/*
 * This file is part of the SDWebImage package.
 * (c) Olivier Poitrey <rs@dailymotion.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

#import "SDWebImageDownloaderOperation.h"
#import "SDWebImageDecoder.h"
#import "UIImage+MultiFormat.h"
#import <ImageIO/ImageIO.h>

@interface SDWebImageDownloaderOperation ()
{
}

@property (copy, nonatomic) SDWebImageDownloaderProgressBlock progressBlock;
@property (copy, nonatomic) SDWebImageDownloaderCompletedBlock completedBlock;
@property (copy, nonatomic) void (^cancelBlock)();

@property (assign, nonatomic, getter = isExecuting) BOOL executing;
@property (assign, nonatomic, getter = isFinished) BOOL finished;
@property (assign, nonatomic) NSInteger expectedSize;
@property (strong, nonatomic) NSMutableData *imageData;
@property (strong, nonatomic) NSURLConnection *connection;
@property (strong, atomic) NSThread *thread;

#if TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
@property (assign, nonatomic) UIBackgroundTaskIdentifier backgroundTaskId;
#endif

@end

@implementation SDWebImageDownloaderOperation {
    size_t width, height;
    BOOL responseFromCached;
}
@synthesize executing = _executing;
@synthesize finished = _finished;

- (id)initWithRequest:(NSURLRequest *)request options:(SDWebImageDownloaderOptions)options progress:(void (^)(NSInteger, NSInteger))progressBlock completed:(void (^)(UIImage *, NSData *, NSError *, BOOL))completedBlock cancelled:(void (^)())cancelBlock {
    if ((self = [super init])) {
        _request = request;
        _options = options;
        _progressBlock = [progressBlock copy];
        _completedBlock = [completedBlock copy];
        _cancelBlock = [cancelBlock copy];
        _executing = NO;
        _finished = NO;
        _expectedSize = 0;
        responseFromCached = YES; // Initially wrong until `connection:willCacheResponse:` is called or not called
    }
    return self;
}

- (void)start {
    @synchronized (self) {
        if (self.isCancelled) {
            self.finished = YES;
            [self reset];
            return;
        }

#if TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
        if ([self shouldContinueWhenAppEntersBackground]) {
            __weak __typeof__ (self) wself = self;
            self.backgroundTaskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
                __strong __typeof (wself) sself = wself;

                if (sself) {
                    [sself cancel];

                    [[UIApplication sharedApplication] endBackgroundTask:sself.backgroundTaskId];
                    sself.backgroundTaskId = UIBackgroundTaskInvalid;
                }
            }];
        }
#endif

        self.executing = YES;
        self.connection = [[NSURLConnection alloc] initWithRequest:self.request delegate:self startImmediately:NO];
        self.thread = [NSThread currentThread];
    }

    [self.connection start];

    if (self.connection) {
        if (self.progressBlock) {
            self.progressBlock(0, NSURLResponseUnknownLength);
        }
        [[NSNotificationCenter defaultCenter] postNotificationName:SDWebImageDownloadStartNotification object:self];

        if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_5_1) {
            // Make sure to run the runloop in our background thread so it can process downloaded data
            // Note: we use a timeout to work around an issue with NSURLConnection cancel under iOS 5
            //       not waking up the runloop, leading to dead threads (see https://github.com/rs/SDWebImage/issues/466)
            CFRunLoopRunInMode(kCFRunLoopDefaultMode, 10, false);
        }
        else {
            CFRunLoopRun();
        }

        if (!self.isFinished) {
            [self.connection cancel];
            [self connection:self.connection didFailWithError:[NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorTimedOut userInfo:@{NSURLErrorFailingURLErrorKey : self.request.URL}]];
        }
    }
    else {
        if (self.completedBlock) {
            self.completedBlock(nil, nil, [NSError errorWithDomain:NSURLErrorDomain code:0 userInfo:@{NSLocalizedDescriptionKey : @"Connection can't be initialized"}], YES);
        }
    }
}

