RenameDialog.xaml.cs

using System.Windows;
using System.Windows.Input;

namespace KnowledgeBaseViewer;

public partial class RenameDialog : Window
{
    public string NewName { get; private set; } = string.Empty;

    public RenameDialog(string currentName)
    {
        InitializeComponent();
        NameTextBox.Text = currentName;
        Loaded += (_, _) =>
        {
            NameTextBox.Focus();
            NameTextBox.SelectAll();
        };
    }

    private void NameTextBox_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
        {
            TryAccept();
        }
        else if (e.Key == Key.Escape)
        {
            DialogResult = false;
        }
    }

    private void RenameButton_Click(object sender, RoutedEventArgs e) => TryAccept();

    private void CancelButton_Click(object sender, RoutedEventArgs e) => DialogResult = false;

    private void TryAccept()
    {
        var name = NameTextBox.Text.Trim();

        if (string.IsNullOrWhiteSpace(name))
        {
            ShowError("Name cannot be empty.");
            return;
        }

        if (name.IndexOfAny(System.IO.Path.GetInvalidFileNameChars()) >= 0)
        {
            ShowError("Name contains invalid characters.");
            return;
        }

        NewName = name;
        DialogResult = true;
    }

    private void ShowError(string message)
    {
        ErrorText.Text = message;
        ErrorText.Visibility = Visibility.Visible;
    }
}