public async Task <IActionResult> PutUser([FromRoute] string id, [FromBody] User user)
        {
            if (id != user.UserName)
            {
                return(BadRequest());
            }

            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            if (!await userService.CheckUserExists(user))
            {
                return(NotFound());
            }
            userService.UpdateUser(id, user);
            await userService.SaveUser();

            return(Ok());
        }