//  MXAudioPlayerFadeOperation.m

//

//  Created by Andrew Mackenzie-Ross on 30/11/10.

//  mackross.net.

//

#import "MXAudioPlayerFadeOperation.h"

#import <AVFoundation/AVFoundation.h>

#define SKVolumeChangesPerSecond 15

@interface MXAudioPlayerFadeOperation ()

@property (nonatomic, strong, readwrite) AVAudioPlayer *audioPlayer;

- (void)beginFadeOperation;

- (void)finishFadeOperation;

@end

@implementation MXAudioPlayerFadeOperation

#pragma mark -

#pragma mark Properties

@synthesize audioPlayer = _audioPlayer;

@synthesize fadeDuration = _fadeDuration;

@synthesize finishVolume = _finishVolume;

@synthesize playBeforeFade = _playBeforeFade;

@synthesize pauseAfterFade = _pauseAfterFade;

@synthesize stopAfterFade = _stopAfterFade;

@synthesize delay = _delay;

#pragma mark -

#pragma mark Accessors

- (AVAudioPlayer *)audioPlayer {

  AVAudioPlayer *result;

  @synchronized(self) {

    result = _audioPlayer;

  }

  return result;

}

- (void)setAudioPlayer:(AVAudioPlayer *)anAudioPlayer {

  @synchronized(self) {

    if (_audioPlayer != anAudioPlayer) {

      _audioPlayer = anAudioPlayer;

    }

  }

}

#pragma mark -

#pragma mark NSOperation

- (id)initFadeWithAudioPlayer:(AVAudioPlayer*)player toVolume:(float)volume overDuration:(NSTimeInterval)duration withDelay:(NSTimeInterval)timeDelay {

  if ((self = [super init])) {

    self.audioPlayer = player;

    [player prepareToPlay];

    _fadeDuration = duration;

    _finishVolume = volume;

    _playBeforeFade = YES;

    _stopAfterFade = NO;

    _pauseAfterFade = (volume == 0.0) ? YES : NO;

    _delay = timeDelay;

  }

  return self;

}

- (id)initFadeWithAudioPlayer:(AVAudioPlayer*)player toVolume:(float)volume overDuration:(NSTimeInterval)duration {

  return [self initFadeWithAudioPlayer:player toVolume:volume overDuration:duration withDelay:0.0];

}

- (id)initFadeWithAudioPlayer:(AVAudioPlayer*)player toVolume:(float)volume {

  return [self initFadeWithAudioPlayer:player toVolume:volume overDuration:1.0];

}

- (id)initFadeWithAudioPlayer:(AVAudioPlayer*)player {

  return [self initFadeWithAudioPlayer:player toVolume:0.0];

}

- (id) init {

  ALog(@"Failed to init class (%@) with AVAudioPlayer instance, use initFadeWithAudioPlayer:",[self class]);

  return nil;

}

- (void)main {

  @autoreleasepool {

  [NSThread sleepForTimeInterval:_delay];

  if ([self.audioPlayer isKindOfClass:[AVAudioPlayer class]]) {

    [self beginFadeOperation];

  }

  else {

    ALog(@"AudioPlayerFadeOperation began with invalid AVAudioPlayer");

  }

  }

}

- (void)beginFadeOperation {

  if (![self.audioPlayer isPlaying] && _playBeforeFade) [self.audioPlayer play];

  if (_fadeDuration != 0.0) {

    NSTimeInterval sleepInterval = (1.0 / SKVolumeChangesPerSecond);

    NSTimeInterval startTime = [[NSDate date] timeIntervalSinceReferenceDate];

    NSTimeInterval now = startTime;

    float startVolume = [self.audioPlayer volume];

    while (now < (startTime + _fadeDuration)) {

      float ratioOfFadeCompleted = (now - startTime)/_fadeDuration;

      float volume = (_finishVolume * ratioOfFadeCompleted) + (startVolume * (1-ratioOfFadeCompleted));

      [self.audioPlayer setVolume:volume];

      [NSThread sleepForTimeInterval:sleepInterval];

      now = [[NSDate date] timeIntervalSinceReferenceDate];

    }

    [self.audioPlayer setVolume:_finishVolume];

    [self finishFadeOperation];

  }

  else {

    [self.audioPlayer setVolume:_finishVolume];

    [self finishFadeOperation];

  }

}

- (void)finishFadeOperation {

  if ([self.audioPlayer isPlaying] && _pauseAfterFade) [self.audioPlayer pause];

  if ([self.audioPlayer isPlaying] && _stopAfterFade) [self.audioPlayer stop];

}

@end