using UnityEngine;

/// <summary>
/// 简单水面接口。你可以替换成自己的水系统。
/// </summary>
public interface IWaterSurfaceProvider
{
    float GetWaterHeight(Vector3 worldPos);
    Vector3 GetWaterNormal(Vector3 worldPos);
}

/// <summary>
/// 浮漂控制模式：
/// 1. AirPhysics：空中/未入水，使用刚体物理
/// 2. WaterPresentation：入水后，关闭重力，Y 和旋转由脚本控制
/// </summary>
public enum BobberControlMode
{
    AirPhysics,
    WaterPresentation
}

/// <summary>
/// 漂像事件类型
/// </summary>
public enum BobberBiteType
{
    None,
    Tap, // 轻点
    SlowSink, // 缓沉
    Lift, // 送漂
    BlackDrift // 黑漂/快速拖入
}

[DisallowMultipleComponent]
[RequireComponent(typeof(Rigidbody))]
public class BobberPresentationController : MonoBehaviour
{
    [Header("Water")] [Tooltip("没有水提供器时使用固定水位")]
    public float fallbackWaterLevel = 0f;

    [Tooltip("可选：挂实现了 IWaterSurfaceProvider 的组件")]
    public MonoBehaviour waterProviderBehaviour;

    [Header("Enter Water")] [Tooltip("底部进入水面多少米后切换为漂像控制")]
    public float enterWaterDepth = 0.002f;

    [Tooltip("离开水面多少米后回到空中物理。一般给负值做滞回")] public float exitWaterDepth = -0.01f;

    [Header("Geometry")] [Tooltip("浮漂总高度（米）")]
    public float floatHeight = 0.08f;

    [Tooltip("如果 Pivot 在浮漂底部，这里填 0；如果 Pivot 在模型中心，就填底部相对 Pivot 的本地 Y")]
    public float bottomOffsetLocalY = 0f;

    [Header("Base Float")] [Tooltip("基础吃铅比例，决定静止时有多少在水下")] [Range(0.05f, 0.95f)]
    public float baseSubmergeRatio = 0.28f;

    [Tooltip("Y 轴平滑时间，越小响应越快")] public float ySmoothTime = 0.08f;

    [Tooltip("最大竖直速度限制（用于 SmoothDamp）")] public float maxYSpeed = 2f;

    [Tooltip("静止小死区，减少微抖")] public float yDeadZone = 0.0005f;

    [Header("Surface Motion")] [Tooltip("是否启用轻微水面起伏")]
    public bool enableSurfaceBobbing = true;

    [Tooltip("水面轻微起伏振幅（米）")] public float surfaceBobAmplitude = 0.0015f;

    [Tooltip("水面轻微起伏频率")] public float surfaceBobFrequency = 1.2f;

    [Header("XZ Motion")] [Tooltip("入水后是否锁定 XZ 到入水点附近")]
    public bool lockXZAroundAnchor = true;

    [Tooltip("XZ 跟随平滑时间")] public float xzSmoothTime = 0.15f;

    [Tooltip("水流/拖拽带来的额外平面偏移最大值")] public float maxPlanarOffset = 0.15f;

    [Header("Upright")] [Tooltip("是否始终保持漂大致竖直")]
    public bool keepUpright = true;

    [Tooltip("姿态平滑速度")] public float rotationLerpSpeed = 8f;

    [Tooltip("允许的最大倾斜角度")] public float maxTiltAngle = 18f;

    [Tooltip("平面拖拽对倾斜的影响强度")] public float planarTiltFactor = 120f;

    [Header("Sink By Weight / Tension")] [Tooltip("外部向下拉力映射为下沉量的系数。你可以把钩/铅/线组的等效向下拉力喂进来")]
    public float downForceToSink = 0.0025f;

    [Tooltip("向下拉力下沉的最大附加量")] public float maxExtraSink = 0.08f;

    [Header("Bottom Touch")] [Tooltip("触底时是否启用修正")]
    public bool enableBottomTouchAdjust = true;

