using System;
using UnityEngine;
using System.Collections.Generic;
using NBC;

namespace NBF
{
    public struct FLineNodeConstraintState
    {
        public Vector3 TargetPosition;
        public float PlanarStrength;
        public float UpwardStrength;
        public float DownwardStrength;
        public float MaxCorrection;
    }

    /// <summary>
    /// 为 FLine 节点提供附加软约束。求解器只依赖这个通用接口，不依赖具体玩法组件。
    /// </summary>
    public interface IFLineNodeConstraintProvider
    {
        bool TryGetConstraintState(out FLineNodeConstraintState state);
    }

    public enum LineType
    {
        Spinning,
        SpinningFloat,
        Hand,
        HandDouble,
    }

    public class FLine : FGearBase
    {
        [Header("基本参数设置")] public LineType LineType;
        [Header("连接点配置")] [SerializeField] private Transform anchorTransform;
        [SerializeField] private List<FLineLogicNode> lineNodes = new List<FLineLogicNode>();

        [Header("物理参数")] [SerializeField] private float positionCorrectionForce = 100f;
        [SerializeField] private float dampingCoefficient = 10f;
        [SerializeField] private int constraintIterations = 10;
        [SerializeField] private bool useMassWeighting = true;

        [Header("动态间距设置")] [SerializeField] private float defaultTransitionSpeed = 2f; // 默认长度变化速度（单位/秒）

        [Header("调试")] [SerializeField] private bool showDebugInfo = true;

        private readonly List<ConnectionConstraint> _constraints = new List<ConnectionConstraint>();

        private readonly List<IFLineNodeConstraintProvider[]> _nodeConstraintProviders =
            new List<IFLineNodeConstraintProvider[]>();

        [System.Serializable]
        public class ConnectionConstraint
        {
            public Rigidbody bodyA;
            public Rigidbody bodyB;
            public float maxDistance;
            public float minDistance;
            public float currentDistance;
            public Vector3 direction;

            // 动态目标距离（用于平滑过渡）
            public float targetMaxDistance;
            public float targetMinDistance;
            public bool hasPendingTransition;
            public bool hasPendingMaxTransition;
            public bool hasPendingMinTransition;
            public float maxTransitionSpeed;
            public float minTransitionSpeed;

            public ConnectionConstraint(Rigidbody a, Rigidbody b, float maxDist, float minDist = 0f)
            {
                bodyA = a;
                bodyB = b;
                maxDistance = maxDist;
                minDistance = minDist;
                targetMaxDistance = maxDist;
                targetMinDistance = minDist;
                hasPendingTransition = false;
                hasPendingMaxTransition = false;
                hasPendingMinTransition = false;
                maxTransitionSpeed = 0f;
                minTransitionSpeed = 0f;
            }

            public void UpdateCurrentState()
            {
                if (bodyA && bodyB)
                {
                    Vector3 delta = bodyB.position - bodyA.position;
                    currentDistance = delta.magnitude;
                    direction = currentDistance > 0.0001f ? delta.normalized : Vector3.right;
                }
            }
        }

        void Awake()
        {
            BuildConstraints();
        }

        protected override void OnInit()
        {
            anchorTransform = Rod.Asset.lineConnector;
        }

        void Start()
        {
            if (_constraints.Count == 0)
            {
                Debug.LogWarning("FLine需要至少2个有效节点");
                enabled = false;
            }
        }

        void FixedUpdate()
        {
            if (!enabled || _constraints.Count == 0) return;

            UpdateAnchorNode();
            // 更新动态过渡
            UpdateTransitions();

            for (int iteration = 0; iteration < constraintIterations; iteration++)
            {
                ApplyDistanceConstraints();
                ApplyNodeConstraints();
            }

            ApplyDamping();
            UpdateBreakCountdown(Time.fixedDeltaTime);
        }

        private void BuildConstraints()
        {
            _constraints.Clear();
            _nodeConstraintProviders.Clear();
            if (lineNodes.Count < 2) return;

            for (int i = 0; i < lineNodes.Count; i++)
            {
                if (lineNodes[i])
                {
                    lineNodes[i].AttachToCable(this);
                    _nodeConstraintProviders.Add(CollectNodeConstraintProviders(lineNodes[i]));
                }
                else
                {
                    _nodeConstraintProviders.Add(Array.Empty<IFLineNodeConstraintProvider>());
                }
            }

