Facebook OAUTH controller for MVC3 projects

FacebookController.cs

using System;
using System.Web.Mvc;
using Newtonsoft.Json.Linq;
using PennyAuction.Models;
using System.Linq;

namespace MyProject.Controllers
{
    public class FacebookController : Controller
    {
        /// <summary>
        /// Initiate the Facebook Login Sequence
        /// </summary>
        public void fbLogin()
        {
            oAuthFacebook oauth = new oAuthFacebook();

            Response.Redirect(oauth.AuthorizationLinkGet());
        }

        public void fbCallback()
        {
            string url = "";
            // cache the Request code, since LINQ does not evaluate at runtime properly
            string authCode = Request["code"];
            oAuthFacebook oAuth = new oAuthFacebook();

            if (authCode == null)
            {
                //Redirect the user back to Facebook for authorization.
                Response.Redirect(oAuth.AuthorizationLinkGet());
            }
            else
            {
                //Get the access token and secret.
                oAuth.AccessTokenGet(authCode);

                if (oAuth.Token.Length > 0)
                {
                    //We now have the credentials, so we can start making API calls
                    url = "https://graph.facebook.com/me/?access_token=" + oAuth.Token;
                    string json = oAuth.WebRequest(oAuthFacebook.Method.GET, url, String.Empty);
                    if (json != null)
                    {
                        // parse the response object first, we may want to create a user from it.
                        JObject o = JObject.Parse(json);

                        // get a data-set to populate
                        using (var context = new AuctionDataContainer())
                        {
                            // query the database for users containing the facebook token, ordered by firstname
                            var users = context.SiteUsers
                                .Where(u => u.FacebookToken == authCode)
                                .ToList();

                            if (users.Count == 0) // we have no users in the database. Migrate them into the DB
                            {
                                // this was throwing errors, creating a guid prior to population then
                                Guid id = Guid.NewGuid();
                                SiteUsers newUser = SiteUsers.CreateSiteUsers(id,
                                    (string)o["first_name"],
                                    (string)o["last_name"],
                                    (string)o["email"],
                                    DateTime.Now,
                                    DateTime.Now);
                                newUser.FacebookToken = authCode;

                                context.SiteUsers.AddObject(newUser);
                                context.SaveChanges(); // commit our user to the database
                            } // TODO: if user exists and decides they want to add facebook -- update their info
                            
                            // by default we should update their last login time.
                            var thisUser = context.SiteUsers
                                .Where(u => u.FacebookToken == authCode)
                                .FirstOrDefault();
                            thisUser.LastLogin = DateTime.Now;
                            context.SaveChanges();

                        }// end of using

                    }

                } // if our token was blank we have failure
                else
                {
                    Response.Redirect("/"); // TODO: set an error code and display it on the main site
                }

                
                Response.Redirect("/");
            }
        } // end of fb callback method

    }
}