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

/// <summary>
/// 双向循环链表
/// </summary>
/// <typeparam name="T"></typeparam>
public class CircleList<T>
{
    /// <summary>
    /// 头节点
    /// </summary>
    public DoubleLinkNode<T> First
    {
        get;
        private set;
    }


    /// <summary>
    /// 尾节点
    /// </summary>
    public DoubleLinkNode<T> Last
    {
        get;
        private set;
    }


    /// <summary>
    /// 链表长度
    /// </summary>
    public int Count
    {
        get;
        private set;
    }


    /// <summary>
    /// 添加指定节点
    /// </summary>
    /// <param name="item"></param>
    public void AddNode(DoubleLinkNode<T> item)
    {
        if (First == null && Last == null)
        {
            First = item;
            Last = item;
        }
        First.PreNode = item;
        Last.NextNode = item;
        item.PreNode = Last;
        item.NextNode = First;
        Last = item;
        Count++;
    }


    /// <summary>
    /// 通过节点数据添加节点
    /// </summary>
    /// <param name="item"></param>
    public void AddNode(T item)
    {
        DoubleLinkNode<T> _node = new DoubleLinkNode<T>(item);
        AddNode(_node);
    }


    /// <summary>
    /// 移除指定节点
    /// </summary>
    /// <param name="node"></param>
    public void RemoveNode(DoubleLinkNode<T> node)
    {
        node.PreNode.NextNode = node.NextNode;
        node.NextNode.PreNode = node.PreNode;
        if (node == First)
        {
            First = node.NextNode;
        }
        if (node==Last)
        {
            Last = node.PreNode;
        }
        Count--;
    }


    /// <summary>
    /// 清除链表数据
    /// </summary>
    public void Clear()
    {
        First = null;
        Last = null;
        Count = 0;
    }
}


/// <summary>
/// 节点类，用来存储数据
/// </summary>
/// <typeparam name="T"></typeparam>
public class DoubleLinkNode<T>
{
    public DoubleLinkNode(T item)
    {
        Value = item;
    }


    /// <summary>
    /// 该节点存储的数据
    /// </summary>
    public T Value
    {
        get;
        set;
    }


    /// <summary>
    /// 上一个节点
    /// </summary>
    public DoubleLinkNode<T> PreNode
    {
        get;
        set;
    }


    /// <summary>
    /// 下一个节点
    /// </summary>
    public DoubleLinkNode<T> NextNode
    {
        get;
        set;
    }
}