/*

 File: URLCacheController.m

 Abstract: The view controller for the URLCache sample.

 Version: 1.1

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 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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 Apple's copyrights in this original Apple software (the "Apple Software"), to

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 modifications, in source and/or binary forms; provided that if you redistribute

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 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

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 Copyright (C) 2008-2010 Apple Inc. All Rights Reserved.

 */

#import "URLCacheController.h"

#import "URLCacheAlert.h"

/* cache update interval in seconds */

const double URLCacheInterval = 86400.0;

@interface NSObject (PrivateMethods)

- (void) initUI;

- (void) startAnimation;

- (void) stopAnimation;

- (void) buttonsEnabled:(BOOL)flag;

- (void) getFileModificationDate;

- (void) displayImageWithURL:(NSURL *)theURL;

- (void) displayCachedImage;

- (void) initCache;

- (void) clearCache;

@end

@implementation URLCacheController

@synthesize dataPath;

@synthesize filePath;

@synthesize fileDate;

@synthesize urlArray;

@synthesize connection;

@synthesize imageView;

@synthesize activityIndicator;

@synthesize statusField;

@synthesize dateField;

@synthesize infoField;

@synthesize toolbarItem1;

@synthesize toolbarItem2;

- (void) viewDidLoad {

    [super viewDidLoad];

    /* By default, the Cocoa URL loading system uses a small shared memory cache.

     We don't need this cache, so we set it to zero when the application launches. */

    /* turn off the NSURLCache shared cache */

    NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0

                                                            diskCapacity:0

                                                                diskPath:nil];

    [NSURLCache setSharedURLCache:sharedCache];

    [sharedCache release];

    /* prepare to use our own on-disk cache */

    [self initCache];

    /* create and load the URL array using the strings stored in URLCache.plist */

    NSString *path = [[NSBundle mainBundle] pathForResource:@"URLCache" ofType:@"plist"];

    if (path) {

        NSArray *array = [[NSArray alloc] initWithContentsOfFile:path];

        self.urlArray = [NSMutableArray array];

        for (NSString *element in array) {

            [self.urlArray addObject:[NSURL URLWithString:element]];

        }

        [array release];

    }

    /* set the view's background to gray pinstripe */

    self.view.backgroundColor = [UIColor groupTableViewBackgroundColor];

    /* set initial state of network activity indicators */

    [self stopAnimation];

    /* initialize the user interface */

    [self initUI];

}

- (void)dealloc {

    [dataPath release];

    [filePath release];

    [fileDate release];

    [urlArray release];

    [connection release];

    [imageView release];

    [activityIndicator release];

    [statusField release];

    [dateField release];

    [infoField release];

    [toolbarItem1 release];

    [toolbarItem2 release];

    [super dealloc];

}

/*

 ------------------------------------------------------------------------

 Action methods that respond to UI events or change the UI

 ------------------------------------------------------------------------

 */

#pragma mark -

#pragma mark IBAction methods

/* Action method for the Display Image button. */

- (IBAction) onDisplayImage:(id)sender

{

    [self initUI];

    [self displayImageWithURL:[urlArray objectAtIndex:0]];

}

/* Action method for the Clear Cache button. */

- (IBAction) onClearCache:(id)sender

{

    NSString *message = NSLocalizedString (@"Do you really want to clear the cache?",

                                           @"Clear Cache alert message");

    URLCacheAlertWithMessageAndDelegate(message, self);

    /* We handle the user response to this alert in the UIAlertViewDelegate

     method alertView:clickedButtonAtIndex: at the end of this file. */

}

/*

 ------------------------------------------------------------------------

 Private methods used only in this file

 ------------------------------------------------------------------------

 */

#pragma mark -

#pragma mark Private methods

/* initialize fields in the user interface */

- (void) initUI

{

    imageView.image = nil;

    statusField.text = @"";

    dateField.text = @"";

    infoField.text = @"";

}

/* show the user that loading activity has started */

- (void) startAnimation

{

    [self.activityIndicator startAnimating];

    UIApplication *application = [UIApplication sharedApplication];

    application.networkActivityIndicatorVisible = YES;

}

/* show the user that loading activity has stopped */

- (void) stopAnimation

{

    [self.activityIndicator stopAnimating];

    UIApplication *application = [UIApplication sharedApplication];

    application.networkActivityIndicatorVisible = NO;

}

/* enable or disable all toolbar buttons */

- (void) buttonsEnabled:(BOOL)flag

{

    toolbarItem1.enabled = flag;

    toolbarItem2.enabled = flag;

}

- (void) initCache

{

    /* create path to cache directory inside the application's Documents directory */

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    self.dataPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"URLCache"];

    /* check for existence of cache directory */

    if ([[NSFileManager defaultManager] fileExistsAtPath:dataPath]) {

        return;

    }

    /* create a new cache directory */

    if (![[NSFileManager defaultManager] createDirectoryAtPath:dataPath

                                   withIntermediateDirectories:NO

                                                    attributes:nil

                                                         error:&error]) {

        URLCacheAlertWithError(error);

        return;

