MVVM for Multi Platforms

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;

using GeographicRepresentation.Interfaces;
using GeographicRepresentation.Lib;

namespace GeographicRepresentation.UILib.View
{
    /// <summary>
    /// Interaction logic for EditContinentWindow.xaml
    /// </summary>
    public partial class EditContinentWindow : Window
    {
        #region Members

        Guid m_ContinentId;
        IEditableContinentViewModel m_DataContext;

        public static RoutedUICommand cmd_SaveContinent = new RoutedUICommand("saveContinent", "saveContinent", typeof(EditContinentWindow));
        public static RoutedUICommand cmd_Cancel = new RoutedUICommand("cancelContinent", "cancelContinent", typeof(EditContinentWindow));

        #endregion

        #region Methods

        #region Ctor        
        
        public EditContinentWindow()
        {
            m_ContinentId = Guid.Empty;
            InitializeComponent();
        }

        /// <summary>
        /// Ctor for editing the continent
        /// </summary>
        /// <param name="continentId"></param>
        public EditContinentWindow(Guid continentId) : this()
        {
            m_ContinentId = continentId;
        }

        #endregion

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            SimpleOperationDelegate delg = new SimpleOperationDelegate(this.GetDataContext);
            delg.BeginInvoke(new AsyncCallback(this.DataContextLoaded), delg);

            if (m_ContinentId == Guid.Empty)
            {
                this.Title = "Add continent";
            }

            CommandBinding cb = new CommandBinding(cmd_SaveContinent, onSave, canSave);
            CommandBindings.Add(cb);
            cb = new CommandBinding(cmd_Cancel, onCancel, canCancel);
            CommandBindings.Add(cb);
        }

        /// <summary>
        /// A request for the data context
        /// </summary>
        private void GetDataContext()
        {
            if (m_ContinentId == Guid.Empty)
            {
                m_DataContext = InterfacesFactory.Instance.GetEditableContinentViewModelForAdd();
            }
            else
            {
                m_DataContext = InterfacesFactory.Instance.GetEditableContinentViewModelForEdit(m_ContinentId);
            }
        }

        /// <summary>
        /// The data context call back. Make all the adjustments in the main thread, using the dispatcher
        /// </summary>
        /// <param name="result"></param>
        private void DataContextLoaded(IAsyncResult result)
        {
            System.Windows.Application.Current.Dispatcher.BeginInvoke(new AsyncCallback(this.DataContextLoadedInMainThread), result);
        }

        /// <summary>
        /// Update the view
        /// </summary>
        /// <param name="result"></param>
        private void DataContextLoadedInMainThread(IAsyncResult result)
        {
            if (result.IsCompleted)
            {
                this.DataContext = m_DataContext;
                SimpleOperationDelegate delg = result.AsyncState as SimpleOperationDelegate;
                delg.EndInvoke(result);
                Button saveButton = (Button)this.Template.FindName("saveButton", this);
                if (saveButton != null)
                {
                    saveButton.Command = EditContinentWindow.cmd_SaveContinent;
                }
                Button cancelButton = (Button)this.Template.FindName("cancelButton", this);
                if (cancelButton != null)
                {
                    cancelButton.Command = EditContinentWindow.cmd_Cancel;
                }
                if (m_ContinentId != Guid.Empty)
                {
                    this.Title = string.Format("Edit {0}", m_DataContext.ContinentName);
                }
            }
        }

        private void onSave(object sender, ExecutedRoutedEventArgs args)
        {
            this.Cursor = Cursors.Wait;
            SimpleOperationDelegate delg = new SimpleOperationDelegate(this.SaveOperation);
            delg.BeginInvoke(this.OperationCompleted, delg);
        }

        /// <summary>
        /// Textual data validation
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        private void canSave(object sender, CanExecuteRoutedEventArgs args)
        {
            int nNum;
            args.CanExecute = txtName.Text.Length > 0 &&
                              txtNumOfCountries.Text.Length > 0 &&
                              int.TryParse(txtNumOfCountries.Text, out nNum) &&
                              nNum > 0;
        }

        private void SaveOperation()
        {
            m_DataContext.Save();
        }

        /// <summary>
        /// The operation call back. Call the dispatcher to update the view from the main thread
        /// </summary>
        /// <param name="result"></param>
        private void OperationCompleted(IAsyncResult result)
        {
            System.Windows.Application.Current.Dispatcher.BeginInvoke(new AsyncCallback(this.EndOperation), result);
        }

        /// <summary>
        /// End the asynchronos call
        /// </summary>
        /// <param name="result"></param>
        private void EndOperation(IAsyncResult result)
        {
            this.Cursor = Cursors.Arrow;

            SimpleOperationDelegate delg = result.AsyncState as SimpleOperationDelegate;
            delg.EndInvoke(result);
            this.DialogResult = true;
            this.Close();            
        }

        /// <summary>
        /// The cancelation button should run if this is the edit mode, othewise, simply close the window
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        private void onCancel(object sender, ExecutedRoutedEventArgs args)
        {
            if (m_ContinentId != Guid.Empty)
            {
                this.Cursor = Cursors.Wait;
                SimpleOperationDelegate delg = new SimpleOperationDelegate(this.CancelOperation);
                delg.BeginInvoke(this.OperationCompleted, delg);
            }
            else
            {
                this.Close();
            }
        }


        private void canCancel(object sender, CanExecuteRoutedEventArgs args)
        {
            args.CanExecute = true;
        }

        private void CancelOperation()
        {
            m_DataContext.Cancel();
        }

        #endregion
    }
}