Silverlight : Simple PopUp Behavior for VM, MVVM

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Interactivity;
using System.ComponentModel;
using System.Reflection;

namespace HisowaPopUpBehaviors
{
    [System.ComponentModel.Description("Launches a Simple Popup on Event Trigger")]
    public class HisowaSimplePopUpBehavior : TargetedTriggerAction<FrameworkElement>, INotifyPropertyChanged
    {
        private ChildWindow PopUp;
        Grid _grid = new Grid();

        //constructor
        public HisowaSimplePopUpBehavior()
        { }

        #region CustomParameterProperty
        public static readonly DependencyProperty CustomParameterProperty = DependencyProperty.Register("CustomParameter", typeof(object), typeof(HisowaSimplePopUpBehavior), null);

        public object CustomParameter
        {
            get
            {
                return base.GetValue(CustomParameterProperty);
            }
            set
            {
                base.SetValue(CustomParameterProperty, value);
            }
        } 
        #endregion

        #region ReturnDialogResultCommandProperty

        public static readonly DependencyProperty ReturnDialogResultCommandProperty = DependencyProperty.Register("ReturnDialogResultCommand", typeof(bool?), typeof(HisowaSimplePopUpBehavior), null);

        public bool? ReturnDialogResultCommand
        {
            get
            {
                return (bool?)base.GetValue(ReturnDialogResultCommandProperty);
            }
            set
            {
                base.SetValue(ReturnDialogResultCommandProperty, value);
                this.NotifyPropertyChanged("ReturnDialogResultCommand");
            }
        }
        #endregion

        #region ReturnICommandProperty

        public static readonly DependencyProperty ReturnICommandProperty = DependencyProperty.Register("ReturnICommand", typeof(ICommand), typeof(HisowaSimplePopUpBehavior), null);

        public ICommand ReturnICommand
        {
            get
            {
                return (ICommand)base.GetValue(ReturnICommandProperty);
            }
            set
            {
                base.SetValue(ReturnICommandProperty, value);
            }
        }
        #endregion

        #region PopUpMessageProperty

        public static readonly DependencyProperty PopUpMessageProperty = DependencyProperty.Register("PopUpMessage", typeof(string), typeof(HisowaSimplePopUpBehavior), null);

        public string PopUpMessage
        {
            get
            {
                if (base.GetValue(PopUpMessageProperty) == null)
                {
                    return "Are you sure?";
                }
                else
                {
                    return (string)base.GetValue(PopUpMessageProperty);
                }
            }
            set
            {
                base.SetValue(PopUpMessageProperty, value);
            }
        }

        #endregion

        #region PopUpYesMessageProperty

        public static readonly DependencyProperty PopUpYesMessageProperty = DependencyProperty.Register("PopUpYesMessage", typeof(string), typeof(HisowaSimplePopUpBehavior), null);

        public string PopUpYesMessage
        {
            get
            {
                if (base.GetValue(PopUpYesMessageProperty) == null)
                {
                    return "Yes";
                }
                else
                {
                    return (string)base.GetValue(PopUpYesMessageProperty);
                }
            }
            set
            {
                base.SetValue(PopUpYesMessageProperty, value);
            }
        }

        #endregion

        #region PopUpNoMessageProperty

        public static readonly DependencyProperty PopUpNoMessageProperty = DependencyProperty.Register("PopUpNoMessage", typeof(string), typeof(HisowaSimplePopUpBehavior), null);

        public string PopUpNoMessage
        {
            get
            {
                if (base.GetValue(PopUpNoMessageProperty) == null)
                {
                    return "No";
                }
                else
                {
                    return (string)base.GetValue(PopUpNoMessageProperty);
                }
            }
            set
            {
                base.SetValue(PopUpNoMessageProperty, value);
            }
        }

        #endregion

        #region BackgroundColor
        public static readonly DependencyProperty BackGroundColorParameterProperty = DependencyProperty.Register("BackGroundColorParameter", typeof(System.Windows.Media.Brush), typeof(HisowaSimplePopUpBehavior), null);

        public System.Windows.Media.Brush BackGroundColorParameter
        {
            get
            {
                return (System.Windows.Media.Brush)base.GetValue(BackGroundColorParameterProperty);
            }
            set
            {
                base.SetValue(BackGroundColorParameterProperty, value);
            }
        }
        #endregion

        #region YesColor
        public static readonly DependencyProperty YesColorParameterProperty = DependencyProperty.Register("YesColorParameter", typeof(System.Windows.Media.Brush), typeof(HisowaSimplePopUpBehavior), null);

        public System.Windows.Media.Brush YesColorParameter
        {
            get
            {
                return (System.Windows.Media.Brush)base.GetValue(YesColorParameterProperty);
            }
            set
            {
                base.SetValue(YesColorParameterProperty, value);
            }
        }
        #endregion

