/*

    File:       ChallengeHandler.m

    Contains:   Base class for handling various authentication challenges.

    Written by: DTS

    Copyright:  Copyright (c) 2011 Apple Inc. All Rights Reserved.

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

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                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,

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                THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN

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*/

#import "ChallengeHandler.h"

@interface ChallengeHandler ()

@property (nonatomic, assign, readwrite, getter=isRunning)  BOOL        running;

@end

@implementation ChallengeHandler

static NSMutableDictionary * sAuthenticationMethodToHandlerClassArray;

+ (void)registerHandlers

{

    assert(NO);         // must be overridden by subclass

}

+ (void)registerAllHandlers

{

    // Register all of our support challenge handlers.  There are various ways 

    // you can automate this (objc_getClassList anyone?), but I decided to just 

    // hardwire the classes right now.

    static BOOL sHaveRegistered;

    if ( ! sHaveRegistered ) {

        for (NSString * className in [NSArray arrayWithObjects:@"AuthenticationChallengeHandler", @"ServerTrustChallengeHandler", @"ClientIdentityChallengeHandler", nil]) {

            Class   cls;

            cls = NSClassFromString(className);

            assert(cls != nil);

            [cls registerHandlers];

        }

        sHaveRegistered = YES;

    }

}

+ (BOOL)supportsProtectionSpace:(NSURLProtectionSpace *)protectionSpace

{

    BOOL                result;

    NSString *          authenticationMethod;

    NSMutableArray *    handlerClasses;

    assert(protectionSpace != nil);

    [self registerAllHandlers];

    authenticationMethod = [protectionSpace authenticationMethod];

    assert(authenticationMethod != nil);

    result = NO;

    if (sAuthenticationMethodToHandlerClassArray != nil) {

        handlerClasses = (NSMutableArray *) [sAuthenticationMethodToHandlerClassArray objectForKey:authenticationMethod];

        if (handlerClasses != nil) {

            assert([handlerClasses isKindOfClass:[NSMutableArray class]]);

            result = YES;

        }

    }

    return result;

}

+ (ChallengeHandler *)handlerForChallenge:(NSURLAuthenticationChallenge *)challenge parentViewController:(UIViewController *)parentViewController

{

    ChallengeHandler *  result;

    NSString *          authenticationMethod;

    NSMutableArray *    handlerClasses;

    assert([NSThread isMainThread]);

    assert(challenge != nil);

    assert(parentViewController != nil);

    [self registerAllHandlers];

    authenticationMethod = [[challenge protectionSpace] authenticationMethod];

    assert(authenticationMethod != nil);

    result = nil;

    if (sAuthenticationMethodToHandlerClassArray != nil) {

        handlerClasses = (NSMutableArray *) [sAuthenticationMethodToHandlerClassArray objectForKey:authenticationMethod];

        if (handlerClasses != nil) {

            assert([handlerClasses isKindOfClass:[NSMutableArray class]]);

            for (Class candidateClass in handlerClasses) {

                result = [[[candidateClass alloc] initWithChallenge:challenge parentViewController:parentViewController] autorelease];

                if (result != nil) {

                    break;

                }

            }

        }

    }

    return result;

}

+ (void)registerHandlerClass:(Class)handlerClass forAuthenticationMethod:(NSString *)authenticationMethod

{

    NSMutableArray *    handlerClasses;

    assert([NSThread isMainThread]);

    assert(handlerClass != nil);

    assert(authenticationMethod != nil);

    if (sAuthenticationMethodToHandlerClassArray == nil) {

        sAuthenticationMethodToHandlerClassArray = [[NSMutableDictionary alloc] init];

        assert(sAuthenticationMethodToHandlerClassArray != nil);

    }

    handlerClasses = (NSMutableArray *) [sAuthenticationMethodToHandlerClassArray objectForKey:authenticationMethod];

    if (handlerClasses == nil) {

        handlerClasses = [NSMutableArray array];

        assert(handlerClasses != nil);

        [sAuthenticationMethodToHandlerClassArray setObject:handlerClasses forKey:authenticationMethod];

    }

    assert([handlerClasses isKindOfClass:[NSMutableArray class]]);

    // Don't register the same class twice.  This is necessary because 

    // NSURLAuthenticationMethodDefault and NSURLAuthenticationMethodHTTPBasic both 

    // have the same value, so you end up with AuthenticationChallengeHandler registered 

    // twice for that value.  That doesn't cause problems, but it's unnecessarily 

    // inefficient.

