using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
using BaseGames.Core.Events;
using BaseGames.Localization;

namespace BaseGames.UI
{
    /// <summary>
    /// Boss 血条 UI（架构 10_UIModule §4）。
    /// 默认隐藏，Boss 战开始时从屏幕底部滑入。
    /// 阶段标记点由 BossHPMax 与 PhaseThreshold 共同决定（此处由外部广播 EVT_BossHPMaxSet 设置）。
    /// </summary>
    public class BossHPBar : MonoBehaviour
    {
        [SerializeField] private TMP_Text  _bossNameText;
        [SerializeField] private Image        _hpFill;
        [SerializeField] private Transform    _phaseMarkersRoot;
        [SerializeField] private GameObject   _phaseMarkerPrefab;
        [SerializeField] private float        _slideDistance = 120f;  // 滑入距离（像素）
        [SerializeField] private float        _slideDuration = 0.3f;

        [Header("Event Channels")]
        [SerializeField] private BoolEventChannelSO   _onBossFightToggled;   // true=开始, false=结束
        [SerializeField] private IntEventChannelSO    _onBossHPChanged;
        [SerializeField] private StringEventChannelSO _onBossNameSet;
        [SerializeField] private IntEventChannelSO    _onBossHPMaxSet;
        [SerializeField] private FloatEventChannelSO  _onBossPhaseThreshold; // 每个阶段切换阈值（0-1）

        private int _maxHP;
        private RectTransform _rect;
        private Vector2 _shownPos;
        private Vector2 _hiddenPos;
        private Coroutine _slideCoroutine;
        private readonly List<float> _pendingThresholds = new();
        private readonly CompositeDisposable _subs = new();

        private void Awake()
        {
            _rect = (RectTransform)transform;
            _shownPos  = _rect.anchoredPosition;
            _hiddenPos = _shownPos - new Vector2(0, _slideDistance);
            _rect.anchoredPosition = _hiddenPos;
            gameObject.SetActive(false);
        }

        private void OnEnable()
        {
            _onBossFightToggled?.Subscribe(OnBossFightToggled).AddTo(_subs);
            _onBossHPChanged?.Subscribe(OnHPChanged).AddTo(_subs);
            _onBossNameSet?.Subscribe(OnNameSet).AddTo(_subs);
            _onBossHPMaxSet?.Subscribe(OnMaxSet).AddTo(_subs);
            _onBossPhaseThreshold?.Subscribe(OnPhaseThreshold).AddTo(_subs);
        }
        private void OnDisable() => _subs.Clear();

        // ── 事件回调 ──────────────────────────────────────────────────────────

        private void OnBossFightToggled(bool started)
        {
            if (_slideCoroutine != null) StopCoroutine(_slideCoroutine);
            if (started)
            {
                gameObject.SetActive(true);
                _slideCoroutine = StartCoroutine(SlideTo(_shownPos));
            }
            else
            {
                _pendingThresholds.Clear();
                _slideCoroutine = StartCoroutine(SlideOut());
            }
        }

        private void OnHPChanged(int hp)
        {
            if (_maxHP > 0) _hpFill.fillAmount = (float)hp / _maxHP;
        }

        private void OnNameSet(string bossName)
        {
            if (_bossNameText == null) return;
            string loc = !string.IsNullOrEmpty(bossName)
                ? LocalizationManager.Get(bossName, LocalizationTable.Character)
                : null;
            _bossNameText.text = !string.IsNullOrEmpty(loc) && loc != bossName ? loc : bossName;
        }

        private void OnMaxSet(int max)
        {
            _maxHP = max;
            // 清除旧标记
            if (_phaseMarkersRoot != null)
            {
                // 逆序删除：避免正序枚举 Transform 子节点同时销毁时的迭代器失效
                for (int i = _phaseMarkersRoot.childCount - 1; i >= 0; i--)
                    Destroy(_phaseMarkersRoot.GetChild(i).gameObject);
            }
            // 延迟一帧：等 Canvas LayoutRebuilder 完成布局后再读取 rect.width，避免得到 0
            StartCoroutine(RebuildMarkersAfterLayout());
        }

        private System.Collections.IEnumerator RebuildMarkersAfterLayout()
        {
            yield return null;   // 等待 Canvas 完成当前帧的 Layout 传递
            foreach (var t in _pendingThresholds)
                PlacePhaseMarker(t);
        }

        private void OnPhaseThreshold(float threshold)
        {
            if (threshold <= 0f || threshold >= 1f) return;
            _pendingThresholds.Add(threshold);
            if (_maxHP > 0) PlacePhaseMarker(threshold);
        }

        private void PlacePhaseMarker(float threshold)
        {
            if (_phaseMarkersRoot == null || _phaseMarkerPrefab == null || _hpFill == null) return;
            var marker = Instantiate(_phaseMarkerPrefab, _phaseMarkersRoot);
            var markerRect = marker.GetComponent<RectTransform>();
            if (markerRect != null)
            {
                float barWidth = _hpFill.rectTransform.rect.width;
                markerRect.anchoredPosition = new Vector2(barWidth * threshold, 0f);
            }
            marker.SetActive(true);
        }

        // ── 动画协程 ──────────────────────────────────────────────────────────

        private IEnumerator SlideTo(Vector2 target)
            => UITween.MoveAnchored(_rect, target, _slideDuration);

        private IEnumerator SlideOut()
        {
            yield return UITween.MoveAnchored(_rect, _hiddenPos, _slideDuration);
            gameObject.SetActive(false);
        }
    }
}