private void BtnSignIn_Click(object sender, EventArgs e)
        {
            AppUser appUser = new AppUser()
            {
                UserName     = txtUserName.Text,
                UserPassword = txtUserPassword.Text
            };

            bool loginControll = loginController.UserSignInControll(appUser);

            if (loginControll)
            {
                HelperStaticClass.appUserStatic = loginController.AppUserGet(appUser);

                if (HelperStaticClass.guestsDictionery.Count >= 1)
                {
                    ReservationFinalScreen reservationFinalScreen = new ReservationFinalScreen();
                    reservationFinalScreen.Show();
                }
                else
                {
                    ReservationScreen reservationScreen = new ReservationScreen();
                    reservationScreen.Show();
                }
                this.Hide();
            }
            else
            {
                MessageBox.Show("Invalid password or username!");
            }
        }
        public void AddReservation()
        {
            HelperStaticClass.reservationStatic.AppUserID = HelperStaticClass.appUserStatic.ID;

            bool result = reservationController.AddReservationController(HelperStaticClass.reservationStatic);

            if (result)
            {
                if (AddReservationRooms())
                {
                    MessageBox.Show("Booking completed successfully.");
                    ReservationScreen reservationScreen = new ReservationScreen();
                    reservationScreen.Show();
                    mail.SendReservationInfoMail(HelperStaticClass.reservationStatic);
                    Hide();
                }
                else
                {
                    MessageBox.Show("Reservation room error!");
                }
            }
            else
            {
                MessageBox.Show("Error while adding reservation!!!");
                ReservationScreen reservationScreen = new ReservationScreen();
                reservationScreen.Show();
                Hide();
            }
        }
        private void btnBack_Click(object sender, EventArgs e)
        {
            ReservationScreen reservationScreen = new ReservationScreen();

            reservationScreen.Show();
            Hide();
            Dispose();
        }