using System.Collections.Generic;

namespace Sarand.Net.Standard.Base.Core
{
	//=======================================================================
	/// <summary>
	/// Stack (LIFO) with limit on length.
	/// </summary>
	/// <typeparam name="ITEM"></typeparam>
	public class StackLimited<ITEM>
	{
		//-------------------------------------------------------------------
		// Data members.
		private int limit = 0;
		private readonly LinkedList<ITEM> items = new LinkedList<ITEM>();
		//-------------------------------------------------------------------
		// Construction.
		public StackLimited (int limit = 0)
		{
			this.limit = limit;
		}
		//-------------------------------------------------------------------
		// Utilities.
		public int Count
		{
			get { return items.Count; }
		}
		public void Clear ()
		{
			items.Clear();
		}
		//-------------------------------------------------------------------
		/// <summary>
		/// Add item to the stack and ensure limit isn't exceeded.
		/// </summary>
		/// <param name="item"></param>
		public void Push (ITEM item)
		{
			items.AddFirst(item);
			while (limit > 0 && items.Count > limit)
				items.RemoveLast();
		}
		//-------------------------------------------------------------------
		/// <summary>
		/// Retrieve and remove last item added to the stack.
		/// </summary>
		/// <returns></returns>
		public ITEM Pop ()
		{
			ITEM item = items.First.Value;
			items.RemoveFirst();
			return item;
		}
		//-------------------------------------------------------------------
	}
	//=======================================================================
}