/*

     File: APLDocument.m

 Abstract: The players document class. It sets up four AVPlaybackViews each of which handle their own AVPlayers.It manages adjusting the playback rate, enables and disables UI elements as appropriate, sets up a time observer for updating the current time (which the UI's time slider is bound to).

  Version: 1.0

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 */

#import "APLDocument.h"

#import "APLPlaybackView.h"

NSString* const AVMSDMouseDownNotification = @"AVMSDMouseDownNotification";

NSString* const AVMSDMouseUpNotification = @"AVMSDMouseUpNotification";

#pragma mark - Timer slider

@interface TimeSliderCell : NSSliderCell

@end

@interface TimeSlider : NSSlider

@end

@implementation TimeSliderCell

- (void)stopTracking:(NSPoint)lastPoint at:(NSPoint)stopPoint inView:(NSView *)controlView mouseIsUp:(BOOL)flag

{

    if (flag) {

        [[NSNotificationCenter defaultCenter] postNotificationName:AVMSDMouseUpNotification object:self];

    }

    [super stopTracking:lastPoint at:stopPoint inView:controlView mouseIsUp:flag];

}

@end

@implementation TimeSlider

- (void)mouseDown:(NSEvent *)theEvent

{

    [[NSNotificationCenter defaultCenter] postNotificationName:AVMSDMouseDownNotification object:self];

    [super mouseDown:theEvent];

}

@end

#pragma mark - Document

@interface APLDocument () <AVPlaybackViewEventHandlingDelegate>

{

    NSInteger       _currentlyActiveViewIndex;

    NSArray        *_playbackViewsArray;

}

@property double            currentTime;

@property (readonly) double duration;

@property float             playRateToRestore;

@property id                timeObserverToken;

@property (weak) IBOutlet APLPlaybackView *bottomLeftView;

@property (weak) IBOutlet APLPlaybackView *bottomRightView;

@property (weak) IBOutlet APLPlaybackView *topLeftView;

@property (weak) IBOutlet APLPlaybackView *topRightView;

@property (weak) IBOutlet TimeSlider *timeSlider;

@end

@implementation APLDocument

- (NSString *)windowNibName

{

    return @"APLDocument";

}

- (void)windowControllerDidLoadNib:(NSWindowController *)aController

{

    [super windowControllerDidLoadNib:aController];

    _playbackViewsArray = @[self.bottomLeftView, self.bottomRightView, self.topLeftView, self.topRightView];

    for (APLPlaybackView *playbackView in _playbackViewsArray) {

            playbackView.delegate = self;

            [playbackView setupPlaybackUsingURL:self.fileURL];

    }

    [self addTimeObserverToPlayer];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(beginScrubbing:)

                                                 name:AVMSDMouseDownNotification

                                               object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(endScrubbing:)

                                                 name:AVMSDMouseUpNotification

                                               object:nil];

}

- (BOOL)readFromURL:(NSURL *)absoluteURL ofType:(NSString *)typeName error:(NSError **)outError

{

    return YES;

}

- (void)close

{

    [self.topLeftView.player removeTimeObserver:_timeObserverToken];

    [super close];

}

- (void)dealloc

{

    [[NSNotificationCenter defaultCenter] removeObserver:self name:AVMSDMouseUpNotification object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self name:AVMSDMouseDownNotification object:nil];

}

- (void)prerollPlayersAndStartPlayback

{

    dispatch_group_t dispatchGroup = dispatch_group_create();

    for (APLPlaybackView *view in _playbackViewsArray) {

        dispatch_group_enter(dispatchGroup);

        [view.player prerollAtRate:1.0 completionHandler:^(BOOL finished){

            if (!finished) {

                printf("Prerolling at rate 1.0 interrupted\n");

            }

            dispatch_group_leave(dispatchGroup);

        }];

    }

    // Wait until all 4 players complete preroll

    dispatch_group_notify(dispatchGroup, dispatch_get_main_queue(), ^(){

        // Start playback when host time is 0.01 sec from now

        CMTime hostTimeNow = CMClockGetTime(CMClockGetHostTimeClock());

        CMTime hostTimeDelta = CMTimeMakeWithSeconds(0.01, hostTimeNow.timescale);

        for (APLPlaybackView *view in _playbackViewsArray) { // Start playback for all views

