using UnityEngine;
using System.Collections.Generic;

namespace NBF
{
    public class LureTrajectorySimulator : MonoBehaviour
    {
        [Header("基础参数")] public int maxSimulationSteps = 1000;
        public float simulationDuration = 10f;
        public float timeStep = 0.02f;

        [Header("抛投力度")] public float minThrowPower = 15f;
        public float maxThrowPower = 45f;

        [Header("空气阻力参数")] [Tooltip("阻力系数，非流线钓饵建议 0.8~1.2")]
        public float dragCoefficient = 0.2f;

        [Tooltip("迎风面积，0.005m² ≈ 5cm²")] public float lureArea = 0.001f;


        public List<Vector3> CalculateTrajectory(FishingLureCastInput input, Vector3 startPosition,
            Vector3 castDirection)
        {
            List<Vector3> trajectory = new List<Vector3>();

            Vector3 position = startPosition;
            Vector3 direction = castDirection.normalized;
            float throwPower = Mathf.Lerp(minThrowPower, maxThrowPower, input.power);
            Vector3 velocity = direction * throwPower;

            float lureMass = input.lureWeight / 1000f; // 转 kg
            Vector3 windDir = input.windDirection.normalized;
            float windStrength = input.windStrength;

            float currentTime = 0f;
            int steps = 0;

            while (currentTime < simulationDuration && steps < maxSimulationSteps)
            {
                if (position.y <= 0f) break;

                // 模拟风力逐渐生效
                float windInfluenceFactor = Mathf.Clamp01(currentTime / 1.5f); // 1.5秒内增长
                Vector3 windVelocity = windDir * windStrength * windInfluenceFactor;

                // 真实空气阻力模型
                Vector3 relVelocity = velocity - windVelocity;

                // 空气阻力
                float dragMag = 0.5f * PhysicsHelper.AirDensity *
                                relVelocity.sqrMagnitude *
                                dragCoefficient * lureArea;


                // --- 钓线空气阻力模拟 ---
                // 假设飞行中展开的线长度近似为当前位置的XZ平面长度
                float lineLength = Vector3.Distance(new Vector3(position.x, 0, position.z),
                    new Vector3(startPosition.x, 0, startPosition.z));
                float lineRadius = input.lineDiameter / 2000f; // mm转m再除以2得到半径

                // 钓线的迎风面积估算：长度 * 直径
                float lineArea = lineLength * (lineRadius * 2f); // 近似为圆柱体侧面积的一部分

                // 简化模型：线的附加空气阻力方向与当前速度方向相反
                float lineDragMag = 0.5f * PhysicsHelper.AirDensity * velocity.sqrMagnitude * dragCoefficient *
                                    lineArea;
                Vector3 lineDragForce = -velocity.normalized * lineDragMag;


                Vector3 dragForce = -relVelocity.normalized * dragMag;

                // 合力 = 重力 + 空气阻力
                // Vector3 acceleration = (Physics.gravity + dragForce / lureMass);
                Vector3 totalForce = dragForce + lineDragForce;
                // 合力 = 重力 + 空气阻力 + 线阻力
                Vector3 acceleration = (Physics.gravity + totalForce / lureMass);


                velocity += acceleration * timeStep;
                position += velocity * timeStep;

                trajectory.Add(position);
                currentTime += timeStep;
                steps++;
            }

            return trajectory;
        }


        // 示例调用
        private List<Vector3> _trajectory;

        private int _windIndex;

        public List<Vector3> Test(Transform cameraTransform)
        {
            Vector3[] directions =
            {
                Vector3.forward,
                Vector3.back,
                Vector3.right,
                Vector3.left,
                (Vector3.forward + Vector3.right).normalized,
                (Vector3.forward + Vector3.left).normalized,
                (Vector3.back + Vector3.right).normalized,
                (Vector3.back + Vector3.left).normalized
            };

            FishingLureCastInput baseInput = new FishingLureCastInput
            {
                power = 1f,
                lureWeight = 2.2f,
                windStrength = 0f, // 风力大小
                lineDiameter = 0.14f
            };


