using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace Infrastructure.Domain
{
    public abstract class BaseTreeEntity<T> : BaseEntity where T : BaseTreeEntity<T>
    {
        [Required]
        public string Name { get; set; }
        [Required]
        public string Number { get; set; }
        public int Order { get; set; }
        public int Left { get; set; }
        public int Right { get; set; }
        public Guid? ParentId { get; set; }
        public T Parent { get; set; }
#pragma warning disable CA2227 // 集合属性应为只读
        public List<T> Children { get; set; } = new List<T>();
#pragma warning restore CA2227 // 集合属性应为只读

        public string GetDisplayName()
        {
            var list = new List<T>();
            var item = this as T;
            while (item != null)
            {
                list.Add(item);
                if (item.Parent == null || item.Parent.Id == this.Id)
                {
                    break;
                }
                item = item.Parent;
            }
            list.Reverse();
            return string.Join(" / ", list.Select(o => o.Name));
        }

        public void Update()
        {
            Left(this as T);
            void Left(T node, int prev = 0)
            {
                if (node.Parent == null)
                {
                    node.Left = 1;
                }
                else
                {
                    node.Left = prev + 1;
                }
                if (node.Children.Any())
                {
                    Left(node.Children.OrderBy(o => o.Order).First(), node.Left);
                }
                else
                {
                    Right(node, node.Left);
                }
            }
            void Right(T node, int prev)
            {
                node.Right = prev + 1;
                if (node.Parent != null)
                {
                    var list = node.Parent.Children.OrderBy(o => o.Order).ToList();
                    var index = list.IndexOf(node);
                    if (list.Count > index + 1)
                    {
                        Left(list[index + 1], node.Right);
                    }
                    else
                    {
                        Right(node.Parent, node.Right);
                    }
                }
            }
        }
    }
}