<?php
/**
 * Extent parameter parsing.
 *
 * @package Mapsemble
 */

namespace Mapsemble\Geo;

/**
 * Parses the widget's `extent` query parameter.
 *
 * Port of the Drupal module's parseBbox(): accepts a WKT
 * `POLYGON((lon lat, …))` or a `minLon,minLat,maxLon,maxLat` csv.
 */
final class BoundingBox {

	/**
	 * Parses an extent string into a bounding box.
	 *
	 * @param string $extent Raw extent parameter.
	 * @return array{minLon: float, minLat: float, maxLon: float, maxLat: float}|null
	 *   The box, or null when the extent is absent or unparseable
	 *   (callers then apply no spatial constraint).
	 */
	public static function parse( string $extent ): ?array {
		if ( '' === $extent ) {
			return null;
		}
		if ( preg_match( '/POLYGON\(\((.+)\)\)/i', $extent, $matches ) ) {
			$lons = array();
			$lats = array();
			foreach ( explode( ',', $matches[1] ) as $pair ) {
				$tokens = (array) preg_split( '/\s+/', trim( $pair ) );
				// Every pair must be two numeric tokens. Junk must not become
				// a constraint: floatval('abc') would be 0.0, collapsing
				// garbage to a box at Null Island that filters out every real
				// feature, so a single bad pair refuses the whole extent —
				// just as the csv branch refuses non-numeric parts.
				if ( count( $tokens ) < 2 || ! is_numeric( $tokens[0] ) || ! is_numeric( $tokens[1] ) ) {
					return null;
				}
				$lons[] = (float) $tokens[0];
				$lats[] = (float) $tokens[1];
			}
			return array(
				'minLon' => (float) min( $lons ),
				'maxLon' => (float) max( $lons ),
				'minLat' => (float) min( $lats ),
				'maxLat' => (float) max( $lats ),
			);
		}
		$parts = explode( ',', $extent );
		if ( 4 === count( $parts ) && 4 === count( array_filter( $parts, 'is_numeric' ) ) ) {
			return array(
				'minLon' => (float) $parts[0],
				'minLat' => (float) $parts[1],
				'maxLon' => (float) $parts[2],
				'maxLat' => (float) $parts[3],
			);
		}
		return null;
	}
}