/*

    File:       QHTTPOperation.m

    Contains:   An NSOperation that runs an HTTP request.

    Written by: DTS

    Copyright:  Copyright (c) 2010 Apple Inc. All Rights Reserved.

    Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc.

                ("Apple") in consideration of your agreement to the following

                terms, and your use, installation, modification or

                redistribution of this Apple software constitutes acceptance of

                these terms.  If you do not agree with these terms, please do

                not use, install, modify or redistribute this Apple software.

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                terms, and subject to these terms, Apple grants you a personal,

                non-exclusive license, under Apple's copyrights in this

                original Apple software (the "Apple Software"), to use,

                reproduce, modify and redistribute the Apple Software, with or

                without modifications, in source and/or binary forms; provided

                that if you redistribute the Apple Software in its entirety and

                without modifications, you must retain this notice and the

                following text and disclaimers in all such redistributions of

                the Apple Software. 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 implied,

                are granted by Apple herein, including but not limited to any

                patent rights that may be infringed by your derivative works or

                by other works in which the Apple Software may be incorporated.

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

                APPLE MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING

                WITHOUT LIMITATION THE IMPLIED WARRANTIES OF NON-INFRINGEMENT,

                MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, REGARDING

                THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN

                COMBINATION WITH YOUR PRODUCTS.

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

                INCIDENTAL OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED

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*/

#import "QHTTPOperation.h"

@interface QHTTPOperation ()

// Read/write versions of public properties

@property (copy,   readwrite) NSURLRequest *        lastRequest;

@property (copy,   readwrite) NSHTTPURLResponse *   lastResponse;

// Internal properties

@property (retain, readwrite) NSURLConnection *     connection;

@property (assign, readwrite) BOOL                  firstData;

@property (retain, readwrite) NSMutableData *       dataAccumulator;

#if ! defined(NDEBUG)

@property (retain, readwrite) NSTimer *             debugDelayTimer;

#endif

@end

@implementation QHTTPOperation

#pragma mark * Initialise and finalise

- (id)initWithRequest:(NSURLRequest *)request

    // See comment in header.

{

    // any thread

    assert(request != nil);

    assert([request URL] != nil);

    // Because we require an NSHTTPURLResponse, we only support HTTP and HTTPS URLs.

    assert([[[[request URL] scheme] lowercaseString] isEqual:@"http"] || [[[[request URL] scheme] lowercaseString] isEqual:@"https"]);

    self = [super init];

    if (self != nil) {

        #if TARGET_OS_EMBEDDED || TARGET_IPHONE_SIMULATOR

            static const NSUInteger kPlatformReductionFactor = 4;

        #else

            static const NSUInteger kPlatformReductionFactor = 1;

        #endif

        self->_request = [request copy];

        self->_defaultResponseSize = 1 * 1024 * 1024 / kPlatformReductionFactor;

        self->_maximumResponseSize = 4 * 1024 * 1024 / kPlatformReductionFactor;

        self->_firstData = YES;

    }

    return self;

}

- (id)initWithURL:(NSURL *)url

    // See comment in header.

{

    assert(url != nil);

    return [self initWithRequest:[NSURLRequest requestWithURL:url]];

}

- (void)dealloc

{

    #if ! defined(NDEBUG)

        [self->_debugError release];

        [self->_debugDelayTimer invalidate];

        [self->_debugDelayTimer release];

    #endif

    // any thread

    [self->_request release];

    [self->_acceptableStatusCodes release];

    [self->_acceptableContentTypes release];

    [self->_responseOutputStream release];

    assert(self->_connection == nil);               // should have been shut down by now

    [self->_dataAccumulator release];

    [self->_lastRequest release];

    [self->_lastResponse release];

    [self->_responseBody release];

    [super dealloc];

}

#pragma mark * Properties

// We write our own settings for many properties because we want to bounce 

// sets that occur in the wrong state.  And, given that we've written the 

// setter anyway, we also avoid KVO notifications when the value doesn't change.

@synthesize request = _request;

@synthesize authenticationDelegate = _authenticationDelegate;

+ (BOOL)automaticallyNotifiesObserversOfAuthenticationDelegate

{

    return NO;

}

- (id<QHTTPOperationAuthenticationDelegate>)authenticationDelegate

{

    return self->_authenticationDelegate;

}

- (void)setAuthenticationDelegate:(id<QHTTPOperationAuthenticationDelegate>)newValue

{

    if (self.state != kQRunLoopOperationStateInited) {

        assert(NO);

    } else {

        if (newValue != self->_authenticationDelegate) {

            [self willChangeValueForKey:@"authenticationDelegate"];

            self->_authenticationDelegate = newValue;

            [self didChangeValueForKey:@"authenticationDelegate"];