            // 创建约束
            for (int i = 0; i < lineNodes.Count - 1; i++)
            {
                FLineLogicNode currentNode = lineNodes[i];
                FLineLogicNode nextNode = lineNodes[i + 1];
                Rigidbody bodyA = currentNode ? currentNode.Rigidbody : null;
                Rigidbody bodyB = nextNode ? nextNode.Rigidbody : null;

                if (bodyA != null && bodyB != null)
                {
                    var constraint = new ConnectionConstraint(
                        bodyA,
                        bodyB,
                        currentNode.NextSegmentMaxLength,
                        currentNode.NextSegmentMinLength
                    );
                    _constraints.Add(constraint);
                }
            }
        }

        private FLineLogicNode GetSegmentNode(int segmentIndex)
        {
            if (segmentIndex < 0 || segmentIndex >= lineNodes.Count - 1)
            {
                return null;
            }

            return lineNodes[segmentIndex];
        }

        private Rigidbody GetBodyAt(int nodeIndex)
        {
            if (nodeIndex < 0 || nodeIndex >= lineNodes.Count)
            {
                return null;
            }

            FLineLogicNode node = lineNodes[nodeIndex];
            return node ? node.Rigidbody : null;
        }

        private IFLineNodeConstraintProvider[] GetNodeConstraintProvidersAt(int nodeIndex)
        {
            if (nodeIndex < 0 || nodeIndex >= _nodeConstraintProviders.Count)
            {
                return Array.Empty<IFLineNodeConstraintProvider>();
            }

            return _nodeConstraintProviders[nodeIndex];
        }

        private static IFLineNodeConstraintProvider[] CollectNodeConstraintProviders(FLineLogicNode node)
        {
            MonoBehaviour[] behaviours = node.GetComponents<MonoBehaviour>();
            List<IFLineNodeConstraintProvider> providers = new List<IFLineNodeConstraintProvider>();

            for (int i = 0; i < behaviours.Length; i++)
            {
                MonoBehaviour behaviour = behaviours[i];
                if (behaviour is IFLineNodeConstraintProvider provider)
                {
                    providers.Add(provider);
                }
            }

            return providers.ToArray();
        }

        private void SyncSegmentMaxLength(int segmentIndex, float maxLength)
        {
            FLineLogicNode node = GetSegmentNode(segmentIndex);
            if (node)
            {
                node.NextSegmentMaxLength = maxLength;
            }
        }

        private void SyncSegmentMinLength(int segmentIndex, float minLength)
        {
            FLineLogicNode node = GetSegmentNode(segmentIndex);
            if (node)
            {
                node.NextSegmentMinLength = minLength;
            }
        }

        private bool ContainsBody(Rigidbody targetBody)
        {
            for (int i = 0; i < lineNodes.Count; i++)
            {
                if (GetBodyAt(i) == targetBody)
                {
                    return true;
                }
            }

            return false;
        }

        /// <summary>
        /// 更新所有活跃的过渡
        /// </summary>
        private void UpdateTransitions()
        {
            float deltaTime = Time.fixedDeltaTime;

            for (int i = 0; i < _constraints.Count; i++)
            {
                var constraint = _constraints[i];

                if (constraint.hasPendingMaxTransition)
                {
                    float nextMaxDistance = Mathf.MoveTowards(
                        constraint.maxDistance,
                        constraint.targetMaxDistance,
                        constraint.maxTransitionSpeed * deltaTime
                    );
                    constraint.maxDistance = nextMaxDistance;
                    SyncSegmentMaxLength(i, nextMaxDistance);

                    if (Mathf.Abs(nextMaxDistance - constraint.targetMaxDistance) < 0.0001f)
                    {
                        constraint.maxDistance = constraint.targetMaxDistance;
                        constraint.hasPendingMaxTransition = false;
                        SyncSegmentMaxLength(i, constraint.targetMaxDistance);
                    }
                }

