using UnityEngine;
using BaseGames.Core.Events;

namespace BaseGames.Combat
{
    /// <summary>
    /// 单次伤害信息。流水线：RawDamage → Amount（护盾修改）→ FinalDamage（防御减免后）。
    /// ⚠️ 保留为可变 struct：HurtBox 流水线需要在方法内修改本地副本的 Amount / FinalDamage。
    ///    Builder 通过独立字段构造，不直接修改 DamageInfo 实例。
    /// </summary>
    [System.Serializable]
    public struct DamageInfo
    {
        public int           RawDamage;         // HitBox 设定的原始值（工厂/Builder 写入一次）
        public int           Amount;            // 流水线中被护盾/防御修改
        public int           FinalDamage;       // HurtBox 写入，最终 HP 扣除量
        public Vector2       KnockbackDirection;
        public float         KnockbackForce;
        public float         HitStunDuration;
        public DamageType    Type;
        public DamageCategory Category;
        public DamageFlags   Flags;
        public DamageTags    Tags;
        public Vector2       SourcePosition;
        public int           SourceLayer;
        public HitFxType     FxType;
        public BreakLevel    Break;
        public string        SourceId;
        public string        SkillId;
        /// <summary>
        /// HitBox 激活实例 ID（由 HitBox.Activate() 自动生成并写入，0 = 无追踪路径）。
        /// HurtBoxOwnerGuard 用此字段做同激活去重，防止多 HurtBox 节点被同一次攻击重复扣血。
        /// [NonSerialized]：每次激活动态生成，不需要序列化。
        /// </summary>
        [System.NonSerialized] public uint HitActivationId;
        /// <summary>
        /// 攻击来源投射物（仅当攻击方是 Projectile 时非 null）。
        /// 用于弹反成功时调用 ReflectAsPlayerProjectile() 翻转阵营。
        /// [NonSerialized]：MonoBehaviour 引用不参与 Unity 资产序列化。
        /// </summary>
        [System.NonSerialized] public Projectile SourceProjectile;

        // ── Builder ──────────────────────────────────────────────────────────
        /// <summary>
        /// 通过独立字段构造 DamageInfo，避免直接持有可变 DamageInfo 实例。
        /// </summary>
        public class Builder
        {
            private int             _raw;
            private DamageType      _type;
            private DamageCategory  _category;
            private DamageFlags     _flags;
            private DamageTags      _tags;
            private string          _skillId;
            private string          _sourceId;
            private Vector2         _knockbackDirection;
            private float           _knockbackForce;
            private float           _hitStunDuration;
            private HitFxType       _fxType;
            private BreakLevel      _break;
            private Vector2         _sourcePosition;
            private int             _sourceLayer;
            private Projectile      _sourceProjectile;

            public Builder() { }

            // SetRaw 同步初始化 Amount（Amount 始终以 RawDamage 为起点）
            public Builder SetRaw(int v)                          { _raw = v;                                          return this; }
            public Builder SetType(DamageType v)                  { _type = v;                                         return this; }
            public Builder SetCategory(DamageCategory v)          { _category = v;                                     return this; }
            public Builder SetFlags(DamageFlags v)                { _flags = v;                                        return this; }
            public Builder SetTags(DamageTags v)                  { _tags = v;                                         return this; }
            public Builder SetSkillId(string v)                   { _skillId = v;                                      return this; }
            public Builder SetSourceId(string v)                  { _sourceId = v;                                     return this; }
            public Builder SetKnockback(Vector2 dir, float force) { _knockbackDirection = dir; _knockbackForce = force; return this; }
            public Builder SetStun(float dur)                     { _hitStunDuration = dur;                            return this; }
            public Builder SetFx(HitFxType v)                     { _fxType = v;                                       return this; }
            public Builder SetBreak(BreakLevel v)                 { _break = v;                                        return this; }
            public Builder SetSourcePos(Vector2 v)                { _sourcePosition = v;                               return this; }
            public Builder SetLayer(int v)                        { _sourceLayer = v;                                  return this; }
            public Builder SetProjectile(Projectile v)            { _sourceProjectile = v;                             return this; }

            public DamageInfo Build() => new DamageInfo
            {
                RawDamage          = _raw,
                Amount             = _raw,
                Type               = _type,
                Category           = _category,
                Flags              = _flags,
                Tags               = _tags,
                SkillId            = _skillId,
                SourceId           = _sourceId,
                KnockbackDirection = _knockbackDirection,
                KnockbackForce     = _knockbackForce,
                HitStunDuration    = _hitStunDuration,
                FxType             = _fxType,
                Break              = _break,
                SourcePosition     = _sourcePosition,
                SourceLayer        = _sourceLayer,
                SourceProjectile   = _sourceProjectile,
            };
        }

        /// <summary>
        /// ⚡ 零堆分配工厂（热路径首选）。从 DamageSourceSO 填入所有静态字段；
        /// 可选传入运行时字段（knockbackDir、sourcePos、sourceLayer），
        /// 无需调用方事后就地赋值。
        /// </summary>
        public static DamageInfo From(
            DamageSourceSO so,
            Vector2        knockbackDir = default,
            Vector2        sourcePos    = default,
            int            sourceLayer  = 0,
            Projectile     sourceProjectile = null)
        {
            int baseAmt = Mathf.RoundToInt(so.BaseDamage * so.DamageMultiplier);
            return new DamageInfo
            {
                RawDamage          = baseAmt,
                Amount             = baseAmt,
                Type               = so.Type,
                Category           = so.Category,
                Flags              = so.Flags,
                Tags               = so.Tags,
                HitStunDuration    = so.HitStunDuration,
                FxType             = so.FxType,
                Break              = so.BreakLevel,
                SourceId           = so.sourceId,
                SkillId            = so.skillId,
                KnockbackDirection = knockbackDir,
                KnockbackForce     = so.KnockbackForce,
                SourcePosition     = sourcePos,
                SourceLayer        = sourceLayer,
                SourceProjectile   = sourceProjectile,
            };
        }
    }

    /// <summary>伤害事件频道（EVT_DamageDealt）。</summary>
    [UnityEngine.CreateAssetMenu(menuName = "Events/DamageDealt")]
    public class DamageInfoEventChannelSO : BaseEventChannelSO<DamageInfo> { }
}