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using System.Collections.Generic;
using XenAPI;
using XenAdmin.Dialogs;
using System.Windows.Forms;
using XenAdmin.Actions;


namespace XenAdmin.Commands
{
    /// <summary>
    /// Reverts the specified VM to the specified snapshot.
    /// </summary>
    internal class RevertToSnapshotCommand : Command
    {
        private readonly VM _snapshot;
        private readonly VM _VM;

        /// <summary>
        /// Initializes a new instance of this Command. The parameter-less constructor is required if 
        /// this Command is to be attached to a ToolStrip menu item or button. It should not be used in any other scenario.
        /// </summary>
        public RevertToSnapshotCommand()
        {
        }

        public RevertToSnapshotCommand(IMainWindow mainWindow, IEnumerable<SelectedItem> selection, VM snapshot)
            : base(mainWindow, selection)
        {
            Util.ThrowIfParameterNull(snapshot, "snapshot");
            _snapshot = snapshot;
            _VM = _snapshot.Connection.Resolve(_snapshot.snapshot_of);
        }

        public RevertToSnapshotCommand(IMainWindow mainWindow, VM vm, VM snapshot)
            : base(mainWindow, vm)
        {
            Util.ThrowIfParameterNull(snapshot, "snapshot");
            _snapshot = snapshot;
            _VM = vm;
        }

        protected override bool CanExecuteCore(SelectedItemCollection selection)
        {
            if (selection.Count == 1)
            {
                VM vm = selection[0].XenObject as VM;
                return vm != null && !vm.is_a_template && !vm.is_a_snapshot;
            }
            return false;
        }

        protected override void ExecuteCore(SelectedItemCollection selection)
        {
            Program.AssertOnEventThread();

            VM vm = (VM)selection[0].XenObject;
            var snapshotAllowed = vm.allowed_operations.Contains(vm_operations.snapshot);

            Program.MainWindow.ConsolePanel.setCurrentSource(vm);

            using (var dialog = new WarningDialog(string.Format(Messages.SNAPSHOT_REVERT_BLURB, _snapshot.Name()),
                ThreeButtonDialog.ButtonYes, ThreeButtonDialog.ButtonNo)
            {
                ShowCheckbox = snapshotAllowed,
                IsCheckBoxChecked = snapshotAllowed,
                CheckboxCaption = Messages.SNAPSHOT_REVERT_NEW_SNAPSHOT
            })
            {
                if (dialog.ShowDialog() != DialogResult.Yes)
                    return;

                if (dialog.IsCheckBoxChecked)
                {
                    TakeSnapshotCommand command = new TakeSnapshotCommand(MainWindowCommandInterface, vm);
                    var action = command.GetCreateSnapshotAction();
                    if (action != null)
                    {
                        // if new snapshot taken, then only revert if this succeeded
                        action.Completed += delegate
                        {
                            if (action.Succeeded)
                                ExecuteRevertAction();
                        };
                        action.RunAsync();
                    }
                }
                else
                {
                    ExecuteRevertAction();
                }
            }
        }

        private void ExecuteRevertAction()
        {
            var action = new VMSnapshotRevertAction(_snapshot);
            action.RunAsync();
        }
    }
}