public (string, User) Authenticate(LoginUserRequestModel login)
        {
            User user = AuthenticateUser(login);

            if (user != null)
            {
                var token = (_jwtTokenProvider.Generate(user), user);
                return(token);
            }

            throw new AuthenticationException();
        }
        private User AuthenticateUser(LoginUserRequestModel loginCredentials)
        {
            User user = appUsers.SingleOrDefault(x => x.UserName == loginCredentials.UserName && x.Password == loginCredentials.Password);

            return(user);
        }