<?php
/**
 * Runs a try-on inside a web request when no background worker does.
 *
 * @package Fitzaro
 */

namespace Fitzaro\Job;

use Fitzaro\Database\Status;

defined( 'ABSPATH' ) || exit;

/**
 * Action Scheduler needs WP-Cron or loopback requests, and many shared hosts block or delay both.
 * The try-on would then wait forever. So:
 *
 * - after POST /tryons answers, the same PHP process starts the job when the server can finish
 *   the response early (PHP-FPM's fastcgi_finish_request, LiteSpeed's litespeed_finish_request);
 * - otherwise the shopper's next status check runs it, once it has waited GRACE seconds.
 *
 * Both go through Runner::run(), whose atomic claim makes sure a request is processed once even
 * when Action Scheduler picks it up at the same time. The `fitzaro/run_in_request` filter turns
 * this off on sites with a reliable real cron.
 */
final class InlineRun {

	/**
	 * Seconds a queued request is left to the background worker first.
	 */
	public const GRACE = 3;

	/**
	 * Whether a request should be run now by the shopper's request.
	 *
	 * @param array<string, mixed> $row Request row.
	 * @param int                  $now Current Unix time.
	 */
	public static function due( array $row, int $now ): bool {
		if ( Status::QUEUED !== ( $row['status'] ?? '' ) ) {
			return false;
		}

		return $now - LeasePolicy::timestamp( $row['created_at'] ?? null, $now ) >= self::GRACE;
	}

	/**
	 * Whether running in web requests is allowed on this site.
	 */
	public static function enabled(): bool {
		/**
		 * Filters whether try-ons may run inside web requests when no background worker picks
		 * them up. Return false on sites with a reliable server cron.
		 *
		 * @since 1.0.0
		 *
		 * @param bool $enabled Default true.
		 */
		return false !== apply_filters( 'fitzaro/run_in_request', true );
	}

	/**
	 * Runs the request after the response is sent, where the server supports finishing early.
	 *
	 * @param string $id Request UUID.
	 */
	public static function after_response( string $id ): void {
		if ( ! self::enabled() || ( ! function_exists( 'fastcgi_finish_request' ) && ! function_exists( 'litespeed_finish_request' ) ) ) {
			return;
		}

		add_action(
			'shutdown',
			static function () use ( $id ): void {
				if ( function_exists( 'fastcgi_finish_request' ) ) {
					fastcgi_finish_request();
				} elseif ( function_exists( 'litespeed_finish_request' ) ) {
					litespeed_finish_request();
				}

				ignore_user_abort( true );
				Jobs::run( $id );
			},
			PHP_INT_MAX
		);
	}

	/**
	 * Runs the request now when it is still waiting for a worker. Blocks until the provider answers.
	 *
	 * @param string $id Request UUID (already checked to belong to the caller).
	 */
	public static function if_stalled( string $id ): void {
		if ( ! self::enabled() ) {
			return;
		}

		$row = Jobs::requests()->find( $id );
		if ( null !== $row && self::due( $row, time() ) ) {
			Jobs::run( $id );
		}
	}
}