xspeed / includes / class-cache.php

class-cache.php in xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN 1.1.2, at includes/class-cache.php

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1	<?php
2	/**
3	* Page cache engine.
4	*
5	* @package XSpeed
6	*/
7
8	namespace XSpeed;
9
10	defined( 'ABSPATH' ) \|\| exit;
11
12	class Cache {
13
14	/**
15	* Output-buffer nesting level at which we opened our cache buffer, so
16	* `close_buffer()` can flush ONLY our buffer and never disturb a buffer
17	* another plugin pushed on top of (or below) ours.
18	*
19	* @var int\|null
20	*/
21	private static $buffer_level = null;
22
23	public function __construct() {
24	add_action( 'template_redirect', array( $this, 'maybe_start_cache' ), 0 );
25
26	// Events that should invalidate cached output. Beyond posts/comments,
27	// this covers user and term changes — the REST cache can serve
28	// /wp/v2/users, /wp/v2/categories, /wp/v2/tags, and these also affect
29	// rendered author bylines / term-archive pages. Without them, an edit
30	// left the matching endpoint (and archives) stale for the full TTL.
31	// (FBS-82408)
32	$invalidate_hooks = array(
33	'save_post', 'deleted_post', 'trashed_post',
34	'comment_post', 'wp_set_comment_status',
35	'switch_theme', 'activated_plugin', 'deactivated_plugin',
36	// Users → /wp/v2/users + author archives.
37	'profile_update', 'user_register', 'deleted_user',
38	// Terms → /wp/v2/{taxonomy} + term archives.
39	'created_term', 'edited_term', 'delete_term',
40	);
41	foreach ( $invalidate_hooks as $hook ) {
42	add_action( $hook, array( __CLASS__, 'purge_all' ) );
43	add_action( $hook, array( 'XSpeed\\Minifier', 'purge_minified' ) );
44	}
45
46	add_action( 'update_option_xspeed_options', array( __CLASS__, 'on_settings_change' ), 10, 2 );
47
48	add_action( 'admin_bar_menu', array( $this, 'admin_bar_purge' ), 100 );
49	add_action( 'admin_post_xspeed_purge', array( $this, 'handle_admin_bar_purge' ) );
50	}
51
52	public static function on_settings_change( $old, $new ) {
53	// gzip_enabled moved to xspeed_module_gzip — GzipModule owns the
54	// .htaccess flip via its own update_option_xspeed_module_gzip hook.
55	// Same migration is planned for cache_expiry + excluded_urls
56	// (Cache module). Keep this handler around for whatever still
57	// lives in the legacy blob (cache_enabled is special and goes
58	// through Cache::toggle anyway).
59
60	// Any settings change — purge caches so changes take effect.
61	self::purge_all( 'settings change' );
62	Minifier::purge_minified();
63	}
64
65	public function maybe_start_cache() {
66	if ( ! self::should_cache() ) {
67	return;
68	}
69
70	$key = self::cache_key();
71	$file = self::cache_file_for( $key );
72
73	if ( file_exists( $file ) && ! self::is_expired( $file ) ) {
74	Hit_Counter::record_hit();
75	// Emit the HIT marker on THIS path too. The drop-in
76	// (advanced-cache.php) sends "HIT (php)" and the nginx static
77	// rewrite sends "HIT (nginx)", but this template_redirect
78	// serve path — the one that runs when the drop-in isn't loaded
79	// (e.g. WP_CACHE not true) — previously streamed the cached
80	// file with NO marker, so a genuine HIT looked like a MISS in
81	// the response headers. Same header + value as the drop-in.
82	if ( ! headers_sent() ) {
83	header( 'X-XSpeed-Cache: HIT (php)' );
84	}
85	// Replay stored response bits so the HIT matches the original:
86	// a non-HTML Content-Type (cached feeds, sitemaps) and a non-200
87	// status (a cached 404 must serve 404, not 200). No-op for
88	// ordinary pages, which write no .meta.
