Cog/Audio/CogPluginMulti.m

//
//  CogPluginMulti.m
//  CogAudio
//
//  Created by Christopher Snowhill on 10/21/13.
//
//

#import "CogPluginMulti.h"

NSArray * sortClassesByPriority(NSArray * theClasses)
{
    NSMutableArray *sortedClasses = [NSMutableArray arrayWithArray:theClasses];
    [sortedClasses sortUsingComparator:
     ^NSComparisonResult(id obj1, id obj2)
     {
         NSString *classString1 = (NSString *)obj1;
         NSString *classString2 = (NSString *)obj2;
         
         Class class1 = NSClassFromString(classString1);
         Class class2 = NSClassFromString(classString2);
         
         float priority1 = [class1 priority];
         float priority2 = [class2 priority];
         
         if (priority1 == priority2) return NSOrderedSame;
         else if (priority1 > priority2) return NSOrderedAscending;
         else return NSOrderedDescending;
     }];
    return sortedClasses;
}

@implementation CogDecoderMulti

+ (NSArray *)mimeTypes
{
    return nil;
}

+ (NSArray *)fileTypes
{
    return nil;
}

+ (float)priority
{
    return -1.0;
}

+ (NSArray *)fileTypeAssociations {
    return nil;
}

- (id)initWithDecoders:(NSArray *)decoders
{
    self = [super init];
    if ( self )
    {
        theDecoders = sortClassesByPriority(decoders);
        theDecoder = nil;
        cachedObservers = [[NSMutableArray alloc] init];
    }
    return self;
}

- (NSDictionary *)properties
{
    if ( theDecoder != nil ) return [theDecoder properties];
    return nil;
}

- (int)readAudio:(void *)buffer frames:(UInt32)frames
{
    if ( theDecoder != nil ) return [theDecoder readAudio:buffer frames:frames];
    return 0;
}

- (BOOL)open:(id<CogSource>)source
{
    for (NSString *classString in theDecoders)
    {
        Class decoder = NSClassFromString(classString);
        theDecoder = [[decoder alloc] init];
        for (NSDictionary *obsItem in cachedObservers) {
            [theDecoder addObserver:[obsItem objectForKey:@"observer"]
                         forKeyPath:[obsItem objectForKey:@"keyPath"]
                            options:[[obsItem objectForKey:@"options"] unsignedIntegerValue]
                            context:(__bridge void *)([obsItem objectForKey:@"context"])];
        }
        if ([theDecoder open:source])
            return YES;
        for (NSDictionary *obsItem in cachedObservers) {
            [theDecoder removeObserver:[obsItem objectForKey:@"observer"] forKeyPath:[obsItem objectForKey:@"keyPath"]];
        }
        if ([source seekable])
            [source seek:0 whence:SEEK_SET];
    }
    theDecoder = nil;
    return NO;
}

- (long)seek:(long)frame
{
    if ( theDecoder != nil ) return [theDecoder seek:frame];
    return -1;
}

- (void)close
{
    if ( theDecoder != nil ) {
        for (NSDictionary *obsItem in cachedObservers) {
            [theDecoder removeObserver:[obsItem objectForKey:@"observer"] forKeyPath:[obsItem objectForKey:@"keyPath"]];
        }
        [cachedObservers removeAllObjects];
        [theDecoder close];
        theDecoder = nil;
    }
}

- (BOOL)setTrack:(NSURL *)track
{
    if ( theDecoder != nil && [theDecoder respondsToSelector: @selector(setTrack:)] ) return [theDecoder setTrack:track];
    return NO;
}

/* By the current design, the core adds its observers to decoders before they are opened */
- (void)addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context
{
    if(context != nil) {
        [cachedObservers addObject:[NSDictionary dictionaryWithObjectsAndKeys:observer, @"observer", keyPath, @"keyPath", @(options), @"options", context, @"context", nil]];
    } else {
        [cachedObservers addObject:[NSDictionary dictionaryWithObjectsAndKeys:observer, @"observer", keyPath, @"keyPath", @(options), @"options", nil]];
    }
    if (theDecoder) {
        [theDecoder addObserver:observer forKeyPath:keyPath options:options context:context];
    }
}

/* And this is currently called after the decoder is closed */
- (void)removeObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath
{
    for (NSDictionary *obsItem in cachedObservers) {
        if ([obsItem objectForKey:@"observer"] == observer && [keyPath isEqualToString:[obsItem objectForKey:@"keyPath"]]) {
            [cachedObservers removeObject:obsItem];
            break;
        }
    }
    if (theDecoder) {
        [theDecoder removeObserver:observer forKeyPath:keyPath];
    }
}


@end

@implementation CogContainerMulti

+ (NSArray *)urlsForContainerURL:(NSURL *)url containers:(NSArray *)containers
{
    NSArray * sortedContainers = sortClassesByPriority(containers);
    for (NSString *classString in sortedContainers)
    {
        Class container = NSClassFromString(classString);
        NSArray * urls = [container urlsForContainerURL:url];
        if ([urls count])
            return urls;
    }
    return nil;
}

@end

@implementation CogMetadataReaderMulti

+ (NSDictionary *)metadataForURL:(NSURL *)url readers:(NSArray *)readers
{
    NSArray * sortedReaders = sortClassesByPriority(readers);
    for (NSString *classString in sortedReaders)
    {
        Class reader = NSClassFromString(classString);
        NSDictionary * data = [reader metadataForURL:url];
        if ([data count])
            return data;
    }
    return nil;
}

@end

@implementation CogPropertiesReaderMulti

+ (NSDictionary *)propertiesForSource:(id<CogSource>)source readers:(NSArray *)readers
{
    NSArray * sortedReaders = sortClassesByPriority(readers);
    for (NSString *classString in sortedReaders)
    {
        Class reader = NSClassFromString(classString);
        NSDictionary * data = [reader propertiesForSource:source];
        if ([data count])
            return data;
        if ([source seekable])
            [source seek:0 whence:SEEK_SET];
    }
    return nil;
}

@end