BoundingBox.php

<?php

/**
 * Class BoundingBox
 */
class BoundingBox {

	/**
	 * @var float $lat
	 * @var float $lon
	 * @var int $radius
	 */
	protected $lat, $lon, $radius;

	const EARTH_RADIUS = 6371;

	/**
	 * BoundingBox constructor.
	 *
	 * @param float $lat
	 * @param float $lon
	 * @param int $radius
	 */
	public function __construct( float $lat, float $lon, int $radius ) {
		$this->lat    = $lat;
		$this->lon    = $lon;
		$this->radius = $radius;
	}

	/**
	 * @return array
	 */
	public function getCenter() {
		return [ 'lat' => $this->lat, 'lon' => $this->lon ];
	}

	/**
	 * @return array
	 */
	public function getLatitudes() {
		$latDeg = rad2deg($this->radius / self::EARTH_RADIUS );

		return [
			'min' => $this->lat - $latDeg,
			'max' => $this->lat + $latDeg,
		];
	}

	/**
	 * @return array
	 */
	public function getLongitudes() {
		$lonDeg = rad2deg($this->radius / self::EARTH_RADIUS / cos( deg2rad( $this->lat ) ) );

		return [
			'min' => $this->lon - $lonDeg,
			'max' => $this->lon + $lonDeg,
		];
	}

	/**
	 * Returns true if the value is between the min and max of the coordinates
	 *
	 * @param float $value
	 * @param array $coords
	 *
	 * @return bool
	 */
	protected function filter( float $value, array $coords ) {
		return $value >= $coords['min'] && $value <= $coords['max'];
	}

	/**
	 * Checks if the $coordinate is in the boundary box
	 *
	 * @param float $lat
	 * @param float $lon
	 *
	 * @return bool
	 */
	public function check( float $lat, float $lon ): bool {
		$isLat = $this->filter( $lat, $this->getLatitudes() );
		$islon = $this->filter( $lon, $this->getLongitudes() );

		return $isLat && $islon;
	}

}