zeling_v2/Assets/_Game/Scripts/Combat/Projectile.cs

using UnityEngine;
using BaseGames.Core;
using BaseGames.Core.Pool;

namespace BaseGames.Combat
{
    /// <summary>
    /// 抛射物基类。子类通过重写 <see cref="OnInitialized"/> 设定初速度。
    /// 依赖 <see cref="HitBox"/> 子组件进行碰撞伤害检测。
    /// </summary>
    [RequireComponent(typeof(Rigidbody2D), typeof(HitBox))]
    public abstract class Projectile : MonoBehaviour
    {
        [HideInInspector] public DamageInfo          DamageInfo;
        [HideInInspector] public Vector2             Direction;

        protected ProjectileConfigSO _config;
        protected Rigidbody2D        _rb;
        protected HitBox             _hitBox;
        protected float              _aliveTimer;
        // Lifetime 在 Initialize 时缓存，避免 Update 每帧访问 SO 成员并做 null check
        private float _lifetime = float.MaxValue;

        // 命中预算：剩余可命中次数（<=0 的 _maxHits 表示无限穿透）
        private int  _maxHits      = 1;
        private int  _hitsRemaining;
        // 弹反帧标记：弹反命中不计入命中预算（避免反射后立即被回收）
        private bool _justReflected;
        // 预制体上配置的初始伤害目标层：对象池复用时还原，避免上一发弹反翻转后的掩码污染下一发
        private LayerMask _initialTargetLayers;

        private PooledObject _pooledObject;

        protected virtual void Awake()
        {
            _rb           = GetComponent<Rigidbody2D>();
            _hitBox       = GetComponent<HitBox>();
            _pooledObject = GetComponent<PooledObject>();
            _initialTargetLayers = _hitBox.TargetLayers;
            // 订阅命中确认：按命中预算决定何时回收（穿透 / 命中即消失）
            _hitBox.OnHitConfirmed += HandleHitConfirmed;
        }

        /// <summary>从对象池取出后的初始化入口。</summary>
        public virtual void Initialize(ProjectileConfigSO config, DamageInfo damageInfo, Vector2 direction, int ownerLayer = 0)
        {
            _config    = config;
            _lifetime  = config.Lifetime;
            DamageInfo = damageInfo;
            Direction  = direction.normalized;
            _aliveTimer = 0f;
            _maxHits       = config.MaxHits;
            _hitsRemaining = config.MaxHits;
            _justReflected = false;
            // 还原预制体配置的伤害目标层（清除上一次弹反翻转的影响）
            _hitBox.TargetLayers = _initialTargetLayers;

            SetFactionLayer(ownerLayer);
            _hitBox.Activate(config.DamageSource);
            OnInitialized();
        }

        /// <summary>根据发射方所在 Layer 切换到对应的 PlayerProjectile / EnemyProjectile 层。</summary>
        private void SetFactionLayer(int ownerLayer)
        {
            int playerLayer     = LayerMask.NameToLayer("Player");
            int playerProjLayer = LayerMask.NameToLayer("PlayerProjectile");
            int enemyProjLayer  = LayerMask.NameToLayer("EnemyProjectile");
            if (playerProjLayer < 0 || enemyProjLayer < 0) return; // Layer 尚未创建，保留现有层
            gameObject.layer = (ownerLayer == playerLayer) ? playerProjLayer : enemyProjLayer;
        }

        /// <summary>
        /// 弹反：将投射物阵营从 EnemyProjectile 切换为 PlayerProjectile。
        /// 反转飞行方向，并重置 HitBox 命中记录使其能够命中新目标（敌人）。
        /// 由 HurtBox.ReceiveDamage() 在弹反成功后调用。
        /// </summary>
        public virtual void ReflectAsPlayerProjectile()
        {
            int playerProjLayer = LayerMask.NameToLayer("PlayerProjectile");
            if (playerProjLayer < 0) return;

            gameObject.layer = playerProjLayer;
            Direction = -Direction;
            _rb.velocity = -_rb.velocity;

            // 重置 HitBox 命中记录，确保反射后可命中新目标
            _hitBox.Deactivate();
            _hitBox.Activate(_config?.DamageSource);
            // 伤害目标随阵营切换（优先取配置的显式目标层）
            ApplyReflectedTargetLayers();

            // 反射后重置命中预算，并跳过本次（弹反）命中的扣减，避免反射后立即被回收
            _hitsRemaining = _maxHits;
            _justReflected = true;
        }

        /// <summary>
        /// 弹反换阵营后应用伤害目标层：
        /// 优先使用 <see cref="ProjectileConfigSO.ReflectedTargetLayers"/> 的显式配置；
        /// 未配置（Nothing）时自动翻转——仅交换 PlayerHurtBox→EnemyHurtBox 位，
        /// 保留可破坏物等其他目标层。
        /// </summary>
        protected void ApplyReflectedTargetLayers()
        {
            if (_config != null && _config.ReflectedTargetLayers.value != 0)
            {
                _hitBox.TargetLayers = _config.ReflectedTargetLayers;
                return;
            }
            int playerHurt = LayerMask.NameToLayer("PlayerHurtBox");
            int enemyHurt  = LayerMask.NameToLayer("EnemyHurtBox");
            if (playerHurt < 0 || enemyHurt < 0) return; // Layer 尚未创建，保留现有掩码
            int mask = _hitBox.TargetLayers.value;
            mask &= ~(1 << playerHurt);
            mask |=   1 << enemyHurt;
            _hitBox.TargetLayers = mask;
        }

        /// <summary>HitBox 命中确认回调：按命中预算决定是否回收（穿透 / 命中即消失）。</summary>
        private void HandleHitConfirmed(DamageInfo _)
        {
            if (_maxHits <= 0) return;                 // 无限穿透：只靠寿命回收
            if (_justReflected) { _justReflected = false; return; } // 弹反命中不计入预算
            if (--_hitsRemaining <= 0) ReturnToPool();
        }

        protected virtual void OnInitialized() { }

        protected virtual void Update()
        {
            _aliveTimer += Time.deltaTime;
            if (_aliveTimer >= _lifetime)
                ReturnToPool();
        }

        /// <summary>停用并归还对象池。</summary>
        protected void ReturnToPool()
        {
            _hitBox.Deactivate();
            gameObject.SetActive(false);
            if (_pooledObject != null && _config != null)
                ServiceLocator.GetOrDefault<IObjectPoolService>()?.Despawn(_config.PoolKey, _pooledObject);
        }

        protected virtual void OnDisable()
        {
            _aliveTimer = 0f;
            _lifetime   = float.MaxValue; // 归还对象池后重置，防止未初始化时自毁
        }
    }
}