using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using UnityEngine;

namespace Framework.Core
{
    [AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
    public class FindComponentAttribute : Attribute
    {
        public readonly string goName;
        public readonly bool getChild;

        /// <summary>
        /// 查找游戏物体组件的特性
        /// </summary>
        /// <param name="goName">游戏物体名字</param>
        /// <param name="getChild">
        /// true => 查找对应名字对象的下一级子物体 通常名字为父物体名字 类型为子物体
        /// false => 查找对应名字的对象 通常会将类型和名字对应</param>
        public FindComponentAttribute(string goName = null, bool getChild = false)
        {
            this.goName = goName;
            this.getChild = getChild;
        }
    }

    [AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
    public class FindComponentsInChildrenAttribute : Attribute
    {
        /// 空类
        /// 直接获取下层所有组件
    }

    public static class UnityTool
    {
        /// <summary>
        /// 查找所有带标记的组件
        /// 与FindComponent特性配合使用
        /// </summary>
        public static void FindComponents(this Component mono)
        {
            Dictionary<Type, Component[]> dic = new();
            var flags = BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance;
            foreach (var field in mono.GetType().GetFields(flags))
            {
                Attribute attribute = GetFindCompAttribute(field);
                if (attribute == null) continue;

                Type type = field.FieldType;
                var components = GetComponentsByType(mono, type, dic);

                switch (attribute)
                {
                    case FindComponentAttribute componentAttribute:
                        HandleFindComponent(mono, field, components, componentAttribute);
                        break;
                    case FindComponentsInChildrenAttribute:
                        HandleFindComponentsInChildren(mono, field, components);
                        break;
                }
            }
        }

        private static Attribute GetFindCompAttribute(FieldInfo field)
        {
            var attr1 = field.GetCustomAttribute<FindComponentAttribute>();
            if (attr1 != null)
            {
                return attr1;
            }

            var attr2 = field.GetCustomAttribute<FindComponentsInChildrenAttribute>();
            return attr2;
        }

        private static void HandleFindComponent(Component mono, FieldInfo field, Component[] components,
            FindComponentAttribute attribute)
        {
            if (string.IsNullOrEmpty(attribute.goName))
            {
                field.SetValue(mono, components[0]);
                return;
            }

            if (attribute.getChild)
            {
                foreach (var component in components)
                {
                    if (component.transform.parent.name == attribute.goName)
                    {
                        field.SetValue(mono, component);
                        break;
                    }
                }
            }
            else
            {
                foreach (var component in components)
                {
                    if (component.name != attribute.goName) continue;
                    field.SetValue(mono, component);
                    break;
                }
            }
        }

        private static void HandleFindComponentsInChildren(Component mono, FieldInfo field, Component[] components)
        {
            field.SetValue(mono, components);
        }

        private static Component[] GetComponentsByType(Component mono, Type type, Dictionary<Type, Component[]> dic)
        {
            if (dic.TryGetValue(type, out var components)) return components;

            if (type.IsArray)
            {
                type = type.GetElementType();
            }

            var selfComponent = mono.GetComponent(type);
            var childrenComponents = mono.GetComponentsInChildren(type, true);
            components = selfComponent != null
                ? new[] { selfComponent }.Concat(childrenComponents).ToArray()
                : childrenComponents;
            
            if (components == null || components.Length == 0)
            {
#if UNITY_EDITOR
                Debug.Log($"无法找到{type}对象");
#endif
                return null;
            }

            dic.Add(type, components);
            return components;
        }
    }
}