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using System;
using System.Collections.Generic;
using System.Text;
using XenAPI;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Windows.Forms;

namespace XenAdmin.Commands
{
    internal class SelectionManager : SelectionBroadcaster
    {
        private SelectedItemCollection _selection = new SelectedItemCollection();
        private SelectedItemCollection savedSelection = null;
        private bool saved = false;

        /// <summary>
        /// Sets the main selection for XenCenter.
        /// </summary>
        /// <param name="selection">The selection.</param>
        public void SetSelection(IEnumerable<SelectedItem> selection)
        {
            Program.AssertOnEventThread();
            Util.ThrowIfParameterNull(selection, "selection");

            int count = 0;
            foreach (SelectedItem item in selection)
            {
                if (item == null)
                    throw new ArgumentException("Null SelectedItem found.", "selection");
                count++;
            }

            if (saved &&  // We have a saved selection: update it instead (CA-147401)
                count != 0)   // although if the new selection is empty, we're just refreshing the view via RefreshSelection(): don't save that
                savedSelection = new SelectedItemCollection(selection);
            else
            {
                _selection = new SelectedItemCollection(selection);
                OnSelectionChanged(EventArgs.Empty);
            }
        }

        /// <summary>
        /// Sets the main selection for XenCenter.
        /// </summary>
        /// <param name="item">The selection.</param>
        public void SetSelection(SelectedItem item)
        {
            SetSelection(new SelectedItem[] { item });
        }

        /// <summary>
        /// Gets the current selection which will be used by listening <see cref="CommandToolStripMenuItem"/>s and
        /// <see cref="CommandToolStripButton"/>s.
        /// </summary>
        public override SelectedItemCollection Selection
        {
            get { return _selection; }
        }

        public override void RefreshSelection()
        {
            SetSelection(Selection);
        }

        public override void SaveAndClearSelection()
        {
            Program.AssertOnEventThread();
            savedSelection = _selection;
            SetSelection(new SelectedItemCollection());
            saved = true;
        }
        
        public override void RestoreSavedSelection() 
        {
            Program.AssertOnEventThread();
            if (saved)
            {
                saved = false;
                SetSelection(savedSelection);
                savedSelection = null;
            }
        }
    }
}
