<?php
/*
 * FastLayer advanced-cache.php drop-in.
 *
 * Ownership marker: wp-fastlayer:advanced-cache-dropin
 *
 * This file is installed and managed automatically by FastLayer. The marker
 * above is how FastLayer tells its own drop-in apart from a drop-in owned by
 * another caching plugin, so that it never overwrites or deletes foreign
 * files. Do not remove the marker, and do not edit this file by hand.
 */
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

$fastlayer_cache_dir = WP_CONTENT_DIR . '/cache/wp-fastlayer/';
$fastlayer_options = array();

// On multisite the options are stored per site, so each site has its own config
// file and sites.json maps a site's home URL to its id. This drop-in runs
// before ms-settings.php sets up the current site, so the site is resolved here
// from the request host and path. On single-site there is no index and
// config.json is authoritative.
$fastlayer_sites_index = $fastlayer_cache_dir . 'sites.json';
$fastlayer_has_index   = file_exists( $fastlayer_sites_index );

if ( $fastlayer_has_index ) {
    $fastlayer_index_options = fastlayer_load_site_options_from_index( $fastlayer_sites_index );
    if ( is_array( $fastlayer_index_options ) ) {
        $fastlayer_options = $fastlayer_index_options;
    }
} else {
    // The canonical single-site config is plain JSON so nothing under
    // wp-content/ is executed.
    $fastlayer_config_json = $fastlayer_cache_dir . 'config.json';
    if ( file_exists( $fastlayer_config_json ) ) {
        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- advanced-cache.php runs before the WP Filesystem API is available.
        $fastlayer_config_raw = file_get_contents( $fastlayer_config_json );
        if ( is_string( $fastlayer_config_raw ) && '' !== $fastlayer_config_raw ) {
            $fastlayer_config_decoded = json_decode( $fastlayer_config_raw, true );
            if ( is_array( $fastlayer_config_decoded ) ) {
                $fastlayer_options = $fastlayer_config_decoded;
            }
        }
    }
}

// Configuration is strictly loaded from config.json (or sites.json on
// multisite). If config.json is not yet generated (e.g. immediately following
// an upgrade from a pre-1.1.0 version), $fastlayer_options remains empty,
// causing fastlayer_cache_enabled() to return false and safely bypassing
// cache serving until Bootstrap::ensure_static_config() generates config.json
// during WordPress initialization. The drop-in never executes PHP files from cache.

$fastlayer_cache_expiration = 36000;
if ( isset( $fastlayer_options['cache_expiration'] ) ) {
    $fastlayer_cache_expiration = max( 1, (int) $fastlayer_options['cache_expiration'] ) * 3600;
}

function fastlayer_cache_enabled() {
    global $fastlayer_options;
    return isset( $fastlayer_options['enable_cache'] ) && '1' === (string) $fastlayer_options['enable_cache'];
}

function fastlayer_get_option_lines( $key ) {
    global $fastlayer_options;
    if ( ! isset( $fastlayer_options[ $key ] ) || ! is_string( $fastlayer_options[ $key ] ) ) {
        return array();
    }
    return preg_split( '/\r?\n/', trim( $fastlayer_options[ $key ] ) );
}

function fastlayer_host_from_url( $url ) {
    if ( ! is_string( $url ) || '' === $url ) {
        return '';
    }
    // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- advanced-cache.php runs before wp_parse_url() is defined (the drop-in is included from wp-settings.php before wp-includes/functions.php).
    $parts = parse_url( $url );
    if ( ! is_array( $parts ) || empty( $parts['host'] ) ) {
        return '';
    }
    return strtolower( $parts['host'] );
}

function fastlayer_expected_hosts() {
    global $fastlayer_options;
    $hosts = array();

    if ( isset( $fastlayer_options['_home_host'] ) && is_array( $fastlayer_options['_home_host'] ) ) {
        foreach ( $fastlayer_options['_home_host'] as $host ) {
            if ( is_string( $host ) && '' !== $host ) {
                $hosts[] = strtolower( $host );
            }
        }
    }

    foreach ( array( 'WP_HOME', 'WP_SITEURL' ) as $constant_name ) {
        if ( defined( $constant_name ) ) {
            $host = fastlayer_host_from_url( constant( $constant_name ) );
            if ( '' !== $host ) {
                $hosts[] = $host;
            }
        }
    }

    return array_values( array_unique( $hosts ) );
}

function fastlayer_normalize_request_host() {
    if ( ! isset( $_SERVER['HTTP_HOST'] ) || ! is_string( $_SERVER['HTTP_HOST'] ) ) {
        return '';
    }

    $host = strtolower( trim( $_SERVER['HTTP_HOST'] ) ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.

