudioGMS_INTERNAL_SoundInstance_UpdatePitch(instance);
}

static void FAudioGMS_INTERNAL_SoundInstance_SetVolume(FAudioGMS_SoundInstance* instance, float volume)
{
    FAudioVoice_SetVolume(instance->handle, volume, 0);
}

static void FAudioGMS_INTERNAL_SoundInstance_SetProperties(FAudioGMS_SoundInstance* instance, double pan, double pitch, double volume, double reverb)
{
    FAudioGMS_INTERNAL_SoundInstance_SetPan(instance, pan);
    FAudioGMS_INTERNAL_SoundInstance_SetPitch(instance, pitch);
    FAudioGMS_INTERNAL_SoundInstance_SetVolume(instance, volume);

    if (reverb > 0.0f)
    {
        FAudioGMS_INTERNAL_SoundInstance_SetReverb(instance, reverb);
    }
}

static void FAudioGMS_INTERNAL_Apply3D(FAudioGMS_SoundInstance* instance)
{
    F3DAUDIO_EMITTER* emitter = instance->emitter;

    if (emitter == NULL)
    {
        Log("Sound instance does not have 3D data! Did you forget to initialize?");
        return;
    }

    F3DAudioCalculate(
        device->handle3D,
        &device->listener,
        emitter,
        F3DAUDIO_CALCULATE_MATRIX | F3DAUDIO_CALCULATE_DOPPLER,
        &instance->dspSettings
    );

    FAudioGMS_INTERNAL_SoundInstance_UpdatePitch(instance);
    FAudioVoice_SetOutputMatrix(
        instance->handle,
        device->masteringVoice,
        instance->dspSettings.SrcChannelCount,
        instance->dspSettings.DstChannelCount,
        instance->dspSettings.pMatrixCoefficients,
        0
    );
}

static FAudioGMS_SoundInstance* FAudioGMS_INTERNAL_SoundInstance_Init(
    uint32_t channelCount,
    uint32_t samplesPerSecond
) {
    FAudioGMS_SoundInstance* instance = SDL_malloc(sizeof(FAudioGMS_SoundInstance));

    instance->handle = NULL;

    instance->loop = 0;
    instance->destroyOnFinish = 0;

    instance->format.wFormatTag = FAUDIO_FORMAT_IEEE_FLOAT;
    instance->format.wBitsPerSample = 32;
    instance->format.nChannels = channelCount;
    instance->format.nBlockAlign = (uint16_t)(4 * channelCount);
    instance->format.nSamplesPerSec = samplesPerSecond;
    instance->format.nAvgBytesPerSec = instance->format.nBlockAlign * samplesPerSecond;

    FAudio_CreateSourceVoice(
        device->handle,
        &instance->handle,
        &instance->format,
        FAUDIO_VOICE_USEFILTER,
        FAUDIO_DEFAULT_FREQ_RATIO,
        NULL,
        NULL,
        NULL);

    if (instance->handle == NULL)
    {
        Log("SoundInstance failed to initialize!");
        SDL_free(instance);
        return NULL;
    }

    instance->dspSettings.DopplerFactor = 1.0f;
    instance->dspSettings.SrcChannelCount = channelCount;
    instance->dspSettings.DstChannelCount = device->deviceDetails.OutputFormat.Format.nChannels;

    uint32_t memsize = 4 * instance->dspSettings.SrcChannelCount * instance->dspSettings.DstChannelCount;
    instance->dspSettings.pMatrixCoefficients = SDL_malloc(memsize);
    SDL_memset(instance->dspSettings.pMatrixCoefficients, 0, memsize);

    instance->reverbAttached = 0;
    instance->reverb = 0.0f;
    instance->lowPassFilter = 0.0f;
    instance->highPassFilter = 0.0f;
    instance->bandPassFilter = 0.0f;

