v1.0.0

includes/class-fontdelbosc-combustible-geo.php

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+<?php
+/**
+ * Haversine distance from Font del Bosc.
+ *
+ * @package FontdelboscCombustible
+ */
+
+declare( strict_types=1 );
+
+defined( 'ABSPATH' ) || exit;
+
+/**
+ * Distance calculations against the fixed origin point.
+ */
+final class Fontdelbosc_Combustible_Geo {
+
+	/**
+	 * Reference latitude of Font del Bosc.
+	 */
+	public const ORIGIN_LAT = 41.4819;
+
+	/**
+	 * Reference longitude of Font del Bosc.
+	 */
+	public const ORIGIN_LON = 1.6483;
+
+	/**
+	 * Great-circle distance in km from Font del Bosc to a point.
+	 *
+	 * @param float $lat2 Target latitude.
+	 * @param float $lon2 Target longitude.
+	 */
+	public static function haversine( float $lat2, float $lon2 ): float {
+		$r    = 6371;
+		$dlat = deg2rad( $lat2 - self::ORIGIN_LAT );
+		$dlon = deg2rad( $lon2 - self::ORIGIN_LON );
+		$a    = ( sin( $dlat / 2 ) ** 2 )
+			+ ( cos( deg2rad( self::ORIGIN_LAT ) ) * cos( deg2rad( $lat2 ) ) * ( sin( $dlon / 2 ) ** 2 ) );
+
+		return 2 * $r * asin( sqrt( $a ) );
+	}
+}