default-cache-control.php

<?php
/**
 * Plugin Name: Be API - Cache-control Defaults
 * Description: Configure default cache-control settings for the cache-control plugin.
 * Version: 2.0
 * Author: BE API Technical team
 * Author URI: https://www.beapi.fr
 * License: GPL v2 or later
 */

namespace BEAPI\Plugin_Defaults\cache_control;

// Prevent direct access
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Default cache control configuration
 *
 * This array defines the default settings for each cache control option.
 * The structure follows the same pattern as the cache-control plugin.
 *
 * Available options for each entry:
 * - max_age: Cache duration in seconds for browsers (defined only 1 time on default_settings function)
 * - s_maxage: Cache duration in seconds for CDN/proxies
 * - staleerror: Duration to serve stale content on server errors (auto-defined x3 s_maxage)
 * - stalereval: Duration to serve stale content while revalidating (auto-defined x5 s_maxage)
 * - paged: Pagination factor (only for paginated content)
 * - mmulti: Enable age multiplier based on last modification (only for singles)
 *
 * @return array Default cache control settings
 */
function get_default_cache_control_settings() {
	// WordPress constants: HOUR_IN_SECONDS = 3600, DAY_IN_SECONDS = 86400
	return [
		'front_page'           => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'singles'              => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
			'mmulti'   => 1,     // Enable age multiplier
		],
		'pages'                => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'home'                 => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
			'paged'    => 5,     // 5 seconds pagination factor. Example : 10 pages * 5 seconds = 50 seconds
		],
		'categories'           => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
			'paged'    => 8,     // 8 seconds pagination factor
		],
		'tags'                 => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
			'paged'    => 10,    // 10 seconds pagination factor
		],
		'authors'              => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
			'paged'    => 10,    // 10 seconds pagination factor
		],
		'dates'                => [
			's_maxage' => 12 * \HOUR_IN_SECONDS, // 12 hours
		],
		'feeds'                => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'attachment'           => [
			's_maxage' => 12 * \HOUR_IN_SECONDS, // 12 hours
		],
		'search'               => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'notfound'             => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'redirect_permanent'   => [
			's_maxage' => 7 * \DAY_IN_SECONDS, // 1 week
		],
		// WooCommerce specific settings (if WooCommerce is active)
		'woocommerce_product'  => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
		'woocommerce_category' => [
			's_maxage' => 10 * \HOUR_IN_SECONDS, // 10 hours
		],
	];
}

/**
 * Apply default cache control settings
 */
function default_settings() {
	global $cache_control_options;

	if ( empty( $cache_control_options ) ) {
		return;
	}

	$default_settings = get_default_cache_control_settings();

	foreach ( $cache_control_options as $index => $options ) {
		// Set browser cache to 5 seconds to enable cache validation testing via HTTP headers
		$options['max_age'] = 5;

		// If default settings for this option, set them
		if ( isset( $default_settings[ $index ] ) ) {
			// Set s_maxage
			$options['s_maxage'] = $default_settings[ $index ]['s_maxage'];

			// Set staleerror
			// On Server error, the page can be served 3 times the original value
			$options['staleerror'] = $default_settings[ $index ]['s_maxage'] * 3;

			// The stored by Varnish will be served for 5 times the original value even if the page is expired.
			// Server will get the new version as soon as one new user get it.
			$options['stalereval'] = $default_settings[ $index ]['s_maxage'] * 5;
		}

		$cache_control_options[ $index ] = $options;
	}
}

// Hook to apply default settings after plugins are loaded
\add_action( 'plugins_loaded', __NAMESPACE__ . '\\default_settings' );

/**
 * Filter cache-control options when they are read from database
 *
 * @param mixed  $pre          Pre-filtered value
 * @param string $option       Option name
 * @param mixed  $default_value Default value
 * @return mixed Filtered value
 */
function filter_option( $pre, $option, $default_value ) {
	// Use always default value for cache-control options
	if ( str_contains( $option, 'cache_control_' ) ) {
		return $default_value;
	}

	return $pre;
}

// Hook to filter options when they are read
\add_filter( 'pre_option', __NAMESPACE__ . '\\filter_option', 10, 3 );

/**
 * Disable cache-control admin page
 */
function disable_admin_page() {
	// Remove the admin menu page
	\remove_submenu_page( 'options-general.php', 'cache_control' );

	// Remove action links from plugin list
	\remove_filter( 'plugin_action_links_' . \plugin_basename( 'cache-control/cache-control.php' ), 'cache_control_admin_action_links' );

	// Remove meta links from plugin list
	\remove_filter( 'plugin_row_meta', 'cache_control_admin_actions', 10 );
}