                if (constraint.hasPendingMinTransition)
                {
                    float nextMinDistance = Mathf.MoveTowards(
                        constraint.minDistance,
                        constraint.targetMinDistance,
                        constraint.minTransitionSpeed * deltaTime
                    );
                    constraint.minDistance = nextMinDistance;
                    SyncSegmentMinLength(i, nextMinDistance);

                    if (Mathf.Abs(nextMinDistance - constraint.targetMinDistance) < 0.0001f)
                    {
                        constraint.minDistance = constraint.targetMinDistance;
                        constraint.hasPendingMinTransition = false;
                        SyncSegmentMinLength(i, constraint.targetMinDistance);
                    }
                }

                constraint.hasPendingTransition =
                    constraint.hasPendingMaxTransition || constraint.hasPendingMinTransition;
            }
        }

        private void ApplyDistanceConstraints()
        {
            for (int i = 0; i < _constraints.Count; i++)
            {
                var constraint = _constraints[i];
                if (!constraint.bodyA || !constraint.bodyB) continue;

                constraint.UpdateCurrentState();

                float currentDist = constraint.currentDistance;
                float maxDist = constraint.maxDistance;
                float minDist = constraint.minDistance;

                float error = 0f;
                bool needCorrection = false;

                if (currentDist > maxDist)
                {
                    error = currentDist - maxDist;
                    needCorrection = true;
                }

                if (!needCorrection || Mathf.Abs(error) < 0.0001f) continue;

                float invMassA = constraint.bodyA.isKinematic ? 0f : 1f / constraint.bodyA.mass;
                float invMassB = constraint.bodyB.isKinematic ? 0f : 1f / constraint.bodyB.mass;
                float totalInvMass = invMassA + invMassB;

                if (totalInvMass < 0.0001f) continue;

                float weightA = useMassWeighting ? (invMassA / totalInvMass) : 0.5f;
                float weightB = useMassWeighting ? (invMassB / totalInvMass) : 0.5f;

                Vector3 correction = constraint.direction * error;
                Vector3 positionCorrectionA = correction * weightA;
                Vector3 positionCorrectionB = -correction * weightB;

                constraint.bodyA.position += positionCorrectionA;
                constraint.bodyB.position += positionCorrectionB;

                Vector3 velocityCorrectionA = positionCorrectionA / Time.fixedDeltaTime;
                Vector3 velocityCorrectionB = positionCorrectionB / Time.fixedDeltaTime;

                constraint.bodyA.AddForce(velocityCorrectionA * constraint.bodyA.mass, ForceMode.Impulse);
                constraint.bodyB.AddForce(velocityCorrectionB * constraint.bodyB.mass, ForceMode.Impulse);
            }
        }

        private void ApplyNodeConstraints()
        {
            for (int i = 0; i < lineNodes.Count; i++)
            {
                Rigidbody body = GetBodyAt(i);
                IFLineNodeConstraintProvider[] providers = GetNodeConstraintProvidersAt(i);

                if (!body || body.isKinematic || providers.Length == 0)
                {
                    continue;
                }

                for (int providerIndex = 0; providerIndex < providers.Length; providerIndex++)
                {
                    IFLineNodeConstraintProvider provider = providers[providerIndex];
                    if (provider == null)
                    {
                        continue;
                    }

                    if (provider is Behaviour behaviour && !behaviour.isActiveAndEnabled)
                    {
                        continue;
                    }

                    if (!provider.TryGetConstraintState(out FLineNodeConstraintState constraint))
                    {
                        continue;
                    }

