Cobak78\GeoHash\GeoHash

Complexity

Total Complexity

11

Size/Duplication

Total Lines	95
Duplicated Lines	0 %

Coupling/Cohesion

Components	0
Dependencies	0

Test Coverage

Coverage

93.94%

Importance

Changes

0

3 Methods

Rating	Name	Duplication	Size	Complexity
B	distance()	0	24	5
B	getGeoHashPrecision()	0	24	2
B	getPrecisionFromArea()	0	26	4

<?php

namespace Cobak78\GeoHash;

/**
 * Class GeoHash
 * @package Cobak78\GeoHash
 */
class GeoHash
{
    /**
     * @param  float  $lat1
     * @param  float  $lon1
     * @param  float  $lat2
     * @param  float  $lon2
     * @param  string $unit
     * @return float
     */
    public function distance(
        float $lat1,
        float $lon1,
        float $lat2,
        float $lon2,
        string $unit = 'K'
    ) {
        $theta = $lon1 - $lon2;
        $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
        $dist = acos($dist);
        $dist = rad2deg($dist);
        $miles = $dist * 60 * 1.1515;

        switch (strtoupper($unit)) {
            case "K":
            case "KM":
                return ($miles * 1.609344);
            case "MN":
            case "N":
                return ($miles * 0.8684);
            default:
                return $miles;
        }
    }

    /**
     * geoBoundBox: [ top_left => [ lat => x, lon => y ], bottom_right => [ lat => x, lon => y ]
     *
     * @param  array      $geoBoundBox
     * @param  int        $squares
     * @return mixed
     * @throws \Exception
     */
    public function getGeoHashPrecision(array $geoBoundBox, int $squares)
    {
        $remainder = $squares % 2;
        $xQuotient = $squares / 2;
        $yQuotient = $xQuotient / 2;

        if (0 !== $remainder) {
            throw new \InvalidArgumentException('geoHash divisions must be multiple of 2');
        }

        // get x distance
        $xDist = $this->distance($geoBoundBox['top_left']['lat'], $geoBoundBox['top_left']['lon'], $geoBoundBox['bottom_right']['lat'], $geoBoundBox['top_left']['lon']);
        $xDist = $xDist * 1000;
        // get y distance
        $yDist = $this->distance($geoBoundBox['top_left']['lat'], $geoBoundBox['top_left']['lon'], $geoBoundBox['top_left']['lat'], $geoBoundBox['bottom_right']['lon']);
        $yDist = $yDist * 1000;

        // geohash distances
        $xGeohashDist = $xDist / $xQuotient;
        $yGeohashDist = $yDist / $yQuotient;

        return $this->getPrecisionFromArea($xGeohashDist, $yGeohashDist);

    }

    private function getPrecisionFromArea($width, $height)
    {
        // return
        $precisionMap = [
            1 => [5009400, 4992000.6],
            2 => [1252300, 624100],
            3 => [156500, 156000],
            4 => [39100, 19500],
            5 => [4900, 4900],
            6 => [1200, 609.4],
            7 => [152.9, 152.4],
            8 => [38.2, 19],
            9 => [4.8, 4.8],
            10 => [1.2, 0.595],
            11 => [0.14, 0.149],
            12 => [0.037, 0.019]
        ];

        foreach ($precisionMap as $key => $value) {
            if ($width > $value[0] || $height > $value[1]) {
                return $key;
            }
        }

        return 12;
    }
}