    FAudioGMS_INTERNAL_SoundInstance_SetPan(instance, 0);
    FAudioGMS_INTERNAL_SoundInstance_SetPitch(instance, 1);
    FAudioGMS_INTERNAL_SoundInstance_SetVolume(instance, 1);

    instance->soundState = SoundState_Stopped;

    instance->is3D = 0;
    instance->emitter = NULL;
    instance->stereoAzimuth[0] = 0.0f;
    instance->stereoAzimuth[1] = 0.0f;

    if (device->soundInstanceIndexStack.count > 0)
    {
        instance->id = IdStack_Pop(&device->soundInstanceIndexStack);
    }
    else
    {
        instance->id = device->soundInstanceCount;

        device->soundInstances = SDL_realloc(device->soundInstances, (device->soundInstanceCount + 1) * sizeof(FAudioGMS_SoundInstance*));
        device->soundInstanceCount += 1;
    }

    device->soundInstances[instance->id] = instance;

    return instance;
}

static FAudioGMS_SoundInstance* FAudioGMS_INTERNAL_SoundInstance_CreateFromStaticSound(
    FAudioGMS_StaticSound *staticSound
) {
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_Init(
        staticSound->channels,
        staticSound->samplesPerSecond
    );

    instance->isStatic = 1;
    instance->soundData.staticSound = staticSound;

    return instance;
}

double FAudioGMS_StreamingSound_LoadOGG(char* filePath)
{
    int error = -1;
    stb_vorbis *fileHandle = stb_vorbis_open_filename(filePath, &error, NULL);

    if (error != 0)
    {
        Log("Error opening OGG file!");
        Log(filePath);
        return -1;
    }

    stb_vorbis_info info = stb_vorbis_get_info(fileHandle);

    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_Init(
        info.channels,
        info.sample_rate
    );

    instance->isStatic = 0;
    instance->soundData.streamingSound.fileHandle = fileHandle;
    instance->soundData.streamingSound.info = info;
    BufferQueue_Init(&instance->soundData.streamingSound.bufferQueue, MAX_BUFFER_QUEUE_COUNT);

    return instance->id;
}

static void FAudioGMS_INTERNAL_StaticSound_AddEmitter(FAudioGMS_SoundInstance* instance, float x, float y, float z)
{
    instance->is3D = 1;

    instance->emitter = SDL_malloc(sizeof(F3DAUDIO_EMITTER));

    /* defaults based on XNA behavior */
    instance->emitter->pCone = NULL;
    instance->emitter->ChannelRadius = 1.0f;
    instance->emitter->pChannelAzimuths = instance->stereoAzimuth;
    instance->emitter->pVolumeCurve = NULL;
    instance->emitter->pLFECurve = NULL;
    instance->emitter->pLPFDirectCurve = NULL;
    instance->emitter->pLPFReverbCurve = NULL;
    instance->emitter->pReverbCurve = NULL;
    instance->emitter->InnerRadius = 0;
    instance->emitter->InnerRadiusAngle = 0;

    instance->emitter->ChannelCount = instance->dspSettings.SrcChannelCount;
    instance->emitter->CurveDistanceScaler = device->spatialDistanceScale;
    instance->emitter->DopplerScaler = 1.0f;

    instance->emitter->Position.x = x;
    instance->emitter->Position.y = y;
    instance->emitter->Position.z = z;

    instance->emitter->Velocity.x = 0;
    instance->emitter->Velocity.y = 0;
    instance->emitter->Velocity.z = 0;

    instance->emitter->OrientTop.x = 0;
    instance->emitter->OrientTop.y = 1;
    instance->emitter->OrientTop.z = 0;

    instance->emitter->OrientFront.x = 0;
    instance->emitter->OrientFront.y = 0;
    instance->emitter->OrientFront.z = 1;

    FAudioGMS_INTERNAL_Apply3D(instance);
}

static void FAudioGMS_INTERNAL_SoundInstance_AddBuffer(FAudioGMS_SoundInstance* instance)
{
    /* NOTE: this function returns samples per channel, not total samples */
    uint32_t samples = stb_vorbis_get_samples_float_interleaved(
        instance->soundData.streamingSound.fileHandle,
        instance->format.nChannels,
        device->streamStagingBuffer,
        STREAMING_BUFFER_SIZE
    );

    uint32_t sampleCount = samples * instance->format.nChannels;
    uint32_t bufferLength = sampleCount * sizeof(float);

    uint8_t* nextBuffer = SDL_malloc(bufferLength);
    SDL_memcpy(nextBuffer, device->streamStagingBuffer, bufferLength);

    BufferQueue_Enqueue(&instance->soundData.streamingSound.bufferQueue, nextBuffer);

    if (instance->soundState != SoundState_Stopped)
    {
        FAudioBuffer buffer;
        buffer.AudioBytes = bufferLength;
        buffer.pAudioData = nextBuffer;
        buffer.PlayLength =
            bufferLength /
            instance->format.nChannels /
            (instance->format.wBitsPerSample / 8);
        buffer.PlayBegin = 0;

        buffer.Flags = 0;
        buffer.LoopBegin = 0;
        buffer.LoopCount = 0;
        buffer.LoopLength = 0;
        buffer.pContext = NULL;

