//
//  MPPlayableContentDataSource.h
//  MobileMusicPlayer
//
//  Copyright (c) 2013 Apple Inc. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <MediaPlayer/MediaPlayerDefines.h>

NS_ASSUME_NONNULL_BEGIN

@class MPContentItem;

/// MPPlayableContentDataSource is a protocol that application objects conform to
/// if they want to support external media players, such as vehicle head units.
/// Data sources are responsible for providing metadata about your media to these
/// systems in a meaningful way, so that features like user interfaces and play
/// queues can be setup automatically.
__TVOS_PROHIBITED
@protocol MPPlayableContentDataSource <NSObject>
@optional

/// Tells the data source to begin loading content items that are children of the
/// item specified by indexPath. This is provided so that applications can begin
/// asynchronous batched loading of content before MediaPlayer begins asking for
/// content items to display.
/// Client applications should always call the completion handler after loading
/// has finished, if this method is implemented.
- (void)beginLoadingChildItemsAtIndexPath:(NSIndexPath *)indexPath completionHandler:(void(^)(NSError * __nullable))completionHandler;

/// Tells MediaPlayer whether the content provided by the data source supports
/// playback progress as a property of its metadata.
/// If this method is not implemented, MediaPlayer will assume that progress is
/// not supported for any content items.
- (BOOL)childItemsDisplayPlaybackProgressAtIndexPath:(NSIndexPath *)indexPath;

@required
/// Returns the number of child nodes at the specified index path. In a virtual
/// filesystem, this would be the number of files in a specific folder. An empty
/// index path represents the root node.
- (NSInteger)numberOfChildItemsAtIndexPath:(NSIndexPath *)indexPath;

/// Returns the content item at the specified index path. If the content item is
/// mutated after returning, its updated contents will be sent to MediaPlayer.
- (nullable MPContentItem *)contentItemAtIndexPath:(NSIndexPath *)indexPath;

@end

NS_ASSUME_NONNULL_END