/*

     File: ATDesktopEntity.m

 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.

  Version: 1.1

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*/

#import "ATDesktopEntity.h"

#define THUMBNAIL_HEIGHT 180.0 

// For the purposes of a demo, we intentionally make things slower.

// Turning off the DEMO_MODE define will make things run at normal speed.

#define DEMO_MODE 1

@implementation ATDesktopEntity

@synthesize fileURL = _fileURL;

@dynamic title;

- (id)initWithFileURL:(NSURL *)fileURL {

    self = [super init];

    _fileURL = [fileURL retain];

    return self;

}

- (void)dealloc {

    [_fileURL release];    

    [super dealloc];

}

- (NSString *)title {

    NSString *result;

    if ([self.fileURL getResourceValue:&result forKey:NSURLLocalizedNameKey error:NULL]) {

        return result;

    }

    return nil;

}

@end

// We create an empty category to add property overrides

@interface ATDesktopImageEntity()

// Private read/write access to the thumbnailImage

@property (readwrite, retain) NSImage *thumbnailImage;

@property (readwrite) BOOL imageLoading;

@end

static NSOperationQueue *ATSharedOperationQueue() {

    static NSOperationQueue *_ATSharedOperationQueue = nil;

    if (_ATSharedOperationQueue == nil) {

        _ATSharedOperationQueue = [[NSOperationQueue alloc] init];

        // We limit the concurrency to see things easier for demo purposes.

        // The default value NSOperationQueueDefaultMaxConcurrentOperationCount will yield

        // better results, as it will create more threads, as appropriate for your processor

        //

#if DEMO_MODE

       [_ATSharedOperationQueue setMaxConcurrentOperationCount:1];

#endif

    }

    return _ATSharedOperationQueue;    

}

@implementation ATDesktopImageEntity

- (id)initWithFileURL:(NSURL *)fileURL {

    self = [super initWithFileURL:fileURL];

    // Initialize our color to specific given color for testing purposes

    static NSInteger lastColorIndex = 0;

    NSColorList *colorList = [NSColorList colorListNamed:@"Crayons"];

    NSArray *keys = [colorList allKeys];

    if (lastColorIndex >= keys.count) {

        lastColorIndex = 0;

    }

    _fillColorName = [[keys objectAtIndex:lastColorIndex++] retain];

    _fillColor = [[colorList colorWithKey:_fillColorName] retain];

    return self;

}

- (void)dealloc {

    [_thumbnailImage release];

    [_image release];

    [_fillColor release];

    [_fillColorName release];

    [super dealloc];

}

@synthesize fillColor = _fillColor;

@synthesize fillColorName = _fillColorName;

@synthesize imageLoading = _imageLoading;

@synthesize image = _image;

@synthesize thumbnailImage = _thumbnailImage;

static NSImage *ATThumbnailImageFromImage(NSImage *image) {

    NSSize imageSize = [image size];

    CGFloat imageAspectRatio = imageSize.width / imageSize.height;

    // Create a thumbnail image from this image (this part of the slow operation)

    NSSize thumbnailSize = NSMakeSize(THUMBNAIL_HEIGHT * imageAspectRatio, THUMBNAIL_HEIGHT);

    NSImage *thumbnailImage = [[NSImage alloc] initWithSize:thumbnailSize];

    [thumbnailImage lockFocus];

    [image drawInRect:NSMakeRect(0, 0, thumbnailSize.width, thumbnailSize.height) fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];                

    [thumbnailImage unlockFocus];

#if DEMO_MODE

    // We delay things with an explicit sleep to get things slower for the demo!

    usleep(250000);

#endif

    return [thumbnailImage autorelease];

}

- (void)loadImage {

    @synchronized (self) {

        if (self.image == nil && !self.imageLoading) {

            self.imageLoading = YES;

            // We would have to keep track of the block with an NSBlockOperation, if we wanted to later support cancelling operations that have scrolled offscreen and are no longer needed. That will be left as an exercise to the user.

            [ATSharedOperationQueue() addOperationWithBlock:^(void) {

                NSImage *image = [[NSImage alloc] initWithContentsOfURL:self.fileURL];

                if (image != nil) {

                    NSImage *thumbnailImage = ATThumbnailImageFromImage(image);

                    // We synchronize access to the image/imageLoading pair of variables

                    @synchronized (self) {

                        self.imageLoading = NO;

                        self.image = image;

                        self.thumbnailImage = thumbnailImage;

                    }

                    [image release];

                }

            }];

        }

    }

}

@end

@implementation ATDesktopFolderEntity

- (void)dealloc {

    [_children release];

    [super dealloc];

}

@dynamic children;

- (NSArray *)children {

    NSArray *result = nil;

    // This property is declared as atomic. We use @synchronized to ensure that promise is kept

    @synchronized(self) {

        // It would be nice if this was asycnhronous to avoid any stalls while we look at the file system.

        // A mechanism similar to how the ATDesktopImageEntity loads images could be used here

        //

        if (_children == nil && self.fileURL != nil) {

            NSArray *imageUTIs = [NSImage imageTypes];

            NSError *error = nil;

            // Grab the URLs for the folder and wrap them in our entity objects

            NSArray *urls = [[[NSFileManager defaultManager] contentsOfDirectoryAtURL:self.fileURL includingPropertiesForKeys:[NSArray arrayWithObjects:NSURLLocalizedNameKey, nil] options:NSDirectoryEnumerationSkipsHiddenFiles | NSDirectoryEnumerationSkipsSubdirectoryDescendants error:&error] retain];

            NSMutableArray *newChildren = [[NSMutableArray alloc] initWithCapacity:urls.count];

            for (NSURL *url in urls) {

                // We create folder items or image items, and ignore everything else; all based on the UTI we get from the URL

                NSString *typeIdentifier;

                if ([url getResourceValue:&typeIdentifier forKey:NSURLTypeIdentifierKey error:NULL]) {

                    ATDesktopEntity *entity;

                    if ([imageUTIs containsObject:typeIdentifier]) {

                        entity = [[[ATDesktopImageEntity alloc] initWithFileURL:url] autorelease];

                    } else if ([typeIdentifier isEqualToString:(NSString *)kUTTypeFolder]) {

                        entity = [[[ATDesktopFolderEntity alloc] initWithFileURL:url] autorelease];;

                    } else {

                        entity = nil;

                    }

                    if (entity) {

                        [newChildren addObject:entity];

                    }

                }

            }

            _children = newChildren;

            [urls release];

        }

        result = [[_children retain] autorelease];

    }

    return result;

}

@end

NSString *const ATEntityPropertyNamedFillColor = @"fillColor";

NSString *const ATEntityPropertyNamedFillColorName = @"fillColorName";

NSString *const ATEntityPropertyNamedImage = @"image";

NSString *const ATEntityPropertyNamedThumbnailImage = @"thumbnailImage";