using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp_Logic
{
    public class LinkedList
    {
		private LinkedTarget _heading;
		private LinkedTarget _ending;
		private LinkedTarget _cache;
		private Counter<int> _amountCounter;

		public LinkedTarget Heading
		{
			get { return _heading; }
			set { _heading = value; }
		}

		public LinkedTarget Ending
		{
			get { return _ending; }
			set { _ending = value; }
		}
		public LinkedTarget Cache
		{
			get { return _cache; }
			set { _cache = value; }
		}
		public Counter<int> AmountCounter
		{
			get { return _amountCounter; }
			set { _amountCounter = value; }
		}

        //构造器
        public LinkedList(Counter<int> counter)
		{
			this._amountCounter = counter;
			_amountCounter.Value = 0;
			_ending = null;
			_heading = null;
		}

		
		public void Add(LinkedTarget target)
		{
			if (_ending != null)
			{
				_ending.Next = target;
				target.Previous = _ending;
				_ending = target;
				_amountCounter.Value++;
			}
			else
			{
				_heading = target;
				_heading.Previous = null;
				_ending = target;
				_ending.Next = null;
			}
		}

		/// <summary>
		/// 根据序号删除一个链表成员。
		/// </summary>
		/// <param name="id"></param>
		public void Remove(int id)
		{
			_cache = null;
			for (int i = 1; i < id; i++)
			{
				_cache = _cache.Next;
			}
			_cache.Previous = _cache.Next;
			_cache.Next = _cache.Previous;
			_cache.Next = null;
			_cache.Previous = null;
			_cache = null;
			_amountCounter.Value--;
		}
		/// <summary>
		/// 快速删除链表中已知名称的一个实例。由于不能判别实例是否存在于链表中故安全性较低。在对安全性有要求的情况下应当使用Remove_s方法。
		/// </summary>
		/// <param name="target"></param>
		public void Remove(LinkedTarget target)
		{
			target.Previous = target.Next;
			target.Next = target.Previous;
			target.Previous = null;
			target.Next = null;
            _amountCounter.Value--;
        }

		/// <summary>
		/// 该方法用于防止传入不属于该链表的实例。
		/// </summary>
		/// <param name="target"></param>
		/// <exception cref="Exception"></exception>
		public void Remove_s(LinkedTarget target)
		{
			bool a = true;
			_cache = _heading;
			for (int i = 0; _cache.Next != null ; i++)
			{
				if (_cache==target)
				{
					Remove(target);
					a = false;
                    _amountCounter.Value--;
                }
			}
			if (a)
			{
				throw new Exception("Target can not be found in this List!");
			}
		}


		

	}
}