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

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 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);
        }
        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
            {
                _slideCoroutine = StartCoroutine(SlideOut());
            }
        }

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

        private void OnNameSet(string bossName)
        {
            if (_bossNameText != null) _bossNameText.text = bossName;
        }

        private void OnMaxSet(int max)
        {
            _maxHP = max;
            // 重建阶段标记（每次 BossHPMax 改变时清空并按已存阈值重建，此处简化为清空）
            if (_phaseMarkersRoot != null)
                foreach (Transform t in _phaseMarkersRoot) Destroy(t.gameObject);
        }

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

        private IEnumerator SlideTo(Vector2 target)
        {
            Vector2 start = _rect.anchoredPosition;
            float t = 0;
            while (t < _slideDuration)
            {
                _rect.anchoredPosition = Vector2.Lerp(start, target, t / _slideDuration);
                t += Time.unscaledDeltaTime;
                yield return null;
            }
            _rect.anchoredPosition = target;
        }

        private IEnumerator SlideOut()
        {
            yield return SlideTo(_hiddenPos);
            gameObject.SetActive(false);
        }
    }
}