public HttpResponseMessage RefreshToken(string expiredToken)
        {
            var userId = JWTManager.DecodeToken(expiredToken).Item3;

            var user = ApplicationDbContext.Instance.Users.FindOne(x => x.Id == userId);

            if (user != null)
            {
                var token = JWTManager.GetToken(user);
                return(Request.CreateResponse(HttpStatusCode.OK, new
                {
                    token = token,
                    user = user
                }));
            }
            else
            {
                return(Request.CreateResponse(HttpStatusCode.BadRequest, "Invalid token."));
            }
        }