How to include social auth and user registration layers in Disqus OAuth grants

authbrowser.cs

using Microsoft.Phone.Controls;
using Microsoft.Phone.Info;
using System;
using System.ComponentModel;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;

namespace DisqusSDK.WP8.Controls
{
    /// <summary>
    /// The UI markup of this page contains a WebBrowser control named "AuthenticationBrowser" (hidden by default)
    /// and 4 buttons covering Disqus, Twitter, Facebook, and Google authentication.
    ///
    /// When the user clicks one of the login options, we load the WebBrowser control the the correct URL
    /// </summary>
    public partial class LoginWindow : UserControl
    {
        public LoginWindow()
        {
            InitializeComponent();
        }
        
        #region Private variables
        
        //
        // The URL used to show the Disqus login/register window
        private string _disqusLoginUri = "https://disqus.com/next/login/?forum={0}";
	
    	//
    	// The URL used to show social auth login window
        private string _disqusAxBaseUri = "http://disqus.com/_ax/{0}/begin/?forum={1}";

	    //
        // URLs that browser will navigate to when the user successfully logs in
        private string[] _completionPatterns = { "disqus.com/next/login-success", "disqus.com/_ax/google/complete", "disqus.com/_ax/twitter/complete", "disqus.com/_ax/facebook/complete" };

	    //
	    // URL that our server-side auth will navigate to once the access token cookie has been set
	    // TODO provide your own URL here
        private string _oAuthSuccessUrl = "example.com/disqus-oauth-success/";
        
        //
        // Your Disqus shortname. Not important, but good for referral statistics
        // TODO provide your own Disqus shortname
        private string _disqusShortname = "example";
        
        //
        // User agent to pass into the browser
        private string _userAgent = "User-Agent: Mozilla/5.0 (compatible; MSIE 10.0; Windows Phone " + Convert.ToString(Environment.OSVersion.Version) + "; Trident/6.0; IEMobile/10.0; ARM; Touch; " + DeviceStatus.DeviceManufacturer + "; " + DeviceStatus.DeviceName + ")";
        
        #endregion
        
        #region Overrides and event hanadlers
        
        //
        // When the user clicks the "Facebook" button in your UI
        private async void FacebookLoginButton_Click(object sender, RoutedEventArgs e)
        {
            try
    	    {
    		    await NavigateToProviderLogin("facebook");	
    	    }
    	    catch { }
        }

	    //
        // When the user clicks the "Twitter" button in your UI
        private async void TwitterLoginButton_Click(object sender, RoutedEventArgs e)
        {
            try
    	    {
    		    await NavigateToProviderLogin("twitter");	
    	    }
    	    catch { }
        }
	
	    //
        // When the user clicks the "Google" button in your UI
        private async void GoogleLoginButton_Click(object sender, RoutedEventArgs e)
        {
            try
    	    {
    		    await NavigateToProviderLogin("google");	
    	    }
    	    catch { }
        }
	
	    //
        // When the user clicks the "Disqus" button in your UI
        private async void DisqusLoginButton_Click(object sender, RoutedEventArgs e)
        {
    	    try
    	    {
    		    await NavigateToProviderLogin("disqus");	
    	    }
    	    catch { }
        }
        
        /// <summary>
        /// Occurs when the document being navigated to has finished downloading.
        /// This is where we look to see if a user logged in successfully
        /// </summary>
        private void AuthenticationBrowser_LoadCompleted(object sender, NavigationEventArgs e)
        {
            if (_completionPatterns.Any(e.Uri.OriginalString.Contains))
            {
                // User completed provider authentication, go to your server-side OAuth URL
                NavigateToOAuthAuthorization();
            }
        }
        
        /// <summary>
        /// Occurs just before navigation to a document.
        /// </summary>
        private void AuthenticationBrowser_Navigating(object sender, NavigatingEventArgs e)
        {
            this.LoadingCircle.IsIndeterminate = true;
            LoadingBackgroundGrid.Visibility = Visibility.Visible;

            if (e.Uri.OriginalString.Contains(_oAuthSuccessUrl)) // This means the access token has been granted and is available
            {
                e.Cancel = true; // Stop navigation to this page

	        	//
	        	// Get the payload from the URL (our server-side script redirects to a page with the access token in the URL)
                string payload = e.Uri.Query.Split('?').LastOrDefault(); // Converts to "access_token=USER_ACCESS_TOKEN"
                string access_token = payload.Replace("access_token=", "");

	        	//
	        	//
                //
                // Everything is done. Do what you need with the access token here
                //
                //
                //
            }
        }
        
        #endregion
        
        #region Methods
        
        /// <summary>
        /// This function tells the browser to navigate to the selected provider login, which will allow them to 
        /// log in or register using Disqus or a social service (features the OAuth dialog doesn't allow).
        /// </summary>
        private async Task NavigateToProviderLogin(string provider)
        {
	        //
	    	// Reset cookies in case there was a previous authorization
	        await ClearCookies();
	
		    //
		    // Set URL depending on what service the user chose
	        string navigationUri = string.Empty;
	
	        if (provider == "disqus")
	            navigationUri = string.Format(_disqusLoginUri, _disqusShortname);
	
	        else
	            navigationUri = string.Format(_disqusAxBaseUri, provider, _disqusShortname);
	
		    //
		    // Navigates to the correct login URL. You must set the user-agent for Facebook login to work
	        this.AuthenticationBrowser.Navigate(new Uri(navigationUri, UriKind.Absolute), null, _userAgent);
        }
        
        /// <summary>
        /// Navigates to the final client for authorizing a user. Use this after user is logged in to Disqus
        /// </summary>
        private void NavigateToOAuthAuthorization()
        {
	        string oauthUrl = String.Format("https://disqus.com/api/oauth/2.0/authorize/?client_id={0}&scope=read,write&response_type=code&redirect_uri={1}", "YOUR_PUBLIC_KEY", "http://www.example.com/oauth_redirect");
	
	        this.AuthenticationBrowser.Navigate(new Uri(oauthUrl, UriKind.Absolute), null, _userAgent);
        }
        
        #endregion
    }
}