FacebookRequest.m

/*
 * Copyright 2010 Facebook
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *    http://www.apache.org/licenses/LICENSE-2.0
 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#import "FacebookRequest.h"
#import "JSON.h"

///////////////////////////////////////////////////////////////////////////////////////////////////
// global 

static NSString *kUserAgent = @"FacebookConnect";
static NSString *kStringBoundary = @"3i2ndDfv2rTHiSisAbouNdArYfORhtTPEefj3q2f";
static const int kGeneralErrorCode = 10000;

static const NSTimeInterval kTimeoutInterval = 10.0;

///////////////////////////////////////////////////////////////////////////////////////////////////

@implementation FacebookRequest

@synthesize delegate     = _delegate,
url          = _url,
httpMethod   = _httpMethod,
params       = _params,
connection   = _connection,
responseText = _responseText;

//////////////////////////////////////////////////////////////////////////////////////////////////
// class public

+ (FacebookRequest *)getRequestWithParams:(NSMutableDictionary *) params
							   httpMethod:(NSString *) httpMethod
								 delegate:(id<FacebookRequestDelegate>) delegate
							   requestURL:(NSString *) url {
	FacebookRequest *request    = [[[FacebookRequest alloc] init] autorelease];
	request.delegate      = [delegate retain]; 
	request.url           = [url retain];
	request.httpMethod    = [httpMethod retain];
	request.params        = [params retain];
	request.connection    = nil;
	request.responseText  = nil;
	
	return request;
}

///////////////////////////////////////////////////////////////////////////////////////////////////
// private

/**
 * Generate get URL
 */
- (NSString *)generateGetURL {
	NSURL *parsedURL = [NSURL URLWithString:_url];
	NSString *queryPrefix = parsedURL.query ? @"&" : @"?";
	
	NSMutableArray *pairs = [NSMutableArray array];
	for (NSString *key in [_params keyEnumerator]) {
		if (([[_params valueForKey:key] isKindOfClass:[NSImage class]]) 
			||([[_params valueForKey:key] isKindOfClass:[NSData class]])) {
			if ([_httpMethod isEqualToString:@"GET"]) {
				NSLog(@"can not use GET to upload a file");      
			}
			continue;
		} 
		
		NSString *escaped_value = (NSString *)CFURLCreateStringByAddingPercentEscapes(
																					  NULL, /* allocator */
																					  (CFStringRef)[_params objectForKey:key],
																					  NULL, /* charactersToLeaveUnescaped */
																					  (CFStringRef)@"!*'();:@&=+$,/?%#[]",
																					  kCFStringEncodingUTF8);
		
		[pairs addObject:[NSString stringWithFormat:@"%@=%@", key, escaped_value]];
		[escaped_value release];
	}
	NSString *params = [pairs componentsJoinedByString:@"&"];
	
	return [NSString stringWithFormat:@"%@%@%@", _url, queryPrefix, params];
}

/**
 * Body append for POST method
 */
- (void)utfAppendBody:(NSMutableData *)body data:(NSString *)data {
	[body appendData:[data dataUsingEncoding:NSUTF8StringEncoding]];
}

/**
 * Generate body for POST method
 */
- (NSMutableData *)generatePostBody {
	NSMutableData *body = [NSMutableData data];
	NSString *endLine = [NSString stringWithFormat:@"\r\n--%@\r\n", kStringBoundary];
	NSMutableDictionary *dataDictionary = [NSMutableDictionary dictionary];
	
	[self utfAppendBody:body data:[NSString stringWithFormat:@"--%@\r\n", kStringBoundary]];
	
	for (id key in [_params keyEnumerator]) {
		
		if (([[_params valueForKey:key] isKindOfClass:[NSImage class]]) 
			||([[_params valueForKey:key] isKindOfClass:[NSData class]])) {
			
			[dataDictionary setObject:[_params valueForKey:key] forKey:key];
			continue;
			
		}
		
		[self utfAppendBody:body
					   data:[NSString 
							 stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", 
							 key]];
		[self utfAppendBody:body data:[_params valueForKey:key]];
		
		[self utfAppendBody:body data:endLine];   
	}
	
	if ([dataDictionary count] > 0) {
		for (id key in dataDictionary) {
			NSObject *dataParam = [dataDictionary valueForKey:key];
			if ([dataParam isKindOfClass:[NSImage class]]) {
				NSBitmapImageRep *rep = [[(NSImage *)dataParam representations] objectAtIndex: 0];
				NSData *imageData = [rep representationUsingType: NSPNGFileType
													  properties: nil];
				[self utfAppendBody:body
							   data:[NSString stringWithFormat:
									 @"Content-Disposition: form-data; filename=\"%@\"\r\n", key]];
				[self utfAppendBody:body
							   data:@"Content-Type: image/png\r\n\r\n"];
				[body appendData:imageData];
			} else {
				NSAssert([dataParam isKindOfClass:[NSData class]], 
						 @"dataParam must be a UIImage or NSData");
				[self utfAppendBody:body
							   data:[NSString stringWithFormat:
									 @"Content-Disposition: form-data; filename=\"%@\"\r\n", key]];
				[self utfAppendBody:body
							   data:@"Content-Type: content/unknown\r\n\r\n"];
				[body appendData:(NSData *)dataParam];
			}
			[self utfAppendBody:body data:endLine];          
			