                    ApplyWorldTargetConstraint(body, constraint);
                }
            }
        }

        private static void ApplyWorldTargetConstraint(Rigidbody body, FLineNodeConstraintState constraint)
        {
            Vector3 delta = constraint.TargetPosition - body.position;
            Vector3 planarDelta = Vector3.ProjectOnPlane(delta, Vector3.up);
            Vector3 correction = planarDelta * Mathf.Clamp01(constraint.PlanarStrength);

            float verticalStrength = delta.y >= 0f
                ? Mathf.Clamp01(constraint.UpwardStrength)
                : Mathf.Clamp01(constraint.DownwardStrength);
            correction.y = delta.y * verticalStrength;

            float maxCorrection = Mathf.Max(0f, constraint.MaxCorrection);
            if (maxCorrection > 0f && correction.magnitude > maxCorrection)
            {
                correction = correction.normalized * maxCorrection;
            }

            if (correction.sqrMagnitude < 1e-8f)
            {
                return;
            }

            body.position += correction;

            Vector3 velocityCorrection = correction / Mathf.Max(Time.fixedDeltaTime, 0.0001f);
            body.AddForce(velocityCorrection * body.mass, ForceMode.Impulse);
        }

        private void ApplyDamping()
        {
            for (int i = 0; i < _constraints.Count; i++)
            {
                var constraint = _constraints[i];
                if (!constraint.bodyA || !constraint.bodyB) continue;

                if (constraint.currentDistance <= constraint.maxDistance) continue;

                Vector3 relativeVelocity = constraint.bodyB.linearVelocity - constraint.bodyA.linearVelocity;
                float velocityInConstraintDir = Vector3.Dot(relativeVelocity, constraint.direction);

                if (velocityInConstraintDir > 0)
                {
                    float dampingForce = -velocityInConstraintDir * dampingCoefficient;
                    Vector3 dampingImpulse = constraint.direction * dampingForce * Time.fixedDeltaTime;

                    constraint.bodyA.AddForce(-dampingImpulse * constraint.bodyA.mass, ForceMode.Impulse);
                    constraint.bodyB.AddForce(dampingImpulse * constraint.bodyB.mass, ForceMode.Impulse);
                }
            }
        }

        private void UpdateAnchorNode()
        {
            if (anchorTransform == null || lineNodes.Count < 1)
            {
                return;
            }

            var startNode = lineNodes[0].Rigidbody;
            startNode.transform.SetPositionAndRotation(anchorTransform.position, anchorTransform.rotation);

            if (!startNode.isKinematic)
            {
                startNode.linearVelocity = Vector3.zero;
                startNode.angularVelocity = Vector3.zero;
            }
        }

        #region 动态间距修改接口

        public void SetLenght(float length)
        {
            SetSegmentMaxLength(0, length);
        }

        /// <summary>
        /// 按速度过渡某段的最大距离
        /// </summary>
        public void SetSegmentMaxLength(int segmentIndex, float targetLength, float transitionSpeed = 2f)
        {
            if (segmentIndex < 0 || segmentIndex >= _constraints.Count) return;

            targetLength = Mathf.Max(0.01f, targetLength);
            float speed = Mathf.Max(0.01f, transitionSpeed > 0 ? transitionSpeed : defaultTransitionSpeed);

            var constraint = _constraints[segmentIndex];
            constraint.targetMaxDistance = targetLength;
            constraint.maxTransitionSpeed = speed;
            constraint.hasPendingMaxTransition = Mathf.Abs(constraint.maxDistance - targetLength) >= 0.0001f;
            constraint.hasPendingTransition = constraint.hasPendingMaxTransition || constraint.hasPendingMinTransition;
        }

        /// <summary>
        /// 按速度过渡某段的最小距离
        /// </summary>
        public void SetSegmentMinLength(int segmentIndex, float targetLength, float transitionSpeed = -1)
        {
            if (segmentIndex < 0 || segmentIndex >= _constraints.Count) return;

            targetLength = Mathf.Max(0f, targetLength);
            float speed = Mathf.Max(0.01f, transitionSpeed > 0 ? transitionSpeed : defaultTransitionSpeed);

            var constraint = _constraints[segmentIndex];
            constraint.targetMinDistance = targetLength;
            constraint.minTransitionSpeed = speed;
            constraint.hasPendingMinTransition = Mathf.Abs(constraint.minDistance - targetLength) >= 0.0001f;
            constraint.hasPendingTransition = constraint.hasPendingMaxTransition || constraint.hasPendingMinTransition;
        }

