/*

    File: MyOpenALSupport.c
Abstract: OpenAL-related support functions
 Version: 1.4

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*/

#include "MyOpenALSupport.h"

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;	
	SInt64							theFileLengthInFrames = 0;
	AudioStreamBasicDescription		theFileFormat;
	UInt32							thePropertySize = sizeof(theFileFormat);
	ExtAudioFileRef					extRef = NULL;
	void*							theData = NULL;
	AudioStreamBasicDescription		theOutputFormat;

    do {
        // Open a file with ExtAudioFileOpen()
        err = ExtAudioFileOpenURL(inFileURL, &extRef);
        if(err) { printf("MyGetOpenALAudioData: ExtAudioFileOpenURL FAILED, Error = %ld\n", err); break; }

        // Get the audio data format
        err = ExtAudioFileGetProperty(extRef, kExtAudioFileProperty_FileDataFormat, &thePropertySize, &theFileFormat);
        if(err) { printf("MyGetOpenALAudioData: ExtAudioFileGetProperty(kExtAudioFileProperty_FileDataFormat) FAILED, Error = %ld\n", err); break; }
        if (theFileFormat.mChannelsPerFrame > 2)  { printf("MyGetOpenALAudioData - Unsupported Format, channel count is greater than stereo\n"); break;}

        // Set the client format to 16 bit signed integer (native-endian) data
        // Maintain the channel count and sample rate of the original source format
        theOutputFormat.mSampleRate = theFileFormat.mSampleRate;
        theOutputFormat.mChannelsPerFrame = theFileFormat.mChannelsPerFrame;

        theOutputFormat.mFormatID = kAudioFormatLinearPCM;
        theOutputFormat.mBytesPerPacket = 2 * theOutputFormat.mChannelsPerFrame;
        theOutputFormat.mFramesPerPacket = 1;
        theOutputFormat.mBytesPerFrame = 2 * theOutputFormat.mChannelsPerFrame;
        theOutputFormat.mBitsPerChannel = 16;
        theOutputFormat.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger;

        // Set the desired client (output) data format
        err = ExtAudioFileSetProperty(extRef, kExtAudioFileProperty_ClientDataFormat, sizeof(theOutputFormat), &theOutputFormat);
        if(err) { printf("MyGetOpenALAudioData: ExtAudioFileSetProperty(kExtAudioFileProperty_ClientDataFormat) FAILED, Error = %ld\n", err); break; }

        // Get the total frame count
        thePropertySize = sizeof(theFileLengthInFrames);
        err = ExtAudioFileGetProperty(extRef, kExtAudioFileProperty_FileLengthFrames, &thePropertySize, &theFileLengthInFrames);
        if(err) { printf("MyGetOpenALAudioData: ExtAudioFileGetProperty(kExtAudioFileProperty_FileLengthFrames) FAILED, Error = %ld\n", err); break; }

        // Read all the data into memory
        UInt32		dataSize = theFileLengthInFrames * theOutputFormat.mBytesPerFrame;;
        theData = malloc(dataSize);
        if (theData)
        {
            AudioBufferList		theDataBuffer;
            theDataBuffer.mNumberBuffers = 1;
            theDataBuffer.mBuffers[0].mDataByteSize = dataSize;
            theDataBuffer.mBuffers[0].mNumberChannels = theOutputFormat.mChannelsPerFrame;
            theDataBuffer.mBuffers[0].mData = theData;

            // Read the data into an AudioBufferList
            err = ExtAudioFileRead(extRef, (UInt32*)&theFileLengthInFrames, &theDataBuffer);
            if(err == noErr)
            {
                // success
                *outDataSize = (ALsizei)dataSize;
                *outDataFormat = (theOutputFormat.mChannelsPerFrame > 1) ? AL_FORMAT_STEREO16 : AL_FORMAT_MONO16;
                *outSampleRate = (ALsizei)theOutputFormat.mSampleRate;
            }
            else
            {
                // failure
                free (theData);
                theData = NULL; // make sure to return NULL
                printf("MyGetOpenALAudioData: ExtAudioFileRead FAILED, Error = %ld\n", err); break;
            }
        }
    } while(0);
	
	// Dispose the ExtAudioFileRef, it is no longer needed
	if (extRef) ExtAudioFileDispose(extRef);
	return theData;
}

