/*

     File: APLPlaybackView.m

 Abstract: The player view class. It sets up AVPlayer and AVPlayerLayer. It defines a protocol for its delegate to receive all user interactions like keyboard hits (spacebar to play/pause and tab to toggle active audio selection) and mouse down events (to display a pop-up menu with list of available media selection options).

  Version: 1.0

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 */

#import "APLPlaybackView.h"

#import <CoreMedia/CMAudioDeviceClock.h>

static void *AVMSPlayerItemTracksContext = &AVMSPlayerItemTracksContext;

@interface APLPlaybackView ()

{

    int                 audibleIndex;

    int                 legibleIndex;

    NSMutableArray      *audioOptions;

    NSMutableArray      *legibleOptions;

    id                  _notificationToken;

    BOOL                _playbackDidBegin;

    NSInteger           _currentlySelectedAudioItem;

    NSInteger           _currentlySelectedLegibleItem;

}

@property NSMenu        *optionsMenu;

@property AVAsset       *asset;

@end

@implementation APLPlaybackView

- (id)initWithFrame:(NSRect)frameRect

{

    self = [super initWithFrame:frameRect];

    if (self) {

        CALayer *layer = [CALayer layer];

        self.layer = layer;

        self.wantsLayer = YES;

        self.layer.backgroundColor = CGColorGetConstantColor(kCGColorBlack);

        // Create the AVPlayer, add rate and status observers

        self.player = [[AVPlayer alloc] init];

        self.player.actionAtItemEnd = AVPlayerActionAtItemEndNone;

        [self addObserver:self forKeyPath:@"player.currentItem.tracks" options:NSKeyValueObservingOptionNew context:AVMSPlayerItemTracksContext];

        audioOptions = [NSMutableArray array];

        legibleOptions = [NSMutableArray array];

        // Add the default audio device clock as the players clock

        [self setMasterClockOnPlayerToDefaultAudioDeviceClock];

        _playbackDidBegin = NO;

    }

    return self;

}

- (void)setMasterClockOnPlayerToDefaultAudioDeviceClock

{

    CMClockRef audioDeviceClock = NULL;

    AudioDeviceID defaultAudioDevice = kAudioObjectUnknown;

    UInt32 size = 0;

    OSStatus audioErr;

    AudioObjectPropertyAddress propAddress = {

                                                kAudioHardwarePropertyDefaultOutputDevice,

                                                kAudioObjectPropertyScopeGlobal,

                                                kAudioObjectPropertyElementMaster };

    size = sizeof( defaultAudioDevice );

    audioErr = AudioObjectGetPropertyData(

                                          kAudioObjectSystemObject,     //AudioObjectID                     inObjectID,

                                          &propAddress,                 //const AudioObjectPropertyAddress* inAddress,

                                          0,                            //UInt32                            inQualifierDataSize,

                                          NULL,                         //const void*                       inQualifierData,

                                          &size,                        //UInt32*                           ioDataSize,

                                          (void *)&defaultAudioDevice); //void*                             outData)

    if (defaultAudioDevice != kAudioObjectUnknown) {

        CMAudioDeviceClockCreateFromAudioDeviceID(kCFAllocatorDefault, defaultAudioDevice, &audioDeviceClock);

    }

    self.player.masterClock = audioDeviceClock;

    if (audioDeviceClock) {

        CFRelease(audioDeviceClock);

    }

}

- (void)addDidPlayToEndTimeNotificationForPlayerItem:(AVPlayerItem *)item

{

    if (_notificationToken)

        _notificationToken = nil;

    /*

     Setting actionAtItemEnd to None prevents the movie from getting paused at item end. A very simplistic, and not gapless, looped playback.

     */

    _player.actionAtItemEnd = AVPlayerActionAtItemEndNone;

    _notificationToken = [[NSNotificationCenter defaultCenter] addObserverForName:AVPlayerItemDidPlayToEndTimeNotification object:item queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *note) {

        // Simple item playback rewind.