89	$meta = self::read_meta( $key );
90	if ( ! headers_sent() ) {
91	if ( ! empty( $meta['status'] ) && function_exists( 'http_response_code' ) ) {
92	http_response_code( (int) $meta['status'] );
93	}
94	if ( ! empty( $meta['content_type'] ) && is_string( $meta['content_type'] ) ) {
95	header( 'Content-Type: ' . $meta['content_type'] );
96	}
97	// Conditional GET: emit Last-Modified + ETag and answer a
98	// matching If-Modified-Since / If-None-Match with 304 so
99	// aggregators (and browsers) skip re-downloading an unchanged
100	// cached response — the bandwidth win feeds are about.
101	// (FBS-82407 #5)
102	if ( self::serve_not_modified( $file ) ) {
103	exit; // 304 sent, no body.
104	}
105	}
106	// Serve the precompressed Brotli sibling when the client accepts
107	// it (an add-on, the Pro Brotli module, wrote <file>.br). On this
108	// PHP serve path the web server never sees the .br, so without
109	// this a br-capable client got the plain .html — precompression
110	// did nothing here. Falls through to plain readfile otherwise.
111	$br = self::maybe_serve_brotli( $file );
112	if ( null !== $br ) {
113	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile -- streaming a static cache file directly; WP_Filesystem would buffer through PHP memory and is not appropriate for response streaming.
114	readfile( $br );
115	exit;
116	}
117	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_readfile -- readfile is optimal for streaming a static cache file directly to the visitor; WP_Filesystem would buffer through PHP memory and is not appropriate for response streaming.
118	readfile( $file );
119	exit;
120	}
121
122	// Cache miss → render fresh + write cache. On LiteSpeed we send an
123	// explicit "stand down" header so the server's LSCache module does
124	// NOT cache + shadow our response — xSpeed's own .htaccess static
125	// rewrite owns hit serving (and hit accounting) here, exactly as on
126	// Apache. See maybe_emit_lscache_headers() for the full rationale.
127	self::maybe_emit_lscache_headers();
128
129	// We're about to render fresh + cache → miss for this request.
130	Hit_Counter::record_miss();
131
132
133	// WP < 6.9 fallback: ob_start() with a callback, paired with an
134	// explicit shutdown close so the buffer lifecycle is visible to
135	// reviewers and Plugin Check, instead of relying on PHP's implicit
136	// request-end flush. We record our nesting level so close_buffer()
137	// flushes ONLY the buffer we opened.
138	ob_start( array( __CLASS__, 'finalize_buffer' ) );
139	self::$buffer_level = ob_get_level();
140
141	add_action( 'shutdown', array( __CLASS__, 'close_buffer' ), 0 );
142	}
143
144	/**
145	* Close the cache buffer opened by maybe_start_cache().
146	*
147	* Guarded by the recorded buffer level so we never flush a buffer that
148	* another plugin pushed on top of (or under) ours. If something else is
149	* currently on top, we leave the stack alone — PHP's shutdown sequence
150	* will unwind buffers in order and our finalize_buffer() callback will
151	* still run when our level becomes the topmost one.
152	*/
153	public static function close_buffer() {
154	if ( null === self::$buffer_level ) {
155	return;
156	}
157	if ( ob_get_level() === self::$buffer_level ) {
158	ob_end_flush();
159	}
160	self::$buffer_level = null;
161	}
162
163	public static function should_cache() {
164	$opts = Settings::get();
165	if ( empty( $opts['cache_enabled'] ) ) {
166	return false;
167	}
168
169	if ( is_user_logged_in() \|\| is_admin() \|\| ( defined( 'DOING_AJAX' ) && DOING_AJAX ) \|\| ( defined( 'DOING_CRON' ) && DOING_CRON ) \|\| ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
170	return false;
171	}
172
173	if ( defined( 'DONOTCACHEPAGE' ) && DONOTCACHEPAGE ) {
174	return false;
175	}
176
177	// All exclusion knobs now owned by CacheModule.
178	$cache_opts = Settings_Manager::get( 'cache' );
179
180	$method = isset( $_SERVER['REQUEST_METHOD'] ) ? strtoupper( sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ) ) ) : '';
181	if ( 'GET' !== $method ) {
182	return false;
183	}
184
185	// Search-results requests carry a `s` query param, which the
186	// query-string gate below would normally reject as "dynamic". An
187	// add-on (xspeed-pro search cache) can opt them in: when this is a
188	// genuine is_search() and the filter returns true, the `s` param is
189	// treated as cacheable (the search term goes into the cache key so
190	// different searches stay distinct — see cache_key()).
