designPatternGuru/DesignPatternGuru/Memonto/Originators/Originator.cs

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

namespace Memonto.Originators
{
    internal class Originator
    {
        private string _state;

        public Originator(string state)
        {
            _state = state;
            Console.WriteLine($"Originator: My initial state is: {state}");
        }

        public void DoSomething()
        {
            Console.WriteLine("Originator: I'm doing something important.");
            _state = GenerateRandomString(30);
            Console.WriteLine($"Originator: And my state has changed to: {_state}");
        }

        private string GenerateRandomString(int length = 10)
        {
            string allowedSymbols = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
            string result = string.Empty;

            while (length > 0 )
            {
                result += allowedSymbols[new Random().Next(0, allowedSymbols.Length)];
                length--;
            }

            return result;
        }

        public IMemento Save()
        {
            return new ConcreteMemento( _state );
        }

        public void Restore(IMemento memento )
        {
            if (!(memento is ConcreteMemento))
                throw new Exception("Unknown memento class " + memento.ToString());

            _state = memento.GetState();
            Console.WriteLine($"Originator: My state has changed to: {_state}");
        }
    }
}