<?php
/**
 * WordPress major version helpers.
 *
 * @package Brachmelder
 */

namespace Brachmelder\Check;

defined( 'ABSPATH' ) || exit;

/**
 * Works out the most recent WordPress major versions (x.y).
 */
final class WpVersions {

	/**
	 * Reduces a version like "6.8.1" to its major version "6.8".
	 *
	 * @param string $version Version string.
	 * @return string Empty string if not parseable.
	 */
	public static function major( string $version ): string {
		if ( ! preg_match( '/^(\d+)\.(\d+)/', trim( $version ), $m ) ) {
			return '';
		}
		return (int) $m[1] . '.' . (int) $m[2];
	}

	/**
	 * Returns the latest $count major versions, newest first.
	 *
	 * WordPress counts x.0 to x.9, then continues with (x+1).0.
	 *
	 * @param string $latest Latest WordPress version.
	 * @param int    $count  Number of majors.
	 * @return string[]
	 */
	public static function last_majors( string $latest, int $count = 3 ): array {
		$major = self::major( $latest );
		if ( '' === $major ) {
			return array();
		}

		list( $x, $y ) = array_map( 'intval', explode( '.', $major ) );
		$majors        = array();
		for ( $i = 0; $i < $count && $x > 0; $i++ ) {
			$majors[] = $x . '.' . $y;
			if ( 0 === $y ) {
				--$x;
				$y = 9;
			} else {
				--$y;
			}
		}
		return $majors;
	}

	/**
	 * Picks the newest of the installed version and the version WordPress offers as update.
	 *
	 * @param string            $installed   Installed WordPress version.
	 * @param object|false|null $update_core Value of the update_core site transient.
	 * @return string
	 */
	public static function latest_known( string $installed, $update_core ): string {
		$latest = $installed;
		if ( is_object( $update_core ) && ! empty( $update_core->updates ) && is_array( $update_core->updates ) ) {
			foreach ( $update_core->updates as $offer ) {
				if ( is_object( $offer ) && ! empty( $offer->current ) && version_compare( (string) $offer->current, $latest, '>' ) ) {
					$latest = (string) $offer->current;
				}
			}
		}
		return $latest;
	}
}