/*

     File: Fetcher.m

 Abstract: 

  Version: 1.0

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 redistribute this Apple software.

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 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

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 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

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 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

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 Copyright (C) 2012 Apple Inc. All Rights Reserved.

 */

#import "Fetcher.h"

@implementation Fetcher

- (void)fetchURL:(NSURL *)url withReply:(void (^)(NSFileHandle *, NSError *))reply {

    if (![[url scheme] isEqualToString:@"http"]) {

        reply(nil, [NSError errorWithDomain:NSPOSIXErrorDomain code:EINVAL userInfo:@{NSLocalizedDescriptionKey : @"Invalid URL"}]);

        return;

    }

    // We'll call back this reply block later. If this were a manual retain/release application, it is required to use 'copy' on this block to make sure it sticks around long enough for us to call it. This is compiled with ARC though, so the compiler will take care of it for us when we do this assignment.

    replyBlock = reply;

    // This object will hold the downloaded data.

    receivedData = [NSMutableData new];

    NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0];

    NSOperationQueue *queue = [NSOperationQueue new];

    urlConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO];

    // By assigning a delegate queue here, NSURLConnection will use dispatch queues instead of relying on a CFRunLoop being present in the current thread. Since this code is executing in a serial queue provided by NSXPCConnection, this is required.

    [urlConnection setDelegateQueue:queue];

    [urlConnection start];

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {

    [receivedData setLength:0];

    expectedSize = [response expectedContentLength];

}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {

    [receivedData appendData:data];

    // Send progress update to other side. The NSXPCListenerDelegate configured the connection to implement the 'FetchProgress' protocol, so we'll send the progress update message through the connection's remoteObjectProxy.

    double progress = ([receivedData length] / (double)expectedSize) * 100.0;

    [[self.xpcConnection remoteObjectProxy] setProgress:progress];

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {

    // Call back the other side's reply block with the error.

    receivedData = nil;

    replyBlock(nil, error);

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

    // Open a temporary file in the temp directory of the container.

    char *tempname;

    if (asprintf(&tempname, "%sfetch.XXXXXXXX", [NSTemporaryDirectory() fileSystemRepresentation]) < 0) {

        replyBlock(nil, [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:@{NSLocalizedDescriptionKey : @"Couldn't get temporary file name"}]);

        return;

    }

    int tempFileFD = -1;

    if ((tempFileFD = mkstemp(tempname)) < 0) {

        free(tempname);

        replyBlock(nil, [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:@{NSLocalizedDescriptionKey : @"Couldn't open temporary file"}]);

    }

    // Unlink the file so it is removed as soon as it is closed.

    (void)unlink(tempname);

    free(tempname);

    // Write the data to the file, and seek to the beginning. Hand ownership of the fd to NSFileHandle.

    NSFileHandle *outFile = [[NSFileHandle alloc] initWithFileDescriptor:tempFileFD closeOnDealloc:YES];

    [outFile writeData:receivedData];

    [outFile seekToFileOffset:0];

    // Clear out our received data, then send the file handle back to the main process.

    receivedData = nil;

    replyBlock(outFile, nil);

}

@end