        }

    }

}

@synthesize acceptableStatusCodes = _acceptableStatusCodes;

+ (BOOL)automaticallyNotifiesObserversOfAcceptableStatusCodes

{

    return NO;

}

- (NSIndexSet *)acceptableStatusCodes

{

    return [[self->_acceptableStatusCodes retain] autorelease];

}

- (void)setAcceptableStatusCodes:(NSIndexSet *)newValue

{

    if (self.state != kQRunLoopOperationStateInited) {

        assert(NO);

    } else {

        if (newValue != self->_acceptableStatusCodes) {

            [self willChangeValueForKey:@"acceptableStatusCodes"];

            [self->_acceptableStatusCodes autorelease];

            self->_acceptableStatusCodes = [newValue copy];

            [self didChangeValueForKey:@"acceptableStatusCodes"];

        }

    }

}

@synthesize acceptableContentTypes = _acceptableContentTypes;

+ (BOOL)automaticallyNotifiesObserversOfAcceptableContentTypes

{

    return NO;

}

- (NSSet *)acceptableContentTypes

{

    return [[self->_acceptableContentTypes retain] autorelease];

}

- (void)setAcceptableContentTypes:(NSSet *)newValue

{

    if (self.state != kQRunLoopOperationStateInited) {

        assert(NO);

    } else {

        if (newValue != self->_acceptableContentTypes) {

            [self willChangeValueForKey:@"acceptableContentTypes"];

            [self->_acceptableContentTypes autorelease];

            self->_acceptableContentTypes = [newValue copy];

            [self didChangeValueForKey:@"acceptableContentTypes"];

        }

    }

}

@synthesize responseOutputStream = _responseOutputStream;

+ (BOOL)automaticallyNotifiesObserversOfResponseOutputStream

{

    return NO;

}

- (NSOutputStream *)responseOutputStream

{

    return [[self->_responseOutputStream retain] autorelease];

}

- (void)setResponseOutputStream:(NSOutputStream *)newValue

{

    if (self.dataAccumulator != nil) {

        assert(NO);

    } else {

        if (newValue != self->_responseOutputStream) {

            [self willChangeValueForKey:@"responseOutputStream"];

            [self->_responseOutputStream autorelease];

            self->_responseOutputStream = [newValue retain];

            [self didChangeValueForKey:@"responseOutputStream"];

        }

    }

}

@synthesize defaultResponseSize   = _defaultResponseSize;

+ (BOOL)automaticallyNotifiesObserversOfDefaultResponseSize

{

    return NO;

}

- (NSUInteger)defaultResponseSize

{

    return self->_defaultResponseSize;

}

- (void)setDefaultResponseSize:(NSUInteger)newValue

{

    if (self.dataAccumulator != nil) {

        assert(NO);

    } else {

        if (newValue != self->_defaultResponseSize) {

            [self willChangeValueForKey:@"defaultResponseSize"];

            self->_defaultResponseSize = newValue;

            [self didChangeValueForKey:@"defaultResponseSize"];

        }

    }

}

@synthesize maximumResponseSize = _maximumResponseSize;

+ (BOOL)automaticallyNotifiesObserversOfMaximumResponseSize

{

    return NO;

}

- (NSUInteger)maximumResponseSize

{

    return self->_maximumResponseSize;

}

- (void)setMaximumResponseSize:(NSUInteger)newValue

{

    if (self.dataAccumulator != nil) {

        assert(NO);

    } else {

        if (newValue != self->_maximumResponseSize) {

            [self willChangeValueForKey:@"maximumResponseSize"];

            self->_maximumResponseSize = newValue;

            [self didChangeValueForKey:@"maximumResponseSize"];

        }

    }

}

@synthesize lastRequest     = _lastRequest;

@synthesize lastResponse    = _lastResponse;

@synthesize responseBody    = _responseBody;

@synthesize connection      = _connection;

@synthesize firstData       = _firstData;

@synthesize dataAccumulator = _dataAccumulator;

- (NSURL *)URL

{

    return [self.request URL];

}

- (BOOL)isStatusCodeAcceptable

{

    NSIndexSet *    acceptableStatusCodes;

    NSInteger       statusCode;

    assert(self.lastResponse != nil);

    acceptableStatusCodes = self.acceptableStatusCodes;

    if (acceptableStatusCodes == nil) {

        acceptableStatusCodes = [NSIndexSet indexSetWithIndexesInRange:NSMakeRange(200, 100)];

    }

    assert(acceptableStatusCodes != nil);

    statusCode = [self.lastResponse statusCode];

    return (statusCode >= 0) && [acceptableStatusCodes containsIndex: (NSUInteger) statusCode];

}

- (BOOL)isContentTypeAcceptable

{

    NSString *  contentType;

    assert(self.lastResponse != nil);

    contentType = [self.lastResponse MIMEType];

    return (self.acceptableContentTypes == nil) || ((contentType != nil) && [self.acceptableContentTypes containsObject:contentType]);

}

#pragma mark * Start and finish overrides

- (void)operationDidStart

    // Called by QRunLoopOperation when the operation starts.  This kicks of an 

    // asynchronous NSURLConnection.