191	$cache_search = self::should_cache_search();
192
193	// Feed opt-in is resolved BEFORE the query-string gate so query-form
194	// feeds (/?feed=rss2, used on plain-permalink sites) aren't rejected
195	// as "dynamic" by that gate — the `feed` param is then allowed through
196	// just like the search `s` param. Feeds are excluded by default (the
197	// `/feed/` pattern in excluded_urls); an add-on (xspeed-pro feed cache)
198	// opts them back in via the filter. (FBS-82407 #4)
199	$is_feed_request = function_exists( 'is_feed' ) && is_feed();
200	/**
201	* Whether to cache the current feed request.
202	*
203	* Default false → feeds fall through to the normal URL-exclusion
204	* rules (so `/feed/` keeps them out). A listener returning true
205	* opts this feed request into caching.
206	*
207	* @param bool $cache_feed Whether to cache this feed request.
208	*/
209	$cache_feed = $is_feed_request && (bool) apply_filters( 'xspeed_should_cache_feed', false );
210
211	// Query string handling: anything OUTSIDE the ignored-params
212	// allow-list (utm_*, fbclid, gclid by default) means a unique
213	// request that we don't want to share with the canonical cache
214	// entry. Skip cache rather than poison the key.
215	$query_raw = isset( $_SERVER['QUERY_STRING'] ) ? sanitize_text_field( wp_unslash( $_SERVER['QUERY_STRING'] ) ) : '';
216	if ( '' !== $query_raw ) {
217	$ignored = is_array( $cache_opts['ignored_query_params'] ?? null ) ? $cache_opts['ignored_query_params'] : array();
218	parse_str( $query_raw, $params );
219	foreach ( $params as $key => $_ ) {
220	// Allow the search param through when search caching is on.
221	if ( $cache_search && 's' === $key ) {
222	continue;
223	}
224	// Allow query-form feed params through when feed caching opted
225	// this request in (?feed=rss2 / &withcomments=1 on feeds).
226	if ( $cache_feed && in_array( $key, array( 'feed', 'withcomments', 'withoutcomments' ), true ) ) {
227	continue;
228	}
229	if ( ! self::query_key_is_ignored( (string) $key, $ignored ) ) {
230	return false;
231	}
232	}
233	}
234
235	$request_uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
236	$path = (string) strtok( $request_uri, '?' );
237
238	$excluded_urls = is_array( $cache_opts['excluded_urls'] ?? null ) ? $cache_opts['excluded_urls'] : array();
239	if ( ! $cache_feed && Glob_Matcher::any_match( $excluded_urls, $path ) ) {
240	return false;
241	}
242
243	// Cookie-based exclusion. We only check cookie NAMES (matching
244	// values would leak content-sensitive logic into the cache key
245	// rules); presence of any matching cookie name skips cache.
246	$excluded_cookies = is_array( $cache_opts['excluded_cookies'] ?? null ) ? $cache_opts['excluded_cookies'] : array();
247	if ( ! empty( $excluded_cookies ) && ! empty( $_COOKIE ) ) {
248	foreach ( array_keys( $_COOKIE ) as $cookie_name ) {
249	if ( Glob_Matcher::any_match( $excluded_cookies, (string) $cookie_name ) ) {
250	return false;
251	}
252	}
253	}
254
255	// User-agent bypass list. Substring match (not glob) since UA
256	// strings have so much variation that glob anchoring rarely
257	// helps and confuses users.
258	$bypass_uas = is_array( $cache_opts['bypass_user_agents'] ?? null ) ? $cache_opts['bypass_user_agents'] : array();
259	if ( ! empty( $bypass_uas ) ) {
260	$ua = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';
261	foreach ( $bypass_uas as $needle ) {
262	if ( '' !== $needle && false !== stripos( $ua, (string) $needle ) ) {
263	return false;
264	}
265	}
266	}
267
268	// Per-post override (Phase 3.4). Honored only on singular
269	// post-context requests — archives / 404s / taxonomies use the
270	// global policy above.
271	if ( Cache_Rules::should_skip_for_post( Cache_Rules::current_post_id() ) ) {
272	return false;
273	}
274
275	/**
276	* Final say on whether the current request is cacheable.
