Memento Design Pattern

A.Memento.cs

public class Program 
{
	public static void Main(string[] args)
	{
		var account = new Account {
			Id = 1,
			Verified = false,
			Credit = 10,
			Notes = "None"
		};
		
		var accountCareTaker = new AccountCareTaker(account);
		
		accountCareTaker.Persist(CheckPoint.Created);
		
		VerifyAccount(account);
		
		accountCareTaker.Persist(CheckPoint.Verified);
		
		DeleteAccount(account);
		
		accountCareTaker.Persist(CheckPoint.Deleted);
				
		Console.WriteLine("Restoring to the creation point");
		accountCareTaker.Restore(CheckPoint.Created);
		
		Console.WriteLine($"Notes: {account.Notes}"); //Prints "None"
		Console.WriteLine($"Credit: {account.Credit}"); //Prints 10
				
		Console.WriteLine("\nRestoring to the verification point");
		accountCareTaker.Restore(CheckPoint.Verified);
		
		Console.WriteLine($"Notes: {account.Notes}"); //Prints "Verified"
		Console.WriteLine($"Credit: {account.Credit}"); //Prints 20
		
		Console.WriteLine("\nRestoring to the deletion point");
		accountCareTaker.Restore(CheckPoint.Deleted);
		
		Console.WriteLine($"Notes: {account.Notes}"); //Prints "Deleted"
		Console.WriteLine($"Credit: {account.Credit}"); //Prints 0
	}
	
	public static void VerifyAccount(Account account)
	{
		account.Verified = true;
		account.Credit *= 2;
		account.Notes = "Verified";
	}
	
	public static void DeleteAccount(Account account)
	{
		account.Verified = false;
		account.Credit = 0;
		account.Notes = "Deleted";
	}
}

B.Account.cs

public class Account //The Originator
{	
	public int Id { get; set; }
	
	public bool Verified { get; set; }
	
	public int Credit { get; set; }
	
	public string Notes { get; set; }
	
	public AccountMemento GetMemento() 
	{
		return new AccountMemento {
			AccountState = $"{Id}-{Verified}-{Credit}-{Notes}"
		};
	}
	
	public void RestoreFromMemento(AccountMemento memento) 
	{
		var state = memento.AccountState.Split('-').ToList();
		Id = int.Parse(state[0]);
		Verified = bool.Parse(state[1]);
		Credit = int.Parse(state[2]);
		Notes = state[3];
	}
}

C.AccountMemento.cs

public class AccountMemento { // The memento holds the state of the originator
	
	public string AccountState { get; set; }
  
}

D.AccountCareTaker.cs

public class AccountCareTaker //The CareTaker acts as the safe keeper for the mementos
{
	
	private readonly IDictionary<CheckPoint, AccountMemento> _accountMementos;
	private readonly Account _account;
	
	public AccountCareTaker(Account account) 
	{
		_accountMementos = new Dictionary<CheckPoint, AccountMemento>();
		_account = account;
	}
	
	public void Restore(CheckPoint checkPoint) 
	{
		if(_accountMementos.TryGetValue(checkPoint, out var result)) 
		{	
			_account.RestoreFromMemento(result);
			return;
		}
		
		throw new Exception("Checkpoint not found...");
	}
	
	public void Persist(CheckPoint checkPoint) {
		
		if(_accountMementos.TryGetValue(checkPoint, out var _)) 
		{
			throw new Exception("Checkpoint already exists");
		}
		
		_accountMementos.Add(checkPoint, _account.GetMemento());
	}
}

E.CheckPoint.cs

public enum CheckPoint {
	Created = 1,
	Verified = 2,
	Deleted = 4
}