        #region NoColor
        public static readonly DependencyProperty NoColorParameterProperty = DependencyProperty.Register("NoColorParameter", typeof(System.Windows.Media.Brush), typeof(HisowaSimplePopUpBehavior), null);

        public System.Windows.Media.Brush NoColorParameter
        {
            get
            {
                return (System.Windows.Media.Brush)base.GetValue(NoColorParameterProperty);
            }
            set
            {
                base.SetValue(NoColorParameterProperty, value);
            }
        }
        #endregion

        #region Invoke

        //Shows popup on event trigger you set in designer

        protected override void Invoke(object parameter)
        {
            ChildWindow _childWindow = new ChildWindow();
            _grid = new Grid();

            _grid.Width = 300;
            _grid.Height = 100;

            //width 3 cols
            _grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
            _grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });
            _grid.ColumnDefinitions.Add(new ColumnDefinition() { Width = new GridLength(1, GridUnitType.Star) });

            //height 3 rows
            _grid.RowDefinitions.Add(new RowDefinition() { Height = new GridLength(1, GridUnitType.Star) });
            _grid.RowDefinitions.Add(new RowDefinition());
            _grid.RowDefinitions.Add(new RowDefinition());

            //add message
            TextBlock tbkMessage = new TextBlock();
            tbkMessage.Text = PopUpMessage;
            tbkMessage.SetValue(Grid.RowProperty, 0);
            tbkMessage.SetValue(Grid.ColumnProperty, 0);
            tbkMessage.SetValue(Grid.ColumnSpanProperty, 3);

            _grid.Children.Add(tbkMessage);

            //add Yes button
            Button btnYes = new Button();
            btnYes.Content = PopUpYesMessage;
            btnYes.SetValue(Grid.ColumnProperty, 0);
            btnYes.SetValue(Grid.RowProperty, 1);
            btnYes.Name = "btnYes";
            btnYes.Click += new RoutedEventHandler(btnYes_Click);

            _grid.Children.Add(btnYes);

            //add No Button
            Button btnNo = new Button();
            btnNo.Content = PopUpNoMessage;
            btnNo.SetValue(Grid.ColumnProperty, 2);
            btnNo.SetValue(Grid.RowProperty, 1);
            btnNo.Name = "btnNo";
            btnNo.Click += new RoutedEventHandler(btnNo_Click);

            _grid.Children.Add(btnNo);

            //style
            _grid.Background = BackGroundColorParameter;
            btnYes.Background = YesColorParameter;
            btnNo.Background = NoColorParameter;

            //Make it a PopUp
            _childWindow.Content = _grid;

            PopUp = _childWindow;

            PopUp.Closing += new EventHandler<CancelEventArgs>(PopUp_Closing);

            PopUp.Show();

        }

        #endregion

        #region BtnClicks

        void btnNo_Click(object sender, RoutedEventArgs e)
        {
            RemoveButtonHandlers();
            PopUp.DialogResult = false;
        }

        void btnYes_Click(object sender, RoutedEventArgs e)
        {
            RemoveButtonHandlers();
            PopUp.DialogResult = true;
        }

        private void RemoveButtonHandlers()
        {
            Button btnYes = (Button)_grid.FindName("btnYes");
            btnYes.Click -= new RoutedEventHandler(btnYes_Click);

            Button btnNo = (Button)_grid.FindName("btnNo");
            btnNo.Click -= new RoutedEventHandler(btnNo_Click);
        }

        #endregion

        #region ChildwindowClosing

        //Runs an Icommand when the Popup is closing
        //you can change what it passes to Icommand to whatever you like
        //be sure that your method can consume them


        void PopUp_Closing(object sender, CancelEventArgs e)
        {
            PopUp.Closing -= new EventHandler<CancelEventArgs>(PopUp_Closing);

            ReturnDialogResultCommand = PopUp.DialogResult;

            if (ReturnICommand != null)
            {
                HisowaSimplePopUpBehaviorResult _result = new HisowaSimplePopUpBehaviorResult();
                _result.DialogResult = PopUp.DialogResult;
                _result.DataContext = PopUp.DataContext;
                _result.InputParameter = CustomParameter;

                ReturnICommand.Execute(_result);
            }
        }

        #endregion

        // Utility

        #region INotifyPropertyChanged
        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }
        #endregion
    }

    public class HisowaSimplePopUpBehaviorResult
    {
        public bool? DialogResult { get; set; }
        public object DataContext { get; set; }
        public object InputParameter { get; set; }
    }
}