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

namespace Atomx.Utils.Extension
{
    public static class TreeExtension
    {
        public static List<T> ToTree<T>(this List<T> list, Func<T, string> getId, Func<T, string> getParentId, Action<T, List<T>> setChildren, string rootParentId = "0")
        {
            var lookup = new Dictionary<string, T>();
            var result = new List<T>();
            foreach (var item in list)
            {
                var id = getId(item);
                lookup[id] = item;
            }
            foreach (var item in list)
            {
                var parentId = getParentId(item);
                if (parentId == rootParentId || !lookup.ContainsKey(parentId))
                {
                    result.Add(item);
                }
                else
                {
                    var parent = lookup[parentId];
                    var children = new List<T>();
                    setChildren(parent, children);
                    children.Add(item);
                }
            }
            return result;
        }
    }
}