#if GRAPH_DESIGNER
using UnityEngine;
using Opsive.BehaviorDesigner.Runtime.Tasks;
using Opsive.BehaviorDesigner.Runtime.Tasks.Actions;
using BaseGames.Enemies;

namespace BaseGames.Enemies.AI
{
    /// <summary>
    /// BD Action：追击玩家（三阶段视线丢失模型）。
    ///
    /// <list type="bullet">
    ///   <item><b>Tracking</b>：持有视线，以奔跑速度追击并更新 LastKnownPlayerPosition。</item>
    ///   <item><b>Searching</b>：视线丢失超过 LostSightBuffer（~0.3s）后进入。速度降低，向最后可见位置行进；若恢复视线即回到 Tracking。</item>
    ///   <item><b>Lost</b>：Searching 持续超过 LoseLinkTimeout → 返回 Failure，让 BD 树切入 BD_InvestigateLastKnown。</item>
    /// </list>
    ///
    /// 短暂遮挡（如绕过柱子）在 LostSightBuffer 内不会改变速度，避免追击手感割裂。
    /// </summary>
    [TaskName("Chase Player")]
    [TaskCategory("BaseGames/Enemy/Movement")]
    [TaskDescription("三段式追击（Tracking→Searching→Lost）；丢失视线后进入缓冲期")]
    public sealed class BD_ChasePlayer : Action
    {
        [Header("距离限制")]
        [Tooltip("追击距离上限（m）；0 = 使用 EnemyStatsSO.MaxChaseDistance")]
        [SerializeField] [Min(0f)] private float m_MaxChaseDistance = 0f;

        [Header("视线丢失")]
        [Tooltip("视线丢失判定超时（s）；0 = 使用 EnemyStatsSO.LoseLinkTimeout")]
        [SerializeField] [Min(0f)] private float m_LoseLinkTimeout = 0f;

        [Tooltip("视线刚丢失后的缓冲期（s）：此期间保持追击速度，短暂遮挡不触发搜索模式")]
        [SerializeField] [Min(0f)] private float m_LostSightBuffer = 0.3f;

        [Header("路径规划")]
        [Tooltip("路径重规划阈值（m）：玩家移动超过此距离后才重新规划，避免每帧请求")]
        [SerializeField] [Min(0.1f)] private float m_ReplanThreshold = 1.5f;

        [Header("搜索阶段")]
        [Tooltip("Searching 阶段速度倍率（相对于行走速度；<1 = 减速搜索）")]
        [SerializeField] [UnityEngine.Range(0.3f, 1.5f)] private float m_SearchSpeedMultiplier = 0.7f;

        private enum ChaseSubState { Tracking, Searching }

        private EnemyBase     _enemy;
        private float         _losTimer;
        private Vector2       _lastReplanPos;
        private ChaseSubState _subState;

        public override void OnAwake() => _enemy = gameObject.GetComponent<EnemyBase>();

        public override void OnStart()
        {
            _enemy.SetAiPhase(AiPhase.Chase);
            _losTimer      = 0f;
            _lastReplanPos = Vector2.positiveInfinity;
            _subState      = ChaseSubState.Tracking;

            float runSpeed = _enemy.Stats?.RunSpeed ?? 4f;
            _enemy.Nav?.SetSpeed(runSpeed);

            var ac = _enemy.AnimConfig;
            if (_enemy.Animancer != null && ac?.Run != null)
                _enemy.Animancer.Play(ac.Run);
        }

        public override TaskStatus OnUpdate()
        {
            if (_enemy == null || _enemy.PlayerTransform == null)
                return TaskStatus.Failure;

            float maxDist  = m_MaxChaseDistance > 0f ? m_MaxChaseDistance : (_enemy.Stats?.MaxChaseDistance ?? 15f);
            float loseTime = m_LoseLinkTimeout  > 0f ? m_LoseLinkTimeout  : (_enemy.Stats?.LoseLinkTimeout  ?? 2f);

            // 超出最大追击距离 → 放弃追击
            if (_enemy.Stats != null && _enemy.Stats.SqrDistanceToPlayer > maxDist * maxDist)
                return TaskStatus.Failure;

            Vector2 playerPos = _enemy.PlayerTransform.position;

            if (_enemy.IsPlayerVisible())
            {
                // 视线恢复：Searching → Tracking，恢复奔跑速度
                if (_subState == ChaseSubState.Searching)
                {
                    _subState = ChaseSubState.Tracking;
                    _enemy.Nav?.SetSpeed(_enemy.Stats?.RunSpeed ?? 4f);
                }
                _losTimer = 0f;
                _enemy.LastKnownPlayerPosition = playerPos;
            }
            else
            {
                _losTimer += Time.deltaTime;

                if (_subState == ChaseSubState.Tracking)
                {
                    // 缓冲期结束 → 切入 Searching：减速并向最后可见位置行进
                    if (_losTimer >= m_LostSightBuffer)
                    {
                        _subState = ChaseSubState.Searching;
                        float searchSpeed = (_enemy.Stats?.WalkSpeed ?? 2f) * m_SearchSpeedMultiplier;
                        _enemy.Nav?.SetSpeed(searchSpeed);
                        _enemy.MoveTo(_enemy.LastKnownPlayerPosition);
                        _lastReplanPos = _enemy.LastKnownPlayerPosition;
                    }
                }
                else // Searching
                {
                    if (_losTimer >= loseTime)
                        return TaskStatus.Failure; // 搜索超时 → 进入 BD_InvestigateLastKnown
                }
            }

            // Tracking 阶段按阈值重规划路径
            if (_subState == ChaseSubState.Tracking)
            {
                float sqrReplan = m_ReplanThreshold * m_ReplanThreshold;
                if ((playerPos - _lastReplanPos).sqrMagnitude > sqrReplan)
                {
                    _enemy.MoveTo(playerPos);
                    _lastReplanPos = playerPos;
                }
            }

            _enemy.FacePlayer();
            return TaskStatus.Running;
        }

        public override void OnEnd()
        {
            float walkSpeed = _enemy?.Stats?.WalkSpeed ?? 2f;
            _enemy?.Nav?.SetSpeed(walkSpeed);
            _enemy?.StopMovement();
            _subState = ChaseSubState.Tracking; // 重置子状态，防止下次激活时以错误状态重入
        }
    }
}
#endif