public IActionResult Post([FromBody] RegistrationInputModel inputModel)
        {
            if (inputModel.Username == null || inputModel.Password == null)
            {
                return(BadRequest("Username is empty"));
            }

            if (!Regex.IsMatch(inputModel.Username, "[A-Za-z0123456789\\-\\._@\\+]{3,}"))
            {
                return(BadRequest("Username should conains only letters or numbers or _@.+."));
            }

            if (inputModel.Password.Length <= 6)
            {
                return(BadRequest("Password should contains more than 6 symbols"));
            }

            if (_userManager.GetByNickName(inputModel.Username) != null)
            {
                return(BadRequest("Username is already exists"));
            }

            var result = _userManager.AddOrUpdate(CreateUserEntity(inputModel));

            if (result == null || result.Id <= 0)
            {
                return(StatusCode(500));
            }

            return(Login(inputModel.Username, inputModel.Password));
        }