		}
	}
	
	return body;
}

/**
 * Formulate the NSError
 */
- (id) formError:(NSInteger)code userInfo:(NSDictionary *) errorData {
	return [NSError errorWithDomain:@"facebookErrDomain" code:code userInfo:errorData];
	
}

/**
 * parse the response data
 */
- (id)parseJsonResponse:(NSData *)data error:(NSError **)error {
	
	NSString *responseString = [[[NSString alloc] initWithData:data 
													  encoding:NSUTF8StringEncoding] 
								autorelease];
	SBJSON *jsonParser = [[SBJSON new] autorelease];
	if ([responseString isEqualToString:@"true"]) {
		return [NSDictionary dictionaryWithObject:@"true" forKey:@"result"];
	} else if ([responseString isEqualToString:@"false"]) {
		if (error != nil) {
			*error = [self formError:kGeneralErrorCode 
							userInfo:[NSDictionary 
									  dictionaryWithObject:@"This operation can not be completed" 
									  forKey:@"error_msg"]];
		}
		return nil;
	}
	
	
	id result = [jsonParser objectWithString:responseString];
	
	if (![result isKindOfClass:[NSArray class]]) {
		if ([result objectForKey:@"error"] != nil) {
			if (error != nil) {
				*error = [self formError:kGeneralErrorCode
								userInfo:result];
			}
			return nil;
		}
		
		if ([result objectForKey:@"error_code"] != nil) {
			if (error != nil) {
				*error = [self formError:[[result objectForKey:@"error_code"] intValue] userInfo:result];
			}
			return nil;
		}
		
		if ([result objectForKey:@"error_msg"] != nil) {
			if (error != nil) {
				*error = [self formError:kGeneralErrorCode userInfo:result];
			}
		}
		
		if ([result objectForKey:@"error_reason"] != nil) {
			if (error != nil) {
				*error = [self formError:kGeneralErrorCode userInfo:result];
			}
		}
	}
	
	return result;
	
}

/*
 * private helper function: call the delegate function when the request fail with Error 
 */
- (void)failWithError:(NSError *)error {
	NSLog(@"failWithError: %@", error);
	if ([_delegate respondsToSelector:@selector(request:didFailWithError:)]) {
		[_delegate request:self didFailWithError:error];
	}
}

/*
 * private helper function: handle the response data 
 */
- (void)handleResponseData:(NSData *)data {
	if ([_delegate respondsToSelector:@selector(request:didLoadRawResponse:)]) {
		[_delegate request:self didLoadRawResponse:data];
	}
	
	if ([_delegate respondsToSelector:@selector(request:didLoad:)] ||
		[_delegate respondsToSelector:@selector(request:didFailWithError:)]) {
		NSError *error = nil;
		id result = [self parseJsonResponse:data error:&error];
		if (error) {
			[self failWithError:error];
		} else if ([_delegate respondsToSelector:@selector(request:didLoad:)]) {
			[_delegate request:self didLoad:(result == nil ? data : result)];
		}
		
	}
	
}



//////////////////////////////////////////////////////////////////////////////////////////////////
// public

/**
 * @return boolean - whether this request is processing
 */
- (BOOL)loading {
	return !!_connection;
}

/**
 * make the Facebook request
 */
- (void)connect:(BOOL)startImmediately {
	
	if ([_delegate respondsToSelector:@selector(requestLoading:)]) {
		[_delegate requestLoading:self];
	}
	
	NSString *url = [self generateGetURL];
	NSMutableURLRequest *request = 
    [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]
                            cachePolicy:NSURLRequestReloadIgnoringLocalCacheData 
                        timeoutInterval:kTimeoutInterval];
	[request setValue:kUserAgent forHTTPHeaderField:@"User-Agent"];
	
	[request setHTTPMethod:self.httpMethod];
	if ([self.httpMethod isEqualToString: @"POST"]) {  
		NSString *contentType = [NSString
								 stringWithFormat:@"multipart/form-data; boundary=%@", kStringBoundary];
		[request setValue:contentType forHTTPHeaderField:@"Content-Type"];
		
		[request setHTTPBody:[self generatePostBody]];
	}
	
	_connection = [[NSURLConnection alloc] initWithRequest:request
												  delegate:self
										  startImmediately:startImmediately];
	
	if (!startImmediately) {
		[_connection scheduleInRunLoop:[NSRunLoop currentRunLoop]
							   forMode:NSModalPanelRunLoopMode];
	
		[_connection start];
	}
}

/**
 * Free internal structure
 */
- (void)dealloc {
	[_connection cancel];
	[_connection release];
	[_delegate release];
	[_responseText release];
	[_url release];
	[_httpMethod release];
	[_params release];
	[super dealloc];
}

//////////////////////////////////////////////////////////////////////////////////////////////////
// NSURLConnectionDelegate

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
	_responseText = [[NSMutableData alloc] init];
	
	NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;
	if ([_delegate respondsToSelector:@selector(request:didReceiveResponse:)]) {    
		[_delegate request:self didReceiveResponse:httpResponse];
	}
}

-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
	[_responseText appendData:data];
}

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection
				 willCacheResponse:(NSCachedURLResponse *)cachedResponse {
	return nil;
}

-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
	[self handleResponseData:_responseText];
	
	[_responseText release];
	_responseText = nil;
	[_connection release];
	_connection = nil;
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {  
	[self failWithError:error];
	
	[_responseText release];
	_responseText = nil;
	[_connection release];
	_connection = nil;
}

@end