    [Tooltip("触底后减少的下沉量（例如铅坠到底，漂会回升一点）")] public float bottomTouchLift = 0.01f;

    [Header("Debug Input")] [Tooltip("调试：按 R 恢复默认")]
    
    public bool debugResetKey = true;
    [Header("Debug Input")] [Tooltip("调试：按 T 触发轻点")]
    public bool debugTapKey = true;

    [Tooltip("调试：按 G 触发缓沉")] public bool debugSlowSinkKey = true;

    [Tooltip("调试：按 H 触发送漂")] public bool debugLiftKey = true;

    [Tooltip("调试：按 B 触发黑漂")] public bool debugBlackDriftKey = true;

    [Header("Debug")] public bool drawDebug = false;

    public BobberControlMode CurrentMode => _mode;

    /// <summary>外部可写：等效向下拉力（不是必须是真实力，作为输入信号即可）</summary>
    public float ExternalDownForce { get; set; }

    /// <summary>外部可写：是否触底</summary>
    public bool IsBottomTouched { get; set; }

    /// <summary>外部可写：额外平面偏移（例如风、水流、拖拽）</summary>
    public Vector2 ExternalPlanarOffset { get; set; }

    private Rigidbody _rb;
    private IWaterSurfaceProvider _waterProvider;
    private BobberControlMode _mode = BobberControlMode.AirPhysics;

    private float _defaultLinearDamping;
    private float _defaultAngularDamping;
    private bool _defaultUseGravity;

    private Vector3 _waterAnchorPos;
    private Vector3 _xzSmoothVelocity;
    private float _ySmoothVelocity;

    private float _biteOffsetY;
    private float _biteOffsetYVelocity;

    private Quaternion _targetRotation;

    // bite event runtime
    private BobberBiteType _activeBiteType = BobberBiteType.None;
    private float _biteTimer;
    private float _biteDuration;
    private float _biteAmplitude;
    private Vector3 _blackDriftDirection;

    private void Awake()
    {
        _rb = GetComponent<Rigidbody>();

        _defaultLinearDamping = _rb.linearDamping;
        _defaultAngularDamping = _rb.angularDamping;
        _defaultUseGravity = _rb.useGravity;

        if (waterProviderBehaviour != null)
            _waterProvider = waterProviderBehaviour as IWaterSurfaceProvider;

        _targetRotation = transform.rotation;
    }

    private void Update()
    {
        HandleDebugKeys();
    }

    private void FixedUpdate()
    {
        float waterY = GetWaterHeight(transform.position);
        Vector3 bottomWorld = GetBottomWorldPosition();
        float submergeDepth = waterY - bottomWorld.y;

        switch (_mode)
        {
            case BobberControlMode.AirPhysics:
                UpdateAirPhysics(submergeDepth);
                break;

            case BobberControlMode.WaterPresentation:
                UpdateWaterPresentation(waterY, submergeDepth);
                break;
        }

        if (drawDebug)
        {
            DrawDebug(waterY);
        }
    }

    #region Main Update

    private void UpdateAirPhysics(float submergeDepth)
    {
        RestoreAirPhysicsState();

        if (submergeDepth > enterWaterDepth)
        {
            EnterWaterPresentationMode();
        }
    }

    private void UpdateWaterPresentation(float waterY, float submergeDepth)
    {
        if (submergeDepth < exitWaterDepth)
        {
            ExitWaterPresentationMode();
            return;
        }

        // 完全关闭刚体干扰
        _rb.useGravity = false;
        _rb.linearVelocity = Vector3.zero;
        _rb.angularVelocity = Vector3.zero;
        _rb.linearDamping = 999f;
        _rb.angularDamping = 999f;

        UpdateBiteAnimation();

        Vector3 pos = transform.position;

        // 1. 算目标 Y
        float targetY = CalculateTargetY(waterY);

        if (Mathf.Abs(pos.y - targetY) < yDeadZone)
        {
            pos.y = targetY;
            _ySmoothVelocity = 0f;
        }
        else
        {
            pos.y = Mathf.SmoothDamp(
                current: pos.y,
                target: targetY,
                currentVelocity: ref _ySmoothVelocity,
                smoothTime: Mathf.Max(0.0001f, ySmoothTime),
                maxSpeed: maxYSpeed,
                deltaTime: Time.fixedDeltaTime
            );
        }

