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

/// <summary>
/// 对象池管理类，日常使用一下两个方法即可
/// 取对象Spawn(name/Prefab)，回收对象Unspawn(name/Prefab)
/// </summary>
public class PoolManager : MonoBehaviour
{
    private static readonly object lockObj = new object();

    private static PoolManager _instance;

    public static PoolManager Instance
    {
        get
        {
            if (_instance == null)
            {
                lock (lockObj)
                {
                    PoolManager[] objs = FindObjectsOfType<PoolManager>();
                    if (objs != null)
                    {
                        for (int i = 0; i < objs.Length; i++)
                        {
                            DestroyImmediate(objs[i].gameObject);
                        }
                    }
                    GameObject go = new GameObject("PoolManager");
                    DontDestroyOnLoad(go);
                    _instance = go.AddComponent<PoolManager>();
                }
            }
            return _instance;
        }
    }

    //预制ID-对象池 集合
    private Dictionary<int, ObjectPool> poolDic = new Dictionary<int, ObjectPool>();
    //对象ID-对象池ID 集合
    private Dictionary<int, int> itemDic = new Dictionary<int, int>();


    /// <summary>
    /// 取对象，通过对象实例
    /// </summary>
    public GameObject Spawn(GameObject prefab)
    {
        if (!poolDic.ContainsKey(prefab.GetInstanceID()))
        {
            CreateNewPool(prefab);
        }
        GameObject item = poolDic[prefab.GetInstanceID()].Spawn();
        if (!itemDic.ContainsKey(item.GetInstanceID()))
        {
            itemDic.Add(item.GetInstanceID(), prefab.GetInstanceID());
        }
        else
        {
            itemDic[item.GetInstanceID()] = prefab.GetInstanceID();
        }
        return item;
    }

    /// <summary>
    /// 回收对象
    /// </summary>
    public void Unspawn(GameObject go)
    {
        if (itemDic.ContainsKey(go.GetInstanceID()))
        {
            int id = itemDic[go.GetInstanceID()];
            if (poolDic.ContainsKey(id))
            {
                poolDic[id].Unspawn(go);
                itemDic.Remove(go.GetInstanceID());
            }
            else
            {
                Debug.LogError("回收对象失败 : " + go.name);
            }
        }
    }

    /// <summary>
    /// 回收某个对象池中所有对象
    /// </summary>
    public void ClearPool(GameObject prefab)
    {
        int id = prefab.GetInstanceID();
        if (poolDic.ContainsKey(id))
        {
            poolDic[id].UnspawnAll();
        }
        else
        {
            Debug.LogError("清空对象池失败 ： " + prefab.name);
        }

        List<int> list = new List<int>();
        foreach (int key in itemDic.Keys)
        {
            if (itemDic[key] == id)
            {
                list.Add(key);
            }
        }
        for (int i = 0; i < list.Count; i++)
        {
            itemDic.Remove(list[i]);
        }
    }

    /// <summary>
    /// 回收所有对象池
    /// </summary>
    public void ClearAll()
    {
        foreach (ObjectPool pool in poolDic.Values)
        {
            pool.UnspawnAll();
        }
        itemDic.Clear();
    }

    /// <summary>
    /// 创建一个新的对象池
    /// </summary>
    public void CreateNewPool(GameObject prefab)
    {
        if (poolDic.ContainsKey(prefab.GetInstanceID()))
        {
            Debug.LogError("无法创建新的对象池，当前对象池已存在 : " + prefab.name);
            return;
        }
        ObjectPool pool = new ObjectPool(prefab);
        poolDic.Add(prefab.GetInstanceID(), pool);
    }

    /// <summary>
    /// 创建一个新的对象池，并初始化
    /// </summary>
    public void CreateNewPool(GameObject prefab, int initSize)
    {
        if (poolDic.ContainsKey(prefab.GetInstanceID()))
        {
            Debug.LogError("无法创建新的对象池，当前对象池已存在 : " + prefab.name);
            return;
        }
        ObjectPool pool = new ObjectPool(prefab);
        pool.InitPool(initSize);
        poolDic.Add(prefab.GetInstanceID(), pool);
    }

