/*

    Copyright (C) 2015 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This is the "ImageFile" class implementation.

*/

#import <Cocoa/Cocoa.h>

#import "AAPLImageFile.h"

@interface AAPLImageFile (Internals)

+ (NSOperationQueue *)previewLoadingOperationQueue;

//@property(copy) NSURL *url;

@property(copy) NSString *fileType;

@property(assign) unsigned long long fileSize;

@property(copy) NSDate *dateLastUpdated;

@property(strong) NSImage *previewImage;

@end

@implementation AAPLImageFile

+ (nonnull NSSet<NSString *> *)keyPathsForValuesAffectingValueForKey:(nonnull NSString *)key {

    if ([key isEqual:@"localizedTypeDescription"]) {

        return [NSSet setWithObject:@"fileType"];

    } else {

        return [super keyPathsForValuesAffectingValueForKey:key];

    }

}

+ (NSOperationQueue *)previewLoadingOperationQueue {

    static NSOperationQueue *queue;

    if (queue == nil) {

        queue = [[NSOperationQueue alloc] init];

        queue.name = @"AAPLImageFile Preview Loading Queue";

    }

    return queue;

}

+ (NSDictionary *)demoTagNamesDictionary {

    static NSDictionary *demoTagNames;

    if (demoTagNames == nil) {

        demoTagNames = @{

             @"Abstract" : @[@"Texture"],

             @"Antelope Canyon" : @[@"Landscape", @"Texture"],

             @"Bahamas Aerial" : @[@"Landscape", @"Texture"],

             @"Beach" : @[@"Landscape", @"Water"],

             @"Blue Pond" : @[@"Flora", @"Landscape", @"Snow", @"Water"],

             @"Bristle Grass" : @[@"Flora", @"Landscape"],

             @"Brushes" : @[@"Texture"],

             @"Circles" : @[@"Texture"],

             @"Death Valley" : @[@"Landscape"],

             @"Desert" : @[@"Landscape", @"Texture"],

             @"Ducks on a Misty Pond" : @[@"Fauna", @"Landscape", @"Water"],

             @"Eagle & Waterfall" : @[@"Fauna", @"Landscape", @"Water"],

             @"Earth and Moon" : @[@"Space"],

             @"Earth Horizon" : @[@"Space"],

             @"Elephant" : @[@"Fauna", @"Landscape"],

             @"Flamingos" : @[@"Fauna", @"Landscape", @"Water"],

             @"Floating Ice" : @[@"Landscape", @"Snow", @"Water"]

        };

    }

    return demoTagNames;

}

+ (NSArray *)demoTagNamesForImageFileURL:(NSURL *)url {

    NSString *filenameWithoutExtension = [[url lastPathComponent] stringByDeletingPathExtension];

    return [[self demoTagNamesDictionary] objectForKey:filenameWithoutExtension];

}

- (id)initWithURL:(NSURL *)newURL {

    self = [super init];

    if (self) {

        self.url = newURL;

        // Get properties that we can obtain from the URL.

        id value;

        NSError *error;

        if ([self.url getResourceValue:&value forKey:NSURLTypeIdentifierKey error:&error]) {

            self.fileType = (NSString *)value;

        }

        if ([self.url getResourceValue:&value forKey:NSURLFileSizeKey error:&error]) {

            self.fileSize = ((NSNumber *)value).unsignedLongLongValue;

        }

        if ([self.url getResourceValue:&value forKey:NSURLContentModificationDateKey error:&error]) {

            self.dateLastUpdated = (NSDate *)value;

        }

        if ([self.url getResourceValue:&value forKey:NSURLTagNamesKey error:&error]) {

            self.tagNames = (NSArray *)value;

        }

        if (self.tagNames == nil) {

            // For Demo purposes, since the image files in "/Library/Desktop Pictures" don't have tags assigned to them, hardwire tagNames of our own.

            self.tagNames = [[self class] demoTagNamesForImageFileURL:self.url];

        }

    }

    return self;

}

#pragma mark File Properties

@synthesize url;

@synthesize fileType;

@synthesize fileSize;

@synthesize dateLastUpdated;

- (NSString *)filename {

    return self.url.lastPathComponent;

}

- (NSString *)filenameWithoutExtension {

    return self.filename.stringByDeletingPathExtension;

