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 *     following disclaimer. 
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 *     copyright notice, this list of conditions and the 
 *     following disclaimer in the documentation and/or other 
 *     materials provided with the distribution. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
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 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
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using System;
using System.Collections.Generic;
using System.Windows.Forms;
using XenAdmin.Controls;
using XenAPI;

namespace XenAdmin.Wizards.BallooningWizard_Pages
{
    public partial class ChooseVMs : XenTabPage
    {
        private List<VM> _checkedVMs = new List<VM>();
        private bool _updating;

        public ChooseVMs()
        {
            InitializeComponent();
        }

        public override string Text => Messages.BALLOONING_PAGE_CHOOSEVMS_TEXT;

        public override string PageTitle => Messages.BALLOONING_PAGE_CHOOSEVMS_PAGETITLE;

        public override string HelpID => "VMs";

        protected override void PageLoadedCore(PageLoadedDirection direction)
        {
            if (direction == PageLoadedDirection.Back)
                return;

            try
            {
                _updating = true;
                listBox.Items.Clear();
                foreach (var vm in CheckedVMs)
                    listBox.Items.Add(vm, true);
            }
            finally
            {
                _updating = false;
            }

            OnPageUpdated();
        }

        public override bool EnableNext()
        {
            clearAllButton.Enabled = CheckedVMs.Count > 0;
            selectAllButton.Enabled = CheckedVMs.Count < listBox.Items.Count;
            return CheckedVMs.Count > 0;
        }

        public List<VM> CheckedVMs
        {
            get => _checkedVMs;
            set => _checkedVMs = value == null ? new List<VM>() : new List<VM>(value);
        }

        private void CheckAll(bool check)
        {
            for (int i = 0; i < listBox.Items.Count; ++i)
                listBox.SetItemChecked(i, check);
        }

        private void listBox_ItemCheck(object sender, ItemCheckEventArgs e)
        {
            if (_updating)
                return;

            // The ItemCheck event is called before the check changes,
            // and there is no event afterwards. Suggestions on the web for workarounds
            // (SelectedIndexChanged and MouseUp) don't work with keyboard access. So we
            // will calculate the new list ourselves.
           
            VM changedVm = (VM)listBox.Items[e.Index];
            
            CheckState newValue = e.NewValue;
            
            if (newValue == CheckState.Unchecked)
                CheckedVMs.Remove(changedVm);
            else
                CheckedVMs.Add(changedVm);

            OnPageUpdated();
        }

        private void selectAllButton_Click(object sender, EventArgs e)
        {
            CheckAll(true);
        }

        private void clearAllButton_Click(object sender, EventArgs e)
        {
            CheckAll(false);
        }
    }
}