<?php
/**
 * Scheduled task (WP-Cron) health.
 *
 * @package Keepwatch
 */

namespace Keepwatch\Checks;

defined( 'ABSPATH' ) || exit;

/**
 * Overdue events mean scheduled posts, e-mails, backups or store tasks are not running on time.
 */
final class CronCheck implements Check {

	public const GRACE_SECONDS    = 900;
	public const CRITICAL_SECONDS = 3600;

	/**
	 * {@inheritDoc}
	 */
	public function group(): string {
		return 'cron';
	}

	/**
	 * {@inheritDoc}
	 */
	public function run(): array {
		return self::evaluate(
			_get_cron_array(),
			time(),
			defined( 'DISABLE_WP_CRON' ) && DISABLE_WP_CRON
		);
	}

	/**
	 * Pure evaluation.
	 *
	 * @param array<int|string, mixed> $cron     _get_cron_array() result (timestamp => hooks).
	 * @param int                      $now      Current time.
	 * @param bool                     $disabled DISABLE_WP_CRON.
	 * @return Result[]
	 */
	public static function evaluate( array $cron, int $now, bool $disabled ): array {
		$overdue = 0;
		$oldest  = 0;
		foreach ( $cron as $timestamp => $hooks ) {
			$timestamp = (int) $timestamp;
			if ( $timestamp > 0 && $timestamp < $now - self::GRACE_SECONDS && is_array( $hooks ) ) {
				foreach ( $hooks as $events ) {
					$overdue += is_array( $events ) ? count( $events ) : 1;
				}
				$oldest = max( $oldest, $now - $timestamp );
			}
		}

		$results = array();

		if ( $overdue > 0 ) {
			$results[] = new Result(
				'cron.overdue',
				$oldest >= self::CRITICAL_SECONDS ? Result::CRITICAL : Result::RECOMMENDED,
				/* translators: %d: number of scheduled tasks */
				sprintf( _n( '%d scheduled task is overdue', '%d scheduled tasks are overdue', $overdue, 'keepwatch' ), $overdue ),
				$disabled
					? __( 'WP-Cron is disabled on this site. Make sure a server cron job calls wp-cron.php regularly.', 'keepwatch' )
					: __( 'WP-Cron runs when someone visits the site. On low-traffic sites, a server cron job keeps tasks on time.', 'keepwatch' )
			);
		} elseif ( $disabled ) {
			$results[] = new Result(
				'cron.disabled',
				Result::GOOD,
				__( 'Scheduled tasks run on time (server cron)', 'keepwatch' ),
				__( 'WP-Cron is disabled and tasks are not falling behind, so a server cron job appears to be working.', 'keepwatch' )
			);
		} else {
			$results[] = new Result( 'cron.overdue', Result::GOOD, __( 'Scheduled tasks run on time', 'keepwatch' ) );
		}

		return $results;
	}
}