/*

     File: AssetBrowserSource.m

 Abstract: Represents a source like the camera roll and vends AssetBrowserItems.

  Version: 1.3

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 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 */

#import "AssetBrowserSource.h"

#import "DirectoryWatcher.h"

#import <MobileCoreServices/UTCoreTypes.h>

#import <MobileCoreServices/UTType.h>

#import <MediaPlayer/MediaPlayer.h>

#import <AssetsLibrary/AssetsLibrary.h>

@interface AssetBrowserSource () <DirectoryWatcherDelegate>

@property (nonatomic, copy) NSArray *items; // NSArray of AssetBrowserItems

@end

@implementation AssetBrowserSource

@synthesize name = sourceName, items = assetBrowserItems, delegate, type = sourceType;

- (NSString*)nameForSourceType

{

    NSString *name = nil;

    switch (sourceType) {

        case AssetBrowserSourceTypeFileSharing:

            name = NSLocalizedString(@"File Sharing", nil);

            break;

        case AssetBrowserSourceTypeCameraRoll:

            name = NSLocalizedString(@"Camera Roll", nil);

            break;

        case AssetBrowserSourceTypeIPodLibrary:

            name = NSLocalizedString(@"iPod Library", nil);

            break;

        default:

            name = nil;

            break;

    }

    return name;

}

+ (AssetBrowserSource*)assetBrowserSourceOfType:(AssetBrowserSourceType)sourceType

{

    return [[self alloc] initWithSourceType:sourceType];

}

- (id)initWithSourceType:(AssetBrowserSourceType)type

{

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

        sourceType = type;

        sourceName = [self nameForSourceType];

        assetBrowserItems = [NSArray array];

        enumerationQueue = dispatch_queue_create("Browser Enumeration Queue", DISPATCH_QUEUE_SERIAL);

        dispatch_set_target_queue(enumerationQueue, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0));

    }

    return self;

}

- (void)updateBrowserItemsAndSignalDelegate:(NSArray*)newItems

{   

    self.items = newItems;

    /* Ideally we would reuse the AssetBrowserItems which remain unchanged between updates.

     This could be done by maintaining a dictionary of assetURLs -> AssetBrowserItems.

     This would also allow us to more easily tell our delegate which indices were added/removed

     so that it could animate the table view updates. */

    if (self.delegate && [self.delegate respondsToSelector:@selector(assetBrowserSourceItemsDidChange:)]) {

        [self.delegate assetBrowserSourceItemsDidChange:self];

    }

}

- (void)dealloc 

{

    if (receivingIPodLibraryNotifications) {

        MPMediaLibrary *iPodLibrary = [MPMediaLibrary defaultMediaLibrary];

        [iPodLibrary endGeneratingLibraryChangeNotifications];

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

    }

    if (assetsLibrary) {

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

    }

    [directoryWatcher invalidate];

    directoryWatcher.delegate = nil;

}

#pragma mark -

#pragma mark iPod Library

- (void)updateIPodLibrary

{

    dispatch_async(enumerationQueue, ^(void) {

        // Grab videos from the iPod Library

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

        NSMutableArray *items = [NSMutableArray arrayWithCapacity:0];

        NSArray *mediaItems = [videoQuery items];

        for (MPMediaItem *mediaItem in mediaItems) {

            NSURL *URL = (NSURL*)[mediaItem valueForProperty:MPMediaItemPropertyAssetURL];

            if (URL) {

                NSString *title = (NSString*)[mediaItem valueForProperty:MPMediaItemPropertyTitle];

                AssetBrowserItem *item = [[AssetBrowserItem alloc] initWithURL:URL title:title];

                [items addObject:item];

            }

        }

        dispatch_async(dispatch_get_main_queue(), ^(void) {

            [self updateBrowserItemsAndSignalDelegate:items];

        });

    });

}

- (void)iPodLibraryDidChange:(NSNotification*)changeNotification

{

    [self updateIPodLibrary];

}

- (void)buildIPodLibrary

{

    MPMediaLibrary *iPodLibrary = [MPMediaLibrary defaultMediaLibrary];

    receivingIPodLibraryNotifications = YES;

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(iPodLibraryDidChange:) 

                                                 name:MPMediaLibraryDidChangeNotification object:nil];