        FAudioSourceVoice_SubmitSourceBuffer(instance->handle, &buffer, NULL);
    }

    /* We have reached the end of the file! */
    if (sampleCount < STREAMING_BUFFER_SIZE)
    {
        if (instance->loop)
        {
            stb_vorbis_seek_start(instance->soundData.streamingSound.fileHandle);
        }
        else
        {
            instance->soundState = SoundState_Stopped;
        }
    }
}

static void FAudioGMS_INTERNAL_SoundInstance_StreamingUpdate(FAudioGMS_SoundInstance* instance)
{
    uint32_t i;
    FAudioVoiceState voiceState;

    if (instance->isStatic) { return; }

    FAudioSourceVoice_GetState(
        instance->handle,
        &voiceState,
        FAUDIO_VOICE_NOSAMPLESPLAYED
    );

    while (instance->soundData.streamingSound.bufferQueue.count > voiceState.BuffersQueued)
    {
        uint8_t* buffer = BufferQueue_Dequeue(&instance->soundData.streamingSound.bufferQueue);
        SDL_free(buffer);
    }

    for (i = MINIMUM_BUFFER_CHECK - instance->soundData.streamingSound.bufferQueue.count; i > 0; i -= 1)
    {
        FAudioGMS_INTERNAL_SoundInstance_AddBuffer(instance);
    }
}

static void FAudioGMS_INTERNAL_SoundInstance_ClearBuffers(FAudioGMS_SoundInstance* instance)
{
    uint32_t i;
    uint32_t bufferCount = instance->soundData.streamingSound.bufferQueue.count;

    for (i = 0; i < bufferCount; i += 1)
    {
        uint8_t* buffer = BufferQueue_Dequeue(&instance->soundData.streamingSound.bufferQueue);
        SDL_free(buffer);
    }
}

static void FAudioGMS_INTERNAL_SoundInstance_Play(FAudioGMS_SoundInstance* instance)
{
    if (instance->soundState == SoundState_Playing)
    {
        return;
    }

    if (instance->isStatic)
    {
        if (instance->loop)
        {
            instance->soundData.staticSound->buffer.LoopCount = FAUDIO_LOOP_INFINITE;
            instance->soundData.staticSound->buffer.LoopBegin = instance->soundData.staticSound->loopStart;
            instance->soundData.staticSound->buffer.LoopLength = instance->soundData.staticSound->loopLength;
        }
        else
        {
            instance->soundData.staticSound->buffer.LoopCount = 0;
            instance->soundData.staticSound->buffer.LoopBegin = 0;
            instance->soundData.staticSound->buffer.LoopLength = 0;
        }

        FAudioSourceVoice_SubmitSourceBuffer(instance->handle, &instance->soundData.staticSound->buffer, NULL);
    }
    else
    {
        FAudioGMS_INTERNAL_SoundInstance_StreamingUpdate(instance);
    }

    FAudioSourceVoice_Start(instance->handle, 0, 0);
    instance->soundState = SoundState_Playing;
}

void FAudioGMS_StaticSound_PlayOneOff(double staticSoundID, double pan, double pitch, double volume, double reverb)
{
    FAudioGMS_StaticSound* staticSound = FAudioGMS_INTERNAL_LookupStaticSound((uint32_t)staticSoundID);

    if (staticSound != NULL)
    {
        FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_CreateFromStaticSound(staticSound);
        instance->destroyOnFinish = 1;
        FAudioGMS_INTERNAL_SoundInstance_SetProperties(instance, pan, pitch, volume, reverb);
        FAudioGMS_INTERNAL_SoundInstance_Play(instance);
    }
    else
    {
        Log("StaticSound_PlayOneOff: Invalid static sound ID! Did you destroy this sound?");
    }
}

void FAudioGMS_StaticSound_PlayOneOffSpatial(double staticSoundID, double x, double y, double z, double pitch, double volume, double reverb)
{
    FAudioGMS_StaticSound* staticSound = FAudioGMS_INTERNAL_LookupStaticSound((uint32_t)staticSoundID);