    // Support bracketed IPv6 literals, with or without a port: [::1] or [::1]:8080.
    if ( '[' === substr( $host, 0, 1 ) ) {
        $end = strpos( $host, ']' );
        if ( false === $end ) {
            return '';
        }
        $literal = substr( $host, 1, $end - 1 );
        if ( '' === $literal || ! filter_var( $literal, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6 ) ) {
            return '';
        }
        // Reject anything after the closing bracket except a valid :port.
        $remainder = substr( $host, $end + 1 );
        if ( '' !== $remainder ) {
            if ( ':' !== substr( $remainder, 0, 1 ) ) {
                return '';
            }
            $port = substr( $remainder, 1 );
            if ( ! preg_match( '/^[0-9]{1,5}$/', $port ) || (int) $port < 1 || (int) $port > 65535 ) {
                return '';
            }
        }
        return '[' . $literal . ']';
    }

    // Bare unbracketed IPv6 literal (e.g. ::1 or 2001:db8::1).
    if ( filter_var( $host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6 ) ) {
        return '[' . $host . ']';
    }

    $colon = strpos( $host, ':' );
    if ( false !== $colon ) {
        $port = substr( $host, $colon + 1 );
        if ( ! preg_match( '/^[0-9]{1,5}$/', $port ) || (int) $port < 1 || (int) $port > 65535 ) {
            return '';
        }
        $host = substr( $host, 0, $colon );
    }

    // Support trailing dot in FQDN (e.g. example.com.).
    $host = rtrim( $host, '.' );

    if ( ! preg_match( '/^[a-z0-9]([a-z0-9._-]*[a-z0-9])?$/', $host ) ) {
        return '';
    }

    return $host;
}

/**
 * Normalizes a host for comparison (lowercase, port removed).
 *
 * Applies the same validation rules as fastlayer_normalize_request_host() so
 * that the two helpers always agree: a bracketed IPv6 literal must contain a
 * valid IPv6 address, have no trailing junk after the closing bracket, and not
 * be unterminated. Bare IPv6 literals are wrapped in brackets for consistency.
 *
 * @param string $host Raw host.
 * @return string Normalised host, or '' when the input is invalid.
 */
function fastlayer_normalize_host( $host ) {
    $host = strtolower( trim( (string) $host ) );
    if ( '' === $host ) {
        return '';
    }

    if ( '[' === substr( $host, 0, 1 ) ) {
        $end = strpos( $host, ']' );
        if ( false === $end ) {
            // Unterminated bracket — invalid.
            return '';
        }
        $literal = substr( $host, 1, $end - 1 );
        if ( '' === $literal || ! filter_var( $literal, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6 ) ) {
            // Not a valid IPv6 address (e.g. [gggg] or [::1%25eth0]).
            return '';
        }
        // Reject trailing characters after the closing bracket (e.g. [::1]x).
        // A port suffix (:port) is acceptable but must be a valid port.
        $remainder = substr( $host, $end + 1 );
        if ( '' !== $remainder ) {
            if ( ':' !== substr( $remainder, 0, 1 ) ) {
                return '';
            }
            $port = substr( $remainder, 1 );
            if ( ! preg_match( '/^[0-9]{1,5}$/', $port ) || (int) $port < 1 || (int) $port > 65535 ) {
                return '';
            }
        }
        return '[' . $literal . ']';
    }

    // Bare unbracketed IPv6 literal (e.g. ::1 or 2001:db8::1).
    if ( filter_var( $host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6 ) ) {
        return '[' . $host . ']';
    }

    $colon = strpos( $host, ':' );
    if ( false !== $colon ) {
        $port = substr( $host, $colon + 1 );
        if ( ! preg_match( '/^[0-9]{1,5}$/', $port ) || (int) $port < 1 || (int) $port > 65535 ) {
            return '';
        }
        $host = substr( $host, 0, $colon );
    }

    // Support trailing dot in FQDN (e.g. example.com.).
    $host = rtrim( $host, '.' );

    if ( ! preg_match( '/^[a-z0-9]([a-z0-9._-]*[a-z0-9])?$/', $host ) ) {
        return '';
    }

    return $host;
}

/**
 * The request path, without query string or fragment.
 *
 * @return string
 */
function fastlayer_request_path() {
    $uri = isset( $_SERVER['REQUEST_URI'] ) && is_string( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : '/'; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision.