        [_player.currentItem seekToTime:kCMTimeZero];

    }];

}

- (void)setupPlaybackUsingURL:(NSURL *)url

{

    // Create an asset with our URL, asychronously load its tracks, its duration, and whether it's playable or protected.

    // When that loading is complete, configure a player to play the asset.

    AVURLAsset *asset = [AVAsset assetWithURL:url];

    self.asset = asset;

    NSArray *assetKeysToLoadAndTest = @[@"playable", @"hasProtectedContent", @"duration", @"availableMediaCharacteristicsWithMediaSelectionOptions"];

    [asset loadValuesAsynchronouslyForKeys:assetKeysToLoadAndTest completionHandler:^(void) {

        // The asset invokes its completion handler on an arbitrary queue when loading is complete.

        // Because we want to access our AVPlayer in our ensuing set-up, we must dispatch our handler to the main queue.

        dispatch_async(dispatch_get_main_queue(), ^(void) {

            [self setUpPlaybackOfAsset:asset withKeys:assetKeysToLoadAndTest];

        });

    }];

}

- (void)setUpPlaybackOfAsset:(AVAsset *)asset withKeys:(NSArray *)keys

{

    // This method is called when the AVAsset for our URL has completed the loading of the values of the specified array of keys.

    // We set up playback of the asset here.

    // First test whether the values of each of the keys we need have been successfully loaded.

    for (NSString *key in keys) {

        NSError *error;

        if ([asset statusOfValueForKey:key error:&error] == AVKeyValueStatusFailed) {

            NSLog(@"Key value loading failed for key: %@ with error: %@", key, error);

            return;

        }

    }

    if (!asset.playable || asset.hasProtectedContent) {

        NSLog(@"Asset is not playable");

        return;

    }

    // We can play this asset. Create a new AVPlayerItem and make it our player's current item.

    AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:asset];

    [self.player replaceCurrentItemWithPlayerItem:playerItem];

    [self addDidPlayToEndTimeNotificationForPlayerItem:playerItem];

}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

{

    if (context == AVMSPlayerItemTracksContext) {

        BOOL foundVideoTrack = NO;

        for (AVPlayerItemTrack *playerItemTrack in self.player.currentItem.tracks) {

            if ([playerItemTrack.assetTrack.mediaType isEqualToString:AVMediaTypeVideo]) {

                foundVideoTrack = YES;

                break;

            }

        }

        if (self.playerLayer == nil && foundVideoTrack) {

            self.playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];

            self.playerLayer.frame = self.layer.bounds;

            self.playerLayer.autoresizingMask = kCALayerWidthSizable | kCALayerHeightSizable;

            [self.layer addSublayer:self.playerLayer];

            self.playerLayer.hidden = NO;

            if (!_playbackDidBegin) {

                self.player.muted = YES;

                [self.delegate playbackViewWillBeginPlaying:self];

                _playbackDidBegin = YES;

            }

        }

    }

    else {

        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];

    }

}

- (void)viewWillMoveToSuperview:(NSView *)newSuperview

{

    if (!newSuperview) {

        [self.player pause];

        [self removeObserver:self forKeyPath:@"player.currentItem.tracks"];

        self.player = nil;

        self.delegate = nil;

        self.playerLayer = nil;

        self.asset = nil;

        self.optionsMenu = nil;

    }

}

- (void)dealloc

{

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

}

- (void)respondToMediaOptionSelection:(NSMenuItem *)selectedItem

{   

    NSInteger selectedItemIndex = [self.optionsMenu indexOfItem:selectedItem];

    if ( selectedItemIndex < legibleIndex) {

        // Audio option selected

        [self.player.currentItem selectMediaOption:audioOptions[(selectedItemIndex - audibleIndex - 1)] inMediaSelectionGroup:[self.asset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicAudible]];

        _currentlySelectedAudioItem = selectedItemIndex;

