using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Input;

namespace Sample
{
    ///////////////////////////////////////////////////////////////////////////
    /// <summary>
    /// Defines the different behaviors of a key.
    /// </summary>
    ///////////////////////////////////////////////////////////////////////////
    public enum KeyBehavior
    {
        ///////////////////////////////////////////////////////////////////////////
        /// <summary>The default behavior.</summary>
        ///////////////////////////////////////////////////////////////////////////
        None,
        ///////////////////////////////////////////////////////////////////////////
        /// <summary>Moves focus to the next control.</summary>
        ///////////////////////////////////////////////////////////////////////////
        NavigateNext
    }

    ///////////////////////////////////////////////////////////////////////////
    /// <summary>
    /// Provides different behaviors for a key press.
    /// </summary>
    ///////////////////////////////////////////////////////////////////////////
    public static class KeyBehaviors
    {
        ///////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Attached property that allows the Enter key to have other behaviors.
        /// </summary>
        ///////////////////////////////////////////////////////////////////////////
        public static readonly DependencyProperty EnterKeyBehaviorProperty = DependencyProperty.RegisterAttached("EnterKeyBehavior", typeof(KeyBehavior), typeof(KeyBehaviors), new PropertyMetadata(KeyBehavior.None, OnEnterKeyBehaviorChanged));

        ///////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Sets the EnterKeyBehavior dependency property.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="value">The value.</param>
        ///////////////////////////////////////////////////////////////////////////
        public static void SetEnterKeyBehavior(DependencyObject source, KeyBehavior value)
        {
            source.SetValue(EnterKeyBehaviorProperty, value);
        }

        ///////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Gets the EnterKeyBehavior dependency property.
        /// </summary>
        /// <param name="source">The source.</param>
        ///////////////////////////////////////////////////////////////////////////
        public static KeyBehavior GetEnterKeyBehavior(DependencyObject source)
        {
            return (KeyBehavior)source.GetValue(EnterKeyBehaviorProperty);
        }

        ///////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Called when the Behavior property changes on something.
        /// </summary>
        /// <param name="source">The source.</param>
        /// <param name="e">The <see cref="System.Windows.DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
        ///////////////////////////////////////////////////////////////////////////
        private static void OnEnterKeyBehaviorChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
        {
            UIElement item = source as UIElement;

            if (item == null)
            {
                throw new InvalidOperationException("The Behavior property is only valid on UIElements.");
            }

            if ((KeyBehavior)e.NewValue == KeyBehavior.NavigateNext)
            {
                //
                // Hook into the preview key down event.
                //
                item.PreviewKeyDown += new KeyEventHandler(OnPreviewKeyDown);
            }
            else if ((KeyBehavior)e.NewValue == KeyBehavior.None)
            {
                item.PreviewKeyDown -= new KeyEventHandler(OnPreviewKeyDown);
            }
        }

        ///////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Called when a key is pressed on a control that we're attached to.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="System.Windows.Input.KeyEventArgs"/> instance containing the event data.</param>
        ////////////////////////////////////////////////////////////////////////////// 
        private static void OnPreviewKeyDown(object sender, KeyEventArgs e)
        {
            UIElement item = e.Source as UIElement;

            if (item != null)
            {
                switch(e.Key)
                {
                    case Key.Enter:
                        bool result = item.MoveFocus(new TraversalRequest(FocusNavigationDirection.Next));
                        break;
                }
            }
        }
    }
}