    //

    // It's also makes life easier for our clients as the user switches between 

    // various states, all of which require the same challenge handler.

    if ( ! [handlerClasses containsObject:handlerClass] ) {

        [handlerClasses addObject:handlerClass];

    }

}

+ (void)deregisterHandlerClass:(Class)handlerClass forAuthenticationMethod:(NSString *)authenticationMethod

{

    NSMutableArray *    handlerClasses;

    assert(handlerClass != nil);

    assert(authenticationMethod != nil);

    // As a matter of policy we allow clients to deregister stuff they haven't registered.

    // This makes it easier for clients to set up their initial state.

    if (sAuthenticationMethodToHandlerClassArray != nil) {

        handlerClasses = (NSMutableArray *) [sAuthenticationMethodToHandlerClassArray objectForKey:authenticationMethod];

        if (handlerClasses != nil) {

            assert([handlerClasses isKindOfClass:[NSMutableArray class]]);

            [handlerClasses removeObject:handlerClass];

            if (handlerClasses.count == 0) {

                [sAuthenticationMethodToHandlerClassArray removeObjectForKey:authenticationMethod];

            }

        }

    }

}

- (id)initWithChallenge:(NSURLAuthenticationChallenge *)challenge parentViewController:(UIViewController *)parentViewController

{

    assert([NSThread isMainThread]);

    assert(challenge != nil);

    assert(parentViewController != nil);

    self = [super init];

    if (self != nil) {

        self->_challenge            = [challenge retain];

        self->_parentViewController = [parentViewController retain];

    }

    return self;

}

- (void)dealloc

{

    assert( ! self->_running );          // should not still be displaying UI

    assert([NSThread isMainThread]);

    [self->_challenge release];

    [self->_parentViewController release];

    [self->_credential release];

    [super dealloc];

}

@synthesize challenge            = _challenge;

@synthesize parentViewController = _parentViewController;

@synthesize credential           = _credential;

@synthesize delegate             = _delegate;

@synthesize running              = _running;

- (void)start

{

    assert([NSThread isMainThread]);

    assert( ! self.running );

    self.running = YES;

    [self didStart];

}

- (void)didStart

{

    // this is just an override point

}

- (void)willFinish

{

    // this is just an override point

}

- (void)didFinish

{

    // this is just an override point

}

+ (NSURLCredential *)noCredential

{

    static NSURLCredential * sNoCredential;

    assert([NSThread isMainThread]);

    if (sNoCredential == nil) {

        // The actual values we supply here are irrelevant.  We always use pointer comparison to detect this singleton.

        sNoCredential = [[NSURLCredential alloc] initWithUser:@"" password:@"" persistence:NSURLCredentialPersistenceNone];

        assert(sNoCredential != nil);

    }

    return sNoCredential;

}

- (void)stopWithCredential:(NSURLCredential *)credential

{

    assert([NSThread isMainThread]);

    // Allow duplicate cancels to make life easier for our clients.

    if (self.running) {

        [self willFinish];

        assert(self->_credential == nil);

        self->_credential = [credential retain];

        self.running = NO;

        [self didFinish];

    }

}

- (void)stop

{

    [self stopWithCredential:nil];

}

- (void)resolve

{

    assert([NSThread isMainThread]);

    assert( ! self.running );

    if (self.credential == nil) {

        [[self.challenge sender] cancelAuthenticationChallenge:self.challenge];

    } else if (self.credential == [ChallengeHandler noCredential]) {

        [[self.challenge sender] continueWithoutCredentialForAuthenticationChallenge:self.challenge];

    } else {

        [[self.challenge sender] useCredential:self.credential forAuthenticationChallenge:self.challenge];

    }

}

@end