    }

}

/* removes every file in the cache directory */

- (void) clearCache

{

    /* remove the cache directory and its contents */

    if (![[NSFileManager defaultManager] removeItemAtPath:dataPath error:&error]) {

        URLCacheAlertWithError(error);

        return;

    }

    /* create a new cache directory */

    if (![[NSFileManager defaultManager] createDirectoryAtPath:dataPath

                                   withIntermediateDirectories:NO

                                                    attributes:nil

                                                         error:&error]) {

        URLCacheAlertWithError(error);

        return;

    }

    [self initUI];

}

/* get modification date of the current cached image */

- (void) getFileModificationDate

{

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

    self.fileDate = [NSDate dateWithTimeIntervalSinceReferenceDate:0];

    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {

        /* retrieve file attributes */

        NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:&error];

        if (attributes != nil) {

            self.fileDate = [attributes fileModificationDate];

        }

        else {

            URLCacheAlertWithError(error);

        }

    }

}

/* display new or existing cached image */

- (void) displayImageWithURL:(NSURL *)theURL

{

    /* get the path to the cached image */

    [filePath release]; /* release previous instance */

    NSString *fileName = [[theURL path] lastPathComponent];

    filePath = [[dataPath stringByAppendingPathComponent:fileName] retain];

    /* apply daily time interval policy */

    /* In this program, "update" means to check the last modified date

     of the image to see if we need to load a new version. */

    [self getFileModificationDate];

    /* get the elapsed time since last file update */

    NSTimeInterval time = fabs([fileDate timeIntervalSinceNow]);

    if (time > URLCacheInterval) {

        /* file doesn't exist or hasn't been updated for at least one day */

        [self initUI];

        [self buttonsEnabled:NO];

        [self startAnimation];

        self.connection = [[URLCacheConnection alloc] initWithURL:theURL delegate:self];

    }

    else {

        statusField.text = NSLocalizedString (@"Previously cached image",

                                              @"Image found in cache and updated in last 24 hours.");

        [self displayCachedImage];

    }

}

/* display existing cached image */

- (void) displayCachedImage

{

    infoField.text = NSLocalizedString (@"The cached image is updated if 24 hours has elapsed since the last update and you press the Display Image button.", @"Information about updates.");

    /* retrieve file attributes */

    [self getFileModificationDate];

    /* format the file modification date for display in Updated field */

    /* NSDateFormatterStyle options give meaningful results in all locales */

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

    [dateFormatter setTimeStyle:NSDateFormatterShortStyle];

    [dateFormatter setDateStyle:NSDateFormatterMediumStyle];

    dateField.text = [@"Updated: " stringByAppendingString:[dateFormatter stringFromDate:fileDate]];

    [dateFormatter release];

    /* display the file as an image */

    UIImage *theImage = [[UIImage alloc] initWithContentsOfFile:filePath];

    if (theImage) {

        imageView.image = theImage;

        [theImage release];

    }

}

/*

 ------------------------------------------------------------------------

 URLCacheConnectionDelegate protocol methods

 ------------------------------------------------------------------------

 */

#pragma mark -

#pragma mark URLCacheConnectionDelegate methods

- (void) connectionDidFail:(URLCacheConnection *)theConnection

{

    [self stopAnimation];

    [self buttonsEnabled:YES];

}

- (void) connectionDidFinish:(URLCacheConnection *)theConnection

{

    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath] == YES) {

        /* apply the modified date policy */

        [self getFileModificationDate];

        NSComparisonResult result = [theConnection.lastModified compare:fileDate];

        if (result == NSOrderedDescending) {

            /* file is outdated, so remove it */

            if (![[NSFileManager defaultManager] removeItemAtPath:filePath error:&error]) {

                URLCacheAlertWithError(error);

            }

        }

    }

    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath] == NO) {

        /* file doesn't exist, so create it */

        [[NSFileManager defaultManager] createFileAtPath:filePath

                                                contents:theConnection.receivedData

                                              attributes:nil];

        statusField.text = NSLocalizedString (@"Newly cached image",

                                              @"Image not found in cache or new image available.");

    }

    else {

        statusField.text = NSLocalizedString (@"Cached image is up to date",

                                              @"Image updated and no new image available.");

    }

    /* reset the file's modification date to indicate that the URL has been checked */

    NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys:[NSDate date], NSFileModificationDate, nil];

    if (![[NSFileManager defaultManager] setAttributes:dict ofItemAtPath:filePath error:&error]) {

        URLCacheAlertWithError(error);

    }

    [dict release];

    [self stopAnimation];

    [self buttonsEnabled:YES];

    [self displayCachedImage];

}

/*

 ------------------------------------------------------------------------

 UIAlertViewDelegate protocol method

 ------------------------------------------------------------------------

 */

#pragma mark -

#pragma mark UIAlertViewDelegate

- (void)alertView:(UIAlertView *)alert clickedButtonAtIndex:(NSInteger)buttonIndex

{

    if (buttonIndex == 0) {

        /* the user clicked the Cancel button */

        return;

    }

    [self clearCache];

}

@end