277	*
278	* Runs at template_redirect (full WP context), so listeners may use
279	* conditional tags (is_search(), is_feed(), is_404(),
280	* wp_is_maintenance_mode(), …). The core engine has already applied
281	* its own exclusion rules and reached `true`; a listener returning
282	* false vetoes caching for this request. This is the documented
283	* extension point add-ons (xspeed-pro) hook to add their own
284	* request-level cache policy without forking the engine.
285	*
286	* Note: this gates the WRITE side. The pre-WP drop-in
287	* (advanced-cache.php) cannot run PHP filters, so request types that
288	* must never be served from a stale file are handled by not
289	* writing them here and/or by purging — see the conflict notes in
290	* advanced-cache.php.
291	*
292	* @param bool $should_cache Whether to cache the current request.
293	*/
294	return (bool) apply_filters( 'xspeed_should_cache', true );
295	}
296
297	/**
298	* Whether the current request is a 404 we may cache.
299	*
300	* True only when: it's a genuine main-query is_404(), an add-on opted
301	* in via `xspeed_should_cache_404` (default false), and the request
302	* isn't a transient 404 we must never freeze — maintenance mode or a
303	* 404 emitted while the DB/site is in an error state. The xspeed-pro
304	* 404 cache flips the filter; Free never caches 404s on its own.
305	*/
306	public static function should_cache_404(): bool {
307	if ( ! function_exists( 'is_404' ) \|\| ! is_404() ) {
308	return false;
309	}
310	// Never cache a 404 served because the site is down for
311	// maintenance — that screen disappears the moment maintenance
312	// ends, and a cached copy would outlive it.
313	if ( function_exists( 'wp_is_maintenance_mode' ) && wp_is_maintenance_mode() ) {
314	return false;
315	}
316
317	/**
318	* Whether to cache the current 404 response.
319	*
320	* Default false. A listener returning true opts the (genuine)
321	* 404 into the page cache, served back for any unknown URL under
322	* one generic key. The 404 status is preserved on the HIT.
323	*
324	* @param bool $cache_404 Whether to cache this 404.
325	*/
326	return (bool) apply_filters( 'xspeed_should_cache_404', false );
327	}
328
329	/**
330	* Whether the current request is an internal search-results page we
331	* may cache.
332	*
333	* True only when: it's a genuine main-query is_search() with a
334	* non-empty term, and an add-on opted in via `xspeed_should_cache_search`
335	* (default false). The search term is folded into the cache key (see
336	* search_term() / cache_key()) so different searches stay distinct.
337	* The xspeed-pro search cache flips the filter; Free never caches
338	* search results on its own.
339	*/
340	public static function should_cache_search(): bool {
341	if ( ! function_exists( 'is_search' ) \|\| ! is_search() ) {
342	return false;
343	}
344	// Empty search (`?s=`) renders the same as a normal archive and
345	// carries no term to key on — let it fall through to the usual
346	// rules rather than caching an ambiguous entry.
347	if ( '' === self::search_term() ) {
348	return false;
349	}
350
351	/**
352	* Whether to cache the current search-results request.
353	*
354	* Default false. A listener returning true opts the search page
355	* into the cache, keyed by the normalized search term.
356	*
357	* @param bool $cache_search Whether to cache this search request.
358	*/
359	return (bool) apply_filters( 'xspeed_should_cache_search', false );
360	}
361
362	/**
363	* The current request's normalized search term, or '' if none. Reads
364	* the raw `s` query param (works on the pre-WP drop-in path too, where
365	* get_search_query() isn't available), trims + lowercases so
366	* "WordPress" and "wordpress" share one entry, and collapses internal
367	* whitespace.
368	*/
369	public static function search_term(): string {
370	$raw = isset( $_GET['s'] ) ? sanitize_text_field( wp_unslash( $_GET['s'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- read-only cache-key derivation from a public search param; no state change.
371	$raw = trim( $raw );
372	if ( '' === $raw ) {
373	return '';
374	}
375	$raw = preg_replace( '/\s+/', ' ', $raw );
376	return function_exists( 'mb_strtolower' ) ? mb_strtolower( $raw ) : strtolower( $raw );
377	}
378
379	/**
380	* Is this query-string key on the ignored-params allow-list? Supports
381	* trailing-star globs (`utm_*` matches `utm_source`, `utm_medium`,
382	* etc.) so users don't have to enumerate every UTM variant.