            [view.player setRate:1.0 time:CMTimeMakeWithSeconds([self currentTime], 1) atHostTime:CMTimeAdd(hostTimeNow, hostTimeDelta)];

        }

    });

}

- (void)addTimeObserverToPlayer

{

    if (_timeObserverToken)

        return;

    __weak APLDocument *weakSelf = self;

    _timeObserverToken = [self.topLeftView.player addPeriodicTimeObserverForInterval:CMTimeMakeWithSeconds(1, 2) queue:dispatch_get_main_queue() usingBlock:

                          ^(CMTime time) {

                              [weakSelf syncScrubber];

                          }];

}

- (void)removeTimeObserverFromPlayer

{

    if (_timeObserverToken) {

        [self.topLeftView.player removeTimeObserver:_timeObserverToken];

        _timeObserverToken = nil;

    }

}

#pragma mark - AVPlaybackViewEventHandlingDelegate

- (void)playbackViewDidTogglePlayPause:(APLPlaybackView *)playbackView

{

    if ([[self.bottomLeftView player] rate] != 1.f)

    {

        [self prerollPlayersAndStartPlayback];

    }

    else

    {

        for (APLPlaybackView *subView in _playbackViewsArray) {

            [subView.player pause];

        }

    }

}

- (void)playbackViewDidToggleActiveAudio:(APLPlaybackView *)playbackView

{

    // Mute the audio on the previously active video

    APLPlaybackView *currentView = _playbackViewsArray[_currentlyActiveViewIndex++];

    currentView.player.muted = YES;

    // _currentlyActiveViewIndex keeps track of the view that is currently active

    if (_currentlyActiveViewIndex > 3) { // 0 -> 1 -> 2 -> 3 -> 0

        _currentlyActiveViewIndex = 0;

    }

    // Unmute the audio on the currently active video

    currentView = _playbackViewsArray[_currentlyActiveViewIndex];

    currentView.player.muted = NO;

}

- (void)playbackViewWillBeginPlaying:(APLPlaybackView *)playbackView

{

    // Audio is active only for the top-left view by default

    _currentlyActiveViewIndex = 1;

    [self playbackViewDidToggleActiveAudio:playbackView];

}

- (void)playbackViewDidMouseDown:(APLPlaybackView *)playbackView

{

    // Unmute the audio on the view on which mouseDown event occurred

    APLPlaybackView *currentlyActiveView = [_playbackViewsArray objectAtIndex:_currentlyActiveViewIndex];

    [currentlyActiveView.player setMuted:YES];

    _currentlyActiveViewIndex = [_playbackViewsArray indexOfObject:playbackView];

    [playbackView.player setMuted:NO];

}

#pragma mark - Scrubbing Utilities

- (void)beginScrubbing:(NSNotification *)notification

{

    _playRateToRestore = self.topLeftView.player.rate;

    [self removeTimeObserverFromPlayer];

    for (APLPlaybackView *subView in _playbackViewsArray) {

        subView.player.rate = 0.0;

    }

}

- (void)endScrubbing:(NSNotification *)notification

{

    if (_playRateToRestore != 0.0) {

        [self prerollPlayersAndStartPlayback];

    }

    [self addTimeObserverToPlayer];

}

- (void)syncScrubber

{

    double time = CMTimeGetSeconds(self.topLeftView.player.currentTime);

    self.timeSlider.doubleValue = time;

}

+ (NSSet *)keyPathsForValuesAffectingDuration

{

    return [NSSet setWithObjects:@"topLeftView.player.currentItem", @"topLeftView.player.currentItem.status", nil];

}

- (double)duration

{

    AVPlayerItem *playerItem = self.topLeftView.player.currentItem;

    if (playerItem.status == AVPlayerItemStatusReadyToPlay)

        return CMTimeGetSeconds(playerItem.asset.duration);

    else

        return 0.f;

}

- (double)currentTime

{

    return CMTimeGetSeconds(self.topLeftView.player.currentTime);

}

- (void)setCurrentTime:(double)time

{

    for (APLPlaybackView *subView in _playbackViewsArray) {

        [subView.player seekToTime:CMTimeMakeWithSeconds(time, 1) toleranceBefore:kCMTimeZero toleranceAfter:kCMTimeZero];

    }

}

@end