/*

     File: AssetBrowserItem.m

 Abstract: Represents an asset in AssetBrowserController.

  Version: 1.3

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 */

#import "AssetBrowserItem.h"

#import <AVFoundation/AVFoundation.h>

#include <AssertMacros.h>

@interface AssetBrowserItem ()

- (AVAsset*)copyAssetIfCreated;

@property (nonatomic, copy) NSString *title;

@property (nonatomic, strong) UIImage *thumbnailImage;

@property (nonatomic, readonly) BOOL canGenerateThumbnails;

@property (nonatomic, readonly) BOOL audioOnly;

@end

@implementation AssetBrowserItem

@synthesize URL = assetURL, title = assetTitle, haveRichestTitle;

@synthesize thumbnailImage, canGenerateThumbnails, audioOnly;

- (id)initWithURL:(NSURL*)URL

{

    return [self initWithURL:URL title:nil];

}

- (id)initWithURL:(NSURL*)URL title:(NSString*)title

{

    if ((self = [super init])) {

        assetURL = URL;

        if (assetURL == nil) {

            return nil;

        }

        haveRichestTitle = title ? YES : NO;

        assetTitle = title ? [title copy] : [[URL lastPathComponent] stringByDeletingPathExtension];

        // Assume we can generate a thumb unless we have loaded the assets or tried already and know otherwise.

        canGenerateThumbnails = YES;

        // Assets can only be accessed from one thread at a time.

        assetQueue = dispatch_queue_create("Asset Queue", DISPATCH_QUEUE_SERIAL);

    }

    return self;

}

- (id)initWithAssetItem:(AssetBrowserItem*)browserItem

{

    if ((self = [super init])) {

        // Inititialization time properties.

        assetURL = browserItem.URL;

        // May have been an initialization time property.

        assetTitle = browserItem.title;

        haveRichestTitle = browserItem.haveRichestTitle;

        thumbnailImage = browserItem.thumbnailImage;

        asset = [browserItem copyAssetIfCreated];

        canGenerateThumbnails = browserItem.canGenerateThumbnails;

        audioOnly = browserItem.audioOnly;

        assetQueue = dispatch_queue_create("Asset Queue", DISPATCH_QUEUE_SERIAL);

    }

    return self;

}

- (id)copyWithZone:(NSZone *)zone

{

    AssetBrowserItem *copy = [[AssetBrowserItem allocWithZone:zone] initWithAssetItem:self];

    return copy;

}

// Do simple equality based on the item's URL.

- (BOOL)isEqual:(id)anObject

{

    if (self == anObject)

        return YES;

    if ([anObject isKindOfClass:[AssetBrowserItem class]]) {

        AssetBrowserItem *item = anObject;

        NSURL *myURL = self.URL;

        NSURL *theirURL = item.URL;

        if (myURL && theirURL) {

            return [myURL isEqual:theirURL];

        }

        return NO;

    }

    return NO;

}

- (NSUInteger)hash

{

    if (self.URL) {

        return [self.URL hash];

    }

    else {

        return [super hash];

    }

}

// Must be called on assetQueue. Will handle lazy asset creation.

- (AVAsset*)getAssetInternal

{

    check( dispatch_get_current_queue() == assetQueue );

    if (asset == nil) {

        asset = [[AVURLAsset alloc] initWithURL:assetURL options:nil];

    }

    return  asset;

}

// Our public accessor always copies the asset since assets can only safely be accessed from one thread at a time.

- (AVAsset*)asset

{   

    __block AVAsset *theAsset = nil;

    dispatch_sync(assetQueue, ^(void) {

        theAsset = [[self getAssetInternal] copy];

    });

    return theAsset;

}

- (AVAsset*)copyAssetIfCreated

{   

    __block AVAsset *theAsset = nil;

    dispatch_sync(assetQueue, ^(void) {

        theAsset = [asset copy];

    });

    return theAsset;

}

- (void)generateTitleFromMetadataAsynchronouslyWithCompletionHandler:(void (^)(NSString *title))handler

{

    if (haveRichestTitle) {

        dispatch_async(dispatch_get_main_queue(), ^(void) {

            if (handler)

                handler(self.title);

        });

        return;

    }

    dispatch_async(assetQueue, ^(void) {

        AVAsset *titleAsset = [self getAssetInternal];

        [titleAsset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"commonMetadata"] completionHandler:^{

            dispatch_async(assetQueue, ^(void) {

                NSString* title = nil;

                NSArray *titles = [AVMetadataItem metadataItemsFromArray:[titleAsset commonMetadata] withKey:AVMetadataCommonKeyTitle keySpace:AVMetadataKeySpaceCommon];

                if ([titles count] > 0)

                {

                    // Try to get a title that matches one of the user's preferred languages.