    $question = strpos( $uri, '?' );
    if ( false !== $question ) {
        $uri = substr( $uri, 0, $question );
    }
    $hash = strpos( $uri, '#' );
    if ( false !== $hash ) {
        $uri = substr( $uri, 0, $hash );
    }

    if ( '' === $uri || '/' !== substr( $uri, 0, 1 ) ) {
        $uri = '/' . $uri;
    }

    return $uri;
}

/**
 * Resolves the current request to a site id using the network index.
 *
 * Mirrors the longest-prefix domain + path match WordPress performs in
 * ms_load_current_site_and_network(), but reads the pre-generated index instead
 * of the database, because the drop-in runs before WordPress is loaded.
 *
 * @param array $index Map of home URL => blog id.
 * @return int Blog id, or 0 when nothing matches.
 */
function fastlayer_resolve_blog_id( $index ) {
    $host = fastlayer_normalize_request_host();
    if ( '' === $host ) {
        return 0;
    }

    $path     = fastlayer_request_path();
    $best_id  = 0;
    $best_len = -1;

    foreach ( $index as $home_url => $blog_id ) {
        $blog_id = (int) $blog_id;
        if ( $blog_id <= 0 ) {
            continue;
        }

        // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- advanced-cache.php runs before wp_parse_url() is defined.
        $parts = parse_url( (string) $home_url );
        if ( ! is_array( $parts ) || empty( $parts['host'] ) ) {
            continue;
        }
        if ( fastlayer_normalize_host( $parts['host'] ) !== $host ) {
            continue;
        }

        $home_path = isset( $parts['path'] ) ? (string) $parts['path'] : '/';
        $home_path = '/' . ltrim( $home_path, '/' );
        $home_path = rtrim( $home_path, '/' );

        if ( '' !== $home_path && $path !== $home_path && 0 !== strpos( $path, $home_path . '/' ) ) {
            continue;
        }

        if ( strlen( $home_path ) > $best_len ) {
            $best_len = strlen( $home_path );
            $best_id  = $blog_id;
        }
    }

    return $best_id;
}

/**
 * Loads the per-site options for the current request on multisite.
 *
 * @param string $index_file Absolute path to sites.json.
 * @return array|null Options array, or null when the site cannot be resolved.
 */
function fastlayer_load_site_options_from_index( $index_file ) {
    global $fastlayer_cache_dir;

    // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- advanced-cache.php runs before the WP Filesystem API is available.
    $index_raw = file_get_contents( $index_file );
    if ( ! is_string( $index_raw ) || '' === $index_raw ) {
        return null;
    }

    $index = json_decode( $index_raw, true );
    if ( ! is_array( $index ) || empty( $index ) ) {
        return null;
    }

    $blog_id = fastlayer_resolve_blog_id( $index );
    if ( $blog_id <= 0 ) {
        return null;
    }

    $site_file = $fastlayer_cache_dir . 'sites/' . (int) $blog_id . '.json';
    if ( ! file_exists( $site_file ) ) {
        return null;
    }

    // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- advanced-cache.php runs before the WP Filesystem API is available.
    $site_raw = file_get_contents( $site_file );
    if ( ! is_string( $site_raw ) || '' === $site_raw ) {
        return null;
    }

    $site_options = json_decode( $site_raw, true );
    return is_array( $site_options ) ? $site_options : null;
}

function fastlayer_is_request_host_trusted() {
    $expected = fastlayer_expected_hosts();
    if ( empty( $expected ) ) {
        return false;
    }

    $host = fastlayer_normalize_request_host();
    if ( '' === $host ) {
        return false;
    }

    return in_array( $host, $expected, true );
}

function fastlayer_strip_url_domain( $url ) {
    // WordPress is not loaded this early, so this mirrors the runtime
    // Page_Cache::strip_url_domain() using the native parse_url() instead of
    // wp_parse_url(). Both cache paths must agree on what an exclusion matches.
    // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- advanced-cache.php runs before wp_parse_url() is defined; mirrors Page_Cache::strip_url_domain() so both cache paths agree.
    $parsed = parse_url( $url );
    if ( ! is_array( $parsed ) || empty( $parsed['path'] ) ) {
        return $url;
    }