383	*/
384	private static function query_key_is_ignored( string $key, array $ignored ): bool {
385	return Glob_Matcher::any_match( $ignored, $key );
386	}
387
388	public static function cache_key() {
389	$host = isset( $_SERVER['HTTP_HOST'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) : 'default';
390
391	// Cacheable 404s share ONE generic per-host entry — keying them by
392	// URL would let a scanner flood (millions of random paths) bloat
393	// the cache with identical 404 bodies. Both the write and the HIT
394	// lookup run through here, so they agree on the key automatically.
395	if ( self::should_cache_404() ) {
396	return md5( $host . '\|404' );
397	}
398
399	$uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '/';
400	// Strip the query string from the key so /post and /post?utm_*=…
401	// share the same cache entry. should_cache() above already
402	// rejected requests with non-ignored params, so by the time we
403	// build the key the only params left are safe to drop.
404	$uri = (string) strtok( $uri, '?' );
405
406	// Optional device bucket: when mobile_separate is on, mobile and
407	// desktop responses live in different cache files so themes that
408	// serve different HTML by device (AMP, WPtouch, Jetpack mobile)
409	// can't poison each other.
410	$device = '';
411	$opts = Settings_Manager::get( 'cache' );
412	if ( ! empty( $opts['mobile_separate'] ) ) {
413	$device = self::is_mobile_request() ? '\|m' : '\|d';
414	}
415
416	// Search-results requests fold the normalized term into the key so
417	// /?s=foo and /?s=bar get distinct entries (the query string is
418	// otherwise stripped above). Only added when search caching opted
419	// in, so non-search URLs are unaffected.
420	$search = self::should_cache_search() ? '\|s=' . self::search_term() : '';
421
422	// Query-form feeds (/?feed=rss2 vs /?feed=atom) share the same path
423	// once the query is stripped, so fold the feed type into the key to
424	// keep the flavors distinct. Pretty-permalink feeds (/feed/rss/) carry
425	// the type in $uri already and are unaffected. (FBS-82407 #4)
426	$feed = '';
427	if ( function_exists( 'is_feed' ) && is_feed() && function_exists( 'get_query_var' ) ) {
428	$feed_type = (string) get_query_var( 'feed' );
429	if ( '' !== $feed_type ) {
430	$feed = '\|feed=' . preg_replace( '/[^a-z0-9]/i', '', $feed_type );
431	}
432	}
433
434	return md5( $host . $uri . $device . $search . $feed );
435	}
436
437	/**
438	* Server-side mobile detection. Prefers WordPress's `wp_is_mobile()`
439	* which uses the same UA tokens as core (so our bucket aligns with
440	* whatever theme-side branching uses). Falls back to a tiny inline
441	* detector if wp_is_mobile() isn't loaded (e.g. the drop-in path).
442	*/
443	private static function is_mobile_request(): bool {
444	if ( function_exists( 'wp_is_mobile' ) ) {
445	return (bool) wp_is_mobile();
446	}
447	// Fallback for the rare context where wp_is_mobile() isn't loaded.
448	// Mirrors core's wp_is_mobile() EXACTLY — including the
449	// Sec-CH-UA-Mobile client hint it checks before UA tokens — so the
450	// bucket this picks matches whatever the engine's primary path (and
451	// the drop-in's own copy of this logic) would pick for the same
452	// request. Drift here re-introduces the cross-path key mismatch.
453	if ( isset( $_SERVER['HTTP_SEC_CH_UA_MOBILE'] ) ) {
454	return '?1' === $_SERVER['HTTP_SEC_CH_UA_MOBILE'];
455	}
456	$ua = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';
457	if ( '' === $ua ) {
458	return false;
459	}
460	return (bool) preg_match( '/(Mobile\|Android\|Silk\/\|Kindle\|BlackBerry\|Opera Mini\|Opera Mobi)/i', $ua );
461	}
462
463	public static function cache_file_for( $key ) {
464	return XSPEED_CACHE_DIR . '/' . $key . '.html';
465	}
466
467	/**
468	* If a precompressed Brotli sibling (`<file>.br`) exists and the client
469	* advertises `Accept-Encoding: br`, emit the Brotli response headers and
470	* return the `.br` path to stream. Returns null to fall through to the
471	* plain file. Keeps the PHP serve path in parity with the web server's
472	* static .br serving (mod_brotli / ngx_brotli rewrite).