{

    assert(self.isActualRunLoopThread);

    assert(self.state == kQRunLoopOperationStateExecuting);

    assert(self.defaultResponseSize > 0);

    assert(self.maximumResponseSize > 0);

    assert(self.defaultResponseSize <= self.maximumResponseSize);

    assert(self.request != nil);

    // If a debug error is set, apply that error rather than running the connection.

    #if ! defined(NDEBUG)

        if (self.debugError != nil) {

            [self finishWithError:self.debugError];

            return;

        }

    #endif

    // Create a connection that's scheduled in the required run loop modes.

    assert(self.connection == nil);

    self.connection = [[[NSURLConnection alloc] initWithRequest:self.request delegate:self startImmediately:NO] autorelease];

    assert(self.connection != nil);

    for (NSString * mode in self.actualRunLoopModes) {

        [self.connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:mode];

    }

    [self.connection start];

}

- (void)operationWillFinish

    // Called by QRunLoopOperation when the operation has finished.  We 

    // do various bits of tidying up.

{

    assert(self.isActualRunLoopThread);

    assert(self.state == kQRunLoopOperationStateExecuting);

    // It is possible to hit this state of the operation is cancelled while 

    // the debugDelayTimer is running.  In that case, hey, we'll just accept 

    // the inevitable and finish rather than trying anything else clever.

    #if ! defined(NDEBUG)

        if (self.debugDelayTimer != nil) {

            [self.debugDelayTimer invalidate];

            self.debugDelayTimer = nil;

        }

    #endif

    [self.connection cancel];

    self.connection = nil;

    // If we have an output stream, close it at this point.  We might never 

    // have actually opened this stream but, AFAICT, closing an unopened stream 

    // doesn't hurt. 

    if (self.responseOutputStream != nil) {

        [self.responseOutputStream close];

    }

}

- (void)finishWithError:(NSError *)error

    // We override -finishWithError: just so we can handle our debug delay.

{

    // If a debug delay was set, don't finish now but rather start the debug delay timer 

    // and have it do the actual finish.  We clear self.debugDelay so that the next 

    // time this code runs its doesn't do this again.

    //

    // We only do this in the non-cancellation case.  In the cancellation case, we 

    // just stop immediately.

    #if ! defined(NDEBUG)

        if (self.debugDelay > 0.0) {

            if ( (error != nil) && [[error domain] isEqual:NSCocoaErrorDomain] && ([error code] == NSUserCancelledError) ) {

                self.debugDelay = 0.0;

            } else {

                assert(self.debugDelayTimer == nil);

                self.debugDelayTimer = [NSTimer timerWithTimeInterval:self.debugDelay target:self selector:@selector(debugDelayTimerDone:) userInfo:error repeats:NO];

                assert(self.debugDelayTimer != nil);

                for (NSString * mode in self.actualRunLoopModes) {

                    [[NSRunLoop currentRunLoop] addTimer:self.debugDelayTimer forMode:mode];

                }

                self.debugDelay = 0.0;

                return;

            }

        } 

    #endif

    [super finishWithError:error];

}

#if ! defined(NDEBUG)

@synthesize debugError      = _debugError;

@synthesize debugDelay      = _debugDelay;

@synthesize debugDelayTimer = _debugDelayTimer;

- (void)debugDelayTimerDone:(NSTimer *)timer

{

    NSError *   error;

    assert(timer == self.debugDelayTimer);

    error = [[[timer userInfo] retain] autorelease];

    assert( (error == nil) || [error isKindOfClass:[NSError class]] );

    [self.debugDelayTimer invalidate];

    self.debugDelayTimer = nil;

    [self finishWithError:error];

}

#endif

#pragma mark * NSURLConnection delegate callbacks

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace

    // See comment in header.

{

    BOOL    result;

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert(protectionSpace != nil);

    #pragma unused(protectionSpace)

    result = NO;

    if (self.authenticationDelegate != nil) {

        result = [self.authenticationDelegate httpOperation:self canAuthenticateAgainstProtectionSpace:protectionSpace];

    }

    return result;

}

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge

    // See comment in header.

{

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert(challenge != nil);

    #pragma unused(challenge)

    if (self.authenticationDelegate != nil) {

        [self.authenticationDelegate httpOperation:self didReceiveAuthenticationChallenge:challenge];

    } else {

        if ( [challenge previousFailureCount] == 0 ) {

            [[challenge sender] continueWithoutCredentialForAuthenticationChallenge:challenge];

        } else {

            [[challenge sender] cancelAuthenticationChallenge:challenge];

        }

    }

}

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)response

    // See comment in header.

