public ActionResult Login(string returnUrl)
        {
            var loginAttempt = new LoginViewModel
            {
                ReturnUrl = returnUrl
            };

            return View(loginAttempt);
        }
        public ActionResult Login(LoginViewModel loginViewModel)
        {
            var staffMember = _staffMemberRepository.GetAll().SingleOrDefault(sm =>
                sm.EmployeeNumber == loginViewModel.EmployeeNumber &&
                sm.PasswordHash == loginViewModel.GetPasswordHash());

            if (staffMember != null)
            {
                FormsAuthentication.SetAuthCookie(loginViewModel.EmployeeNumber, false);
                TempData["message"] = "You have successfully logged in.";
                return Redirect(loginViewModel.ReturnUrl);
            }

            ViewData["message"] = "The login credentials provided were invalid.";
            return View(loginViewModel);
        }