notifications-for-youtube/Notifications for YouTube/NYTAuthentication.m

//
//  NYTAuthentication.m
//  Notifications for YouTube
//
//  Created by Kim Wittenburg on 21.07.13.
//  Copyright (c) 2013 Kim Wittenburg. All rights reserved.
//

#import "NYTAuthentication.h"

// API Imports
#import "OAuth2.h"

// Core Imports
#import "NYTUser.h"
#import "NYTUtil.h"
#import "NYTUpdateManager.h"

// Google Access Constants
NSString * const DeveloperKey = @"key=AI39si6ubNmTeFzFTFz27hFn6r-51knz0_CDWvqgyL-nVKBcFWu5C_c46TWQcHTwwK9bOBlrhdlKatyEqjEnJhZd2dMB7UgFhQ";
NSString * const DeveloperKeyHTTPHeaderField = @"X-GData-Key";
NSString * const ClientID = @"908431532405.apps.googleusercontent.com";
NSString * const ClientSecret = @"hKcyoNAzEIuHZaz0pdTUBMBv";
NSString * const KeychainItemName = @"Notifications for YouTube";

@interface NYTAuthentication ()

@property (readwrite) GTMOAuth2Authentication *authentication;
@property (readwrite) NYTUser *loggedInUser;

@end

@implementation NYTAuthentication

#pragma mark *** Initialization ***

static NYTAuthentication *sharedAuthentication = nil;

+ (NYTAuthentication *)sharedAuthentication
{
    if (!sharedAuthentication) {
        sharedAuthentication = [[self alloc] init];
    }
    return sharedAuthentication;
}

- (id)init
{
    // Allow exactly one instance at all (for any way of initialization)
    if (sharedAuthentication) {
        return sharedAuthentication;
    }
    self = [super init];
    if (self) {
        sharedAuthentication = self;
    }
    return self;
}

#pragma mark *** KVO/KVC Additions to Properties ***

+ (NSSet *)keyPathsForValuesAffectingIsLoggedIn
{
    return [NSSet setWithObjects:@"authentication", nil];
}

#pragma mark *** Login ***

- (void)tryLoginFromKeychainWithCompletionHandler:(void(^)(void))handler
{
    // Get keychain data
    GTMOAuth2Authentication *auth = [GTMOAuth2WindowController authForGoogleFromKeychainForName:KeychainItemName clientID:ClientID clientSecret:ClientSecret];
    if (auth.canAuthorize) {
        // Possible success (keychain)
        // Login (to refresh tokens/validate values) in background
        dispatch_queue_t prevQueue = dispatch_get_current_queue();
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            // Try logging in
            NSError *error = [self completeLoginWithAuthentication:auth];
            dispatch_async(prevQueue, ^{
                if (!error) {
                    // We suceeded so update the authentication object properly
                    self.authentication = auth;
                    // Refresh the feeds without notifications to set the 'known' state
                    [[NYTUpdateManager sharedManager] refreshFeedsWithErrorHandler:NULL notify:NO];
                }
                if (handler) {
                    handler();
                }
            });
        });
    } else {
        // Failed (keychain)
        if (handler) {
            handler();
        }
    }
}

- (void)beginLoginSheetForWindow:(NSWindow *)window completionHandler:(void (^)(NSError *))handler
{
    [[NYTUpdateManager sharedManager] pauseAutoRefreshing];

    // Show the login window
    GTMOAuth2WindowController *windowController = [[GTMOAuth2WindowController alloc] initWithScope:@"https://gdata.youtube.com" clientID:ClientID clientSecret:ClientSecret keychainItemName:KeychainItemName resourceBundle:nil];
    [windowController signInSheetModalForWindow:window completionHandler:^(GTMOAuth2Authentication *auth, NSError *error) {
        if (error) {
            // If an error occured just return
            if (handler) {
                handler(error);
            }
            [[NYTUpdateManager sharedManager] resumeAutoRefreshing];
        } else {
            // Complete the login asynchronously (because we are very likely currently operating on the main thread)
            dispatch_queue_t prevQueue = dispatch_get_current_queue();
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
                // Complete the login
                NSError *error = [self completeLoginWithAuthentication:auth];

                // Handle the error on the caller's queue
                dispatch_async(prevQueue, ^{
                    if (!error) {
                        self.authentication = auth;
                        [[NYTUpdateManager sharedManager] refreshFeedsWithErrorHandler:NULL notify:NO];
                    }
                    if (handler) {
                        handler(error);
                    }
                    [[NYTUpdateManager sharedManager] resumeAutoRefreshing];
                });
            });
        }
    }];
}

- (NSError *)completeLoginWithAuthentication:(GTMOAuth2Authentication *)auth
{
    // Get the user's data
    NSError *error;
    static NSString *userPageURL = @"https://gdata.youtube.com/feeds/api/users/default";
    NSXMLDocument *document = LoadXMLDocumentSynchronous(userPageURL, auth, &error);
    if (!document) {
        return error;
    }

    // Parse the data and store them app-friendly
    NYTUser *user = [[NYTUser alloc] initWithUserProfilePage:document];
    dispatch_async(dispatch_get_main_queue(), ^{
        // Set on the main queue due to bindings relations
        self.loggedInUser = user;
    });
    return nil;
}

#pragma mark *** Logout ***

- (void)discardLogin
{
    // Also remove from keychain
    [GTMOAuth2WindowController removeAuthFromKeychainForName:KeychainItemName];
    self.authentication = nil;
    self.loggedInUser = nil;
}

#pragma mark *** Login Information ***

- (BOOL)isLoggedIn
{
    return self.authentication != nil && self.authentication.canAuthorize;
}

@end