// Hook to disable admin page after it's been added
\add_action( 'admin_menu', __NAMESPACE__ . '\\disable_admin_page', 999 );

/**
 * Add warning notice on cache-control admin page
 */
function add_admin_notice() {
	// Only show on cache-control admin page
	// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Only reading $_GET['page'], no action performed
	if ( 'cache_control' === ( isset( $_GET['page'] ) ? $_GET['page'] : '' ) ) {
		?>
		<div class="notice notice-warning is-dismissible">
			<p>
				<strong>⚠️ Configuration locked</strong><br>
				This page is displayed but no action is possible. Cache settings are automatically managed by the mu-plugin <code>default-cache-control.php</code>.
			</p>
		</div>
		<?php
	}
}

// Hook to add notice on admin pages
\add_action( 'admin_notices', __NAMESPACE__ . '\\add_admin_notice' );

/**
 * Sends HTTP cache control headers for post type archives.
 *
 * This function checks if `cache_control_send_http_header` exists
 * and if the current page is a post type archive (`is_post_type_archive()`).
 * If both conditions are met, it removes its own hook to prevent duplicate execution
 * and sends cache headers based on the 'categories' option.
 *
 * @return void
 */
function cache_control_send_post_type_archive_headers() {
	if ( ! function_exists( 'cache_control_send_http_header' ) || ! is_post_type_archive() ) {
		return;
	}

	remove_action( 'template_redirect', 'cache_control_send_headers' );

	cache_control_send_http_header( cache_control_build_directive_from_option( 'categories' ) );
}

\add_action( 'template_redirect', __NAMESPACE__ . '\\cache_control_send_post_type_archive_headers', 9 );

/**
 * Sends HTTP cache control headers for robots.txt.
 *
 * This function hooks into 'do_robots' action to send cache headers
 * Cache duration: 1 hour.
 *
 * @return void
 */
function cache_control_send_robots_headers() {
	$s_maxage = \HOUR_IN_SECONDS;

	// Set browser cache to 5 seconds to enable cache validation testing via HTTP headers
	$max_age = 5;

	// Send cache headers directly
	header(
		sprintf(
			'Cache-Control: public, max-age=%d, s-maxage=%d, stale-while-revalidate=%d, stale-if-error=%d',
			$max_age,
			$s_maxage,
			$s_maxage * 5,
			$s_maxage * 3
		),
		true // Replace existing Cache-Control header
	);
}

\add_action( 'do_robots', __NAMESPACE__ . '\\cache_control_send_robots_headers', 1 );

/**
 * Sends Cache-Control HTTP headers for WordPress REST API responses.
 *
 * Applies a conservative caching policy (1 hour) for GET/HEAD requests.
 * No header is sent for logged-in users to avoid caching personalized responses.
 *
 * @since 2.1.0
 *
 * @param mixed             $result Response to send.
 * @param \WP_REST_Server  $server Server instance.
 * @param \WP_REST_Request $request Request used to generate the response.
 * @return mixed Modified response.
 */
function cache_control_send_rest_api_headers( $result, $server, $request ) {
	$method = $request->get_method();

	if ( ! \in_array( $method, [ 'GET', 'HEAD' ], true ) ) {
		return $result;
	}

	if ( \is_user_logged_in() ) {
		return $result;
	}

	if ( ! $result instanceof \WP_REST_Response ) {
		return $result;
	}

	$route = $request->get_route();

	/**
	 * Filter the REST routes allowed to receive Cache-Control headers.
	 *
	 * Return an empty array (default) to allow all routes.
	 *
	 * @param string[]            $whitelist List of allowed routes.
	 * @param \WP_REST_Request    $request  Current REST request.
	 * @param \WP_REST_Server     $server   REST server instance.
	 */
	$whitelist = \apply_filters(
		'cache_control_rest_route_whitelist',
		[],
		$request,
		$server
	);

	if ( ! empty( $whitelist ) ) {
		if ( ! \is_array( $whitelist ) || ! \in_array( $route, $whitelist, true ) ) {
			return $result;
		}
	}

	$s_maxage = \HOUR_IN_SECONDS;

	// Set browser cache to 5 seconds to enable cache validation testing via HTTP headers
	$max_age = 5;

	$result->header(
		'Cache-Control',
		sprintf(
			'public, max-age=%d, s-maxage=%d, stale-while-revalidate=%d, stale-if-error=%d',
			$max_age,
			$s_maxage,
			$s_maxage * 5,
			$s_maxage * 3
		)
	);

	return $result;
}

\add_filter( 'rest_post_dispatch', __NAMESPACE__ . '\\cache_control_send_rest_api_headers', 10, 3 );