FBRequest.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 "FBRequest.h"
#import "JSON.h"

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

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

static const NSTimeInterval kTimeoutInterval = 180.0;

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

@implementation FBRequest

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

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

+ (FBRequest *)getRequestWithParams:(NSMutableDictionary *) params
                         httpMethod:(NSString *) httpMethod
                           delegate:(id<FBRequestDelegate>) delegate
                         requestURL:(NSString *) url {

  FBRequest* request = [[[FBRequest alloc] init] autorelease];
  request.delegate = delegate;
  request.url = url;
  request.httpMethod = httpMethod;
  request.params = params;
  request.connection = nil;
  request.responseText = nil;

  return request;
}

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

+ (NSString *)serializeURL:(NSString *)baseUrl
                   params:(NSDictionary *)params {
  return [self serializeURL:baseUrl params:params httpMethod:@"GET"];
}

/**
 * Generate get URL
 */
+ (NSString*)serializeURL:(NSString *)baseUrl
                   params:(NSDictionary *)params
               httpMethod:(NSString *)httpMethod {

  NSURL* parsedURL = [NSURL URLWithString:baseUrl];
  NSString* queryPrefix = parsedURL.query ? @"&" : @"?";

  NSMutableArray* pairs = [NSMutableArray array];
  for (NSString* key in [params keyEnumerator]) {
    if (([[params valueForKey:key] isKindOfClass:[UIImage 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* query = [pairs componentsJoinedByString:@"&"];

  return [NSString stringWithFormat:@"%@%@%@", baseUrl, queryPrefix, query];
}

/**
 * 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:[UIImage 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:[UIImage class]]) {
        NSData* imageData = UIImagePNGRepresentation((UIImage*)dataParam);
        [self utfAppendBody:body
                       data:[NSString stringWithFormat:
                             @"Content-Disposition: form-data; filename=\"%@\"\r\n", key]];
        [self utfAppendBody:body
                       data:[NSString stringWithString:@"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:[NSString stringWithString:@"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
 *                          fails with error
 */
- (void)failWithError:(NSError *)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 {

  if ([_delegate respondsToSelector:@selector(requestLoading:)]) {
    [_delegate requestLoading:self];
  }

  NSString* url = [[self class] serializeURL:_url params:_params httpMethod:_httpMethod];
  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];

}

/**
 * Free internal structure
 */
- (void)dealloc {
  [_connection cancel];
  [_connection 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