            Vector3 startPos = cameraTransform.position;
            Vector3 throwDir = cameraTransform.forward.normalized;

            baseInput.windDirection = directions[_windIndex];
            _trajectory = CalculateTrajectory(baseInput, startPos, throwDir);
            _trajectory = SimplifyTrajectoryRDP(_trajectory, 0.1f);
            _windIndex++;
            if (_windIndex >= directions.Length)
            {
                _windIndex = 0;
            }

            var length = CalculateTrajectoryLength(_trajectory);
            var distance = CalculateHorizontalDistance(_trajectory);
            Debug.LogError($"轨迹点位数={_trajectory.Count} length={length} distance={distance}");
            SceneSettings.Instance.LineRenderer.startWidth = 0.1f;
            SceneSettings.Instance.LineRenderer.endWidth = 0.1f;
            SceneSettings.Instance.LineRenderer.positionCount = _trajectory.Count;
            SceneSettings.Instance.LineRenderer.useWorldSpace = true;
            SceneSettings.Instance.LineRenderer.SetPositions(_trajectory.ToArray());
            return _trajectory;
        }

        /// <summary>
        /// 计算轨迹总长度（线的实际长度）
        /// </summary>
        public float CalculateTrajectoryLength(List<Vector3> trajectory)
        {
            if (trajectory == null || trajectory.Count < 2)
                return 0f;

            float totalLength = 0f;
            for (int i = 1; i < trajectory.Count; i++)
            {
                totalLength += Vector3.Distance(trajectory[i - 1], trajectory[i]);
            }

            return totalLength;
        }

        /// <summary>
        /// 计算水平距离（XZ平面上的直线距离）
        /// </summary>
        public float CalculateHorizontalDistance(List<Vector3> trajectory)
        {
            if (trajectory == null || trajectory.Count == 0)
                return 0f;

            Vector3 startPoint = trajectory[0];
            Vector3 endPoint = trajectory[trajectory.Count - 1];

            // 将Y坐标设为相同（地面高度）
            startPoint.y = 0;
            endPoint.y = 0;

            return Vector3.Distance(startPoint, endPoint);
        }

        private void OnDrawGizmos()
        {
            if (_trajectory == null) return;

            Gizmos.color = Color.cyan;
            for (int i = 0; i < _trajectory.Count - 1; i++)
            {
                Gizmos.DrawLine(_trajectory[i], _trajectory[i + 1]);
            }

            if (_trajectory.Count > 0)
            {
                Gizmos.color = Color.green;
                Gizmos.DrawSphere(_trajectory[0], 0.1f);

                Gizmos.color = Color.red;
                Gizmos.DrawSphere(_trajectory[_trajectory.Count - 1], 0.1f);

                for (int i = 1; i < _trajectory.Count; i += 10)
                {
                    Gizmos.color = Color.Lerp(Color.green, Color.red, i / (float)_trajectory.Count);
                    Gizmos.DrawSphere(_trajectory[i], 0.05f);
                }
            }
        }


        public static List<Vector3> SimplifyTrajectoryRDP(List<Vector3> points, float tolerance)
        {
            if (points == null || points.Count < 3)
                return new List<Vector3>(points);

            List<Vector3> result = new List<Vector3>();
            SimplifySection(points, 0, points.Count - 1, tolerance, result);
            result.Add(points[points.Count - 1]);
            return result;
        }

        private static void SimplifySection(List<Vector3> points, int start, int end, float tolerance,
            List<Vector3> result)
        {
            if (end <= start + 1)
                return;

            float maxDistance = -1f;
            int index = -1;
            Vector3 startPoint = points[start];
            Vector3 endPoint = points[end];

            for (int i = start + 1; i < end; i++)
            {
                float distance = PerpendicularDistance(points[i], startPoint, endPoint);
                if (distance > maxDistance)
                {
                    maxDistance = distance;
                    index = i;
                }
            }

            if (maxDistance > tolerance)
            {
                SimplifySection(points, start, index, tolerance, result);
                result.Add(points[index]);
                SimplifySection(points, index, end, tolerance, result);
            }
        }

        private static float PerpendicularDistance(Vector3 point, Vector3 lineStart, Vector3 lineEnd)
        {
            if (lineStart == lineEnd) return Vector3.Distance(point, lineStart);
            Vector3 projected = Vector3.Project(point - lineStart, lineEnd - lineStart);
            Vector3 closest = lineStart + projected;
            return Vector3.Distance(point, closest);
        }
    }

    public static class PhysicsHelper
    {
        public const float AirDensity = 1.225f;
    }
}