geohash.php

<?php
namespace Bitrix\Main\Text;
 
 
use Bitrix\Main\SystemException;
 
class GeoHash
{
    const MAX_LENGTH = 15;
 
    protected static $latitudeInterval = array(-90.0, 90.0);
    protected static $longitudeInterval = array(-180.0, 180.0);
    protected static $bits = array(16, 8, 4, 2, 1);
    protected static $base32Chars = array(
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'b', 'c', 'd', 'e', 'f', 'g',
        'h', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
    );
 
    public static function encode(array $coordinate, $length = self::MAX_LENGTH)
    {
        $latitudeInterval = static::$latitudeInterval;
        $longitudeInterval = static::$longitudeInterval;
 
        $isEven = true;
        $bit = 0;
        $charIndex = 0;
 
        $geohash = '';
 
        while(mb_strlen($geohash) < $length)
        {
            if($isEven)
            {
                $middle = ($longitudeInterval[0] + $longitudeInterval[1]) / 2;
                if($coordinate[1] > $middle)
                {
                    $charIndex |= static::$bits[$bit];
                    $longitudeInterval[0] = $middle;
                }
                else
                {
                    $longitudeInterval[1] = $middle;
                }
            }
            else
            {
                $middle = ($latitudeInterval[0] + $latitudeInterval[1]) / 2;
                if($coordinate[0] > $middle)
                {
                    $charIndex |= static::$bits[$bit];
                    $latitudeInterval[0] = $middle;
                }
                else
                {
                    $latitudeInterval[1] = $middle;
                }
            }
            if($bit < 4)
            {
                $bit++;
            }
            else
            {
                $geohash .= static::$base32Chars[$charIndex];
                $bit = 0;
                $charIndex = 0;
            }
            $isEven = $isEven ? false : true;
        }
 
        return $geohash;
    }
 
    public static function decode($geohash)
    {
        $base32DecodeMap = array_flip(static::$base32Chars);
 
        $latitudeInterval = static::$latitudeInterval;
        $longitudeInterval = static::$longitudeInterval;
 
        $isEven = true;
        $geohashLength = mb_strlen($geohash);
        for($i = 0; $i < $geohashLength; $i++)
        {
            if(!isset($base32DecodeMap[$geohash[$i]]))
            {
                throw new SystemException('This geo hash is invalid.');
            }
            $currentChar = $base32DecodeMap[$geohash[$i]];
            $bitsTotal = count(static::$bits);
            for($j = 0; $j < $bitsTotal; $j++)
            {
                $mask = static::$bits[$j];
                if($isEven)
                {
                    if(($currentChar & $mask) !== 0)
                    {
                        $longitudeInterval[0] = ($longitudeInterval[0] + $longitudeInterval[1]) / 2;
                    }
                    else
                    {
                        $longitudeInterval[1] = ($longitudeInterval[0] + $longitudeInterval[1]) / 2;
                    }
                }
                else
                {
                    if(($currentChar & $mask) !== 0)
                    {
                        $latitudeInterval[0] = ($latitudeInterval[0] + $latitudeInterval[1]) / 2;
                    }
                    else
                    {
                        $latitudeInterval[1] = ($latitudeInterval[0] + $latitudeInterval[1]) / 2;
                    }
                }
                $isEven = $isEven ? false : true;
            }
        }
 
        return array(
            ($latitudeInterval[0] + $latitudeInterval[1]) / 2,
            ($longitudeInterval[0] + $longitudeInterval[1]) / 2
        );
    }
}