                    NSArray *preferredLanguages = [NSLocale preferredLanguages];

                    for (NSString *thisLanguage in preferredLanguages)

                    {

                        NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:thisLanguage];

                        NSArray *titlesForLocale = [AVMetadataItem metadataItemsFromArray:titles withLocale:locale];

                        if ([titlesForLocale count] > 0)

                        {

                            title = [[titlesForLocale objectAtIndex:0] stringValue];

                            break;

                        }

                    }

                    // No matches in any of the preferred languages. Just use the primary title metadata we find.

                    if (title == nil)

                    {

                        title = [[titles objectAtIndex:0] stringValue];

                    }

                }

                dispatch_async(dispatch_get_main_queue(), ^{

                    haveRichestTitle = YES;

                    if (title)

                        self.title = title;

                    if (handler)

                        handler(self.title);

                });

            });

        }];

    });

}

CGRect makeRectWithAspectRatioOutsideRect(CGSize aspectRatio, CGRect containerRect)

{

    CGSize scale = CGSizeMake(containerRect.size.width / aspectRatio.width, containerRect.size.height / aspectRatio.height);

    CGFloat maxScale = fmax(scale.width, scale.height);

    CGPoint centerPoint = CGPointMake(CGRectGetMidX(containerRect), CGRectGetMidY(containerRect));

    CGSize size = CGSizeMake(aspectRatio.width * maxScale, aspectRatio.height * maxScale);

    return CGRectMake(centerPoint.x - 0.5f * size.width, centerPoint.y - 0.5f * size.height, size.width, size.height);

}

- (CGSize)maxSizeForImageGeneratorToCropAsset:(AVAsset*)thumbnailAsset toSize:(CGSize)size

{

    CGSize naturalSize = CGSizeZero;

    CGSize naturalSizeTransformed = CGSizeZero;

    NSArray *videoTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeVideo];

    if ( ([videoTracks count] > 0) ) {

        AVAssetTrack *videoTrack = [videoTracks objectAtIndex:0];

        NSArray *formatDescriptions = [videoTrack formatDescriptions];

        if ([formatDescriptions count] > 0) {

            CMVideoFormatDescriptionRef videoFormatDescription = (__bridge CMFormatDescriptionRef)[formatDescriptions objectAtIndex:0];

            naturalSize = CMVideoFormatDescriptionGetPresentationDimensions(videoFormatDescription, YES, YES);

            naturalSizeTransformed = CGSizeApplyAffineTransform (naturalSize, videoTrack.preferredTransform);

            naturalSizeTransformed.width = fabs(naturalSizeTransformed.width);

            naturalSizeTransformed.height = fabs(naturalSizeTransformed.height);

        }

        else {

            return CGSizeZero;

        }

    }

    else {

        return CGSizeZero;

    }

    CGRect croppedRect = CGRectZero;

    croppedRect.size = size;

    CGRect containerRect = makeRectWithAspectRatioOutsideRect(naturalSizeTransformed, croppedRect);

    containerRect.origin = CGPointZero;

    containerRect = CGRectIntegral(containerRect);

    return containerRect.size;

}

- (UIImage*)copyImageFromCGImage:(CGImageRef)image croppedToSize:(CGSize)size

{

    UIImage *thumbUIImage = nil;

    CGRect thumbRect = CGRectMake(0.0, 0.0, CGImageGetWidth(image), CGImageGetHeight(image));

    CGRect cropRect = AVMakeRectWithAspectRatioInsideRect(size, thumbRect);

    cropRect.origin.x = round(cropRect.origin.x);

    cropRect.origin.y = round(cropRect.origin.y);

    cropRect = CGRectIntegral(cropRect);

    CGImageRef croppedThumbImage = CGImageCreateWithImageInRect(image, cropRect);

    thumbUIImage = [[UIImage alloc] initWithCGImage:croppedThumbImage];

    CGImageRelease(croppedThumbImage);

    return thumbUIImage;

}

// Must be called on assetQueue.

- (BOOL)assetHasVideoTrack:(AVAsset*)thumbnailAsset

{   

    check( dispatch_get_current_queue() == assetQueue );

    NSArray *videoTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeVideo];

    if ([videoTracks count] == 0) {

        canGenerateThumbnails = NO;

        NSArray *audioTracks = [thumbnailAsset tracksWithMediaType:AVMediaTypeAudio];

        if ([audioTracks count] != 0) {

            audioOnly = YES;

        }

        return NO;

    }

    return YES;

}

// Must be called on assetQueue.

- (void)generateNonVideoThumbnailWithSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler

{   

    check( dispatch_get_current_queue() == assetQueue );

    UIImage *thumb = nil;

    if (audioOnly) {

        thumb = [UIImage imageNamed:@"Browser-AudioOnly"];

    }

    else {

        thumb = [UIImage imageNamed:@"Browser-ErrorLoading"];

    }

    if ( mode == AssetBrowserItemFillModeCrop ) {

        CGRect boundingRect = CGRectZero;

        boundingRect.size = thumb.size;

        boundingRect.size.width *= thumb.scale;

        boundingRect.size.height *= thumb.scale;

        CGSize cropSize = AVMakeRectWithAspectRatioInsideRect(size, boundingRect).size;

        if ( !CGSizeEqualToSize(cropSize, size) ) {

            thumb = [self copyImageFromCGImage:[thumb CGImage] croppedToSize:cropSize];

        }

    }

    dispatch_async(dispatch_get_main_queue(), ^(void) {

        self.thumbnailImage = thumb;

        if (handler) {      

            handler(thumb);

        }   

    });

}

// Must be called on assetQueue.

- (void)generateThumbnailFromAsset:(AVAsset*)thumbnailAsset withSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler

{   

    check( dispatch_get_current_queue() == assetQueue );

    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:thumbnailAsset];

    imageGenerator.appliesPreferredTrackTransform = YES;

    if ( mode == AssetBrowserItemFillModeAspectFit )

        imageGenerator.maximumSize = size;

    if ( mode == AssetBrowserItemFillModeCrop )

        imageGenerator.maximumSize = [self maxSizeForImageGeneratorToCropAsset:thumbnailAsset toSize:size];

    NSValue *imageTimeValue = [NSValue valueWithCMTime:CMTimeMake(2, 1)];

    [imageGenerator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:imageTimeValue] completionHandler:

     ^(CMTime requestedTime, CGImageRef image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error) 

     {  

         if (result == AVAssetImageGeneratorFailed) {

             dispatch_sync(assetQueue, ^(void) {

                 canGenerateThumbnails = NO;

                 [self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler];

             });

         }

         else {

             UIImage *thumbUIImage = nil;

             if (image) {

                 if (mode == AssetBrowserItemFillModeCrop) {

                     thumbUIImage = [self copyImageFromCGImage:image croppedToSize:size];

                 }

                 else {

                     thumbUIImage = [[UIImage alloc] initWithCGImage:image];

                 }

             }

             dispatch_async(dispatch_get_main_queue(), ^{

                 self.thumbnailImage = thumbUIImage;

                 if (handler) {

                     handler(self.thumbnailImage);

                 }

             });

         }

     }];

}

- (void)generateThumbnailAsynchronouslyWithSize:(CGSize)size fillMode:(AssetBrowserItemFillMode)mode completionHandler:(void (^)(UIImage *thumbnail))handler

{   

    dispatch_async(assetQueue, ^(void) {

        if (!canGenerateThumbnails) {

            [self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler];

            return;

        }

        AVAsset *thumbnailAsset = [self getAssetInternal];

        [thumbnailAsset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:^(void) {

            dispatch_async(assetQueue, ^(void) {

                AVKeyValueStatus postLoadingStatus = [thumbnailAsset statusOfValueForKey:@"tracks" error:NULL];

                if ((postLoadingStatus == AVKeyValueStatusLoaded) && [self assetHasVideoTrack:thumbnailAsset]) {

                    [self generateThumbnailFromAsset:thumbnailAsset withSize:size fillMode:mode completionHandler:handler];

                }

                else {

                    canGenerateThumbnails = NO;

                    [self generateNonVideoThumbnailWithSize:size fillMode:mode completionHandler:handler];

                }

            });

        }];

    });

}

- (UIImage*)placeHolderImage

{

    return [UIImage imageNamed:@"Browser-Placeholder"];

}

- (void)clearThumbnailCache

{

    self.thumbnailImage = nil;

}

- (void)clearAssetCache

{

    dispatch_sync(assetQueue, ^(void) {

        asset = nil;

    });

}

- (NSString*)description

{

    return [NSString stringWithFormat:@"<AssetBrowserItem: %p, '%@'>", self, self.title];

}

@end