ItemSelectionChangedBehavior

using System.Collections;
using System.Diagnostics;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using Telerik.Windows.Controls;
using System;

namespace App.UI.Behaviors
{

    public class ItemSelectionChangedBehavior
    {
        #region Command Dependency Property

        public static readonly DependencyProperty CommandProperty = DependencyProperty.RegisterAttached(
            "Command",
            typeof(ICommand),
            typeof(ItemSelectionChangedBehavior),
            new UIPropertyMetadata(null, OnCommandChanged));


        public static ICommand GetCommand(DependencyObject obj)
        {
            return (ICommand)obj.GetValue(CommandProperty);
        }

        public static void SetCommand(DependencyObject obj, ICommand value)
        {
            obj.SetValue(CommandProperty, value);
        }

        static void OnCommandChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
        {
            if (args.OldValue != null)
            {
                if (sender is RadListBox)
                {
                    var lstBox = sender as RadListBox;
                    if (lstBox != null)
                    {
                        lstBox.SelectionChanged -= ListBox_SelectionChanged;
                    }
                }
                else if (sender is RadGridView)
                {
                    var gview = sender as RadGridView;
                    if (gview != null)
                    {
                        gview.SelectionChanged -= GridView_SelectionChanged;
                    }
                }
            }

            if (args.NewValue != null)
            {
                if (sender is RadListBox)
                {
                    var lstBox = sender as RadListBox;
                    if (lstBox != null)
                    {
                        lstBox.SelectionChanged += ListBox_SelectionChanged;
                    }
                }
                else if (sender is RadGridView)
                {
                    var gview = sender as RadGridView;
                    if (gview != null)
                    {
                        gview.SelectionChanged += GridView_SelectionChanged;
                    }
                }
            }
        }

        #endregion

        static void ListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            var listBox = sender as RadListBox;
            if (listBox == null)
                return;

            var selectedFiles = (IList)listBox.SelectedItems;
            var command = GetCommand(listBox);
            if (command != null)
            {
                if (command.CanExecute(selectedFiles))
                {
                    command.Execute(selectedFiles);
                }
            }
            Debug.WriteLineIf(false, string.Format("ItemSelectionChangedBehavior -> ListBox.SelectedItems.Count: {0}", SelectedFiles.Count));
        }

        static void GridView_SelectionChanged(object sender, SelectionChangeEventArgs e)
        {
            var gridView = sender as RadGridView;
            if (gridView == null)
                return;

            var selectedFiles = gridView.SelectedItems.ToList();
            var command = GetCommand(gridView);
            if (command != null)
            {
                if (command.CanExecute(selectedFiles))
                {
                    command.Execute(selectedFiles);
                }
            }

            Debug.WriteLineIf(false, string.Format("ItemSelectionChangedBehavior -> Grid.SelectedItems.Count: {0}", selectedFiles.Count));
        }
    }
}