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

namespace YKMoon.Math
{
    /// <summary>
    /// 星球相关
    /// </summary>
    public partial class YKMath
    {
        /// <summary>
        /// 纬度类型
        /// </summary>
        public enum LatitudeType
        {
            S,
            N
        }
        /// <summary>
        /// 经度类型
        /// </summary>
        public enum LogitudeType
        {
            E,
            W,
        }
        public class CoordinateInfo
        {
            /// <summary>
            /// 纬度，弧度
            /// </summary>
            public float latitudeValue;
            /// <summary>
            /// 纬度类型，北纬南纬
            /// </summary>
            public LatitudeType latitude {
                get {
                    if (latitudeValue < 0) {
                        return LatitudeType.S;
                    } else {
                        return LatitudeType.N;
                    }
                }
            }
            /// <summary>
            /// 经度，弧度
            /// </summary>
            public float logitudeValue;
            /// <summary>
            /// 经度类型，东经西经
            /// </summary>
            public LogitudeType logitude {
                get {
                    if (logitudeValue<0) {
                        return LogitudeType.W;
                    } else {
                        return LogitudeType.E;
                    }
                }
            }
        }

        /// <summary>
        /// 计算经纬度，减少GC用ref
        /// </summary>
        /// <param name="result">经纬度信息</param>
        /// <param name="planetTransform">星球中心</param>
        /// <param name="surfacePos">星球表面点</param>
        public static void CalculateEarthCoordinate(ref CoordinateInfo result, Transform planetTransform, Vector3 surfacePos)
        {
            float radius = Vector3.Distance(planetTransform.position, surfacePos);
            var delta = planetTransform.InverseTransformPoint(surfacePos);
            result.latitudeValue = Mathf.Asin(delta.y / radius) * Mathf.Rad2Deg;
            result.logitudeValue = Mathf.Atan2(delta.z, delta.x) * Mathf.Rad2Deg;
        }
        /// <summary>
        /// 计算经纬度
        /// </summary>
        /// <param name="planetTransform">星球中心</param>
        /// <param name="surfacePos">星球表面点</param>
        /// <returns>经纬度信息</returns>
        public static CoordinateInfo CalculateEarthCoordinate(Transform planetTransform, Vector3 surfacePos)
        {
            CoordinateInfo result = new CoordinateInfo();
            CalculateEarthCoordinate(ref result, planetTransform, surfacePos);
            return result;
        }

        /// <summary>
        /// 经纬度转球面坐标
        /// </summary>
        /// <param name="radius">半径</param>
        /// <param name="latitude">纬度</param>
        /// <param name="logitude">经度</param>
        /// <returns>球面坐标</returns>
        public static Vector3 GetSurfacePosInEarth(float radius, float latitude, float logitude)
        {
            Vector3 delta = Vector3.zero;
            delta.y = Mathf.Sin(latitude / Mathf.Rad2Deg) * radius;
            var angle = logitude / Mathf.Rad2Deg;
            delta.z = Mathf.Sin(angle) * radius;
            delta.x = Mathf.Cos(angle) * radius;
            return delta;
        }

    }
}