473	*
474	* Free has no Brotli logic of its own — this only fires when an add-on
475	* (the Pro Brotli module) actually wrote the .br, so it's a safe no-op
476	* on Free-only installs.
477	*
478	* @param string $file Absolute path to the cached .html file.
479	* @return string\|null The .br path to stream, or null to serve $file.
480	*/
481	public static function maybe_serve_brotli( string $file ): ?string {
482	if ( headers_sent() ) {
483	return null;
484	}
485	$accept = isset( $_SERVER['HTTP_ACCEPT_ENCODING'] )
486	? strtolower( sanitize_text_field( wp_unslash( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ) )
487	: '';
488	// Match `br` as a token (comma/space delimited), not a substring, so
489	// a hypothetical "xbr" encoding can't false-positive.
490	if ( ! preg_match( '/(^\|[\s,])br([\s,;]\|$)/', $accept ) ) {
491	return null;
492	}
493	$br = $file . '.br';
494	if ( ! is_string( $br ) \|\| ! file_exists( $br ) \|\| ! is_readable( $br ) ) {
495	return null;
496	}
497	header( 'Content-Encoding: br' );
498	header( 'Vary: Accept-Encoding', false );
499	// The byte length changes for the compressed body — drop any
500	// Content-Length the caller may have set so the stream isn't
501	// truncated/padded. readfile() lets the SAPI set the right length.
502	header_remove( 'Content-Length' );
503	return $br;
504	}
505
506	/**
507	* Sidecar metadata file for a cache entry. Holds response bits the HIT
508	* path must replay — Content-Type (cached feeds → application/rss+xml,
509	* sitemaps → text/xml) and status (a cached 404 must serve 404, not
510	* 200). JSON, one tiny file per entry, written only when there's
511	* something non-default to replay.
512	*/
513	public static function cache_meta_for( $key ) {
514	return XSPEED_CACHE_DIR . '/' . $key . '.meta';
515	}
516
517	/**
518	* Read the .meta sidecar for a cache entry as an array, or [] if none.
519	* Keys: 'content_type' (string), 'status' (int). Used on the HIT path
520	* to replay them before streaming the file.
521	*/
522	private static function read_meta( $key ): array {
523	$meta_file = self::cache_meta_for( $key );
524	if ( ! file_exists( $meta_file ) ) {
525	return array();
526	}
527	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- our own cache dir; WP_Filesystem needs admin creds unavailable on a frontend HIT.
528	$raw = file_get_contents( $meta_file );
529	$data = json_decode( (string) $raw, true );
530	return is_array( $data ) ? $data : array();
531	}
532
533	/**
534	* Conditional-GET support for a cache HIT. Emits Last-Modified + ETag
535	* derived from the cache file's mtime, and — when the request's
536	* If-Modified-Since / If-None-Match still match — sends 304 Not Modified
537	* and returns true (caller should exit without a body). Returns false to
538	* proceed with a normal 200 body. Lets aggregators/browsers skip
539	* re-downloading an unchanged cached response. (FBS-82407 #5)
540	*
541	* @param string $file Absolute path to the cache .html file.
542	* @return bool True when a 304 was sent.
543	*/
544	public static function serve_not_modified( string $file ): bool {
545	$mtime = (int) filemtime( $file );
546	if ( $mtime <= 0 ) {
547	return false;
548	}
549	$last_modified = gmdate( 'D, d M Y H:i:s', $mtime ) . ' GMT';
550	$etag = '"' . md5( $file . '\|' . $mtime ) . '"';
551	header( 'Last-Modified: ' . $last_modified );
552	header( 'ETag: ' . $etag );
553
554	$ims = isset( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ? trim( sanitize_text_field( wp_unslash( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) ) : '';
555	$inm = isset( $_SERVER['HTTP_IF_NONE_MATCH'] ) ? trim( sanitize_text_field( wp_unslash( $_SERVER['HTTP_IF_NONE_MATCH'] ) ) ) : '';
556
557	$etag_match = '' !== $inm && false !== strpos( $inm, $etag );
558	$time_match = '' !== $ims && ( strtotime( $ims ) >= $mtime );
559
560	if ( $etag_match \|\| $time_match ) {
561	if ( function_exists( 'http_response_code' ) ) {
562	http_response_code( 304 );
563	}
564	return true;
565	}
566	return false;
567	}
568
569	public static function is_expired( $file ) {
570	// cache_expiry now owned by CacheModule; per-post override
571	// (Phase 3.4) shrinks the TTL further when the editor set one.
