/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 The SequencerViewController class provides specific UI Elements to interact with the AVAudioSequencer object. The sequencer is not directly part of AVAudioEngine.

                 UISlider *sequencerPlaybackRateSlider;  Set the playback rate for the sequencer

                 UISlider *sequencerPositionSlider;      Set the current position for the current track

                 UIButton *sequencerPlayButton;          Toggle the state of the sequencer

*/

#import "SequencerViewController.h"

@interface SequencerViewController () {

    dispatch_source_t _sequencerPositionSliderUpdateTimer;

}

@property (unsafe_unretained, nonatomic) IBOutlet UISlider *sequencerPlaybackRateSlider;

@property (unsafe_unretained, nonatomic) IBOutlet UISlider *sequencerPositionSlider;

@property (unsafe_unretained, nonatomic) IBOutlet UIButton *sequencerPlayButton;

@end

@implementation SequencerViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view.

}

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

- (void)updateUIElements

{

    self.sequencerPositionSlider.value = 0;

    [self.sequencerPositionSlider setContinuous:NO];

    self.sequencerPlaybackRateSlider.value = self.audioEngine.sequencerPlaybackRate;

    self.sequencerPlayButton.layer.cornerRadius = 5;

    [self styleButton: _sequencerPlayButton isPlaying: self.audioEngine.sequencerIsPlaying];

}

- (void)startTimer

{

    _sequencerPositionSliderUpdateTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatch_get_main_queue());

    if (_sequencerPositionSliderUpdateTimer) {

        dispatch_source_set_timer(_sequencerPositionSliderUpdateTimer, DISPATCH_TIME_NOW, 0.1 * NSEC_PER_SEC, 0);

        dispatch_source_set_event_handler(_sequencerPositionSliderUpdateTimer, ^{

            _sequencerPositionSlider.value = self.audioEngine.sequencerCurrentPosition;

        });

        dispatch_resume(_sequencerPositionSliderUpdateTimer);

    }

}

- (void)stopTimer

{

    if (_sequencerPositionSliderUpdateTimer) {

        dispatch_source_cancel(_sequencerPositionSliderUpdateTimer);

        _sequencerPositionSliderUpdateTimer = nil;

    }

}

- (IBAction)togglePlaySequencer:(id)sender {

    [self.audioEngine toggleSequencer];

    [self styleButton: _sequencerPlayButton isPlaying: self.audioEngine.sequencerIsPlaying];

    if (self.audioEngine.sequencerIsPlaying) {

        [self startTimer];

    } else {

        [self stopTimer];

    }

}

- (IBAction)sequencerPositionSliderTouchDown:(id)sender {

    if (self.audioEngine.sequencerIsPlaying) {

        [self stopTimer];

    }

}

- (IBAction)sequencerPositionSliderValueChanged:(id)sender {

    if (self.audioEngine.sequencerIsPlaying) {

        self.audioEngine.sequencerCurrentPosition = ((UISlider *)sender).value;

        [self startTimer];

    }

}

- (IBAction)setSequencerPlaybackRate:(id)sender {

    self.audioEngine.sequencerPlaybackRate = ((UISlider *)sender).value;

}

@end