        // 2. 算目标 XZ
        Vector3 targetXZ = CalculateTargetXZ();
        Vector3 planarPos = new Vector3(pos.x, 0f, pos.z);
        Vector3 planarTarget = new Vector3(targetXZ.x, 0f, targetXZ.z);

        planarPos = Vector3.SmoothDamp(
            planarPos,
            planarTarget,
            ref _xzSmoothVelocity,
            Mathf.Max(0.0001f, xzSmoothTime),
            Mathf.Infinity,
            Time.fixedDeltaTime
        );

        pos.x = planarPos.x;
        pos.z = planarPos.z;

        transform.position = pos;

        // 3. 算目标旋转
        UpdateTargetRotation();
        transform.rotation = Quaternion.Slerp(
            transform.rotation,
            _targetRotation,
            1f - Mathf.Exp(-rotationLerpSpeed * Time.fixedDeltaTime)
        );
    }

    #endregion

    #region Mode Switch

    private void EnterWaterPresentationMode()
    {
        _mode = BobberControlMode.WaterPresentation;

        _waterAnchorPos = transform.position;
        _ySmoothVelocity = 0f;
        _xzSmoothVelocity = Vector3.zero;
        _biteOffsetY = 0f;
        _biteOffsetYVelocity = 0f;
        _activeBiteType = BobberBiteType.None;
        _biteTimer = 0f;

        _rb.useGravity = false;
        _rb.linearVelocity = Vector3.zero;
        _rb.angularVelocity = Vector3.zero;
        _rb.linearDamping = 999f;
        _rb.angularDamping = 999f;
    }

    private void ExitWaterPresentationMode()
    {
        _mode = BobberControlMode.AirPhysics;
        RestoreAirPhysicsState();
    }

    private void RestoreAirPhysicsState()
    {
        _rb.useGravity = _defaultUseGravity;
        _rb.linearDamping = _defaultLinearDamping;
        _rb.angularDamping = _defaultAngularDamping;
    }

    #endregion

    #region Target Calculation

    private float CalculateTargetY(float waterY)
    {
        float baseSinkDepth = floatHeight * Mathf.Clamp01(baseSubmergeRatio);

        float sinkByForce = Mathf.Clamp(
            ExternalDownForce * downForceToSink,
            0f,
            maxExtraSink
        );

        float bottomAdjust = 0f;
        if (enableBottomTouchAdjust && IsBottomTouched)
        {
            bottomAdjust -= bottomTouchLift;
        }

        float surfaceBob = 0f;
        if (enableSurfaceBobbing)
        {
            surfaceBob = Mathf.Sin(Time.time * surfaceBobFrequency * Mathf.PI * 2f) * surfaceBobAmplitude;
        }

        // Pivot 对应的目标 Y：
        // target bottom = waterY - sinkDepth
        // pivotY = target bottom - bottomOffsetLocalY + 动画偏移
        float totalSink = baseSinkDepth + sinkByForce + bottomAdjust;
        float targetBottomY = waterY - totalSink;
        float targetPivotY = targetBottomY - bottomOffsetLocalY + surfaceBob + _biteOffsetY;

        return targetPivotY;
    }

    private Vector3 CalculateTargetXZ()
    {
        Vector2 planarOffset = Vector2.ClampMagnitude(ExternalPlanarOffset, maxPlanarOffset);

        Vector3 basePos = lockXZAroundAnchor ? _waterAnchorPos : transform.position;

        // 黑漂时额外平面位移
        if (_activeBiteType == BobberBiteType.BlackDrift)
        {
            float t = Mathf.Clamp01(_biteDuration > 0f ? _biteTimer / _biteDuration : 1f);
            float drift = Mathf.SmoothStep(0f, 1f, t) * 0.08f;
            Vector3 blackDrift = _blackDriftDirection * drift;
            basePos += new Vector3(blackDrift.x, 0f, blackDrift.z);
        }

        return new Vector3(
            basePos.x + planarOffset.x,
            transform.position.y,
            basePos.z + planarOffset.y
        );
    }

    private void UpdateTargetRotation()
    {
        if (!keepUpright)
        {
            _targetRotation = transform.rotation;
            return;
        }