    if (staticSound != NULL)
    {
        FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_CreateFromStaticSound(staticSound);
        instance->destroyOnFinish = 1;
        FAudioGMS_INTERNAL_SoundInstance_SetProperties(instance, 0, pitch, volume, reverb);
        FAudioGMS_INTERNAL_StaticSound_AddEmitter(instance, x, y, z);
        FAudioGMS_INTERNAL_SoundInstance_Play(instance);
    }
    else
    {
        Log("StaticSound_PlayOneOffSpatial: Invalid static sound ID! Did you destroy this sound?");
    }
}

double FAudioGMS_StaticSound_Play(double staticSoundID, double pan, double pitch, double volume, double reverb, double loop)
{
    FAudioGMS_StaticSound* staticSound = FAudioGMS_INTERNAL_LookupStaticSound((uint32_t)staticSoundID);

    if (staticSound != NULL)
    {
        FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_CreateFromStaticSound(staticSound);
        instance->loop = (uint8_t)loop;
        FAudioGMS_INTERNAL_SoundInstance_SetProperties(instance, pan, pitch, volume, reverb);
        FAudioGMS_INTERNAL_SoundInstance_Play(instance);
        return (double)instance->id;
    }
    else
    {
        Log("StaticSound_Play: Invalid static sound ID! Did you destroy this sound?");
        return -1;
    }
}

double FAudioGMS_StaticSound_PlaySpatial(double staticSoundID, double x, double y, double z, double pitch, double volume, double reverb, double loop)
{
    FAudioGMS_StaticSound* staticSound = FAudioGMS_INTERNAL_LookupStaticSound((uint32_t)staticSoundID);

    if (staticSound != NULL)
    {
        FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_SoundInstance_CreateFromStaticSound(staticSound);
        instance->loop = (uint8_t)loop;
        FAudioGMS_INTERNAL_SoundInstance_SetProperties(instance, 0, pitch, volume, reverb);
        FAudioGMS_INTERNAL_StaticSound_AddEmitter(instance, x, y, z);
        FAudioGMS_INTERNAL_SoundInstance_Play(instance);
        return (double)instance->id;
    }
    else
    {
        Log("StaticSound_PlaySpatial: Invalid static sound ID! Did you destroy this sound?");
        return -1;
    }
}

void FAudioGMS_SoundInstance_Play(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);

    if (instance != NULL)
    {
        FAudioGMS_INTERNAL_SoundInstance_Play(instance);
    }
}

void FAudioGMS_SoundInstance_Pause(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);

    if (instance != NULL)
    {
        if (instance->soundState == SoundState_Playing)
        {
            FAudioSourceVoice_Stop(instance->handle, 0, 0);
            instance->soundState = SoundState_Paused;
        }
    }
    else
    {
        Log("SoundInstance_Pause: Invalid sound instance ID! Did you destroy this instance?");
    }
}

static void FAudioGMS_INTERNAL_SoundInstance_Stop(FAudioGMS_SoundInstance* instance)
{
    if (instance != NULL)
    {
        if (instance->isStatic)
        {
            FAudioSourceVoice_ExitLoop(instance->handle, 0);
        }

        instance->soundState = SoundState_Stopped;
    }
    else
    {
        Log("SoundInstance_Stop: Invalid sound instance ID! Did you destroy this instance?");
    }
}

void FAudioGMS_SoundInstance_Stop(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);
    FAudioGMS_INTERNAL_SoundInstance_Stop(instance);
}

static void FAudioGMS_INTERNAL_SoundInstance_StopImmediate(FAudioGMS_SoundInstance* instance)
{
    if (instance != NULL)
    {
        FAudioSourceVoice_Stop(instance->handle, 0, 0);
        FAudioSourceVoice_FlushSourceBuffers(instance->handle);

        if (!instance->isStatic)
        {
            FAudioGMS_INTERNAL_SoundInstance_ClearBuffers(instance);
        }

        instance->soundState = SoundState_Stopped;
    }
    else
    {
        Log("SoundInstance_Stop: Invalid sound instance ID! Did you destroy this instance?");
    }
}

void FAudioGMS_SoundInstance_StopImmediate(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);
    FAudioGMS_INTERNAL_SoundInstance_StopImmediate(instance);
}

void FAudioGMS_SoundInstance_Set3DPosition(double soundInstanceID, double x, double y, double z)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)soundInstanceID);

    if (instance != NULL)
    {
        if (!instance->is3D)
        {
            Log("Not a 3D sound!");
            return;
        }

