private void ButtonAcceptDialogHost_Click(object sender, RoutedEventArgs e)
        {
            if (TextBoxUserName.Text == "")
            {
                var message = "Name required to login!";
                SnackBarDialogHostMessageDisplay(message, 1000);
            }

            if (PasswordBoxUserPassword.Password != "")
            {
                if (PasswordBoxUserPassword.Password.Length < 13)
                {
                    var message = "Password is too short!";
                    SnackBarDialogHostMessageDisplay(message, 1000);
                    PasswordBoxUserPassword.Focus();
                    e.Handled = true;
                }
                else
                {
                    //if userLogin fails
                    if (!SQL_Connect())
                    {
                        var message = "User does not exist!";
                        SnackBarDialogHostMessageDisplay(message, 1000);
                        PasswordBoxUserPassword.Password = "";
                        TextBoxUserName.Text             = "";
                        TextBoxUserName.Focus();
                        return;
                    }



                    Console.WriteLine("Closing Dialog Host");
                    AcceptButtonIsPressed = true;

                    var message1 = "Welcome," + AppUser.Name + "!";
                    SnackbarMessageDisplay(message1, 1000);
                    BUTTONCLOSEDIALOG.Command.Execute(null);
                    var target = Application.Current.Windows.Cast <Window>().FirstOrDefault(window => window is MainWindow) as MainWindow;
                    target.MenuToggleButton.IsEnabled = true;
                    if (!AppUser.isTeacher)
                    {
                        target.ButtonBooks.Visibility = Visibility.Collapsed;
                        target.ButtonUsers.Visibility = Visibility.Collapsed;
                    }
                    else
                    {
                        target.ButtonBooks.Visibility = Visibility.Visible;
                        target.ButtonUsers.Visibility = Visibility.Visible;
                    }
                    e.Handled = true;
                }
            }
            else
            {
                var message = "CNP can not be empty!";
                SnackBarDialogHostMessageDisplay(message, 1000);
                e.Handled = true;
            }
        }
 //when DialogHostLogIn is opened, execute the following code
 private void DialogHostLogIn_DialogOpened(object sender, DialogOpenedEventArgs eventArgs)
 {
     TextBoxUserName.Text = TextBoxNameInput.Text;
     Console.WriteLine("Login Opened");
     Dispatcher.Invoke(new Action(() => { PasswordBoxUserPassword.Focus();
                                          Console.WriteLine("Set focus on PasswordBox"); }));
     //Keyboard.Focus(PasswordBoxUserPassword);
 }