        /// <summary>
        /// 同时按速度过渡某段的最大和最小距离
        /// </summary>
        public void SetSegmentLengths(int segmentIndex, float targetMaxLength, float targetMinLength,
            float transitionSpeed = -1)
        {
            if (segmentIndex < 0 || segmentIndex >= _constraints.Count) return;

            targetMaxLength = Mathf.Max(0.01f, targetMaxLength);
            targetMinLength = Mathf.Max(0f, targetMinLength);
            float speed = Mathf.Max(0.01f, transitionSpeed > 0 ? transitionSpeed : defaultTransitionSpeed);

            var constraint = _constraints[segmentIndex];
            constraint.targetMaxDistance = targetMaxLength;
            constraint.targetMinDistance = targetMinLength;
            constraint.maxTransitionSpeed = speed;
            constraint.minTransitionSpeed = speed;
            constraint.hasPendingMaxTransition = Mathf.Abs(constraint.maxDistance - targetMaxLength) >= 0.0001f;
            constraint.hasPendingMinTransition = Mathf.Abs(constraint.minDistance - targetMinLength) >= 0.0001f;
            constraint.hasPendingTransition = constraint.hasPendingMaxTransition || constraint.hasPendingMinTransition;
        }

        /// <summary>
        /// 扩展整个绳索（所有段均匀缩放）
        /// </summary>
        public void ExtendAllSegments(float scaleFactor, float transitionSpeed = -1)
        {
            float speed = transitionSpeed > 0 ? transitionSpeed : defaultTransitionSpeed;

            for (int i = 0; i < _constraints.Count; i++)
            {
                var constraint = _constraints[i];
                float newMaxLength = constraint.maxDistance * scaleFactor;
                float newMinLength = constraint.minDistance * scaleFactor;

                SetSegmentLengths(i, newMaxLength, newMinLength, speed);
            }
        }

        /// <summary>
        /// 收缩/拉紧绳索（所有段向目标长度过渡）
        /// </summary>
        public void TightenAllSegments(float targetLength, float transitionSpeed = -1)
        {
            float speed = transitionSpeed > 0 ? transitionSpeed : defaultTransitionSpeed;

            for (int i = 0; i < _constraints.Count; i++)
            {
                var constraint = _constraints[i];
                SetSegmentLengths(i, targetLength, Mathf.Min(constraint.minDistance, targetLength), speed);
            }
        }

        /// <summary>
        /// 对特定段施加拉力（减小最大距离）
        /// </summary>
        public void PullSegment(int segmentIndex, float amount, float transitionSpeed = -1)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                var constraint = _constraints[segmentIndex];
                float newMaxLength = Mathf.Max(0.01f, constraint.targetMaxDistance - amount);
                SetSegmentMaxLength(segmentIndex, newMaxLength, transitionSpeed);
            }
        }

        /// <summary>
        /// 放松特定段（增加最大距离）
        /// </summary>
        public void RelaxSegment(int segmentIndex, float amount, float transitionSpeed = -1)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                var constraint = _constraints[segmentIndex];
                float newMaxLength = constraint.targetMaxDistance + amount;
                SetSegmentMaxLength(segmentIndex, newMaxLength, transitionSpeed);
            }
        }

        /// <summary>
        /// 移除指定段的过渡
        /// </summary>
        private void RemoveExistingTransition(int segmentIndex, bool removeMax, bool removeMin)
        {
            if (segmentIndex < 0 || segmentIndex >= _constraints.Count)
            {
                return;
            }

            var constraint = _constraints[segmentIndex];
            if (removeMax)
            {
                constraint.hasPendingMaxTransition = false;
                constraint.targetMaxDistance = constraint.maxDistance;
            }

            if (removeMin)
            {
                constraint.hasPendingMinTransition = false;
                constraint.targetMinDistance = constraint.minDistance;
            }

            constraint.hasPendingTransition = constraint.hasPendingMaxTransition || constraint.hasPendingMinTransition;
        }