{

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert( (response == nil) || [response isKindOfClass:[NSHTTPURLResponse class]] );

    self.lastRequest  = request;

    self.lastResponse = (NSHTTPURLResponse *) response;

    return request;

}

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

    // See comment in header.

{

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert([response isKindOfClass:[NSHTTPURLResponse class]]);

    self.lastResponse = (NSHTTPURLResponse *) response;

    // We don't check the status code here because we want to give the client an opportunity 

    // to get the data of the error message.  Perhaps we /should/ check the content type 

    // here, but I'm not sure whether that's the right thing to do.

}

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

    // See comment in header.

{

    BOOL    success;

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert(data != nil);

    // If we don't yet have a destination for the data, calculate one.  Note that, even 

    // if there is an output stream, we don't use it for error responses.

    success = YES;

    if (self.firstData) {

        assert(self.dataAccumulator == nil);

        if ( (self.responseOutputStream == nil) || ! self.isStatusCodeAcceptable ) {

            long long   length;

            assert(self.dataAccumulator == nil);

            length = [self.lastResponse expectedContentLength];

            if (length == NSURLResponseUnknownLength) {

                length = self.defaultResponseSize;

            }

            if (length <= (long long) self.maximumResponseSize) {

                self.dataAccumulator = [NSMutableData dataWithCapacity:(NSUInteger)length];

            } else {

                [self finishWithError:[NSError errorWithDomain:kQHTTPOperationErrorDomain code:kQHTTPOperationErrorResponseTooLarge userInfo:nil]];

                success = NO;

            }

        }

        // If the data is going to an output stream, open it.

        if (success) {

            if (self.dataAccumulator == nil) {

                assert(self.responseOutputStream != nil);

                [self.responseOutputStream open];

            }

        }

        self.firstData = NO;

    }

    // Write the data to its destination.

    if (success) {

        if (self.dataAccumulator != nil) {

            if ( ([self.dataAccumulator length] + [data length]) <= self.maximumResponseSize ) {

                [self.dataAccumulator appendData:data];

            } else {

                [self finishWithError:[NSError errorWithDomain:kQHTTPOperationErrorDomain code:kQHTTPOperationErrorResponseTooLarge userInfo:nil]];

            }

        } else {

            NSUInteger      dataOffset;

            NSUInteger      dataLength;

            const uint8_t * dataPtr;

            NSError *       error;

            NSInteger       bytesWritten;

            assert(self.responseOutputStream != nil);

            dataOffset = 0;

            dataLength = [data length];

            dataPtr    = [data bytes];

            error      = nil;

            do {

                if (dataOffset == dataLength) {

                    break;

                }

                bytesWritten = [self.responseOutputStream write:&dataPtr[dataOffset] maxLength:dataLength - dataOffset];

                if (bytesWritten <= 0) {

                    error = [self.responseOutputStream streamError];

                    if (error == nil) {

                        error = [NSError errorWithDomain:kQHTTPOperationErrorDomain code:kQHTTPOperationErrorOnOutputStream userInfo:nil];

                    }

                    break;

                } else {

                    dataOffset += bytesWritten;

                }

            } while (YES);

            if (error != nil) {

                [self finishWithError:error];

            }

        }

    }

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection

    // See comment in header.

{

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert(self.lastResponse != nil);

    // Swap the data accumulator over to the response data so that we don't trigger a copy.

    assert(self->_responseBody == nil);

    self->_responseBody = self->_dataAccumulator;

    self->_dataAccumulator = nil;

    // Because we fill out _dataAccumulator lazily, an empty body will leave _dataAccumulator 

    // set to nil.  That's not what our clients expect, so we fix it here.

    if (self->_responseBody == nil) {

        self->_responseBody = [[NSData alloc] init];

        assert(self->_responseBody != nil);

    }

    if ( ! self.isStatusCodeAcceptable ) {

        [self finishWithError:[NSError errorWithDomain:kQHTTPOperationErrorDomain code:self.lastResponse.statusCode userInfo:nil]];

    } else if ( ! self.isContentTypeAcceptable ) {

        [self finishWithError:[NSError errorWithDomain:kQHTTPOperationErrorDomain code:kQHTTPOperationErrorBadContentType userInfo:nil]];

    } else {

        [self finishWithError:nil];

    }

}

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

    // See comment in header.

{

    assert(self.isActualRunLoopThread);

    assert(connection == self.connection);

    #pragma unused(connection)

    assert(error != nil);

    [self finishWithError:error];

}

@end

NSString * kQHTTPOperationErrorDomain = @"kQHTTPOperationErrorDomain";