#pragma mark - UIImage(YCHUD)
@interface UIImage (YCHUD)
+ (UIImage *)YCHUDImageWithSmallGIFData:(NSData *)data scale:(CGFloat)scale;
@end

#pragma mark - UIImage(YCHUD)
@implementation UIImage (YCHUD)
+ (UIImage *)YCHUDImageWithSmallGIFData:(NSData *)data scale:(CGFloat)scale {
    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFTypeRef)(data), NULL);
    if (!source) return nil;
    
    size_t count = CGImageSourceGetCount(source);
    if (count <= 1) {
        CFRelease(source);
        return [self.class imageWithData:data scale:scale];
    }
    
    NSUInteger frames[count];
    double oneFrameTime = 1 / 50.0; // 50 fps
    NSTimeInterval totalTime = 0;
    NSUInteger totalFrame = 0;
    NSUInteger gcdFrame = 0;
    for (size_t i = 0; i < count; i++) {
        NSTimeInterval delay = YCHUDCGImageSourceGetGIFFrameDelayAtIndex(source, i);
        totalTime += delay;
        NSInteger frame = lrint(delay / oneFrameTime);
        if (frame < 1) frame = 1;
        frames[i] = frame;
        totalFrame += frames[i];
        if (i == 0) gcdFrame = frames[i];
        else {
            NSUInteger frame = frames[i], tmp;
            if (frame < gcdFrame) {
                tmp = frame; frame = gcdFrame; gcdFrame = tmp;
            }
            while (true) {
                tmp = frame % gcdFrame;
                if (tmp == 0) break;
                frame = gcdFrame;
                gcdFrame = tmp;
            }
        }
    }
    NSMutableArray *array = [NSMutableArray new];
    for (size_t i = 0; i < count; i++) {
        CGImageRef imageRef = CGImageSourceCreateImageAtIndex(source, i, NULL);
        if (!imageRef) {
            CFRelease(source);
            return nil;
        }
        size_t width = CGImageGetWidth(imageRef);
        size_t height = CGImageGetHeight(imageRef);
        if (width == 0 || height == 0) {
            CFRelease(source);
            CFRelease(imageRef);
            return nil;
        }
        
        CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef) & kCGBitmapAlphaInfoMask;
        BOOL hasAlpha = NO;
        if (alphaInfo == kCGImageAlphaPremultipliedLast ||
            alphaInfo == kCGImageAlphaPremultipliedFirst ||
            alphaInfo == kCGImageAlphaLast ||
            alphaInfo == kCGImageAlphaFirst) {
            hasAlpha = YES;
        }
        // BGRA8888 (premultiplied) or BGRX8888
        // same as UIGraphicsBeginImageContext() and -[UIView drawRect:]
        CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host;
        bitmapInfo |= hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNoneSkipFirst;
        CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
        CGContextRef context = CGBitmapContextCreate(NULL, width, height, 8, 0, space, bitmapInfo);
        CGColorSpaceRelease(space);
        if (!context) {
            CFRelease(source);
            CFRelease(imageRef);
            return nil;
        }
        CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); // decode
        CGImageRef decoded = CGBitmapContextCreateImage(context);
        CFRelease(context);
        if (!decoded) {
            CFRelease(source);
            CFRelease(imageRef);
            return nil;
        }
        UIImage *image = [UIImage imageWithCGImage:decoded scale:scale orientation:UIImageOrientationUp];
        CGImageRelease(imageRef);
        CGImageRelease(decoded);
        if (!image) {
            CFRelease(source);
            return nil;
        }
        for (size_t j = 0, max = frames[i] / gcdFrame; j < max; j++) {
            [array addObject:image];
        }
    }
    CFRelease(source);
    UIImage *image = [self.class animatedImageWithImages:array duration:totalTime];
    return image;
}

static NSTimeInterval YCHUDCGImageSourceGetGIFFrameDelayAtIndex(CGImageSourceRef source, size_t index) {
    NSTimeInterval delay = 0;
    CFDictionaryRef dic = CGImageSourceCopyPropertiesAtIndex(source, index, NULL);
    if (dic) {
        CFDictionaryRef dicGIF = CFDictionaryGetValue(dic, kCGImagePropertyGIFDictionary);
        if (dicGIF) {
            NSNumber *num = CFDictionaryGetValue(dicGIF, kCGImagePropertyGIFUnclampedDelayTime);
            if (num.doubleValue <= __FLT_EPSILON__) {
                num = CFDictionaryGetValue(dicGIF, kCGImagePropertyGIFDelayTime);
            }
            delay = num.doubleValue;
        }
        CFRelease(dic);
    }
    
    if (delay < 0.02) delay = 0.1;
    return delay;
}
@end