}

- (NSString *)localizedTypeDescription {

    NSString *type = self.fileType;

    return type ? [[NSWorkspace sharedWorkspace] localizedDescriptionForType:self.fileType] : nil;

}

- (NSString *)dimensionsDescription {

    return [NSString stringWithFormat:@"%ld x %ld", (long)(self.pixelsWide), (long)(self.pixelsHigh)];

}

#pragma mark Image Properties

- (NSInteger)pixelsWide {

    if (imageProperties == nil) {

        [self loadMetadata];

    }

    return [[imageProperties valueForKey:(NSString *)kCGImagePropertyPixelWidth] intValue];

}

- (NSInteger)pixelsHigh {

    if (imageProperties == nil) {

        [self loadMetadata];

    }

    return [[imageProperties valueForKey:(NSString *)kCGImagePropertyPixelHeight] intValue];

}

@synthesize previewImage;

#pragma mark Loading

/* Many kinds of image files contain prerendered thumbnail images that can be quickly loaded without having to decode the entire contents of the image file and reconstruct the full-size image.  The ImageIO framework's CGImageSource API provides a means to do this, using the CGImageSourceCreateThumbnailAtIndex() function.  For more information on CGImageSource objects and their capabilities, see the CGImageSource reference on the Apple Developer Connection website, at http://developer.apple.com/documentation/GraphicsImaging/Reference/CGImageSource/Reference/reference.html

*/

- (BOOL)createImageSource {

    if (imageSource == NULL) {

        // Compose absolute URL to file.

        NSURL *sourceURL = [[self url] absoluteURL];

        if (sourceURL == nil) {

            return NO;

        }

        // Create a CGImageSource from the URL.

        imageSource = CGImageSourceCreateWithURL((CFURLRef)sourceURL, NULL);

        if (imageSource == NULL) {

            return NO;

        }

        CFStringRef imageSourceType = CGImageSourceGetType(imageSource);

        if (imageSourceType == NULL) {

            CFRelease(imageSource);

            return NO;

        }

    }

    return imageSource ? YES : NO;

}

- (BOOL)loadMetadata {

    if (imageProperties == NULL) {

        // Get image properties.

        if (![self createImageSource]) {

            return NO;

        }

        // This code looks at the first image only.

        // To be truly general, we'd need to handle the possibility of an image source

        // having more than one image to offer us.

        //

        NSInteger index = 0;

        imageProperties = (NSDictionary *)CFBridgingRelease(CGImageSourceCopyPropertiesAtIndex(imageSource, index, NULL));

    }

    // Return indicating success!

    return imageProperties ? YES : NO;

}

- (void)requestPreviewImage {

    if (self.previewImage == nil) {

        [[[self class] previewLoadingOperationQueue] addOperationWithBlock:^{

            if ([self createImageSource]) {

                NSDictionary *options = [[NSDictionary alloc] initWithObjectsAndKeys:

                                         // Ask ImageIO to create a thumbnail from the file's image data, if it can't find

                                         // a suitable existing thumbnail image in the file.  We could comment out the following

                                         // line if only existing thumbnails were desired for some reason (maybe to favor

                                         // performance over being guaranteed a complete set of thumbnails).

                                         [NSNumber numberWithBool:YES], (NSString *)kCGImageSourceCreateThumbnailFromImageIfAbsent,

                                         [NSNumber numberWithInt:160], (NSString *)kCGImageSourceThumbnailMaxPixelSize,

                                         nil];

                CGImageRef thumbnail = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, (CFDictionaryRef)options);

                if (thumbnail) {

                    NSImage *image = [[NSImage alloc] initWithCGImage:thumbnail size:NSZeroSize];

                    if (image) {

                        [[NSOperationQueue mainQueue] addOperationWithBlock:^{

                            self.previewImage = image;

                        }];

                    }

                    CGImageRelease(thumbnail);

                }

            }

        }];

    }

}

#pragma mark Debugging Assistance

- (NSString *)description {

    return [NSString stringWithFormat:@"{ImageFile: %@, tags=%@}", self.url.absoluteString, self.tagNames];

}

#pragma mark Teardown

- (void)dealloc {

    if (imageSource) {

        CFRelease(imageSource);

    }

}

@end