using UnityEngine;

[DisallowMultipleComponent]
[RequireComponent(typeof(Rigidbody))]
[RequireComponent(typeof(CapsuleCollider))]
public class BobberBuoyancyStable : MonoBehaviour
{
    [Header("Water Physics")] public float waterLevel = 0f;

    [Tooltip("浮力倍数 (建议1.0-1.5)")] public float buoyancyMultiplier = 1.2f;

    [Tooltip("阻尼系数")] public float dampingFactor = 0.3f;

    [Header("Debug")] public bool showDebugInfo = true;

    private Rigidbody rb;
    private CapsuleCollider capsule;

    void Awake()
    {
        rb = GetComponent<Rigidbody>();
        capsule = GetComponent<CapsuleCollider>();
        rb.useGravity = true;

        if (showDebugInfo)
        {
            Debug.Log($"Initial mass: {rb.mass}kg, Volume: {CalculateTotalVolume():F6}m³");
        }
    }

    void FixedUpdate()
    {
        ApplyCorrectedBuoyancy();
    }

    void ApplyCorrectedBuoyancy()
    {
        // 使用本地坐标系计算边界，支持任意旋转角度
        Vector3 localUp = transform.up; // 获取物体的本地向上向量
        Vector3 localDown = -localUp;

        // 正确获取世界坐标下的胶囊体边界（考虑旋转）
        Vector3 worldBottom = transform.TransformPoint(capsule.center +
                                                       localDown * (capsule.height * 0.5f));
        Vector3 worldTop = transform.TransformPoint(capsule.center +
                                                    localUp * (capsule.height * 0.5f));

        float bottomY = worldBottom.y;
        float topY = worldTop.y;
        float totalHeight = Mathf.Abs(topY - bottomY); // 使用绝对值确保高度为正

        // 计算浸入深度
        float immersionDepth = Mathf.Max(0, waterLevel - bottomY);

        if (immersionDepth <= 0) return;

        // 计算浸入比例
        float immersionRatio = Mathf.Clamp01(immersionDepth / totalHeight);

        // 计算总重量
        float weight = rb.mass * 9.81f;

        // 计算排水体积（关键修正）
        float totalVolume = CalculateTotalVolume();
        float displacedVolume = totalVolume * immersionRatio;
        if (displacedVolume < 0)
        {
            Debug.LogError($"入水深度异常={displacedVolume}");
            displacedVolume = 0;
        }

        // 计算浮力
        float buoyantForce = displacedVolume * 1000f * 9.81f * buoyancyMultiplier;

        // 净浮力 = 浮力 - 重量
        float netForce = buoyantForce - weight;

        // 浮力作用点
        float buoyancyY = bottomY + (immersionDepth * 0.5f);
        Vector3 buoyancyPoint = new Vector3(transform.position.x, buoyancyY, transform.position.z);

        // 应用力
        rb.AddForceAtPosition(Vector3.up * netForce, buoyancyPoint, ForceMode.Force);

        // 添加阻尼稳定浮动
        Vector3 velocity = rb.GetPointVelocity(buoyancyPoint);
        Vector3 dampingForce = -velocity * dampingFactor * immersionRatio;
        rb.AddForceAtPosition(dampingForce, buoyancyPoint, ForceMode.Force);

        if (showDebugInfo)
        {
            Debug.Log($"Immersion: {immersionRatio:P1}, " +
                      $"DispVol: {displacedVolume:F6}m³, " +
                      $"Buoyancy: {buoyantForce:F2}N, " +
                      $"NetForce: {netForce:F2}N");
        }
    }

    float CalculateTotalVolume()
    {
        // 胶囊体总体积 = 圆柱体 + 两个半球
        float radius = capsule.radius;
        float cylinderHeight = capsule.height - (2 * radius); // 减去两端球冠

        // 圆柱体积
        float cylinderVolume = Mathf.PI * radius * radius * cylinderHeight;

        // 两个半球 = 一个完整球体
        float sphereVolume = (4f / 3f) * Mathf.PI * Mathf.Pow(radius, 3);

        float totalVolume = cylinderVolume + sphereVolume;

        return totalVolume;
    }

    void OnDrawGizmos()
    {
        if (capsule == null) return;

        // 显示胶囊体边界
        Vector3 worldBottom = transform.TransformPoint(capsule.center -
                                                       Vector3.up * (capsule.height * 0.5f));
        Vector3 worldTop = transform.TransformPoint(capsule.center +
                                                    Vector3.up * (capsule.height * 0.5f));

        Gizmos.color = Color.white;
        Gizmos.DrawLine(worldBottom, worldTop);

        // 显示浸入部分
        float immersion = Mathf.Max(0, waterLevel - worldBottom.y);
        if (immersion > 0)
        {
            Gizmos.color = new Color(0, 0, 1, 0.3f);
            float submergedHeight = Mathf.Min(immersion, capsule.height);
            Vector3 submergedCenter = new Vector3(
                transform.position.x,
                worldBottom.y + submergedHeight * 0.5f,
                transform.position.z
            );
            Gizmos.DrawSphere(submergedCenter, capsule.radius);
        }

        // 显示水面
        Gizmos.color = Color.blue;
        Vector3 waterPos = new Vector3(transform.position.x, waterLevel, transform.position.z);
        Gizmos.DrawWireSphere(waterPos, 0.05f);
    }
}