#ifndef COMMON_H
#define COMMON_H

#include <math.h>


//#define RAD(d) ((d)*PI/180.0)
/**
 * @brief EARTH RADIUS unit: 1km
 */
const double EARTH_RADIUS = 6371.004;
const double PI = 3.1415926;

class Common
{
public:

    static double DEGREE(double d)
    {
        return ((d) * 180 / PI);
    }

    static double RADIAN(double d)
    {
        return ((d)*PI/180.0);
    }

    static float Distance(double lat1, double lng1, double lat2, double lng2)
    {
        float s;
        double a,b;
        double radLat1,radLat2,radLng1,radLng2;
        radLat1 = RADIAN(lat1);
        radLat2 = RADIAN(lat2);
        radLng1 = RADIAN(lng1);
        radLng2 = RADIAN(lng2);
        a = radLat1 - radLat2;//radLat1 - radLat2;
        b = radLng1 - radLng2;//RAD(lng1) - RAD(lng2);
        s = 2 * asin(sqrt(pow(sin(a/2),2) + cos(lat1)*cos(lat2)*pow(sin(b/2),2)));
        s = s * EARTH_RADIUS;
       return s;
    }
};




#endif // COMMON_H