//
//  MAAudioManager.m
//  Minimal Noise
//
//  Created by Carlo Caione on 1/14/12.
//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
//

#import "MAAudioManager.h"

#define BUFFER_SIZE 16384
#define BUFFER_COUNT 3

@implementation MAAudioManager

- (id)initWithBufferCount:(UInt32)bCount
                   ofSize:(UInt32)bSize
{
    if (self = [super init])
    {
        deviceFormat.mSampleRate = 44100;
        deviceFormat.mFormatID = kAudioFormatLinearPCM;
        deviceFormat.mFormatFlags = kLinearPCMFormatFlagIsSignedInteger;
        deviceFormat.mBytesPerPacket = 4;
        deviceFormat.mFramesPerPacket = 1;
        deviceFormat.mBytesPerFrame = 4;
        deviceFormat.mChannelsPerFrame = 2;
        deviceFormat.mBitsPerChannel = 16;
        deviceFormat.mReserved = 0;

        bufferCount = bCount;
        bufferSize = bSize;

        isPlaying = NO;
    }
    return self;
}

- (id)init
{
    return [self initWithBufferCount:BUFFER_COUNT ofSize:BUFFER_SIZE];
}

- (void)start
{
    OSStatus err;

    if(isPlaying == NO)
    {
        err = AudioQueueNewOutput(&deviceFormat,
                                  AudioQueueCallback,
                                  (__bridge void *) self,
                                  nil,
                                  nil,
                                  0,
                                  &audioQueue);
        if(err != noErr)
            NSLog(@"AudioQueueNewOutput() error: %d", err);

        for (int i = 0; i < bufferCount; ++i) {
            AudioQueueBufferRef mBuffer;
            err = AudioQueueAllocateBuffer(audioQueue,
                                           bufferSize,
                                           &mBuffer);
            if (err != noErr){
                NSLog(@"AudioQueueAllocateBuffer() error: %d", err);
                break;
            }
            [noiseGenerator generateNoise:mBuffer];
            err = AudioQueueEnqueueBuffer(audioQueue, mBuffer, 0, NULL);
            if(err != noErr){
                NSLog(@"AudioQueueEnqueueBuffer() error: %d", err);
            }
        }

        err = AudioQueueStart(audioQueue, NULL);
        if (err == noErr){
            isPlaying = YES;
        } else {
            isPlaying = NO;
            NSLog(@"AudioQueueStart() error: %d", err);
        }
    } else {
        NSLog(@"Error: audio is already playing back.");
    }

}

- (void)stop
{
    OSStatus err;

    err = AudioQueueStop(audioQueue, true);
    if(err != noErr) {
        NSLog(@"Error: it is not possible to stop audio.");
    } else {
        isPlaying = NO;
    }
}

- (void)processOutputBuffer:(AudioQueueBufferRef)buffer
{
    OSStatus err;

    if(isPlaying == YES)
    {
        [outputLock lock];
        [noiseGenerator generateNoise:buffer];
        err = AudioQueueEnqueueBuffer(audioQueue, buffer, 0, NULL);
        if(err != noErr){
            NSLog(@"AudioQueueEnqueueBuffer() error: %d", err);
            isPlaying = NO;
        }
        [outputLock unlock];
    } else {
        [self stop];
    }
}

- (void)registerNoiseGenerator:(MANoise *)noiseGen
{
    noiseGenerator = noiseGen;
}

@end

void AudioQueueCallback(void* inUserData,
                        AudioQueueRef inAQ,
                        AudioQueueBufferRef inBuffer)
{
    MAAudioManager *audioMngr = (__bridge MAAudioManager *) inUserData;
    [audioMngr processOutputBuffer:inBuffer];
}