        /// <summary>
        /// 取消所有正在进行的过渡
        /// </summary>
        public void CancelAllTransitions()
        {
            foreach (var constraint in _constraints)
            {
                constraint.hasPendingTransition = false;
                constraint.hasPendingMaxTransition = false;
                constraint.hasPendingMinTransition = false;
                constraint.targetMaxDistance = constraint.maxDistance;
                constraint.targetMinDistance = constraint.minDistance;
            }
        }

        /// <summary>
        /// 取消指定段的过渡
        /// </summary>
        public void CancelTransition(int segmentIndex)
        {
            RemoveExistingTransition(segmentIndex, true, true);
            if (segmentIndex < _constraints.Count)
            {
                _constraints[segmentIndex].hasPendingTransition = false;
            }
        }

        /// <summary>
        /// 获取某个段是否正在进行过渡
        /// </summary>
        public bool IsSegmentTransitioning(int segmentIndex)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                return _constraints[segmentIndex].hasPendingTransition;
            }

            return false;
        }

        /// <summary>
        /// 获取某段当前的目标最大距离
        /// </summary>
        public float GetTargetMaxLength(int segmentIndex)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                return _constraints[segmentIndex].targetMaxDistance;
            }

            return -1f;
        }

        /// <summary>
        /// 获取某段当前的目标最小距离
        /// </summary>
        public float GetTargetMinLength(int segmentIndex)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                return _constraints[segmentIndex].targetMinDistance;
            }

            return -1f;
        }

        /// <summary>
        /// 设置默认长度变化速度
        /// </summary>
        public void SetDefaultTransitionSpeed(float speed)
        {
            defaultTransitionSpeed = Mathf.Max(0.01f, speed);
        }

        #endregion

        #region 极限判定

        /// <summary>
        /// 当前逻辑链总长度超出配置总长度的部分，小于等于零时记为 0。
        /// </summary>
        [Header("Limit Detection")]
        public float CurrentStretchLength { get; private set; }

        /// <summary>
        /// 总长度
        /// </summary>
        public float TotalLength { get; private set; }

        [Min(0f)]
        // 极限判定的长度容差，允许链路在总长或单段长度上存在少量误差。
        [SerializeField]
        private float lengthLimitTolerance = 0.01f;

        [Min(0f)]
        // 达到极限后，只有当前超长值大于该阈值时，才开始进入断线候选计时。
        [SerializeField]
        private float breakStretchThreshold = 0.3f;

        [Min(0f)]
        // UI 百分比开始起算的最小超长值；低于或等于该值时统一按 0% 处理。
        [SerializeField]
        private float breakStretchPercentMinThreshold = 0.06f;

        [Min(0f)]
        // 断线候选状态允许持续的最大时间；超过后会发出一次断线消息。
        [SerializeField]
        private float breakLimitDuration = 3f;

        /// <summary>
        /// 当鱼线达到断线条件时发出的一次性消息。
        /// 外部可订阅该事件，在回调中执行切线、播放表现或状态切换。
        /// </summary>
        public event Action<FLine> OnLineBreakRequested;

        /// <summary>
        /// 当前是否处于极限状态。
        /// 只要整链超出总长度容差，或任一逻辑段超出单段容差，即认为到达极限。
        /// </summary>
        public bool IsAtLimit { get; private set; }

        /// <summary>
        /// 当前断线候选状态的累计时间。
        /// 只有在处于极限状态，且 CurrentStretchLength 大于断线阈值时才会累加；否则重置为 0。
        /// </summary>
        public float LimitStateTime { get; private set; }

        /// <summary>
        /// 当前极限断线消息是否已经发出过。
        /// 在退出断线候选状态前只会发一次，避免重复通知。
        /// </summary>
        public bool HasBreakNotificationSent { get; private set; }

        /// <summary>
        /// 当前拉力极限百分比。
        /// 当超长值小于等于 breakStretchPercentMinThreshold 时为 0；
        /// 当超长值大于等于 breakStretchThreshold 时为 100；
        /// 中间区间按线性比例映射，供 UI 显示使用。
        /// </summary>
        public float CurrentBreakStretchPercent => EvaluateBreakStretchPercent(CurrentStretchLength);

