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

namespace Magic.Core;

/// <summary>
/// 树基类
/// </summary>
public interface ITreeNode
{
    /// <summary>
    /// 获取节点id
    /// </summary>
    /// <returns></returns>
    long GetId();

    /// <summary>
    /// 获取节点父id
    /// </summary>
    /// <returns></returns>
    long GetPid();

    /// <summary>
    /// 设置Children
    /// </summary>
    /// <param name="children"></param>
    void SetChildren(IList children);
}

/// <summary>
/// 递归工具类，用于遍历有父子关系的节点，例如菜单树，字典树等等
/// </summary>
/// <typeparam name="T"></typeparam>
public class TreeBuildUtil<T> where T : ITreeNode
{
    /// <summary>
    /// 顶级节点的父节点Id(默认0)
    /// </summary>
    private readonly long _rootParentId = 0L;

    /// <summary>
    /// 构造树节点
    /// </summary>
    /// <param name="nodes"></param>
    /// <returns></returns>
    public List<T> DoTreeBuild(List<T> nodes)
    {
        nodes.ForEach(u => BuildChildNodes(nodes, u, new List<T>()));

        var results = new List<T>();
        nodes.ForEach(u =>
        {
            if (_rootParentId == u.GetPid())
                results.Add(u);
        });
        return results;
    }

    /// <summary>
    /// 构造子节点集合
    /// </summary>
    /// <param name="totalNodes"></param>
    /// <param name="node"></param>
    /// <param name="childNodeLists"></param>
    private void BuildChildNodes(List<T> totalNodes, T node, List<T> childNodeLists)
    {
        var nodeSubLists = new List<T>();
        totalNodes.ForEach(u =>
        {
            if (u.GetPid().Equals(node.GetId()))
                nodeSubLists.Add(u);
        });
        nodeSubLists.ForEach(u => BuildChildNodes(totalNodes, u, new List<T>()));
        childNodeLists.AddRange(nodeSubLists);
        node.SetChildren(childNodeLists);
    }
}