designPatternGuru/DesignPatternGuru/Memonto/Mementos/Caretaker.cs

using Memonto.Originators;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Memonto.Mementos
{
    internal class Caretaker
    {
        private List<IMemento> _mementos = new List<IMemento>();

        private Originator _originator = null;

        public Caretaker(Originator originator)
        {
            _originator = originator;
        }

        public void Backup()
        {
            Console.WriteLine();
            Console.WriteLine("Caretaker: Saving originator's state...");
            _mementos.Add(_originator.Save());
        }

        public void Undo()
        {
            if (_mementos.Count < 1)
                return;

            IMemento memento = _mementos.Last();
            _mementos.Remove(memento);

            Console.WriteLine($"Caretaker: Restoring state to: {memento.GetName()}");
            try
            {
                _originator.Restore(memento);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Undo exception: {ex.Message}");
                Undo();
            }
        }

        public void ShowHistory()
        {
            Console.WriteLine("Caretaker: Here's the list of mementos: ");
            foreach (var memento in _mementos)
            {
                Console.WriteLine(memento.GetName());
            }
        }
    }
}