/*

File: URLCacheConnection.m

Abstract: The NSURL connection class for the URLCache sample.

Version: 1.1

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*/

#import "URLCacheConnection.h"

#import "URLCacheAlert.h"

@implementation URLCacheConnection

@synthesize delegate;

@synthesize receivedData;

@synthesize lastModified;

@synthesize connection;

/* This method initiates the load request. The connection is asynchronous,

 and we implement a set of delegate methods that act as callbacks during

 the load. */

- (id) initWithURL:(NSURL *)theURL delegate:(id<URLCacheConnectionDelegate>)theDelegate

{

    if (self = [super init]) {

        self.delegate = theDelegate;

        /* Create the request. This application does not use a NSURLCache

         disk or memory cache, so our cache policy is to satisfy the request

         by loading the data from its source. */

        NSURLRequest *theRequest = [NSURLRequest requestWithURL:theURL

                                                    cachePolicy:NSURLRequestReloadIgnoringLocalCacheData

                                                timeoutInterval:60];

        /* Create the connection with the request and start loading the

         data. The connection object is owned both by the creator and the

         loading system. */

        self.connection = [NSURLConnection connectionWithRequest:theRequest delegate:self];

        if (self.connection == nil) {

            /* inform the user that the connection failed */

            NSString *message = NSLocalizedString (@"Unable to initiate request.",

                                                   @"NSURLConnection initialization method failed.");

            URLCacheAlertWithMessage(message);

        }

    }

    return self;

}

- (void)dealloc

{

    [receivedData release];

    [lastModified release];

    [connection release];

    [super dealloc];

}

#pragma mark NSURLConnection delegate methods

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

{

    /* This method is called when the server has determined that it has

     enough information to create the NSURLResponse. It can be called

     multiple times, for example in the case of a redirect, so each time

     we reset the data capacity. */

    /* create the NSMutableData instance that will hold the received data */

    long long contentLength = [response expectedContentLength];

    if (contentLength == NSURLResponseUnknownLength) {

        contentLength = 500000;

    }

    self.receivedData = [NSMutableData dataWithCapacity:(NSUInteger)contentLength];

    /* Try to retrieve last modified date from HTTP header. If found, format

     date so it matches format of cached image file modification date. */

    if ([response isKindOfClass:[NSHTTPURLResponse self]]) {

        NSDictionary *headers = [(NSHTTPURLResponse *)response allHeaderFields];

        NSString *modified = [headers objectForKey:@"Last-Modified"];

        if (modified) {

            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

            /* avoid problem if the user's locale is incompatible with HTTP-style dates */

            [dateFormatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"] autorelease]];

            [dateFormatter setDateFormat:@"EEE, dd MMM yyyy HH:mm:ss zzz"];

            self.lastModified = [dateFormatter dateFromString:modified];

            [dateFormatter release];

        }

        else {

            /* default if last modified date doesn't exist (not an error) */

            self.lastModified = [NSDate dateWithTimeIntervalSinceReferenceDate:0];

        }

    }

}

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

{

    /* Append the new data to the received data. */

    [self.receivedData appendData:data];

}

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

{

    URLCacheAlertWithError(error);

    [self.delegate connectionDidFail:self];

}

- (NSCachedURLResponse *) connection:(NSURLConnection *)connection

                   willCacheResponse:(NSCachedURLResponse *)cachedResponse

{

    /* this application does not use a NSURLCache disk or memory cache */

    return nil;

}

- (void) connectionDidFinishLoading:(NSURLConnection *)connection

{

    [self.delegate connectionDidFinish:self];

}

@end