package com.moral.util;

import java.text.DecimalFormat;

public class mapUtils {
    /**
     * 获取AB连线与正北方向的角度
     * @param A  A点的经纬度
     * @param B  B点的经纬度
     * @return  AB连线与正北方向的角度（0~360）
     */
    /** 180° **/
    private static final DecimalFormat df = new DecimalFormat("0.000000");
    //地球平均半径
    private static final double EARTH_RADIUS = 6378137;
    //把经纬度转为度（°）
    private static double rad(double d){
        return d * Math.PI / 180.0;
    }

    public static double getDistance(double lng1, double lat1, double lng2, double lat2){
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(
                Math.sqrt(
                        Math.pow(Math.sin(a/2),2)
                                + Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)
                )
        );
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000) / 10000;
        return s;
    }


    public  static double getAngle(MyLatLng A,MyLatLng B){
        double dx=(B.m_RadLo-A.m_RadLo)*A.Ed;
        double dy=(B.m_RadLa-A.m_RadLa)*A.Ec;
        double angle=0.0;
        angle=Math.atan(Math.abs(dx/dy))*180./Math.PI;
        double dLo=B.m_Longitude-A.m_Longitude;
        double dLa=B.m_Latitude-A.m_Latitude;
        if(dLo>0&&dLa<=0){
            angle=(90.-angle)+90;
        }
        else if(dLo<=0&&dLa<0){
            angle=angle+180.;
        }else if(dLo<0&&dLa>=0){
            angle= (90.-angle)+270;
        }
        return angle;
    }
    public static String[] calLocationByDistanceAndLocationAndDirection(double angle, double startLong,double startLat, double distance){
        String[] result = new String[2];
        //将距离转换成经度的计算公式
        double δ = distance/EARTH_RADIUS;
        // 转换为radian，否则结果会不正确
        angle = Math.toRadians(angle);
        startLong = Math.toRadians(startLong);
        startLat = Math.toRadians(startLat);
        double lat = Math.asin(Math.sin(startLat)*Math.cos(δ)+Math.cos(startLat)*Math.sin(δ)*Math.cos(angle));
        double lon = startLong + Math.atan2(Math.sin(angle)*Math.sin(δ)*Math.cos(startLat),Math.cos(δ)-Math.sin(startLat)*Math.sin(lat));
        // 转为正常的10进制经纬度
        lon = Math.toDegrees(lon);
        lat = Math.toDegrees(lat);
        result[0] = df.format(lon);
        result[1] = df.format(lat);
        return result;
    }

}