        /// <summary>
        /// 当前是否正在进行断线候选计时。
        /// </summary>
        public bool IsBreakCountdownActive => IsAtLimit && CurrentStretchLength > breakStretchThreshold;

        private float EvaluateBreakStretchPercent(float stretchLength)
        {
            var percentMinThreshold = Mathf.Max(lengthLimitTolerance, breakStretchPercentMinThreshold);

            if (stretchLength <= percentMinThreshold)
            {
                return 0f;
            }

            if (stretchLength >= breakStretchThreshold)
            {
                return 100f;
            }

            if (breakStretchThreshold <= percentMinThreshold)
            {
                return 100f;
            }

            return Mathf.InverseLerp(percentMinThreshold, breakStretchThreshold, stretchLength) * 100f;
        }

        private void SetLimitState(bool isAtLimit)
        {
            IsAtLimit = isAtLimit;
        }

        private void UpdateBreakCountdown(float deltaTime)
        {
            if (lineNodes.Count < 2)
            {
                SetLimitState(false);
                ResetLimitState();
                return;
            }

            var startNode = lineNodes[0];
            var endNode = lineNodes[^1];
            TotalLength = 0;
            foreach (var node in lineNodes)
            {
                if (node.NodeType == FLineLogicNodeType.End) continue;
                TotalLength += node.NextSegmentMaxLength;
            }

            var realLen = Vector3.Distance(startNode.transform.position, endNode.transform.position);
            CurrentStretchLength = realLen - TotalLength;
            if (CurrentStretchLength < 0f)
            {
                CurrentStretchLength = 0f;
            }

            SetLimitState(CurrentStretchLength > lengthLimitTolerance);

            if (CurrentStretchLength > 1)
            {
                Log.Error($"水电费 realLen={realLen} TotalLength={TotalLength}");
            }

            if (!IsBreakCountdownActive)
            {
                LimitStateTime = 0f;
                HasBreakNotificationSent = false;
                return;
            }

            LimitStateTime += Mathf.Max(0f, deltaTime);
            if (HasBreakNotificationSent || LimitStateTime < breakLimitDuration)
            {
                return;
            }

            HasBreakNotificationSent = true;
            NotifyLineBreakRequested();
        }

        /// <summary>
        /// 发出鱼线达到断线条件的消息。
        /// 这里预留给外部订阅，当前不在求解器内部直接执行断线逻辑。
        /// </summary>
        private void NotifyLineBreakRequested()
        {
            OnLineBreakRequested?.Invoke(this);
        }

        private void ResetLimitState()
        {
            CurrentStretchLength = 0f;
            IsAtLimit = false;
            LimitStateTime = 0f;
            HasBreakNotificationSent = false;
        }

        #endregion

        #region 公共接口

        /// <summary>
        /// 获取一个节点
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public FLineLogicNode GetNode(FLineLogicNodeType type)
        {
            foreach (var node in lineNodes)
            {
                if (node.NodeType == type)
                {
                    return node;
                }
            }

            return null;
        }


        public float GetCurrentSegmentLength(int segmentIndex)
        {
            if (segmentIndex >= 0 && segmentIndex < _constraints.Count)
            {
                _constraints[segmentIndex].UpdateCurrentState();
                return _constraints[segmentIndex].currentDistance;
            }

            return -1f;
        }

        public void AddConnectedBody(Rigidbody rb, float maxLength = 1f, float minLength = 0f)
        {
            if (rb == null)
            {
                return;
            }

            FLineLogicNode node = rb.GetComponent<FLineLogicNode>();
            if (!node)
            {
                Debug.LogWarning("AddConnectedBody需要目标刚体上挂有FLineLogicNode");
                return;
            }

            if (!lineNodes.Contains(node))
            {
                if (lineNodes.Count > 0 && lineNodes[lineNodes.Count - 1])
                {
                    lineNodes[lineNodes.Count - 1].SetSegmentLengths(maxLength, minLength);
                }

                node.AttachToCable(this);
                lineNodes.Add(node);
                BuildConstraints();
                enabled = _constraints.Count > 0;
            }
        }

