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

namespace Game
{
    public delegate void PoolItemInitHandler<in TItem>(TItem item);

    public class ObjectPoolItemBase : MetaDataHandler
    {
        public bool IsAlive;

        public void Create()
        {
            if (IsAlive) return;
            IsAlive = true;
            OnCreate();
            CreateBind();
        }

        public void Destroy()
        {
            if (!IsAlive) return;
            IsAlive = false;
            OnDestroy();
            ClearBind();
        }

        protected virtual void OnCreate()
        {
        }

        protected virtual void OnDestroy()
        {
        }
    }

    public class ObjectPoolBase<TManager> : ManagerBase<TManager> where TManager : new()
    {
        public GameObject Root;
        protected Dictionary<object, List<ObjectPoolItemBase>> ObjectPool;

        public override void OnInit()
        {
            ObjectPool = new Dictionary<object, List<ObjectPoolItemBase>>();
            CreateRoot(typeof(TManager).Name);
        }

        private void CreateRoot(string rootName)
        {
            Root = new GameObject(rootName);
            Object.DontDestroyOnLoad(Root);
        }

        protected T Create<T>(object objType, PoolItemInitHandler<T> callback)
            where T : ObjectPoolItemBase, new()
        {
            var pool = EnSureGetPool(objType);
            foreach (var obj in from obj in pool where !obj.IsAlive select obj as T)
            {
                obj.Create();
                return obj;
            }

            var newObj = new T();
            pool.Add(newObj);
            callback?.Invoke(newObj);
            newObj.Create();
            return newObj;
        }

        protected void PreCreate<T>(object objType, PoolItemInitHandler<T> callback, int num)
            where T : ObjectPoolItemBase, new()
        {
            var pool = EnSureGetPool(objType);
            for (var _ = 0; _ < num; _++)
            {
                var newObj = Create(objType, callback);
                newObj.Destroy();
            }
        }

        protected List<ObjectPoolItemBase> EnSureGetPool(object objType)
        {
            if (!ObjectPool.ContainsKey(objType)) ObjectPool[objType] = new List<ObjectPoolItemBase>();
            return ObjectPool[objType];
        }
    }
}