    [iPodLibrary beginGeneratingLibraryChangeNotifications];

    [self updateIPodLibrary];   

}

#pragma mark -

#pragma mark Assets Library

- (void)updateAssetsLibrary

{

    NSMutableArray *assetItems = [NSMutableArray arrayWithCapacity:0];

    ALAssetsLibrary *assetLibrary = assetsLibrary;

    [assetLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

         if (group) {

             [group setAssetsFilter:[ALAssetsFilter allVideos]];

             [group enumerateAssetsUsingBlock:

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

              {

                  if (asset) {

                      ALAssetRepresentation *defaultRepresentation = [asset defaultRepresentation];

                      NSString *uti = [defaultRepresentation UTI];

                      NSURL *URL = [[asset valueForProperty:ALAssetPropertyURLs] valueForKey:uti];

                      NSString *title = [NSString stringWithFormat:@"%@ %lu", NSLocalizedString(@"Video", nil), [assetItems count]+1];

                      AssetBrowserItem *item = [[AssetBrowserItem alloc] initWithURL:URL title:title];

                      [assetItems addObject:item];

                  }

              }];

         }

        // group == nil signals we are done iterating.

        else {

            dispatch_async(dispatch_get_main_queue(), ^{

                [self updateBrowserItemsAndSignalDelegate:assetItems];

            });

        }

    }

    failureBlock:^(NSError *error) {

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

    }];

}

- (void)assetsLibraryDidChange:(NSNotification*)changeNotification

{

    [self updateAssetsLibrary];

}

- (void)buildAssetsLibrary

{

    assetsLibrary = [[ALAssetsLibrary alloc] init];

    ALAssetsLibrary *notificationSender = nil;

    NSString *minimumSystemVersion = @"4.1";

    NSString *systemVersion = [[UIDevice currentDevice] systemVersion];

    if ([systemVersion compare:minimumSystemVersion options:NSNumericSearch] != NSOrderedAscending)

        notificationSender = assetsLibrary;

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(assetsLibraryDidChange:) 

                                                 name:ALAssetsLibraryChangedNotification object:notificationSender];

    [self updateAssetsLibrary];

}

#pragma mark -

#pragma mark iTunes File Sharing

- (NSArray*)browserItemsInDirectory:(NSString*)directoryPath

{

    NSMutableArray *paths = [NSMutableArray arrayWithCapacity:0];

    NSArray *subPaths = [[[NSFileManager alloc] init] contentsOfDirectoryAtPath:directoryPath 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 = [directoryPath stringByAppendingPathComponent:subPath];

            if (fileConformsToUTI) {

                [paths addObject:path];

            }

        }

    }

    NSMutableArray *browserItems = [NSMutableArray arrayWithCapacity:0];

    for (NSString *path in paths) {

        AssetBrowserItem *item = [[AssetBrowserItem alloc] initWithURL:[NSURL fileURLWithPath:path]];

        [browserItems addObject:item];

    }

    return browserItems;

}

- (void)directoryDidChange:(DirectoryWatcher *)folderWatcher

{

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    dispatch_async(enumerationQueue, ^(void) {

        NSArray *browserItems = [self browserItemsInDirectory:documentsDirectory];

        dispatch_async(dispatch_get_main_queue(), ^(void) {

            [self updateBrowserItemsAndSignalDelegate:browserItems];

        });

    });

}

- (void)buildFileSharingLibrary

{

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    NSArray *browserItems = [self browserItemsInDirectory:documentsDirectory];

    [self updateBrowserItemsAndSignalDelegate:browserItems];

    directoryWatcher = [DirectoryWatcher watchFolderWithPath:documentsDirectory delegate:self];

}

- (void)buildSourceLibrary

{

    if (haveBuiltSourceLibrary)

        return;

    switch (sourceType) {

        case AssetBrowserSourceTypeFileSharing:

            [self buildFileSharingLibrary];

            break;

        case AssetBrowserSourceTypeCameraRoll:

            [self buildAssetsLibrary];

            break;

        case AssetBrowserSourceTypeIPodLibrary:

            [self buildIPodLibrary];

            break;

        default:

            break;

    }

    haveBuiltSourceLibrary = YES;

}

@end