using UnityEngine;
using UnityEngine.SceneManagement;
using BaseGames.Core;
using BaseGames.Core.Events;
using BaseGames.Core.Save;

namespace BaseGames.World
{
    /// <summary>
    /// 管理死亡遗骸（Death Shade）的生命周期与持久化。
    ///
    /// 挂载位置：Persistent 场景的根 GameObject（DontDestroyOnLoad）。
    ///
    /// 流程：
    ///   玩家死亡  → OnPlayerDied：记录死亡位置与灵珠量，在当前场景生成遗骸。
    ///   切换场景  → OnSceneLoaded：若新场景即遗骸所在场景，自动生成遗骸。
    ///   回收遗骸  → OnShadeCollected：清除待存储的遗骸数据。
    ///   存档      → OnSave：将遗骸数据（null = 无遗骸）写入 SaveData.Player.DeathShade。
    ///   读档      → OnLoad：从 SaveData 恢复遗骸数据；实际 GameObject 在下次进入该场景时生成。
    /// </summary>
    public class DeathShadeManager : SaveableMonoBehaviour
    {
        [SerializeField] private DeathShade           _shadePrefab;
        [SerializeField] private VoidEventChannelSO   _onPlayerDied;
        [SerializeField] private StringEventChannelSO _onShadeCollected;

        private DeathShadeSaveData _pendingSave;
        private DeathShade         _activeShade;

        private readonly CompositeDisposable _subs = new();

        protected override void OnEnable()
        {
            base.OnEnable();
            _onPlayerDied?    .Subscribe(OnPlayerDied)    .AddTo(_subs);
            _onShadeCollected?.Subscribe(OnShadeCollected).AddTo(_subs);
            SceneManager.sceneLoaded += OnSceneLoaded;
        }

        protected override void OnDisable()
        {
            base.OnDisable();
            _subs.Clear();
            SceneManager.sceneLoaded -= OnSceneLoaded;
        }

        private void OnPlayerDied()
        {
            var playerGo = GameObject.FindWithTag("Player");
            if (playerGo == null) return;

            int    lingZhu = playerGo.GetComponent<ILingZhuProvider>()?.CurrentLingZhu ?? 0;
            var    pos     = (Vector2)playerGo.transform.position;
            string sceneId = SceneManager.GetActiveScene().name;

            if (_activeShade != null)
            {
                Destroy(_activeShade.gameObject);
                _activeShade = null;
            }

            _pendingSave = new DeathShadeSaveData
            {
                PosX          = pos.x,
                PosY          = pos.y,
                SceneId       = sceneId,
                LingZhuAmount = lingZhu,
            };

            TrySpawnShade(sceneId);
        }

        private void OnSceneLoaded(Scene scene, LoadSceneMode _)
        {
            _activeShade = null; // 前一场景的 GameObject 已被 Unity 卸载
            TrySpawnShade(scene.name);
        }

        private void TrySpawnShade(string sceneName)
        {
            if (_shadePrefab == null || _pendingSave == null) return;
            if (_pendingSave.SceneId != sceneName) return;

            _activeShade = Instantiate(_shadePrefab);
            _activeShade.Initialize(
                _pendingSave.LingZhuAmount,
                _pendingSave.SceneId,
                new Vector2(_pendingSave.PosX, _pendingSave.PosY));
        }

        private void OnShadeCollected(string _)
        {
            _pendingSave = null;
            _activeShade = null;
        }

        public override void OnSave(SaveData data)
        {
            data.Player.DeathShade = _pendingSave;
        }

        public override void OnLoad(SaveData data)
        {
            if (_activeShade != null)
            {
                Destroy(_activeShade.gameObject);
                _activeShade = null;
            }
            _pendingSave = data.Player.DeathShade;
            // 遗骸 GameObject 将在 OnSceneLoaded 中按需生成
        }
    }
}