WPF DataGrid Context Menus

using System;
using System.Linq;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using Microsoft.Practices.Prism.Commands;

namespace Client.Models
{
    /// <summary>
    /// Provides global DatgGrid context menu functions
    /// </summary>
    public class DataGridContextMenus
    {
        static readonly DataGridContextMenus _instance = new DataGridContextMenus();
        public static DataGridContextMenus Instance
        {
            get { return _instance; }
        }

        /// <summary>Called by the price grid's context menu</summary>
        public ICommand ExportGridToExcelCommand { get; set; }

        /// <summary>Called by the grid's context menu</summary>
        public ICommand CopyGridToClipboardCommand { get; set; }

        public DataGridContextMenus()
        {
            ExportGridToExcelCommand = new DelegateCommand<object>(OnExportGridToExcel);
            CopyGridToClipboardCommand = new DelegateCommand<object>(OnCopyToClipboard);
        }

        void OnExportGridToExcel(object sender)
        {
            var cm = sender as ContextMenu;
            if (cm == null)
                return;
            var grid = cm.PlacementTarget as DataGrid;
            if (grid == null)
                return;

            var result = CopyGridToClipboard(grid);

            string tempfile = Path.Combine(Path.GetTempPath(), string.Format("Exported_{0}.csv", DateTime.Now.Ticks));
            using (StreamWriter sw = new StreamWriter(tempfile))
            {
                sw.Write(result);
                sw.Close();
                Process.Start(new ProcessStartInfo(tempfile) { UseShellExecute = true });
            }
        }

        void OnCopyToClipboard(object sender)
        {
            var cm = sender as ContextMenu;
            if (cm == null)
                return;

            var grid = cm.PlacementTarget as DataGrid;
            if (grid == null)
                return;
            CopyGridToClipboard(grid);
        }

        string CopyGridToClipboard(DataGrid grid)
        {
            DataGridSelectionMode selectionMode = grid.SelectionMode;
            try
            {
                if (selectionMode != DataGridSelectionMode.Extended)
                    grid.SelectionMode = DataGridSelectionMode.Extended;
                grid.SelectAllCells();
                grid.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;
                ApplicationCommands.Copy.Execute(null, grid);
            }
            finally
            {
                grid.UnselectAllCells();
                if (selectionMode != DataGridSelectionMode.Extended)
                    grid.SelectionMode = selectionMode;
            }

            string result = (string)Clipboard.GetData(DataFormats.CommaSeparatedValue);
            return result;
        }
    }
}