/*

 Copyright (C) 2016 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 OpenAL-related support functions

 */

#import <OpenAL/al.h>

#import <OpenAL/alc.h>

#import <AudioToolbox/AudioToolbox.h>

#import <AVFoundation/AVAudioSession.h>

typedef ALvoid  AL_APIENTRY (*alBufferDataStaticProcPtr) (const ALint bid, ALenum format, ALvoid* data, ALsizei size, ALsizei freq);

ALvoid  alBufferDataStaticProc(const ALint bid, ALenum format, ALvoid* data, ALsizei size, ALsizei freq)

{

    static  alBufferDataStaticProcPtr   proc = NULL;

    if (proc == NULL) {

        proc = (alBufferDataStaticProcPtr) alcGetProcAddress(NULL, (const ALCchar*) "alBufferDataStatic");

    }

    if (proc)

        proc(bid, format, data, size, freq);

    return;

}

void* MyGetOpenALAudioData(CFURLRef inFileURL, ALsizei *outDataSize, ALenum *outDataFormat, ALsizei*    outSampleRate)

{

    OSStatus                        err = noErr;    

    UInt64                          fileDataSize = 0;

    AudioStreamBasicDescription     theFileFormat;

    UInt32                          thePropertySize = sizeof(theFileFormat);

    AudioFileID                     afid = 0;

    void*                           theData = NULL;

    // Open a file with ExtAudioFileOpen()

    err = AudioFileOpenURL(inFileURL, kAudioFileReadPermission, 0, &afid);

    if(err) { printf("MyGetOpenALAudioData: AudioFileOpenURL FAILED, Error = %d\n", (int)err); goto Exit; }

    // Get the audio data format

    err = AudioFileGetProperty(afid, kAudioFilePropertyDataFormat, &thePropertySize, &theFileFormat);

    if(err) { printf("MyGetOpenALAudioData: AudioFileGetProperty(kAudioFileProperty_DataFormat) FAILED, Error = %d\n", (int)err); goto Exit; }

    if (theFileFormat.mChannelsPerFrame > 2)  { 

        printf("MyGetOpenALAudioData - Unsupported Format, channel count is greater than stereo\n"); goto Exit;

    }

    if ((theFileFormat.mFormatID != kAudioFormatLinearPCM) || (!TestAudioFormatNativeEndian(theFileFormat))) { 

        printf("MyGetOpenALAudioData - Unsupported Format, must be little-endian PCM\n"); goto Exit;

    }

    if ((theFileFormat.mBitsPerChannel != 8) && (theFileFormat.mBitsPerChannel != 16)) { 

        printf("MyGetOpenALAudioData - Unsupported Format, must be 8 or 16 bit PCM\n"); goto Exit;

    }

    thePropertySize = sizeof(fileDataSize);

    err = AudioFileGetProperty(afid, kAudioFilePropertyAudioDataByteCount, &thePropertySize, &fileDataSize);

    if(err) { printf("MyGetOpenALAudioData: AudioFileGetProperty(kAudioFilePropertyAudioDataByteCount) FAILED, Error = %d\n", (int)err); goto Exit; }

    // Read all the data into memory

    UInt32      dataSize = (UInt32)fileDataSize;

    theData = malloc(dataSize);

    if (theData)

    {

        AudioFileReadBytes(afid, false, 0, &dataSize, theData);

        if(err == noErr)

        {

            // success

            *outDataSize = (ALsizei)dataSize;

            *outDataFormat = (theFileFormat.mChannelsPerFrame > 1) ? AL_FORMAT_STEREO16 : AL_FORMAT_MONO16;

            *outSampleRate = (ALsizei)theFileFormat.mSampleRate;

        }

        else 

        { 

            // failure

            free (theData);

            theData = NULL; // make sure to return NULL

            printf("MyGetOpenALAudioData: ExtAudioFileRead FAILED, Error = %d\n", (int)err); goto Exit;

        }   

    }

Exit:

    // Dispose the ExtAudioFileRef, it is no longer needed

    if (afid) AudioFileClose(afid);

    return theData;

}

void TeardownOpenAL()

{

    ALCcontext  *context = NULL;

    ALCdevice   *device = NULL;

    ALuint      returnedName;

    // Delete the Sources

    alDeleteSources(1, &returnedName);

    // Delete the Buffers

    alDeleteBuffers(1, &returnedName);

    //Get active context

    context = alcGetCurrentContext();

    //Get device for active context

    device = alcGetContextsDevice(context);

    //Release context

    alcDestroyContext(context);

    //Close device

    alcCloseDevice(device);

}