572	$opts = Settings_Manager::get( 'cache' );
573	$max_age = (int) $opts['cache_expiry'] * HOUR_IN_SECONDS;
574	$post_override = Cache_Rules::expiry_override_seconds_for_post( Cache_Rules::current_post_id() );
575	if ( null !== $post_override ) {
576	$max_age = $post_override;
577	}
578
579	/**
580	* Filter the max-age (seconds) for the current cache entry.
581	*
582	* Lets an add-on apply a request-type-specific TTL — e.g. the
583	* xspeed-pro feed cache gives feeds a longer expiry than pages,
584	* since aggregators tolerate more staleness. Return seconds.
585	*
586	* @param int $max_age Computed max-age in seconds.
587	*/
588	$max_age = (int) apply_filters( 'xspeed_cache_max_age', $max_age );
589
590	return ( time() - filemtime( $file ) ) > $max_age;
591	}
592
593	/**
594	* Accumulator for the full response body across all output-handler phases.
595	*
596	* PHP invokes an ob_start() callback once per flush, and each invocation
597	* only receives the chunk produced since the previous flush. If anything
598	* during the render calls `ob_flush()` or `flush()` (some themes, lazy-
599	* load plugins, AMP, etc. do), the final-phase call would otherwise only
600	* see the tail of the page — and we'd cache a truncated response that
601	* gets served repeatedly until purge. We accumulate every chunk here so
602	* the cache file always reflects the complete page.
603	*
604	* @var string
605	*/
606	private static $accumulated = '';
607
608	public static function finalize_buffer( $buffer, $phase = PHP_OUTPUT_HANDLER_FINAL ) {
609	self::$accumulated .= $buffer;
610
611	// On non-final phases (mid-request flushes), pass the current chunk
612	// through to the client unmodified and keep collecting. The WP 6.9
613	// filter path always passes the full body in one shot with the
614	// default $phase, so it falls straight through to the final block.
615	$is_final = ( $phase & ( PHP_OUTPUT_HANDLER_FINAL \| PHP_OUTPUT_HANDLER_END ) ) !== 0;
616	if ( ! $is_final ) {
617	return $buffer;
618	}
619
620	$full = self::$accumulated;
621	self::$accumulated = '';
622
623	if ( strlen( $full ) < 255 ) {
624	return $buffer;
625	}
626
627	// Status gate. We cache 200 by default. A 404 may be cached too,
628	// but only when an add-on (xspeed-pro 404 cache) opts in for a
629	// genuine is_404() — never a transient 404 (maintenance screen,
630	// DB error, or a 404 emitted outside the main query), which would
631	// otherwise be frozen until purge. Any other status is skipped.
632	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
633	if ( 200 !== $status ) {
634	if ( 404 !== $status \|\| ! self::should_cache_404() ) {
635	return $buffer;
636	}
637	}
638
639	// If no mid-request flush happened, $buffer === $full and we can
640	// safely minify the on-wire bytes too. Otherwise earlier chunks have
641	// already been sent unminified, so we minify only what goes to disk —
642	// the first visitor sees unminified HTML, every cache hit after that
643	// is minified.
644	$single_chunk = ( $buffer === $full );
645
646	/**
647	* Filter: xspeed_cache_final_html
648	*
649	* Last chance to transform the fully-rendered page HTML before it is
650	* minified and written to the cache file. Runs on cache MISS only, so
651	* whatever a listener injects here is baked into the cached HTML and
652	* replayed on every subsequent HIT (the drop-in short-circuits before
653	* PHP on a HIT — a wp_head hook would never fire there).
654	*
655	* The Preload module uses this to inject the LCP-image <link rel=preload>
656	* + preconnect hints and add fetchpriority="high" to the hero <img>.
657	* Keep listeners fast and idempotent; this is the on-wire body.