        public void RemoveConnectedBody(Rigidbody rb)
        {
            if (rb == null)
            {
                return;
            }

            for (int i = 0; i < lineNodes.Count; i++)
            {
                if (GetBodyAt(i) == rb)
                {
                    lineNodes.RemoveAt(i);
                    BuildConstraints();
                    enabled = _constraints.Count > 0;
                    break;
                }
            }
        }

        public List<Rigidbody> GetConnectedBodies()
        {
            List<Rigidbody> bodies = new List<Rigidbody>(lineNodes.Count);
            for (int i = 0; i < lineNodes.Count; i++)
            {
                bodies.Add(GetBodyAt(i));
            }

            return bodies;
        }

        public List<FLineLogicNode> GetLineNodes()
        {
            return new List<FLineLogicNode>(lineNodes);
        }

        public bool TryGetAdjacentBodies(FLineLogicNode node, out Rigidbody previousBody, out Rigidbody nextBody)
        {
            previousBody = null;
            nextBody = null;

            if (!node)
            {
                return false;
            }

            int index = lineNodes.IndexOf(node);
            if (index < 0)
            {
                return false;
            }

            if (index > 0 && lineNodes[index - 1])
            {
                previousBody = lineNodes[index - 1].Rigidbody;
            }

            if (index < lineNodes.Count - 1 && lineNodes[index + 1])
            {
                nextBody = lineNodes[index + 1].Rigidbody;
            }

            return previousBody || nextBody;
        }

        public void ApplyForceAtBody(Rigidbody targetBody, Vector3 force, ForceMode mode = ForceMode.Force)
        {
            if (targetBody && ContainsBody(targetBody))
            {
                targetBody.AddForce(force, mode);
            }
        }

        public float GetSegmentMaxLength(int segmentIndex)
        {
            FLineLogicNode node = GetSegmentNode(segmentIndex);
            if (node)
                return node.NextSegmentMaxLength;

            return -1f;
        }

        #endregion

        #region 可视化调试

        void OnDrawGizmos()
        {
            if (!showDebugInfo || lineNodes.Count < 2) return;

            for (int i = 0; i < lineNodes.Count - 1; i++)
            {
                Rigidbody bodyA = GetBodyAt(i);
                Rigidbody bodyB = GetBodyAt(i + 1);
                FLineLogicNode segmentNode = GetSegmentNode(i);

                if (bodyA != null && bodyB != null)
                {
                    float currentDist = Vector3.Distance(bodyA.position, bodyB.position);
                    float maxDist = segmentNode ? segmentNode.NextSegmentMaxLength : 1f;
                    float minDist = segmentNode ? segmentNode.NextSegmentMinLength : 0f;

                    // 颜色：如果正在过渡用橙色，绿色=正常范围，红色=超出最大距离，蓝色=小于最小距离
                    if (IsSegmentTransitioning(i))
                        Gizmos.color = new Color(1f, 0.5f, 0f); // 橙色表示正在过渡
                    else if (currentDist > maxDist)
                        Gizmos.color = Color.red;
                    else if (currentDist < minDist && minDist > 0)
                        Gizmos.color = Color.blue;
                    else
                        Gizmos.color = Color.green;

                    Gizmos.DrawLine(bodyA.position, bodyB.position);

                    Vector3 midPoint = (bodyA.position + bodyB.position) * 0.5f;
                    Gizmos.DrawWireSphere(midPoint, 0.1f);

#if UNITY_EDITOR
                    string info = $"距离:{currentDist:F2}";
                    if (IsSegmentTransitioning(i))
                        info += $"\n过渡中→{GetTargetMaxLength(i):F2}";
                    else
                        info += $" [最大:{maxDist:F2}";
                    info += $"]";
                    UnityEditor.Handles.Label(midPoint, info);
#endif
                }
            }

            Gizmos.color = Color.red;
            for (int i = 0; i < lineNodes.Count; i++)
            {
                Rigidbody body = GetBodyAt(i);
                if (body != null)
                {
                    Gizmos.DrawSphere(body.position, 0.05f);
                }
            }
        }

        #endregion
    }
}