How to mirror live Tridion publish actions on staging using the Event System

MirrorOnStagingEvent.cs

using System;
using System.Linq;
using System.Collections.Generic;
using Tridion.ContentManager.CommunicationManagement;
using Tridion.ContentManager.ContentManagement;
using Tridion.ContentManager.Extensibility;
using Tridion.ContentManager.Extensibility.Events;

namespace Example.Events
{
	[TcmExtension("Publish Events Example")]
	public class Events : TcmExtension
	{
		public Events()
		{
			EventSystem.Subscribe<RepositoryLocalObject, PublishOrUnPublishEventArgs>(MirrorOnStaging, EventPhases.Initiated);
		}

		private void MirrorOnStaging(RepositoryLocalObject item, PublishOrUnPublishEventArgs args, EventPhases phases)
		{
			var stagingTargetTypeUri = "tcm:0-4-65538";
			var targets = args.Targets.ToList();
			if (targets.Where(t => t.Id.ToString() == stagingTargetTypeUri).FirstOrDefault() == null)
			{
				targets.Add((TargetType)item.Session.GetObject(stagingTargetTypeUri));
				args.Targets = targets;
			}
		}
	}
}