using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net.Sockets;
using System.Reflection.Emit;


namespace UndoRedoFunctionality;

///****************************(Classes)********************************/
class Node
{
    public string action;
    public Node next;
    public Node prev;

    public Node(string action)
    {
        this.action = action;
        next = null;
        prev = null;
    }
}

class UndoRedo
{
    private Node curr;

    public UndoRedo()
    {
        Console.WriteLine("#  You can add actions and use undo/redo  #");
        curr = null;
    }

    public void addAction(string action)
    {
        Node newNode = new Node(action);

        if (curr != null)
        {
            curr.next = null; // you can't undo the first action
            
            newNode.prev = curr;
            curr.next = newNode;
        }
        curr = newNode;
        Console.Write("Action added: " + curr.action + " -> ");
        display();
    }

    public void undo()
    {
        if (curr == null)
        {
            Console.WriteLine("No action to undo");
            return;
        }
        Console.Write("Undo " + curr.action + " -> ");
        curr = curr.prev;
        display();
        
    }

    public void redo()
    {
        if (curr == null || curr.next == null)
        {
            Console.WriteLine("No action to redo");
            return;
        }
        Console.Write("Redo " + curr.action + " -> ");
        curr = curr.next;
        display();
        
    }
    public void display()
    {
        if (curr == null)
        {
            Console.WriteLine("No actions to display");
            return;
        }

        Node temp = curr;
        while (temp.prev != null)
            temp = temp.prev;
        
        while (temp != curr)
        {
            Console.Write(temp.action + "   ");
            temp = temp.next;
        }

        Console.WriteLine(curr.action);
    }
}

/********************************************************************/
internal class Program
{

    ///-----------------------(funcoins )--------------------------------/
    
    //------------------------------------------------------------------------/

    static void Main()
    {
        UndoRedo test = new UndoRedo(); 
        test.addAction("A"); // Action added: A -> A
        test.addAction("B"); // Action added: B -> A   B
        test.addAction("C"); // Action added: C -> A   B   C
        test.addAction("D"); // Action added: D -> A   B   C   D
        test.display(); // A   B   C   D
        test.undo(); // Undo D -> A   B   C
        test.undo(); // Undo C -> A   B
        test.redo(); // Redo C -> A   B   C
        test.undo(); // Undo C -> A   B
        test.undo();  // Undo B -> A
        test.undo(); // Undo A -> No actions to display
        test.undo(); // No actions to undo
        test.display(); // No actions to display
    }

}