VICacheConfiguration.m

//
//  VICacheConfiguration.m
//  VIMediaCacheDemo
//
//  Created by Vito on 4/21/16.
//  Copyright © 2016 Vito. All rights reserved.
//

#import "VICacheConfiguration.h"
#import "VICacheManager.h"
#import <MobileCoreServices/MobileCoreServices.h>

static NSString *kFileNameKey = @"kFileNameKey";
static NSString *kCacheFragmentsKey = @"kCacheFragmentsKey";
static NSString *kDownloadInfoKey = @"kDownloadInfoKey";
static NSString *kContentInfoKey = @"kContentInfoKey";
static NSString *kURLKey = @"kURLKey";

@interface VICacheConfiguration () <NSCoding>

@property (nonatomic, copy) NSString *filePath;
@property (nonatomic, copy) NSString *fileName;
@property (nonatomic, copy) NSArray<NSValue *> *internalCacheFragments;
@property (nonatomic, copy) NSArray *downloadInfo;

@end

@implementation VICacheConfiguration

+ (instancetype)configurationWithFilePath:(NSString *)filePath {
    filePath = [self configurationFilePathForFilePath:filePath];
    VICacheConfiguration *configuration = [NSKeyedUnarchiver unarchiveObjectWithFile:filePath];
    
    if (!configuration) {
        configuration = [[VICacheConfiguration alloc] init];
        configuration.fileName = [filePath lastPathComponent];
    }
    configuration.filePath = filePath;
    
    return configuration;
}

+ (NSString *)configurationFilePathForFilePath:(NSString *)filePath {
    return [filePath stringByAppendingPathExtension:@"mt_cfg"];
}

- (NSArray<NSValue *> *)internalCacheFragments {
    if (!_internalCacheFragments) {
        _internalCacheFragments = [NSArray array];
    }
    return _internalCacheFragments;
}

- (NSArray *)downloadInfo {
    if (!_downloadInfo) {
        _downloadInfo = [NSArray array];
    }
    return _downloadInfo;
}

- (NSArray<NSValue *> *)cacheFragments {
    return [_internalCacheFragments copy];
}

- (float)progress {
    float progress = self.downloadedBytes / (float)self.contentInfo.contentLength;
    return progress;
}

- (long long)downloadedBytes {
    float bytes = 0;
    @synchronized (self.internalCacheFragments) {
        for (NSValue *range in self.internalCacheFragments) {
            bytes += range.rangeValue.length;
        }
    }
    return bytes;
}

- (float)downloadSpeed {
    long long bytes = 0;
    NSTimeInterval time = 0;
    @synchronized (self.downloadInfo) {
        for (NSArray *a in self.downloadInfo) {
            bytes += [[a firstObject] longLongValue];
            time += [[a lastObject] doubleValue];
        }
    }
    return bytes / 1024.0 / time;
}

#pragma mark - NSCoding

- (void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.fileName forKey:kFileNameKey];
    [aCoder encodeObject:self.internalCacheFragments forKey:kCacheFragmentsKey];
    [aCoder encodeObject:self.downloadInfo forKey:kDownloadInfoKey];
    [aCoder encodeObject:self.contentInfo forKey:kContentInfoKey];
    [aCoder encodeObject:self.url forKey:kURLKey];
}

- (nullable instancetype)initWithCoder:(NSCoder *)aDecoder {
    self = [super init];
    if (self) {
        _fileName = [aDecoder decodeObjectForKey:kFileNameKey];
        _internalCacheFragments = [[aDecoder decodeObjectForKey:kCacheFragmentsKey] mutableCopy];
        if (!_internalCacheFragments) {
            _internalCacheFragments = [NSArray array];
        }
        _downloadInfo = [aDecoder decodeObjectForKey:kDownloadInfoKey];
        _contentInfo = [aDecoder decodeObjectForKey:kContentInfoKey];
        _url = [aDecoder decodeObjectForKey:kURLKey];
    }
    return self;
}

#pragma mark - NSCopying

- (id)copyWithZone:(nullable NSZone *)zone {
    VICacheConfiguration *configuration = [[VICacheConfiguration allocWithZone:zone] init];
    configuration.fileName = self.fileName;
    configuration.filePath = self.filePath;
    configuration.internalCacheFragments = self.internalCacheFragments;
    configuration.downloadInfo = self.downloadInfo;
    configuration.url = self.url;
    configuration.contentInfo = self.contentInfo;
    
    return configuration;
}

#pragma mark - Update

- (void)save {
    @synchronized (self.internalCacheFragments) {
        [NSKeyedArchiver archiveRootObject:self toFile:self.filePath];
    }
}

