public IActionResult Register(ClientViewModel clientData)
        {
            string firstName   = clientData.FirstName;
            string lastName    = clientData.LastName;
            string password    = clientData.Password;
            int    phoneNumber = clientData.PhoneNumber;

            if (_clientsRepository.Register(firstName, lastName, password, phoneNumber))
            {
                ViewBag.UserName     = firstName + " " + lastName;
                ViewBag.UserRegister = "Rejestracja przebiegła pomyślnie.";
            }
            else
            {
                ViewBag.UserName     = firstName + " " + lastName;
                ViewBag.UserRegister = "Nie udało się! Taki użytkownik już istnieje.";
            }
            return(View("Registered"));
        }