PixiEditor/PixiEditor/ViewModels/SubViewModels/Main/UndoViewModel.cs

using PixiEditor.Helpers;
using PixiEditor.Models.Undo;
using System;
using System.IO;

namespace PixiEditor.ViewModels.SubViewModels.Main
{
    public class UndoViewModel : SubViewModel<ViewModelMain>
    {
        public RelayCommand UndoCommand { get; set; }

        public RelayCommand RedoCommand { get; set; }

        public event EventHandler UndoRedoCalled;

        public UndoViewModel(ViewModelMain owner)
            : base(owner)
        {
            UndoCommand = new RelayCommand(Undo, CanUndo);
            RedoCommand = new RelayCommand(Redo, CanRedo);

            var result = Directory.CreateDirectory(StorageBasedChange.DefaultUndoChangeLocation);

            //ClearUndoTempDirectory();
        }

        /// <summary>
        ///     Redo last action.
        /// </summary>
        /// <param name="parameter">CommandProperty.</param>
        public void Redo(object parameter)
        {
            UndoRedoCalled?.Invoke(this, EventArgs.Empty);

            //sometimes CanRedo gets changed after UndoRedoCalled invoke, so check again (normally this is checked by the relaycommand)
            if (CanRedo(null))
            {
                Owner.BitmapManager.ActiveDocument.UndoManager.Redo();
                Owner.BitmapManager.ActiveDocument.ChangesSaved = false;
            }
        }

        /// <summary>
        ///     Undo last action.
        /// </summary>
        /// <param name="parameter">CommandParameter.</param>
        public void Undo(object parameter)
        {
            UndoRedoCalled?.Invoke(this, EventArgs.Empty);

            //sometimes CanUndo gets changed after UndoRedoCalled invoke, so check again (normally this is checked by the relaycommand)
            if (CanUndo(null))
            {
                Owner.BitmapManager.ActiveDocument.UndoManager.Undo();
                Owner.BitmapManager.ActiveDocument.ChangesSaved = false;
            }
        }

        /// <summary>
        /// Removes all files from %tmp%/PixiEditor/UndoStack/.
        /// </summary>
        public void ClearUndoTempDirectory()
        {
            DirectoryInfo dirInfo = new DirectoryInfo(StorageBasedChange.DefaultUndoChangeLocation);
            foreach (FileInfo file in dirInfo.GetFiles())
            {
                file.Delete();
            }
        }

        /// <summary>
        ///     Returns true if undo can be done.
        /// </summary>
        /// <param name="property">CommandParameter.</param>
        /// <returns>True if can undo.</returns>
        private bool CanUndo(object property)
        {
            return Owner.BitmapManager.ActiveDocument?.UndoManager.CanUndo ?? false;
        }

        /// <summary>
        ///     Returns true if redo can be done.
        /// </summary>
        /// <param name="property">CommandProperty.</param>
        /// <returns>True if can redo.</returns>
        private bool CanRedo(object property)
        {
            return Owner.BitmapManager.ActiveDocument?.UndoManager.CanRedo ?? false;
        }
    }
}