    } else {

        // Legible option selected

        [self.player.currentItem selectMediaOption:legibleOptions[(selectedItemIndex - legibleIndex - 1)] inMediaSelectionGroup:[self.asset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicLegible]];

        _currentlySelectedLegibleItem = selectedItemIndex;

    }

    // Update the menu item selection

    for (NSMenuItem *item in [self.optionsMenu itemArray]) {

        NSInteger index = [self.optionsMenu indexOfItem:item];

        if (index == _currentlySelectedAudioItem || index == _currentlySelectedLegibleItem) {

            item.state = NSOnState;

        } else {

            item.state = NSOffState;

        }

    }

}

- (void)listMediaSelectionOptionsForCurrentItemWithEvent:(NSEvent *)theEvent

{

    if (!self.optionsMenu) {

        int index = 0;

        // Audible Options

        AVMediaSelectionGroup *audibleGroup = [self.asset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicAudible];

        self.optionsMenu = [[NSMenu alloc] initWithTitle:@"Contextual Menu"];

        if ([[audibleGroup options] count] > 0) {

            NSArray *filteredAudioOptions = [AVMediaSelectionGroup mediaSelectionOptionsFromArray:[audibleGroup options] withMediaCharacteristics:@[AVMediaCharacteristicIsMainProgramContent]];

            audibleIndex = index;

            [self.optionsMenu insertItemWithTitle:@"Audio" action:nil keyEquivalent:@"" atIndex:index++];

            for (AVMediaSelectionOption *thisOption in filteredAudioOptions) {

                [self.optionsMenu insertItemWithTitle:[thisOption displayName] action:@selector(respondToMediaOptionSelection:) keyEquivalent:@"" atIndex:index++];

                [audioOptions addObject:thisOption];

            }

        }

        // Legible Options

        AVMediaSelectionGroup *legibleGroup = [self.asset mediaSelectionGroupForMediaCharacteristic:AVMediaCharacteristicLegible];

        if ([[legibleGroup options] count] > 0) {

            NSArray *filteredSubtitleOptions = [AVMediaSelectionGroup mediaSelectionOptionsFromArray:[legibleGroup options] withoutMediaCharacteristics:@[AVMediaCharacteristicContainsOnlyForcedSubtitles, AVMediaCharacteristicIsAuxiliaryContent]];

            [self.optionsMenu insertItem:[NSMenuItem separatorItem] atIndex:index++];

            legibleIndex = index;

            [self.optionsMenu insertItemWithTitle:@"Subtitles" action:nil keyEquivalent:@"" atIndex:index++];

            for (AVMediaSelectionOption *thisOption in filteredSubtitleOptions) {

                [self.optionsMenu insertItemWithTitle:[thisOption displayName] action:@selector(respondToMediaOptionSelection:) keyEquivalent:@"" atIndex:index++];

                [legibleOptions addObject:thisOption];

            }

        }

    }

    [NSMenu popUpContextMenu:self.optionsMenu withEvent:theEvent forView:self];

}

- (void)mouseDown:(NSEvent *)theEvent

{   

    [self listMediaSelectionOptionsForCurrentItemWithEvent:theEvent];

    // Inform the delegate that the current view's audio has to be active

    [self.delegate playbackViewDidMouseDown:self];

    [super mouseDown:theEvent];

}

- (void)keyDown:(NSEvent *)theEvent

{

    if ([theEvent.characters isEqualToString:@" "]) { // Space bar is used to toggle play pause

        [self.delegate playbackViewDidTogglePlayPause:self];

    } else if ([theEvent.characters isEqualToString:@"  "]) { // Tab is used to switch between active view for audio

        [self.delegate playbackViewDidToggleActiveAudio:self];

    }

    [super keyDown:theEvent];

}

- (BOOL)acceptsFirstResponder

{

    return YES;

}

- (void)drawFocusRingMask

{

    NSRectFill([self bounds]);

}

- (NSRect)focusRingMaskBounds

{

    return [self bounds];

}

@end