/*

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

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 A sample model object. A base abstract class (ATDesktopEntity) implements caching of a file URL. One concrete subclass implements the ability to have an array of children (ATDesktopFolderEntity). Another (ATDesktopImageEntity) represents an image suitable for the desktop wallpaper.

 */

@import Cocoa;

// KVO key path for thumbnail.

extern NSString *const ATEntityPropertyNamedThumbnailImage;

// Base abstract class that wraps a file system URL 

@interface ATDesktopEntity : NSObject <NSPasteboardWriting, NSPasteboardReading>

- (instancetype)initWithFileURL:(NSURL *)fileURL NS_DESIGNATED_INITIALIZER;

@property (strong) NSString *title;

@property (strong) NSURL *fileURL;

+ (ATDesktopEntity *)entityForURL:(NSURL *)url;

@end

#pragma mark -

// Concrete subclass of ATDesktopEntity that loads children from a folder

@interface ATDesktopFolderEntity : ATDesktopEntity

@property(strong) NSMutableArray *children;

@end

#pragma mark -

// Concrete subclass of ATDesktopEntity that adds support for loading an image at the given URL and stores a fillColor property

@interface ATDesktopImageEntity : ATDesktopEntity

@property (strong) NSColor *fillColor;

@property (copy) NSString *fillColorName;

// Access to the image. This property can be observed to find out when it changes and is fully loaded.

@property (strong) NSImage *image;

@property (readonly, strong, nonatomic) NSImage *thumbnailImage;

// Asynchronously loads the image (if not already loaded). A KVO notification is sent out when the image is loaded.

- (void)loadImage;

// A nil image isn't loaded (or couldn't be loaded).

// An image that is in the process of loading has imageLoading set to YES.

@property (readonly) BOOL imageLoading;

@end