using System.Collections.Generic;
using UnityEngine;

namespace BaseGames.Combat
{
    /// <summary>
    /// 攻击判定盒。挂载在武器 Prefab 或技能 HitBox Prefab 的子节点上。
    /// Phase 1 简化：直接挂在 Player Prefab 子节点 [HitBoxGround/Up/Down/Air]。
    /// Collider2D 需设 IsTrigger = true，Layer = PlayerHitBox 或 EnemyHitBox。
    /// </summary>
    [RequireComponent(typeof(Collider2D))]
    public class HitBox : MonoBehaviour
    {
        [SerializeField] private DamageSourceSO _defaultSource;
        [SerializeField] private float          _hitCooldown = 0.1f;

        private DamageSourceSO _currentSource;
        private Transform      _attackerTransform;
        private bool           _isActive;

        /// <summary>命中确认委托（PlayerCombat / EnemyCombat 订阅）。</summary>
        public System.Action<DamageInfo> OnHitConfirmed;

        /// <summary>
        /// 激活 HitBox。source/attacker 均可选，未传则使用 Inspector 默认值。
        /// ⚠️ 不存在 Activate(float duration) 重载。
        /// </summary>
        public void Activate(DamageSourceSO source = null, Transform attacker = null)
        {
            _currentSource     = source   ?? _defaultSource;
            _attackerTransform = attacker ?? transform;
            _isActive          = true;
        }

        public void Deactivate() => _isActive = false;

        private void Awake()
        {
            // 确保 Collider2D 是 Trigger
            var col = GetComponent<Collider2D>();
            if (!col.isTrigger)
                Debug.LogWarning($"[HitBox] {name}: Collider2D.isTrigger 应为 true。", this);
        }

        private void OnDisable()
        {
            _isActive = false;
            _hitCooldownTimers.Clear();
        }

        private void OnTriggerEnter2D(Collider2D other)
        {
            if (!_isActive) return;
            if (_currentSource == null)
            {
                Debug.LogWarning($"[HitBox] {name}: 无 DamageSourceSO，跳过命中。", this);
                return;
            }
            if (!CheckCooldown(other)) return;

            Vector2 knockDir = ((Vector2)other.bounds.center
                               - (Vector2)_attackerTransform.position).normalized;

            // ⚡ 零 GC：struct 工厂，就地赋值运行时字段
            var info = DamageInfo.From(_currentSource);
            info.KnockbackDirection = knockDir;
            info.KnockbackForce     = _currentSource.KnockbackForce;
            info.SourcePosition     = _attackerTransform.position;
            info.SourceLayer        = _attackerTransform.gameObject.layer;

            // ① 命中 HurtBox
            var hurtBox = other.GetComponent<HurtBox>();
            if (hurtBox != null)
            {
                hurtBox.ReceiveDamage(info);
                OnHitConfirmed?.Invoke(info);
                return;
            }

            // ② 命中 IBreakable（机关/障碍物）
            other.GetComponent<IBreakable>()?.TryInteract(info);
        }

        // ── 同目标多帧命中冷却 ────────────────────────────────────────────────
        private readonly Dictionary<Collider2D, float> _hitCooldownTimers = new();

        private bool CheckCooldown(Collider2D other)
        {
            float now = Time.time;
            if (_hitCooldownTimers.TryGetValue(other, out float last) && now - last < _hitCooldown)
                return false;
            _hitCooldownTimers[other] = now;
            return true;
        }
    }
}