using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace BF
{
    public class BFStackPool<T>
    {
        private BFNode<T> top;

        private int count;

        public int Count { get { return count; } }

        public BFStackPool()
        {
            top = null;
            count = 0;
        }

        public BFStackPool(int count)
        {
            for (int i = 0; i < count; i++)
            {
                var node = new BFNode<T>();
                Push(node);
            }
        }

        public BFNode<T> Alloc(T item)
        {
            var node = SafePop();
            node.item = item;
            return node;
        }

        public void Free(BFNode<T> node)
        {
            node.Invalidate();
            Push(node);
        }

        public BFNode<T> SafePop()
        {
            if (count == 0)
                return new BFNode<T>();
            var temp = top;
            top = top.next;
            --count;
            return temp;
        }

        public void Push(BFNode<T> node)
        {
            var temp = top;
            node.next = top;
            top = node;
            ++count;
        }

        public void Clear()
        {
            top = null;
            count = 0;
        }
    }
}