/*

     File: VideoLibrary.m

 Abstract: Class that mediates the interaction between the controllers and the Media and Asset Library, as well as the contents of the app bundle.

  Version: 1.0

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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 */

#import "VideoLibrary.h"

#import "AssetItem.h"

#import <MediaPlayer/MediaPlayer.h>

#import <AssetsLibrary/AssetsLibrary.h>

#import <MobileCoreServices/MobileCoreServices.h>

@interface VideoLibrary ()

- (void)buildMediaLibrary;

- (void)buildAssetLibrary;

- (void)buildApplicationBundleLibrary;

- (void)addURL:(NSURL *)url;

@property(readwrite, strong) NSMutableArray *assetItems;

@property(readonly, unsafe_unretained) dispatch_queue_t assetItemsQueue;

@property(readonly, unsafe_unretained) dispatch_group_t libraryGroup;

@property(readonly, unsafe_unretained) dispatch_queue_t libraryQueue;

@end

@implementation VideoLibrary

@synthesize assetItems = _assetItems;

@synthesize assetItemsQueue = _assetItemsQueue;

@synthesize libraryGroup = _libraryGroup;

@synthesize libraryQueue = _libraryQueue;

- (id)initWithLibraryChangedHandler:(void (^)(void))libraryChangedHandler

{

    self = [super init];

    if (self) 

    {

        _assetItems = [NSMutableArray array];

        _assetItemsQueue = dispatch_queue_create("com.apple.avmovieexporter.assetItemLibraryQueue", DISPATCH_QUEUE_SERIAL);

        _libraryGroup = dispatch_group_create();

        _libraryQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);

        // Update the table view whenever the library changes

        [[NSNotificationCenter defaultCenter] addObserverForName:ALAssetsLibraryChangedNotification 

                                                          object:nil 

                                                           queue:[NSOperationQueue mainQueue] 

                                                      usingBlock:^(NSNotification *block){

                                                               libraryChangedHandler();

                                                           }];

    }

    return self;

}

- (void)dealloc

{

    dispatch_release(_assetItemsQueue);

    dispatch_release(_libraryQueue);

    dispatch_release(_libraryGroup);

    [[NSNotificationCenter defaultCenter] removeObserver:self name:ALAssetsLibraryChangedNotification object:nil];

}

- (void)loadLibraryWithCompletionBlock:(void (^)(void))completionHandler

{

    // Load content using the Media Library and AssetLibrary APIs, also check for content included in the application bundle

    [self.assetItems removeAllObjects];

    [self buildMediaLibrary];

    [self buildAssetLibrary];

    [self buildApplicationBundleLibrary];

    dispatch_group_notify(self.libraryGroup, self.libraryQueue, ^{

        dispatch_async(dispatch_get_main_queue(), ^{

            completionHandler();

        });

    });

}

- (void)addURL:(NSURL *)url

{

    __unsafe_unretained __block VideoLibrary *weakSelf = (VideoLibrary *)self;

    if (url == nil)

        return;

    dispatch_async(self.assetItemsQueue, ^{

        [weakSelf.assetItems addObject:[[AssetItem alloc] initWithURL:url]];

    });

}

#pragma mark - iPod Library

- (void)buildMediaLibrary

{

    __unsafe_unretained __block VideoLibrary *weakSelf = (VideoLibrary *)self;

    dispatch_group_async(self.libraryGroup, self.libraryQueue, ^{

        NSLog(@"started building media library...");

        // Search for video content in the Media Library

#if  __IPHONE_OS_VERSION_MAX_ALLOWED >= 50000

        NSNumber *videoTypeNum = [NSNumber numberWithInteger:MPMediaTypeAnyVideo];

#else

        NSNumber *videoTypeNum = [NSNumber numberWithInteger:(MPMediaTypeAny ^ MPMediaTypeAnyAudio)];

#endif

        MPMediaPropertyPredicate *videoPredicate = [MPMediaPropertyPredicate predicateWithValue:videoTypeNum forProperty:MPMediaItemPropertyMediaType];

        MPMediaQuery *videoQuery = [[MPMediaQuery alloc] init];

        [videoQuery addFilterPredicate: videoPredicate];

        NSArray *items = [videoQuery items];

        for (MPMediaItem *mediaItem in items) 

            [weakSelf addURL:[mediaItem valueForProperty:MPMediaItemPropertyAssetURL]];

        NSLog(@"done building media library...");

    });

}

- (void)buildAssetLibrary

{

    NSLog(@"started building asset library...");

    __unsafe_unretained __block VideoLibrary *weakSelf = (VideoLibrary *)self;

    dispatch_group_enter(weakSelf.libraryGroup);

    ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];

    // Enumerate through all the groups in the Asset Library

    [assetLibrary enumerateGroupsWithTypes:ALAssetsGroupAll 

                                usingBlock:

     ^(ALAssetsGroup *group, BOOL *stop)

     {

         if (group != nil)

         {

             // Filter by groups that contain video

             [group setAssetsFilter:[ALAssetsFilter allVideos]];

             [group enumerateAssetsUsingBlock:

              ^(ALAsset *asset, NSUInteger index, BOOL *stop)

              {

                  if (asset)

                      [weakSelf addURL:[[asset defaultRepresentation] url]];

              }];

         }

         else

         {

             dispatch_group_leave(weakSelf.libraryGroup);

             NSLog(@"done building asset library...");

         }

     }

                              failureBlock:^(NSError *error)

     {

         dispatch_group_leave(weakSelf.libraryGroup);

         NSLog(@"error enumerating AssetLibrary groups %@\n", error);

     }];

}

- (void)buildApplicationBundleLibrary

{

    __unsafe_unretained __block VideoLibrary *weakSelf = (VideoLibrary *)self;

    dispatch_group_async(self.libraryGroup, self.libraryQueue, ^{

        NSLog(@"started building bundle library...");

        NSString *appBundleDirectory = [[NSBundle mainBundle] bundlePath];

        // Search for audio/video content in the app bundle

        NSArray *subPaths = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:appBundleDirectory error:nil];

        if (subPaths)

        {

            for (NSString *subPath in subPaths)

            {

                NSString *pathExtension = [subPath pathExtension];

                CFStringRef preferredUTI = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)pathExtension, NULL);

                BOOL fileConformsToUTI = UTTypeConformsTo(preferredUTI, kUTTypeAudiovisualContent);

                CFRelease(preferredUTI);

                NSString *path = [appBundleDirectory stringByAppendingPathComponent:subPath];

                if (fileConformsToUTI)

                    [weakSelf addURL:[NSURL fileURLWithPath:path]];

            }

        }

        NSLog(@"done building bundle library...");

    });

}

+ (BOOL)saveMovieAtPathToAssetLibrary:(NSURL *)path withCompletionHandler:(void (^)(NSError *))completionHandler

{

    // Write a movie back to the asset library so it can be viewed by other apps

    BOOL success = YES;

    ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];

    [assetLibrary writeVideoAtPathToSavedPhotosAlbum:path completionBlock:^(NSURL *assetURL, NSError *error){

        if (error != nil)

        {

            dispatch_async(dispatch_get_main_queue(), ^{

                completionHandler(error);

            });

        }

        else

        {

            NSError *removeError = nil;

            [[NSFileManager defaultManager] removeItemAtURL:path error:&removeError];

            dispatch_async(dispatch_get_main_queue(), ^{

                completionHandler(error);

            });

        }

    }];

    return success;

}

@end