        instance->emitter->Velocity.x = x - instance->emitter->Position.x;
        instance->emitter->Velocity.y = y - instance->emitter->Position.y;
        instance->emitter->Velocity.z = z - instance->emitter->Position.z;

        instance->emitter->Position.x = x;
        instance->emitter->Position.y = y;
        instance->emitter->Position.z = z;
    }
}

void FAudioGMS_SetListenerPosition(double x, double y, double z)
{
    device->listener.Velocity.x = x - device->listener.Position.x;
    device->listener.Velocity.y = y - device->listener.Position.y;
    device->listener.Velocity.z = z - device->listener.Position.z;

    device->listener.Position.x = x;
    device->listener.Position.y = y;
    device->listener.Position.z = z;
}

static void FAudioGMS_INTERNAL_SoundInstance_Destroy(FAudioGMS_SoundInstance* instance)
{
    if (instance != NULL)
    {
        device->soundInstances[instance->id] = NULL;
        IdStack_Push(&device->soundInstanceIndexStack, instance->id);
        FAudioGMS_INTERNAL_SoundInstance_StopImmediate(instance);
        FAudioVoice_DestroyVoice(instance->handle);
        if (!instance->isStatic)
        {
            SDL_free(instance->soundData.streamingSound.bufferQueue.buffers);
            stb_vorbis_close(instance->soundData.streamingSound.fileHandle);
        }
        if (instance->is3D)
        {
            SDL_free(instance->emitter);
        }
        SDL_free(instance->dspSettings.pMatrixCoefficients);
        SDL_free(instance);
    }
}

void FAudioGMS_SoundInstance_Destroy(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);

    if (instance != NULL)
    {
        FAudioGMS_INTERNAL_SoundInstance_Destroy(instance);
    }
}

void FAudioGMS_SoundInstance_DestroyWhenFinished(double id)
{
    FAudioGMS_SoundInstance* instance = FAudioGMS_INTERNAL_LookupSoundInstance((uint32_t)id);

    if (instance != NULL)
    {
        instance->destroyOnFinish = 1;
    }
}

/* FIXME: this will die horribly if a sound is playing */
static void FAudioGMS_INTERNAL_StaticSound_Destroy(FAudioGMS_StaticSound* sound)
{
    if (sound != NULL)
    {
        device->staticSounds[sound->id] = NULL;
        IdStack_Push(&device->staticSoundIndexStack, sound->id);
        SDL_free((void*)sound->buffer.pAudioData);
        SDL_free(sound);
    }
}

void FAudioGMS_StaticSound_Destroy(double id)
{
    if (id >= 0 && id < device->staticSoundCount)
    {
        FAudioGMS_INTERNAL_StaticSound_Destroy(device->staticSounds[(uint32_t)id]);
    }
    else
    {
        Log("Invalid ID for destroy!");
    }
}

void FAudioGMS_Update()
{
    uint32_t i;

    for (i = 0; i < device->soundInstanceCount; i += 1)
    {
        FAudioGMS_SoundInstance* instance = device->soundInstances[i];

        if (instance != NULL)
        {
            if (instance->is3D)
            {
                FAudioGMS_INTERNAL_Apply3D(instance);
            }

            /* Update streaming instance */
            if (!instance->isStatic && instance->soundState == SoundState_Playing)
            {
                FAudioGMS_INTERNAL_SoundInstance_StreamingUpdate(instance);
            }

            if (instance->destroyOnFinish)
            {
                FAudioVoiceState state;
                FAudioSourceVoice_GetState(instance->handle, &state, FAUDIO_VOICE_NOSAMPLESPLAYED);

                if (state.BuffersQueued == 0)
                {
                    FAudioGMS_INTERNAL_SoundInstance_Destroy(instance);
                }
            }
        }
    }
}

void FAudioGMS_Destroy()
{
    uint32_t i = 0;

    for (i = 0; i < device->soundInstanceCount; i += 1)
    {
        FAudioGMS_INTERNAL_SoundInstance_Destroy(device->soundInstances[i]);
    }

    for (i = 0; i < device->staticSoundCount; i += 1)
    {
        FAudioGMS_INTERNAL_StaticSound_Destroy(device->staticSounds[i]);
    }

    FAudio_Release(device->handle);
    SDL_free(device);
    device = NULL;

    Log("FAudio cleaned up successfully!");
}