    /// <summary>
    /// 创建一个新的对象池，并初始化，同时设定对象池最大容量
    /// </summary>
    public void CreateNewPool(GameObject prefab, int initSize, int maxSize)
    {
        if (poolDic.ContainsKey(prefab.GetInstanceID()))
        {
            Debug.LogError("无法创建新的对象池，当前对象池已存在 : " + prefab.name);
            return;
        }
        ObjectPool pool = new ObjectPool(prefab, maxSize);
        pool.InitPool(initSize);
        poolDic.Add(prefab.GetInstanceID(), pool);
    }
}

/// <summary>
/// 对象池-子池
/// </summary>
public class ObjectPool
{
    //对象池元素
    public GameObject prefab;

    //对象池最大容量，此值小于等于0时，对象池动态增加，不设上限
    private int maxSize;

    //对象池名称
    public string Name
    {
        get { return prefab.name; }
    }

    //对象池当前容量
    private int CurrentSize
    {
        get { return activeObjectList.Count + inactiveObjectList.Count; }
    }

    private List<GameObject> activeObjectList = new List<GameObject>();      //已用对象列表
    private List<GameObject> inactiveObjectList = new List<GameObject>();    //待用对象列表

    public ObjectPool(GameObject obj)
    {
        this.prefab = obj;
        maxSize = -1;
    }

    public ObjectPool(GameObject obj, int maxCount)
    {
        this.prefab = obj;
        maxSize = maxCount;
    }

    /// <summary>
    /// 初始化对象池
    /// </summary>
    public void InitPool(int initSize)
    {
        if (maxSize > 0 && initSize > maxSize)
        {
            Debug.LogError("对象池初始容量不能超过其最大容量！！");
            for (int i = 0; i < maxSize; i++)
            {
                GameObject go = GameObject.Instantiate(prefab);
                go.name = prefab.name;
                go.SetActive(false);
                inactiveObjectList.Add(go);
            }
        }
        else
        {
            for (int i = 0; i < initSize; i++)
            {
                GameObject go = GameObject.Instantiate(prefab);
                go.name = prefab.name;
                go.SetActive(false);
                inactiveObjectList.Add(go);
            }
        }
    }

    /// <summary>
    /// 取对象
    /// </summary>
    public GameObject Spawn()
    {
        if (inactiveObjectList.Count == 0)
        {
            if (maxSize > 0 && CurrentSize >= maxSize)
            {
                Debug.LogError("警告：对象池 " + Name + " 当前容量已达到最大设定值 : " + maxSize);
                GameObject go = activeObjectList[0];
                return go;
            }
            else
            {
                GameObject go = GameObject.Instantiate(prefab);
                go.SetActive(true);
                activeObjectList.Add(go);
                return go;
            }
        }
        else
        {
            GameObject go = inactiveObjectList[0];
            go.SetActive(true);
            inactiveObjectList.RemoveAt(0);
            activeObjectList.Add(go);
            return go;
        }
    }

    /// <summary>
    /// 回收对象
    /// </summary>
    public void Unspawn(GameObject go)
    {
        if (activeObjectList.Contains(go))
        {
            go.SetActive(false);
            activeObjectList.Remove(go);
            inactiveObjectList.Add(go);
        }
        else
        {
            Debug.LogError("回收对象异常，当前对象不在对象列表中!!");
        }
    }

    /// <summary>
    /// 回收池中所有对象
    /// </summary>
    public void UnspawnAll()
    {
        //回收修改
        int count = activeObjectList.Count;
        for (int i = 0; i < count; i++)
        {
            if (activeObjectList.Count >= 1)
            {
                Unspawn(activeObjectList[0]);
            }
        }
    }
}