        Vector3 up = Vector3.up;
        Vector3 planar = new Vector3(_xzSmoothVelocity.x, 0f, _xzSmoothVelocity.z);

        float speed = planar.magnitude;
        Vector3 tiltAxis = speed > 1e-5f ? Vector3.Cross(up, planar.normalized) : Vector3.zero;

        float tiltAngle = Mathf.Clamp(speed * planarTiltFactor, 0f, maxTiltAngle);

        Quaternion upright = Quaternion.FromToRotation(transform.up, Vector3.up) * transform.rotation;
        Quaternion tilt = tiltAxis.sqrMagnitude > 1e-6f
            ? Quaternion.AngleAxis(tiltAngle, tiltAxis.normalized)
            : Quaternion.identity;

        _targetRotation = tilt * upright;
    }

    #endregion

    #region Bite Presentation

    /// <summary>
    /// 轻点：快速下顿再回弹
    /// </summary>
    public void PlayTap(float amplitude = 0.008f, float duration = 0.18f)
    {
        StartBite(BobberBiteType.Tap, amplitude, duration);
    }

    /// <summary>
    /// 缓沉：在持续时间内逐渐下沉
    /// </summary>
    public void PlaySlowSink(float amplitude = 0.025f, float duration = 1.2f)
    {
        StartBite(BobberBiteType.SlowSink, amplitude, duration);
    }

    /// <summary>
    /// 送漂：向上抬
    /// </summary>
    public void PlayLift(float amplitude = 0.015f, float duration = 0.6f)
    {
        StartBite(BobberBiteType.Lift, amplitude, duration);
    }

    /// <summary>
    /// 黑漂：快速下沉，并可配合平面拖拽
    /// </summary>
    public void PlayBlackDrift(float amplitude = 0.06f, float duration = 0.8f, Vector3? driftDirection = null)
    {
        StartBite(BobberBiteType.BlackDrift, amplitude, duration);
        _blackDriftDirection = (driftDirection ?? transform.forward).normalized;
    }

    public void StopBite()
    {
        _activeBiteType = BobberBiteType.None;
        _biteTimer = 0f;
        _biteDuration = 0f;
        _biteAmplitude = 0f;
        _biteOffsetY = 0f;
        _biteOffsetYVelocity = 0f;
    }

    private void StartBite(BobberBiteType type, float amplitude, float duration)
    {
        if (_mode != BobberControlMode.WaterPresentation)
            return;

        _activeBiteType = type;
        _biteTimer = 0f;
        _biteDuration = Mathf.Max(0.01f, duration);
        _biteAmplitude = amplitude;
        _biteOffsetYVelocity = 0f;

        if (type == BobberBiteType.BlackDrift && _blackDriftDirection.sqrMagnitude < 1e-6f)
        {
            _blackDriftDirection =
                transform.forward.sqrMagnitude > 1e-6f ? transform.forward.normalized : Vector3.forward;
        }
    }

    private void UpdateBiteAnimation()
    {
        if (_activeBiteType == BobberBiteType.None)
        {
            _biteOffsetY = Mathf.SmoothDamp(_biteOffsetY, 0f, ref _biteOffsetYVelocity, 0.08f, Mathf.Infinity,
                Time.fixedDeltaTime);
            return;
        }

