public HttpResponseMessage LoginUser(UserLoginModel model)
        {
            var responseMsg = this.ExceptionHandler(
                 () =>
                 {
                     var context = new AutoMorgueContext();

                     UserDataPersister.ValidateUsername(model.Username);
                     UserDataPersister.ValidateAuthCode(model.AuthCode);

                     var usernameToLower = model.Username.ToLower();

                     var users = context.Users;
                     var user = users.FirstOrDefault(
                           usr => usr.Username == usernameToLower && usr.AuthCode == model.AuthCode);

                     if (user == null)
                     {
                         throw new InvalidOperationException("Invalid Username or Password");
                     }

                     user.SessionKey = UserDataPersister.GenerateSessionKey(user.Id);
                     context.SaveChanges();

                     var loggedModel = new UserLoggedModel
                     {
                         DisplayName = user.DisplayName,
                         SessionKey = user.SessionKey
                     };

                     var response = this.Request.CreateResponse(HttpStatusCode.Created, loggedModel);
                     response.Headers.Location = new Uri(Url.Link("DefaultApi", new { id = user.Id }));

                     return response;
                 });

            return responseMsg;
        }
        public HttpResponseMessage LogoutUser(
            [ValueProvider(typeof(HeaderValueProviderFactory<string>))] string sessionKey)
        {
            var responseMsg = this.ExceptionHandler(
                 () =>
                 {
                     var context = new AutoMorgueContext();

                     var users = context.Users;
                     var user = users.FirstOrDefault(
                           usr => usr.SessionKey == sessionKey);

                     if (user == null)
                     {
                         throw new InvalidOperationException("Invalid Username or Password");
                     }

                     user.SessionKey = null;
                     context.SaveChanges();

                    var probUser = new UserLoginModel(){
                                           AuthCode = "10a81501e9a609a425db71c9a59be60dabbeea86",
                                           Username ="******"
                                           };
                     var response = this.Request.CreateResponse(HttpStatusCode.OK,
                         probUser);

                     return response;
                 });

            return responseMsg;
        }