Fix Right Hand Rule Geo JSON clockwise

PolygonFixer.php

<?php
declare(strict_types=1);

namespace ArrayIterator;


/**
 * Class PolygonFixer
 * @package ArrayIterator
 * Like a Geo Jeon right-hand-rule Fixer based on {@link https://mapster.me/right-hand-rule-geojson-fixer/}
 * use http://geojsonlint.com/ to lint geo json
 */
class PolygonFixer
{
    /**
     * @param array $source
     * @param bool $outer
     * @return array
     */
    public function rewind(array $source, $outer = true)
    {
        $type = is_array($source) && isset($source['type']) ? $source['type'] : null;
        switch ($type) {
            case 'FeatureCollection':
                $source['features'] = array_map(function ($b) use ($outer) {
                    return $this->rewind($b, $outer);
                }, $source['features']);
                return $source;
            case 'Feature':
                $source['geometry'] = $this->rewind($source['geometry'], $outer);
                return $source;
            case 'Polygon':
            case 'MultiPolygon':
                return $this->correct($source, $outer);
            default:
                return $source;
        }
    }

    /**
     * @param array $source
     * @param bool $dir
     * @return array
     */
    protected function wind($source, bool $dir)
    {
        if (!is_array($source)) {
            return $source;
        }

        return $this->cw($source) === $dir ? $source : array_reverse($source);
    }

    /**
     * @param array $source
     * @param bool $outer
     * @return array
     */
    protected function correctRings($source, bool $outer)
    {
        if (!is_array($source)) {
            return $source;
        }

        $outer = !!$outer;
        if (!isset($source[0])) {
            return $source;
        }
        $source[0] = $this->wind($source[0], !$outer);
        for ($i = 1; $i < count($source); $i++) {
            $source[$i] = $this->wind($source[$i], $outer);
        }
        return $source;
    }

    /**
     * @param array $source
     * @param bool $outer
     * @return array
     */
    protected function correct($source, bool $outer)
    {
        if (!is_array($source) || !isset($source['type'])) {
            return $source;
        }
        if ($source['type'] === 'Polygon') {
            $source['coordinates'] = $this->correctRings($source['coordinates'], $outer);
        } else if ($source['type'] === 'MultiPolygon') {
            $source['coordinates'] = array_map(function ($a) use ($outer) {
                return $this->correctRings($a, $outer);
            }, $source['coordinates']);
        }

        return $source;
    }

    /**
     * @param array $source
     * @return bool
     */
    protected function cw($source) : bool
    {
        return $this->ringArea($source) >= 0;
    }

    /**
     * @param array $source
     * @return float|int|null
     */
    protected function geometry($source)
    {
        if (!is_array($source) || !isset($source['type'])) {
            return null;
        }
        if ($source['type'] === 'Polygon') {
            return $this->polygonArea($source['coordinates']);
        } elseif ($source['type'] === 'MultiPolygon') {
            $area = 0;
            for ($i = 0; $i < count($source['coordinates']); $i++) {
                $area += $this->polygonArea($source['coordinates'][$i]);
            }
            return $area;
        } else {
            return null;
        }
    }

    /**
     * @param array $coords
     * @return float|int
     */
    protected function polygonArea($coords)
    {
        $area = 0;
        if (!is_array($coords)) {
            return $area;
        }

        if ($coords && count($coords) > 0) {
            $area += abs($this->ringArea($coords[0]));
            for ($i = 1; $i < count($coords); $i++) {
                $area -= abs($this->ringArea($coords[$i]));
            }
        }
        return $area;
    }

    /**
     * @param array $coords
     * @return float|int
     */
    protected function ringArea($coords)
    {
        $area = 0;
        if (!is_array($coords)) {
            return $area;
        }
        if (count($coords) > 2) {
            $p1 = null;
            $p2 = null;
            for ($i = 0; $i < count($coords) - 1; $i++) {
                $p1 = $coords[$i];
                $p2 = $coords[$i + 1];
                $area += $this->rad($p2[0] - $p1[0]) * (2 + sin($this->rad($p1[1])) + sin($this->rad($p2[1])));
            }

            $area = $area * 6378137 * 6378137 / 2;
        }

        return $area;
    }

    /**
     * @param float $number
     * @return float|int
     */
    protected function rad($number)
    {
        if (!is_numeric($number)) {
            return 0;
        }
        return $number * pi() / 180;
    }
}