#include "maidenhead.h"
#include <math.h>
#include <stdio.h>
#include <string.h>

/*
This is from https://github.com/sp6q/maidenhead

MIT License

Copyright (c) 2021 Mateusz Salwach

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

#ifdef __cplusplus
extern "C"
{
#endif
    char letterize(int x)
    {
        return (char)x + 65;
    }

    char *get_mh(double lat, double lon, int size)
    {
        static char locator[11];
        double LON_F[] = {20, 2.0, 0.083333, 0.008333, 0.0003472083333333333};
        double LAT_F[] = {10, 1.0, 0.0416665, 0.004166, 0.0001735833333333333};
        int i;
        lon += 180;
        lat += 90;

        if (size <= 0 || size > 10)
            size = 6;
        size /= 2;
        size *= 2;

        for (i = 0; i < size / 2; i++)
        {
            if (i % 2 == 1)
            {
                locator[i * 2] = (char)(lon / LON_F[i] + '0');
                locator[i * 2 + 1] = (char)(lat / LAT_F[i] + '0');
            }
            else
            {
                locator[i * 2] = letterize((int)(lon / LON_F[i]));
                locator[i * 2 + 1] = letterize((int)(lat / LAT_F[i]));
            }
            lon = fmod(lon, LON_F[i]);
            lat = fmod(lat, LAT_F[i]);
        }
        locator[i * 2] = 0;
        return locator;
    }

    char *complete_mh(char *locator)
    {
        static char locator2[11] = "LL55LL55LL";
        int len = strlen(locator);
        if (len >= 10)
            return locator;
        memcpy(locator2, locator, strlen(locator));
        return locator2;
    }

    double mh2lon(char *locator)
    {
        double field, square, subsquare, extsquare, precsquare;
        int len = strlen(locator);
        if (len > 10)
            return 0;
        if (len < 10)
            locator = complete_mh(locator);
        field = (locator[0] - 'A') * 20.0;
        square = (locator[2] - '0') * 2.0;
        subsquare = (locator[4] - 'A') / 12.0;
        extsquare = (locator[6] - '0') / 120.0;
        precsquare = (locator[8] - 'A') / 2880.0;
        return field + square + subsquare + extsquare + precsquare - 180;
    }

    double mh2lat(char *locator)
    {
        double field, square, subsquare, extsquare, precsquare;
        int len = strlen(locator);
        if (len > 10)
            return 0;
        if (len < 10)
            locator = complete_mh(locator);
        field = (locator[1] - 'A') * 10.0;
        square = (locator[3] - '0') * 1.0;
        subsquare = (locator[5] - 'A') / 24.0;
        extsquare = (locator[7] - '0') / 240.0;
        precsquare = (locator[9] - 'A') / 5760.0;
        return field + square + subsquare + extsquare + precsquare - 90;
    }
#ifdef __cplusplus
}
#endif