- (void)addCacheFragment:(NSRange)fragment {
    if (fragment.location == NSNotFound || fragment.length == 0) {
        return;
    }
    
    @synchronized (self.internalCacheFragments) {
        NSMutableArray *internalCacheFragments = [self.internalCacheFragments mutableCopy];
        
        NSValue *fragmentValue = [NSValue valueWithRange:fragment];
        NSInteger count = self.internalCacheFragments.count;
        if (count == 0) {
            [internalCacheFragments addObject:fragmentValue];
        } else {
            NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSet];
            [internalCacheFragments enumerateObjectsUsingBlock:^(NSValue * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
                NSRange range = obj.rangeValue;
                if ((fragment.location + fragment.length) <= range.location) {
                    if (indexSet.count == 0) {
                        [indexSet addIndex:idx];
                    }
                    *stop = YES;
                } else if (fragment.location <= (range.location + range.length) && (fragment.location + fragment.length) > range.location) {
                    [indexSet addIndex:idx];
                } else if (fragment.location >= range.location + range.length) {
                    if (idx == count - 1) { // Append to last index
                        [indexSet addIndex:idx];
                    }
                }
            }];
            
            if (indexSet.count > 1) {
                NSRange firstRange = self.internalCacheFragments[indexSet.firstIndex].rangeValue;
                NSRange lastRange = self.internalCacheFragments[indexSet.lastIndex].rangeValue;
                NSInteger location = MIN(firstRange.location, fragment.location);
                NSInteger endOffset = MAX(lastRange.location + lastRange.length, fragment.location + fragment.length);
                NSRange combineRange = NSMakeRange(location, endOffset - location);
                [internalCacheFragments removeObjectsAtIndexes:indexSet];
                [internalCacheFragments insertObject:[NSValue valueWithRange:combineRange] atIndex:indexSet.firstIndex];
            } else if (indexSet.count == 1) {
                NSRange firstRange = self.internalCacheFragments[indexSet.firstIndex].rangeValue;
                
                NSRange expandFirstRange = NSMakeRange(firstRange.location, firstRange.length + 1);
                NSRange expandFragmentRange = NSMakeRange(fragment.location, fragment.length + 1);
                NSRange intersectionRange = NSIntersectionRange(expandFirstRange, expandFragmentRange);
                if (intersectionRange.length > 0) { // Should combine
                    NSInteger location = MIN(firstRange.location, fragment.location);
                    NSInteger endOffset = MAX(firstRange.location + firstRange.length, fragment.location + fragment.length);
                    NSRange combineRange = NSMakeRange(location, endOffset - location);
                    [internalCacheFragments removeObjectAtIndex:indexSet.firstIndex];
                    [internalCacheFragments insertObject:[NSValue valueWithRange:combineRange] atIndex:indexSet.firstIndex];
                } else {
                    if (firstRange.location > fragment.location) {
                        [internalCacheFragments insertObject:fragmentValue atIndex:[indexSet lastIndex]];
                    } else {
                        [internalCacheFragments insertObject:fragmentValue atIndex:[indexSet lastIndex] + 1];
                    }
                }
            }
        }
        
        self.internalCacheFragments = [internalCacheFragments copy];
    }
}

- (void)addDownloadedBytes:(long long)bytes spent:(NSTimeInterval)time {
    @synchronized (self.downloadInfo) {
        self.downloadInfo = [self.downloadInfo arrayByAddingObject:@[@(bytes), @(time)]];
    }
}

@end

@implementation VICacheConfiguration (VIConvenient)

+ (BOOL)createAndSaveDownloadedConfigurationForURL:(NSURL *)url error:(NSError **)error {
    NSString *filePath = [VICacheManager cachedFilePathForURL:url];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSDictionary<NSFileAttributeKey, id> *attributes = [fileManager attributesOfItemAtPath:filePath error:error];
    if (!attributes) {
        return NO;
    }
    
    long long fileSize = attributes.fileSize;
    NSRange range = NSMakeRange(0, fileSize);
    
    VICacheConfiguration *configuration = [VICacheConfiguration configurationWithFilePath:filePath];
    configuration.url = url;
    
    VIContentInfo *contentInfo = [VIContentInfo new];
    
    NSString *fileExtension = [url pathExtension];
    NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)fileExtension, NULL);
    NSString *contentType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)UTI, kUTTagClassMIMEType);
    if (!contentType) {
        contentType = @"application/octet-stream";
    }
    contentInfo.contentType = contentType;
    
    contentInfo.contentLength = fileSize;
    contentInfo.byteRangeAccessSupported = YES;
    contentInfo.downloadedContentLength = fileSize;
    configuration.contentInfo = contentInfo;
    
    [configuration addCacheFragment:range];
    [configuration save];
    
    return YES;
}

@end