using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// 特效专用对象池 — 按 prefab.GetInstanceID() 分桶
/// 粒子播放完自动回池(通过 EffectAutoReturn 组件检测)
/// 用法:
///     var go = EffectPool.Instance.Get(prefab, pos, rot, parent);
///     // 无需手动回收,EffectAutoReturn 会在粒子播完后自动回池
///     EffectPool.Instance.ClearAll();  // 切场景时彻底清理
/// </summary>
public class EffectPool : Singleton<EffectPool>
{
    // prefab.GetInstanceID() → 该 prefab 的池
    private Dictionary<int, BulletPoolData> dic = new Dictionary<int, BulletPoolData>();

    // 活跃特效映射:特效GameObject → prefab.GetInstanceID()
    private Dictionary<GameObject, int> activeMap = new Dictionary<GameObject, int>();

    private const int MaxCachePerPrefab = 100;

    private GameObject poolRoot;

    /// <summary>从池中取一个特效(池空则 Instantiate),取出后自动播放并在播完时回池</summary>
    public GameObject Get(GameObject prefab, Vector3 position, Quaternion rotation, Transform parent)
    {
        if (prefab == null) return null;

        int prefabID = prefab.GetInstanceID();
        GameObject obj = null;

        if (dic.TryGetValue(prefabID, out var data))
        {
            // 循环跳过已销毁的坏对象
            while (data.poolList.Count > 0)
            {
                obj = data.GetObj();
                if (obj != null) break;
                obj = null;
            }
        }

        if (obj != null)
        {
            obj.transform.SetParent(parent, false);
            obj.transform.position = position;
            obj.transform.rotation = rotation;
            obj.SetActive(true);
        }
        else
        {
            obj = GameObject.Instantiate(prefab, position, rotation, parent);
            obj.SetActive(true);
        }

        activeMap[obj] = prefabID;

        // 挂上自动回收组件(已挂则复用)
        var autoReturn = obj.GetComponent<EffectAutoReturn>();
        if (autoReturn == null)
            autoReturn = obj.AddComponent<EffectAutoReturn>();
        autoReturn.prefabID = prefabID;
        autoReturn.Play();

        return obj;
    }

    /// <summary>回收特效到池(通常由 EffectAutoReturn 自动调用)</summary>
    public void Return(GameObject obj)
    {
        if (obj == null) return;

        if (!activeMap.TryGetValue(obj, out int prefabID) || prefabID == 0)
        {
            GameObject.Destroy(obj);
            return;
        }
        activeMap.Remove(obj);

        if (!dic.TryGetValue(prefabID, out var data))
            dic[prefabID] = data = new BulletPoolData(EnsurePoolRoot().transform, prefabID);

        if (data.poolList.Count >= MaxCachePerPrefab)
        {
            GameObject.Destroy(obj);
            return;
        }

        data.PushObj(obj);
    }

    /// <summary>销毁所有活跃特效 + 清空所有池(切场景调用)</summary>
    public void ClearAll()
    {
        foreach (var kv in activeMap.Keys)
        {
            if (kv != null) GameObject.Destroy(kv);
        }
        activeMap.Clear();

        foreach (var kv in dic.Values)
            kv.Clear();
        dic.Clear();

        if (poolRoot != null)
        {
            GameObject.Destroy(poolRoot);
            poolRoot = null;
        }
    }

    private GameObject EnsurePoolRoot()
    {
        if (poolRoot == null)
        {
            poolRoot = new GameObject("[EffectPool]");
            poolRoot.SetActive(false);
        }
        return poolRoot;
    }
}

/// <summary>挂在池内特效上,粒子播放完自动回池</summary>
public class EffectAutoReturn : MonoBehaviour
{
    [HideInInspector] public int prefabID;

    private ParticleSystem[] particles;
    private float checkTimer;
    private const float MinPlayTime = 0.3f;  // 至少播 0.3s 再检测,避免第一帧 IsAlive=false 误判
    private const float MaxLifetime = 6f;     // ⭐ 兜底:超过 6 秒强制回池,防止 looping 残留导致特效永生

    /// <summary>重新播放所有粒子</summary>
    public void Play()
    {
        if (particles == null || particles.Length == 0)
            particles = GetComponentsInChildren<ParticleSystem>(true);

        checkTimer = 0f;
        foreach (var p in particles)
        {
            if (p != null)
            {
                // ⭐ 强制关闭 looping:有些预制体子级 ParticleSystem 设了 looping=1,
                //   会导致 IsAlive(true) 永远返回 true,特效一直累加直至内存爆满死机
                var main = p.main;
                main.loop = false;

                p.Clear(true);
                p.Play(true);
            }
        }
    }

    void Update()
    {
        checkTimer += Time.deltaTime;
        if (checkTimer < MinPlayTime) return;

        // ⭐ 6 秒兜底:无论是否还存活,超过 6 秒强制回池
        if (checkTimer >= MaxLifetime)
        {
            EffectPool.Instance.Return(gameObject);
            return;
        }

        // 所有粒子都播完 → 回池
        if (particles == null || particles.Length == 0)
        {
            EffectPool.Instance.Return(gameObject);
            return;
        }

        bool anyAlive = false;
        foreach (var p in particles)
        {
            if (p != null && p.IsAlive(true)) { anyAlive = true; break; }
        }
        if (!anyAlive)
        {
            EffectPool.Instance.Return(gameObject);
        }
    }
}