    $path = $parsed['path'];
    if ( isset( $parsed['query'] ) ) {
        $path .= '?' . $parsed['query'];
    }

    return $path;
}

function fastlayer_matches_patterns( $value, $patterns ) {
    foreach ( $patterns as $pattern ) {
        $pattern = trim( $pattern );
        if ( '' === $pattern ) {
            continue;
        }

        if ( false !== strpos( $pattern, '*' ) || false !== strpos( $pattern, '(.*)' ) ) {
            $regex = '#^' . str_replace( array( '\*', '(.*)' ), array( '.*', '.*' ), preg_quote( $pattern, '#' ) ) . '$#i';
            if ( preg_match( $regex, $value ) || preg_match( $regex, fastlayer_strip_url_domain( $value ) ) ) {
                return true;
            }
            continue;
        }

        $value_compare   = fastlayer_strip_url_domain( $value );
        $pattern_compare = fastlayer_strip_url_domain( $pattern );

        if ( stripos( $value_compare, $pattern_compare ) !== false || stripos( $value, $pattern ) !== false ) {
            return true;
        }
    }

    return false;
}

function fastlayer_has_excluded_cookie() {
    $patterns = fastlayer_get_option_lines( 'exclude_cookies' );

    // Standard e-commerce & session cookies always excluded
    $ecommerce_cookies = array(
        'woocommerce_items_in_cart',
        'woocommerce_cart_hash',
        'wp_woocommerce_session_',
        'edd_items_in_cart',
    );

    if ( ! isset( $_COOKIE ) || ! is_array( $_COOKIE ) ) {
        return false;
    }

    foreach ( $_COOKIE as $cookie_name => $cookie_value ) {
        $c_name = (string) $cookie_name;
        foreach ( $ecommerce_cookies as $ec_cookie ) {
            if ( false !== stripos( $c_name, $ec_cookie ) ) {
                return true;
            }
        }
        if ( ! empty( $patterns ) ) {
            foreach ( $patterns as $pattern ) {
                $pattern = trim( $pattern );
                if ( '' !== $pattern && false !== stripos( $c_name, $pattern ) ) {
                    return true;
                }
            }
        }
    }

    return false;
}

function fastlayer_should_skip_cache() {
    // WordPress is not loaded this early, so HTTP_HOST is fully client
    // controlled. It must be validated before it can be used in a cache key.
    if ( ! fastlayer_is_request_host_trusted() ) {
        return true;
    }

    // FastLayer's preload job reads the sitemap documents over HTTP in order to
    // discover which pages to warm. Those responses are XML, not HTML, so they
    // must never become a cache entry that a later request could be served.
    // Only FastLayer's own preload requests carry this header, so visitors are
    // unaffected.
    if ( ! empty( $_SERVER['HTTP_X_FASTLAYER_PRELOAD'] ) ) {
        return true;
    }

    // Check logged in cookie first, since is_user_logged_in() is not defined early.
    if ( isset( $_COOKIE ) && is_array( $_COOKIE ) ) {
        foreach ( $_COOKIE as $key => $value ) {
            if ( 0 === strpos( $key, 'wordpress_logged_in_' ) ) {
                return true;
            }
        }
    }

    if ( function_exists( 'is_user_logged_in' ) && is_user_logged_in() ) {
        return true;
    }

    // POST and HEAD are both excluded, matching class-page-cache.php.
    if ( isset( $_SERVER['REQUEST_METHOD'] ) && is_string( $_SERVER['REQUEST_METHOD'] ) ) {
        if ( in_array( strtoupper( $_SERVER['REQUEST_METHOD'] ), array( 'POST', 'HEAD' ), true ) ) {
            return true;
        }
    }

    if ( defined( 'DOING_AJAX' ) && DOING_AJAX ) {
        return true;
    }

    if ( defined( 'DOING_CRON' ) && DOING_CRON ) {
        return true;
    }

    if ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) {
        return true;
    }

    if ( defined( 'WP_ADMIN' ) && WP_ADMIN ) {
        return true;
    }

    $request_uri = isset( $_SERVER['REQUEST_URI'] ) && is_string( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.

    // REST_REQUEST is defined long after this drop-in runs, so match both the
    // pretty permalink path and the ?rest_route= query form as well.
    if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
        return true;
    }
    if ( false !== strpos( $request_uri, 'rest_route=' ) ) {
        return true;
    }

    // Preview and search, matching is_preview() and is_search() at runtime.
    if ( isset( $_GET['preview'] ) || isset( $_GET['preview_id'] ) || isset( $_GET['post_preview'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only cache-decision input in the pre-WordPress drop-in; no nonce exists and no state changes.
        return true;
    }
    if ( isset( $_GET['s'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only cache-decision input in the pre-WordPress drop-in; no nonce exists and no state changes.
        return true;
    }
    // A 404 cannot be detected before WordPress parses the query. It is already
    // covered the other way round: class-page-cache.php never writes a 404 or
    // search response to disk, so no such file exists for this drop-in to serve.