- (void)cancel {
    @synchronized (self) {
        if (self.thread) {
            [self performSelector:@selector(cancelInternalAndStop) onThread:self.thread withObject:nil waitUntilDone:NO];
        }
        else {
            [self cancelInternal];
        }
    }
}

- (void)cancelInternalAndStop {
    [self cancelInternal];
    CFRunLoopStop(CFRunLoopGetCurrent());
}

- (void)cancelInternal {
    if (self.isFinished) return;
    [super cancel];
    if (self.cancelBlock) self.cancelBlock();

    if (self.connection) {
        [self.connection cancel];
        [[NSNotificationCenter defaultCenter] postNotificationName:SDWebImageDownloadStopNotification object:self];

        // As we cancelled the connection, its callback won't be called and thus won't
        // maintain the isFinished and isExecuting flags.
        if (self.isExecuting) self.executing = NO;
        if (!self.isFinished) self.finished = YES;
    }

    [self reset];
}

- (void)done {
    self.finished = YES;
    self.executing = NO;
    [self reset];
}

- (void)reset {
    self.cancelBlock = nil;
    self.completedBlock = nil;
    self.progressBlock = nil;
    self.connection = nil;
    self.imageData = nil;
    self.thread = nil;
}

- (void)setFinished:(BOOL)finished {
    [self willChangeValueForKey:@"isFinished"];
    _finished = finished;
    [self didChangeValueForKey:@"isFinished"];
}

- (void)setExecuting:(BOOL)executing {
    [self willChangeValueForKey:@"isExecuting"];
    _executing = executing;
    [self didChangeValueForKey:@"isExecuting"];
}

- (BOOL)isConcurrent {
    return YES;
}

#pragma mark NSURLConnection (delegate)

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    if (![response respondsToSelector:@selector(statusCode)] || [((NSHTTPURLResponse *)response) statusCode] < 400) {
        NSInteger expected = response.expectedContentLength > 0 ? (NSInteger)response.expectedContentLength : 0;
        self.expectedSize = expected;
        if (self.progressBlock) {
            self.progressBlock(0, expected);
        }

        self.imageData = [[NSMutableData alloc] initWithCapacity:expected];
    }
    else {
        [self.connection cancel];

        [[NSNotificationCenter defaultCenter] postNotificationName:SDWebImageDownloadStopNotification object:nil];

        if (self.completedBlock) {
            self.completedBlock(nil, nil, [NSError errorWithDomain:NSURLErrorDomain code:[((NSHTTPURLResponse *)response) statusCode] userInfo:nil], YES);
        }

        [self done];
    }
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.imageData appendData:data];

    if ((self.options & SDWebImageDownloaderProgressiveDownload) && self.expectedSize > 0 && self.completedBlock) {
        // The following code is from http://www.cocoaintheshell.com/2011/05/progressive-images-download-imageio/
        // Thanks to the author @Nyx0uf

        // Get the total bytes downloaded
        const NSInteger totalSize = self.imageData.length;

        // Update the data source, we must pass ALL the data, not just the new bytes
        CGImageSourceRef imageSource = CGImageSourceCreateIncremental(NULL);
        CGImageSourceUpdateData(imageSource, (__bridge CFDataRef)self.imageData, totalSize == self.expectedSize);

        if (width + height == 0) {
            CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(imageSource, 0, NULL);
            if (properties) {
                CFTypeRef val = CFDictionaryGetValue(properties, kCGImagePropertyPixelHeight);
                if (val) CFNumberGetValue(val, kCFNumberLongType, &height);
                val = CFDictionaryGetValue(properties, kCGImagePropertyPixelWidth);
                if (val) CFNumberGetValue(val, kCFNumberLongType, &width);
                CFRelease(properties);
            }
        }

        if (width + height > 0 && totalSize < self.expectedSize) {
            // Create the image
            CGImageRef partialImageRef = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL);

