using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
using BaseGames.Core.Events;
using BaseGames.Combat.StatusEffects;
using StatusEffectType = BaseGames.Combat.StatusEffects.StatusEffectType;

namespace BaseGames.UI.HUD
{
    /// <summary>
    /// 状态效果 HUD —— 在 HUD 上为玩家展示当前激活的状态效果图标、叠层数和倒计时。
    ///
    /// 布局约定：挂在 HUD Canvas 内，持有一个 _slotTemplate（默认 inactive）和一个 _container。
    /// 每种 StatusEffectType 最多对应一个槽位实例，通过字典管理。
    ///
    /// 订阅的事件频道：
    ///   _onStatusEffectApplied  → OnStatusEffectApplied
    ///   _onStatusEffectExpired  → OnStatusEffectExpired
    /// </summary>
    public class StatusEffectHUD : MonoBehaviour
    {
        // ── Inspector 字段 ────────────────────────────────────────────────────

        [Header("Slot")]
        [Tooltip("槽位模板预制（设为 inactive）；每种效果类型会从此 Instantiate 一个实例。")]
        [SerializeField] private GameObject _slotTemplate;

        [Tooltip("槽位实例的父节点（水平/垂直 LayoutGroup 即可）。")]
        [SerializeField] private Transform  _container;

        [Header("效果图标配置")]
        [SerializeField] private SlotConfig[] _slotConfigs;

        [Header("Event Channels")]
        [SerializeField] private StatusEffectEventChannelSO _onStatusEffectApplied;
        [SerializeField] private StatusEffectEventChannelSO _onStatusEffectExpired;

        // ── 内部数据 ──────────────────────────────────────────────────────────

        /// <summary>每种 StatusEffectType 对应的 Inspector 配置（图标 Sprite）。</summary>
        [System.Serializable]
        public struct SlotConfig
        {
            public StatusEffectType effectType;
            [Tooltip("该状态效果在 HUD 上显示的图标。")]
            public Sprite           icon;
        }

        private class SlotInstance
        {
            public GameObject  root;
            public Image       iconImage;
            public TMP_Text    durationText;   // 倒计时文本（可为 null）
            public TMP_Text    stackText;      // 叠层数文本（可为 null）
            public Coroutine   countdown;
        }

        private readonly Dictionary<StatusEffectType, SlotInstance> _activeSlots = new();
        private readonly CompositeDisposable                        _subs        = new();

        // 倒计时节流：缓存 WaitForSecondsRealtime 以避免每帧堆分配
        private readonly WaitForSecondsRealtime _countdownTick = new(0.1f);

        // 图标快速查找表： Awake 时一次性从 _slotConfigs 构建，避免 OnStatusEffectApplied 高频线性扫描
        private Dictionary<StatusEffectType, Sprite>               _iconLookup;

        // ── 生命周期 ───────────────────────────────────────────────────────

        private void Awake()
        {
            _iconLookup = new Dictionary<StatusEffectType, Sprite>(_slotConfigs?.Length ?? 0);
            if (_slotConfigs != null)
                foreach (var cfg in _slotConfigs)
                    _iconLookup[cfg.effectType] = cfg.icon;
        }

        private void OnEnable()
        {
            _onStatusEffectApplied?.Subscribe(OnStatusEffectApplied).AddTo(_subs);
            _onStatusEffectExpired?.Subscribe(OnStatusEffectExpired).AddTo(_subs);
        }

        private void OnDisable()
        {
            _subs.Clear();
            StopAllCoroutines();
            foreach (var slot in _activeSlots.Values)
                if (slot.root != null) slot.root.SetActive(false);
            _activeSlots.Clear();
        }

        // ── 事件处理 ──────────────────────────────────────────────────────────

        private void OnStatusEffectApplied(StatusEffectEvent e)
        {
            if (!_activeSlots.TryGetValue(e.EffectType, out var slot))
            {
                slot = CreateSlot(e.EffectType);
                if (slot == null) return;
                _activeSlots[e.EffectType] = slot;
            }

            slot.root.SetActive(true);
            RefreshSlotDisplay(slot, e.StackCount, e.RemainingDuration);

            // 重启倒计时协程（OnStack 刷新持续时间时也会走到这里）
            if (slot.countdown != null)
                StopCoroutine(slot.countdown);
            slot.countdown = StartCoroutine(CountdownRoutine(slot, e.RemainingDuration));
        }

        private void OnStatusEffectExpired(StatusEffectEvent e)
        {
            if (!_activeSlots.TryGetValue(e.EffectType, out var slot)) return;

            if (slot.countdown != null)
            {
                StopCoroutine(slot.countdown);
                slot.countdown = null;
            }
            slot.root.SetActive(false);
        }

        // ── 协程 ─────────────────────────────────────────────────────────────

        private IEnumerator CountdownRoutine(SlotInstance slot, float totalDuration)
        {
            float endTime = Time.realtimeSinceStartup + totalDuration;

            while (Time.realtimeSinceStartup < endTime)
            {
                float remaining = endTime - Time.realtimeSinceStartup;
                if (slot.durationText != null)
                    slot.durationText.text = remaining.ToString("F1");
                yield return _countdownTick;   // 0.1s 节忍，替代每帧 yield return null
            }

            slot.countdown = null;
            slot.root.SetActive(false);
        }

        // ── 内部辅助 ──────────────────────────────────────────────────────────

        private void RefreshSlotDisplay(SlotInstance slot, int stackCount, float duration)
        {
            if (slot.durationText != null)
                slot.durationText.text = duration.ToString("F1");

            bool multiStack = stackCount > 1;
            if (slot.stackText != null)
            {
                slot.stackText.gameObject.SetActive(multiStack);
                if (multiStack) slot.stackText.text = stackCount.ToString();
            }
        }

        private SlotInstance CreateSlot(StatusEffectType type)
        {
            if (_slotTemplate == null || _container == null) return null;

            _iconLookup.TryGetValue(type, out Sprite icon);   // O(1) 查找

            var go = Instantiate(_slotTemplate, _container);
            go.SetActive(false);

            var slot = new SlotInstance { root = go };

            // 约定：第一个 Image 子节点作为图标；第一个 TMP_Text 作为倒计时；第二个作为叠层数
            var images = go.GetComponentsInChildren<Image>(includeInactive: true);
            if (images.Length > 0)
            {
                slot.iconImage = images[0];
                if (icon != null) slot.iconImage.sprite = icon;
            }

            var texts = go.GetComponentsInChildren<TMP_Text>(includeInactive: true);
            if (texts.Length > 0) slot.durationText = texts[0];
            if (texts.Length > 1) slot.stackText    = texts[1];

            return slot;
        }
    }
}