        _biteTimer += Time.fixedDeltaTime;
        float t = Mathf.Clamp01(_biteTimer / _biteDuration);

        float targetOffset = 0f;

        switch (_activeBiteType)
        {
            case BobberBiteType.Tap:
                // 先快速下压，再回弹
                if (t < 0.35f)
                {
                    float k = t / 0.35f;
                    targetOffset = -Mathf.SmoothStep(0f, _biteAmplitude, k);
                }
                else
                {
                    float k = (t - 0.35f) / 0.65f;
                    targetOffset = -Mathf.Lerp(_biteAmplitude, 0f, k);
                }

                break;

            case BobberBiteType.SlowSink:
                targetOffset = -Mathf.SmoothStep(0f, _biteAmplitude, t);
                break;

            case BobberBiteType.Lift:
                targetOffset = Mathf.SmoothStep(0f, _biteAmplitude, t);
                break;

            case BobberBiteType.BlackDrift:
                targetOffset = -Mathf.SmoothStep(0f, _biteAmplitude, t);
                break;
        }

        _biteOffsetY = Mathf.SmoothDamp(
            _biteOffsetY,
            targetOffset,
            ref _biteOffsetYVelocity,
            0.03f,
            Mathf.Infinity,
            Time.fixedDeltaTime
        );

        if (_biteTimer >= _biteDuration)
        {
            if (_activeBiteType == BobberBiteType.SlowSink || _activeBiteType == BobberBiteType.BlackDrift)
            {
                // 这两种默认停留在最终状态，由外部决定何时 StopBite
                return;
            }

            _activeBiteType = BobberBiteType.None;
        }
    }

    #endregion

    #region Utilities

    private float GetWaterHeight(Vector3 worldPos)
    {
        return _waterProvider != null ? _waterProvider.GetWaterHeight(worldPos) : fallbackWaterLevel;
    }

    private Vector3 GetBottomWorldPosition()
    {
        return transform.TransformPoint(new Vector3(0f, bottomOffsetLocalY, 0f));
    }

    private void HandleDebugKeys()
    {
        if (!Application.isPlaying)
            return;

        if (debugResetKey && Input.GetKeyDown(KeyCode.R))
        {
            StopBite();
        }
        
        if (debugTapKey && Input.GetKeyDown(KeyCode.T))
            PlayTap();

        if (debugSlowSinkKey && Input.GetKeyDown(KeyCode.G))
            PlaySlowSink();

        if (debugLiftKey && Input.GetKeyDown(KeyCode.H))
            PlayLift();

        if (debugBlackDriftKey && Input.GetKeyDown(KeyCode.B))
            PlayBlackDrift();
    }

    private void DrawDebug(float waterY)
    {
        Vector3 p = transform.position;
        Vector3 b = GetBottomWorldPosition();

        Debug.DrawLine(
            new Vector3(p.x - 0.05f, waterY, p.z),
            new Vector3(p.x + 0.05f, waterY, p.z),
            Color.cyan
        );

        Debug.DrawLine(b, b + Vector3.up * floatHeight, Color.yellow);

        if (_mode == BobberControlMode.WaterPresentation)
        {
            Vector3 a = _waterAnchorPos;
            Debug.DrawLine(a + Vector3.left * 0.03f, a + Vector3.right * 0.03f, Color.green);
            Debug.DrawLine(a + Vector3.forward * 0.03f, a + Vector3.back * 0.03f, Color.green);
        }
    }

#if UNITY_EDITOR
    private void OnValidate()
    {
        floatHeight = Mathf.Max(0.001f, floatHeight);
        ySmoothTime = Mathf.Max(0.001f, ySmoothTime);
        maxYSpeed = Mathf.Max(0.01f, maxYSpeed);
        xzSmoothTime = Mathf.Max(0.001f, xzSmoothTime);
        rotationLerpSpeed = Mathf.Max(0.01f, rotationLerpSpeed);
        maxTiltAngle = Mathf.Clamp(maxTiltAngle, 0f, 89f);
        maxPlanarOffset = Mathf.Max(0f, maxPlanarOffset);
        downForceToSink = Mathf.Max(0f, downForceToSink);
        maxExtraSink = Mathf.Max(0f, maxExtraSink);
        surfaceBobAmplitude = Mathf.Max(0f, surfaceBobAmplitude);
        surfaceBobFrequency = Mathf.Max(0f, surfaceBobFrequency);
        yDeadZone = Mathf.Max(0f, yDeadZone);
    }
#endif

    #endregion
}