using UnityEngine;
using BaseGames.Core;
using BaseGames.Core.Events;

namespace BaseGames.Enemies
{
    /// <summary>
    /// 敌人运行时数值组件（架构 07_EnemyModule §2）。
    /// 由 EnemyBase.Awake() 通过 Initialize(EnemyStatsSO) 注入配置。
    /// 同时订阅难度变更事件，支持游戏进行中切换难度（架构 19 §5）。
    /// </summary>
    public class EnemyStats : MonoBehaviour
    {
        private EnemyStatsSO _config;

        [SerializeField] private DifficultyChangedEventChannel _onDifficultyChanged;

        public int   MaxHP               { get; private set; }
        public int   CurrentHP           { get; private set; }
        public int   Defense             { get; private set; }
        public float AttackCooldownTimer { get; private set; }

        // ── 移动速度（透传 SO，供 BD 任务运行时读取）────────────────────────
        public float WalkSpeed => _config?.WalkSpeed ?? 2f;
        public float RunSpeed  => _config?.RunSpeed  ?? 4f;

        // ── AI 追击配置（透传 SO）──────────────────────────────────────────
        public float MaxChaseDistance    => _config?.MaxChaseDistance    ?? 15f;
        public float LoseLinkTimeout     => _config?.LoseLinkTimeout     ?? 2f;
        public float AlertDuration       => _config?.AlertDuration       ?? 0.6f;
        public float InvestigateDuration => _config?.InvestigateDuration ?? 3f;
        public float HomeRadius          => _config?.HomeRadius          ?? 0.5f;

        /// <summary>
        /// 每帧由 EnemyBase 更新（sqrMagnitude，避免 sqrt 开销）。
        /// 使用方请与 range*range 比较，而非直接与 range 比较。
        /// </summary>
        public float SqrDistanceToPlayer { get; set; }

        private readonly CompositeDisposable _subs = new();

        private void OnEnable()
        {
            _onDifficultyChanged?.Subscribe(HandleDifficultyChanged).AddTo(_subs);
        }

        private void OnDisable()
        {
            _subs.Clear();
        }

        public void Initialize(EnemyStatsSO so)
        {
            _config = so;
            Defense = so.Defense;           // Defense 不随难度缩放（架构 19 §5）
            ApplyHPScaler();
            CurrentHP = MaxHP;
        }

        /// <summary>难度变更时重算 HP（保持 HP 比例，架构 19 §5）。</summary>
        private void HandleDifficultyChanged(DifficultyLevel _)
        {
            if (_config == null) return;
            float hpRatio = MaxHP > 0 ? (float)CurrentHP / MaxHP : 1f;
            ApplyHPScaler();
            CurrentHP = Mathf.Clamp(Mathf.RoundToInt(MaxHP * hpRatio), 1, MaxHP);
        }

        private void ApplyHPScaler()
        {
            if (_config == null) return;
            var scaler = ServiceLocator.GetOrDefault<IDifficultyService>()?.CurrentScaler;
            int raw = scaler != null
                ? Mathf.RoundToInt(_config.MaxHP * scaler.EnemyHPMultiplier)
                : _config.MaxHP;
            MaxHP = Mathf.Max(1, raw);   // 防止 MaxHP=0 导致 HP 比例计算 NaN
        }

        public void TakeDamage(int amount)
        {
            CurrentHP = Mathf.Max(0, CurrentHP - amount);
        }

        public void TickAttackCooldown(float dt)
        {
            if (AttackCooldownTimer > 0f)
                AttackCooldownTimer -= dt;
        }

        public void ResetAttackCooldown()
        {
            AttackCooldownTimer = _config.AttackCooldown;
        }
    }
}