//
//  JSbdecoder.m
//  BitMaster
//
//  Created by Jon Shier on 4/9/07.
//  Copyright 2007 __MyCompanyName__. All rights reserved.
//
#import "JSbdecoder.h"
 
@implementation JSbdecoder
 
- (NSDictionary *) decodeTorrentFile: (NSString *) pathToTorrentFile {
    torrentData = [NSData dataWithContentsOfFile: pathToTorrentFile options: NSUncachedRead error: nil];
    rawTorrentData = [torrentData bytes];
    position = 0;
 
    return [self convertObjectDataToStrings:[[self bdecodeData] objectAtIndex: 0]];
}
 
- (NSArray *) bdecodeData {
    NSMutableArray *methodArray = [NSMutableArray array];
    do {
        if(rawTorrentData[position] == 'i') {
            position++;
            [methodArray addObject:[self decodeInt]];
        } else if(rawTorrentData[position] == 'l') {
            position++;
            [methodArray addObject:[self decodeList]];
        } else if(rawTorrentData[position] == 'd') {
            position++;
            [methodArray addObject:[self decodeDictionary]];
        } else if(isdigit(rawTorrentData[position])) {
            [methodArray addObject:[self decodeBytes]];
        } else if(rawTorrentData[position] == 'e') {
            position++;
            //Should only hit this when at the end of lists, dictionaries, or integers.
            break;
        } else {
            NSLog(@"Error decoding torrent. Unexpected character '%c' at position %d.", rawTorrentData[position], position);
            return methodArray;
        }
    } while (position < [torrentData length]);
 
    return methodArray;
}
 
- (NSNumber *) decodeInt {
    NSUInteger methodPosition = position;
    while(rawTorrentData[position] != 'e') {
       position++;
    }
    position++;
    return [NSNumber numberWithInteger: [[NSString stringWithUTF8String: [[torrentData subdataWithRange: NSMakeRange(methodPosition, (position - methodPosition))] bytes]] integerValue]];
}
 
- (NSData *) decodeBytes {
    NSUInteger methodPosition = position;
    while(rawTorrentData[position] != ':') {
        position++;
    }
    NSUInteger bytesLength = [[NSString stringWithUTF8String: [[torrentData subdataWithRange: NSMakeRange(methodPosition, (position - methodPosition))] bytes]] integerValue];
    position++;
    methodPosition = position;
    position += bytesLength;
 
    return [torrentData subdataWithRange: NSMakeRange(methodPosition, bytesLength)];
}
 
- (NSArray *) decodeList {
    return [self bdecodeData];
}
 
- (NSDictionary *) decodeDictionary {
    NSMutableDictionary *methodDictionary = [NSMutableDictionary dictionary];
    NSArray *methodArray = [NSArray arrayWithArray:[self bdecodeData]];
    for(NSUInteger i = 0; i < [methodArray count]; i += 2) {
        [methodDictionary setObject: [methodArray objectAtIndex: i + 1] forKey: [methodArray objectAtIndex: i]];
    }
 
    return methodDictionary;
}
 
- (id) convertObjectDataToStrings: (id) object {
    if ([object conformsToProtocol: @protocol(NSFastEnumeration)]) {
        NSMutableArray *valueArray = [NSMutableArray array];
        if ([object isKindOfClass: [NSArray class]]) {
            for (id enumeratedObject in object) {
                [valueArray addObject: [self convertObjectDataToStrings: enumeratedObject]];
            }
            return valueArray;
        } else if ([object isKindOfClass: [NSDictionary class]]) {
            valueArray = [[object allValues] mutableCopy];
            NSMutableArray *keyArray = [NSMutableArray arrayWithArray: [object allKeys]];
            for (NSUInteger i = 0; i < [keyArray count]; i++) {
                [keyArray replaceObjectAtIndex: i withObject: [self convertObjectDataToStrings: [keyArray objectAtIndex: i]]];
            }
            for (NSUInteger i = 0; i < [valueArray count]; i++) {
                if (![[keyArray objectAtIndex: i] isEqualToString: @"pieces"]) {
                    [valueArray replaceObjectAtIndex: i withObject: [self convertObjectDataToStrings: [valueArray objectAtIndex: i]]];
                }
            }
            return [NSDictionary dictionaryWithObjects: valueArray forKeys: keyArray];
        }
    } else if ([object isKindOfClass: [NSNumber class]]) {
        return object;
    } else if ([object isKindOfClass: [NSData class]]) {
        return [[NSString alloc] initWithBytes: [object bytes] length: [object length] encoding: NSUTF8StringEncoding];
    } else {
        NSLog(@"Unexpected object %@ of class %@", object, [object class]);
    }
    return object;
}
 
@end