using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;
using BaseGames.Core.Events;
using BaseGames.Combat;

namespace BaseGames.UI
{
    /// <summary>
    /// 伤害飘字（架构 10_UIModule §10）。
    /// 从对象池取出后由 FloatingDamageSpawner 调用 Show()；协程完成后归还。
    /// 挂在预制体根 GameObject 上（Canvas_HUD 子节点，World Space Canvas 或 Screen Space）。
    /// </summary>
    public class FloatingDamageText : MonoBehaviour
    {
        [SerializeField] private TMP_Text  _text;
        [SerializeField] private float     _floatDistance = 1.5f;
        [SerializeField] private float     _duration      = 0.8f;

        /// <summary>
        /// 父级 Canvas（用于 RectTransformUtility 坐标转换）。
        /// 适配所有 Canvas 渲染模式（Overlay / Camera / World Space），
        /// Screen Space - Overlay 时可传 null（会自动 fallback 到 null camera）。
        /// </summary>
        [SerializeField] private Canvas _parentCanvas;

        private RectTransform _rectTransform;
        private Coroutine _animCoroutine;
        // 每次 Show() 解析一次，协程期间（< 1s）复用，避免每帧走 FindObjectByTag
        private Camera _cachedCamera;

        private void Awake()
        {
            _rectTransform = (RectTransform)transform;
        }

        /// <summary>
        /// 在世界坐标位置显示伤害数字并开始飘动动画。
        /// 动画结束后由对象池回收（Deactivate）。
        /// </summary>
        public void Show(Vector2 worldPosition, int damage, DamageType type)
        {
            if (_animCoroutine != null) StopCoroutine(_animCoroutine);

            // 每次 Show 解析一次摄像机：动画时长 < 1s，期间不会切换主摄像机；
            // 若 Boss 过场后再次 Show，会自动获取新的主摄像机。
            _cachedCamera = (_parentCanvas != null && _parentCanvas.renderMode == RenderMode.ScreenSpaceCamera)
                ? _parentCanvas.worldCamera
                : UnityEngine.Camera.main;

            _text.text  = damage.ToString();
            _text.color = GetColorForType(type);

            SetAnchoredPosition(worldPosition);
            _animCoroutine = StartCoroutine(FloatAndFade(worldPosition));
        }

        private void SetAnchoredPosition(Vector2 worldPosition)
        {
            var cam = _cachedCamera;

            var screenPoint = cam != null
                ? (Vector2)cam.WorldToScreenPoint(worldPosition)
                : Vector2.zero;

            var canvasRect = _parentCanvas != null
                ? (RectTransform)_parentCanvas.transform
                : null;

            if (canvasRect != null)
            {
                RectTransformUtility.ScreenPointToLocalPointInRectangle(
                    canvasRect, screenPoint, cam, out var localPoint);
                _rectTransform.anchoredPosition = localPoint;
            }
            else
            {
                _rectTransform.anchoredPosition = screenPoint;
            }
        }

        private IEnumerator FloatAndFade(Vector2 startWorld)
        {
            float elapsed  = 0f;
            var color      = _text.color;
            var startAlpha = color.a;

            while (elapsed < _duration)
            {
                float t = elapsed / _duration;

                SetAnchoredPosition(startWorld + new Vector2(0, _floatDistance * t));

                // alpha 淡出（后半段开始）—— 修改 struct 的 a 分量并回写，避免每帧 new Color 堆分配
                color.a     = Mathf.Lerp(startAlpha, 0f, Mathf.Clamp01((t - 0.5f) / 0.5f));
                _text.color = color;

                elapsed += Time.deltaTime;
                yield return null;
            }

            gameObject.SetActive(false); // 归还对象池
        }

        private static Color GetColorForType(DamageType type) => type switch
        {
            DamageType.Fire    => new Color(1f,  0.5f, 0f),   // 橙
            DamageType.Poison  => new Color(0.3f,0.9f, 0.3f), // 绿
            DamageType.True    => new Color(1f,  0.95f,0.4f), // 黄
            DamageType.Ice     => new Color(0.5f,0.85f,1f),   // 冰蓝
            DamageType.Lightning=>new Color(0.9f,0.9f, 0.2f), // 闪黄
            _                  => Color.white
        };
    }

    // ─────────────────────────────────────────────────────────────────────────
    /// <summary>
    /// 伤害飘字生成器（挂在 Canvas_HUD 上）。
    /// 订阅 EVT_DamageDealt 事件频道，从 Addressables 池取出 FloatingDamageText 显示。
    /// </summary>
    public class FloatingDamageSpawner : MonoBehaviour
    {
        [Header("事件频道")]
        [SerializeField] private DamageInfoEventChannelSO _onDamageDealt;

        [Header("预制体（对象池 key = AddressKeys.PrefabUIFloatingDmgText）")]
        [SerializeField] private GameObject _floatingDmgPrefab;  // Fallback：Inspector 直接拖入

        private readonly List<FloatingDamageText> _pool = new();
        private readonly CompositeDisposable _subs = new();

        private void OnEnable()  => _onDamageDealt?.Subscribe(OnDamageDealt).AddTo(_subs);
        private void OnDisable() => _subs.Clear();

        private void OnDamageDealt(DamageInfo info)
        {
            if (info.FinalDamage <= 0) return;
            var text = GetOrCreate();
            if (text != null)
                text.Show(info.SourcePosition, info.FinalDamage, info.Type);
        }

        private FloatingDamageText GetOrCreate()
        {
            // 线性扫描全部已创建实例，找首个未激活的复用
            for (int i = 0; i < _pool.Count; i++)
            {
                var pooled = _pool[i];
                if (pooled != null && !pooled.gameObject.activeSelf)
                {
                    pooled.gameObject.SetActive(true);
                    return pooled;
                }
            }

            // 没有可用实例则实例化新的，加入列表供下次复用
            if (_floatingDmgPrefab == null) return null;
            var go = Instantiate(_floatingDmgPrefab, transform);
            var comp = go.GetComponent<FloatingDamageText>();
            if (comp != null) _pool.Add(comp);
            return comp;
        }
    }
}