#ifdef TARGET_OS_IPHONE
            // Workaround for iOS anamorphic image
            if (partialImageRef) {
                const size_t partialHeight = CGImageGetHeight(partialImageRef);
                CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
                CGContextRef bmContext = CGBitmapContextCreate(NULL, width, height, 8, width * 4, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
                CGColorSpaceRelease(colorSpace);
                if (bmContext) {
                    CGContextDrawImage(bmContext, (CGRect){.origin.x = 0.0f, .origin.y = 0.0f, .size.width = width, .size.height = partialHeight}, partialImageRef);
                    CGImageRelease(partialImageRef);
                    partialImageRef = CGBitmapContextCreateImage(bmContext);
                    CGContextRelease(bmContext);
                }
                else {
                    CGImageRelease(partialImageRef);
                    partialImageRef = nil;
                }
            }
#endif

            if (partialImageRef) {
                UIImage *image = [UIImage imageWithCGImage:partialImageRef];
                UIImage *scaledImage = [self scaledImageForKey:self.request.URL.absoluteString image:image];
                image = [UIImage decodedImageWithImage:scaledImage];
                CGImageRelease(partialImageRef);
                dispatch_main_sync_safe(^{
                    if (self.completedBlock) {
                        self.completedBlock(image, nil, nil, NO);
                    }
                });
            }
        }

        CFRelease(imageSource);
    }

    if (self.progressBlock) {
        self.progressBlock(self.imageData.length, self.expectedSize);
    }
}

- (UIImage *)scaledImageForKey:(NSString *)key image:(UIImage *)image {
    return SDScaledImageForKey(key, image);
}

- (void)connectionDidFinishLoading:(NSURLConnection *)aConnection {
    CFRunLoopStop(CFRunLoopGetCurrent());
    self.connection = nil;

    [[NSNotificationCenter defaultCenter] postNotificationName:SDWebImageDownloadStopNotification object:nil];

    SDWebImageDownloaderCompletedBlock completionBlock = self.completedBlock;

    if (completionBlock) {
        if (self.options & SDWebImageDownloaderIgnoreCachedResponse && responseFromCached) {
            completionBlock(nil, nil, nil, YES);
            self.completionBlock = nil;
            [self done];
        }
        else {

            UIImage *image = [UIImage sd_imageWithData:self.imageData];

            image = [self scaledImageForKey:self.request.URL.absoluteString image:image];

            if (!image.images) // Do not force decod animated GIFs
            {
                image = [UIImage decodedImageWithImage:image];
            }

            if (CGSizeEqualToSize(image.size, CGSizeZero)) {
                completionBlock(nil, nil, [NSError errorWithDomain:@"SDWebImageErrorDomain" code:0 userInfo:@{NSLocalizedDescriptionKey : @"Downloaded image has 0 pixels"}], YES);
            }
            else {
                completionBlock(image, self.imageData, nil, YES);
            }
            self.completionBlock = nil;
            [self done];
        }
    }
    else {
        [self done];
    }
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    CFRunLoopStop(CFRunLoopGetCurrent());
    [[NSNotificationCenter defaultCenter] postNotificationName:SDWebImageDownloadStopNotification object:nil];

    if (self.completedBlock) {
        self.completedBlock(nil, nil, error, YES);
    }

    [self done];
}

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
    responseFromCached = NO; // If this method is called, it means the response wasn't read from cache
    if (self.request.cachePolicy == NSURLRequestReloadIgnoringLocalCacheData) {
        // Prevents caching of responses
        return nil;
    }
    else {
        return cachedResponse;
    }
}

- (BOOL)shouldContinueWhenAppEntersBackground {
    return self.options & SDWebImageDownloaderContinueInBackground;
}

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
    return [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];
}

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    BOOL trustAllCertificates = (self.options & SDWebImageDownloaderAllowInvalidSSLCertificates);
    if (trustAllCertificates && [challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
        [challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust]
             forAuthenticationChallenge:challenge];
    }

    [challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
}

@end