    $skip_paths = array(
        '/wp-admin/',
        '/wp-login.php',
        '/wp-register.php',
        '/wp-json/',
        '/cart/',
        '/checkout/',
        '/my-account/',
        '/order-received/',
        '/wc-api/',
        'wc-ajax=',
        '/edd-checkout/',
        '/feed/',
    );

    foreach ( $skip_paths as $path ) {
        if ( false !== strpos( $request_uri, $path ) ) {
            return true;
        }
    }

    if ( fastlayer_matches_patterns( $request_uri, fastlayer_get_option_lines( 'exclude_urls' ) ) ) {
        return true;
    }

    if ( fastlayer_has_excluded_cookie() ) {
        return true;
    }

    $user_agent = isset( $_SERVER['HTTP_USER_AGENT'] ) && is_string( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.
    if ( fastlayer_matches_patterns( $user_agent, fastlayer_get_option_lines( 'exclude_user_agents' ) ) ) {
        return true;
    }

    return false;
}

function fastlayer_get_accept_cache_variant() {
    $accept = isset( $_SERVER['HTTP_ACCEPT'] ) && is_string( $_SERVER['HTTP_ACCEPT'] ) ? strtolower( $_SERVER['HTTP_ACCEPT'] ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.

    if ( false !== strpos( $accept, 'image/avif' ) ) {
        return 'accept-avif';
    }

    if ( false !== strpos( $accept, 'image/webp' ) ) {
        return 'accept-webp';
    }

    return 'accept-legacy';
}

function fastlayer_get_cache_file() {
    global $fastlayer_cache_dir;

    $protocol = function_exists( 'is_ssl' ) && is_ssl() ? 'https' : 'http';
    $host = isset( $_SERVER['HTTP_HOST'] ) && is_string( $_SERVER['HTTP_HOST'] ) ? $_SERVER['HTTP_HOST'] : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.
    $request_uri = isset( $_SERVER['REQUEST_URI'] ) && is_string( $_SERVER['REQUEST_URI'] ) ? $_SERVER['REQUEST_URI'] : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized, WordPress.Security.ValidatedSanitizedInput.MissingUnslash -- advanced-cache.php is included before wp-includes/functions.php (wp_unslash()/sanitize_* are undefined) and before wp_magic_quotes() slashes the superglobals; the value is only used for a read-only cache decision or a validated cache key.
    $url = $protocol . '://' . $host . $request_uri;
    $cache_key = md5( $url . '|' . fastlayer_get_accept_cache_variant() );

    return $fastlayer_cache_dir . $cache_key . '.html';
}

function fastlayer_is_cache_expired( $file ) {
    global $fastlayer_cache_expiration;
    return ( time() - filemtime( $file ) ) > $fastlayer_cache_expiration;
}

function fastlayer_is_safe_path( $path ) {
    global $fastlayer_cache_dir;
    $realpath = realpath( $path );
    if ( false === $realpath ) {
        return false;
    }

    $cache_realpath = realpath( $fastlayer_cache_dir );
    if ( false === $cache_realpath ) {
        return false;
    }

    return 0 === strpos( $realpath, $cache_realpath );
}

if ( fastlayer_cache_enabled() && ! fastlayer_should_skip_cache() ) {
    $fastlayer_cache_file = fastlayer_get_cache_file();

    if ( file_exists( $fastlayer_cache_file ) && fastlayer_is_safe_path( $fastlayer_cache_file ) ) {
        if ( fastlayer_is_cache_expired( $fastlayer_cache_file ) ) {
            // phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink -- advanced-cache.php runs before wp_delete_file() is defined (the drop-in is included before wp-includes/functions.php).
            @unlink( $fastlayer_cache_file );
        } else {
            if ( ! headers_sent() ) {
                $fastlayer_expiration = $fastlayer_cache_expiration;
                header( 'Vary: Accept', false );
                header( 'X-Cache-Status: HIT' );
                header( 'Cache-Control: public, max-age=' . $fastlayer_expiration . ', s-maxage=' . $fastlayer_expiration );
                header( 'X-Cache-Generated: yes' );
            }
            // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile -- advanced-cache.php runs before WP_Filesystem exists; readfile() streams the cache file and the request ends here.
            readfile( $fastlayer_cache_file );
            exit;
        }
    }
}