658	*
659	* @param string $full Complete page HTML.
660	*/
661	$full = (string) apply_filters( 'xspeed_cache_final_html', $full );
662	if ( $single_chunk ) {
663	$buffer = $full;
664	}
665
666	// minify_html now owned by the Minify module; read through the
667	// module's storage so this stays consistent with the engine that
668	// applies CSS/JS minification.
669	$minify_opts = Settings_Manager::get( 'minify' );
670	if ( ! empty( $minify_opts['minify_html'] ) ) {
671	$full = Minifier::minify_html( $full );
672	if ( $single_chunk ) {
673	$buffer = $full;
674	}
675	}
676
677	if ( ! file_exists( XSPEED_CACHE_DIR ) ) {
678	wp_mkdir_p( XSPEED_CACHE_DIR );
679	self::write_silence( XSPEED_CACHE_DIR );
680	}
681
682	// Path safety: cache_file_for() builds `XSPEED_CACHE_DIR . '/' . $key . '.html'`
683	// where $key comes from md5() — guaranteed to be exactly 32 lowercase
684	// hex chars, so no traversal sequence ('..', '/', null byte, etc.)
685	// can appear. The write is therefore always inside XSPEED_CACHE_DIR.
686	$key = self::cache_key();
687	$file = self::cache_file_for( $key );
688	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- WP_Filesystem requires admin context for credentials; cache writes happen on frontend requests where it's unavailable.
689	file_put_contents( $file, $full, LOCK_EX );
690
691	/**
692	* Fires after the flat hash cache file ({md5}.html) is written.
693	*
694	* Mirror of `xspeed_static_file_written` for the flat cache. The PHP
695	* serve path (Cache::maybe_serve_brotli / the drop-in) serves THIS
696	* file and looks for a `{md5}.html.br` sibling — which only the Pro
697	* Brotli listener on this hook writes. Without it the .br sibling was
698	* never created and the PHP path could never serve Brotli (FBS-83039,
699	* Blocker 2): the static-tree .br (written on xspeed_static_file_written)
700	* lives in a different cache layout the PHP path never reads.
701	*
702	* @param string $file Absolute path to the flat cache file just written.
703	* @param string $full The HTML written to it.
704	*/
705	do_action( 'xspeed_flat_file_written', $file, $full );
706
707	// Persist a non-default Content-Type so the HIT path can replay it
708	// (cached feeds must serve application/rss+xml, not text/html).
709	// Only written when the response set a content-type other than
710	// the HTML default — pages don't pay for an extra file.
711	self::write_meta( $key );
712
713	// Static-cache tree (xspeed-static/{host}{path}/index.html). The
714	// .htaccess rewrite block serves this file directly via the web
715	// server, bypassing PHP for ~3-5× lower TTFB vs the drop-in path.
716	// store_static() returns silently on any path/permission issue —
717	// the drop-in remains the safety net.
718	//
719	// Skip it entirely when mobile_separate is on: the rewrite is
720	// disabled in that mode (static_rewrite_allowed()), so a static file
721	// would only be dead weight — and a device-blind one at that.
722	// Skip the static-tree write for responses the web server can't replay
723	// correctly: a non-200 status (a cached 404 would be served as a soft
724	// 200, FBS-82406) or a non-HTML content-type (a cached feed would go
725	// out as text/html, FBS-82407). The web server serves these .html files
726	// directly with no PHP, so there's no .meta replay — keep them on the
727	// drop-in / PHP path instead, which DOES replay status + content-type.
728	if ( self::static_rewrite_allowed() && self::response_is_plain_html() ) {
729	self::store_static( $full );
730	}
731
732	return $buffer;
733	}
734
735	/**
736	* Write the current response to the static-cache tree at
737	* `xspeed-static/{host}{request_uri}/index.html`. The web-server
738	* rewrite block points at this path so cache hits skip PHP
739	* entirely. Caller already minified/finalized $html.
740	*
741	* Path safety: $host is restricted to a `[a-zA-Z0-9.\-]` allowlist;
742	* $uri has its query string stripped, null bytes removed, '..'
743	* sequences collapsed, and after concatenation we verify the
744	* resolved real path stays inside XSPEED_CACHE_STATIC_DIR before
745	* any write. Anything off the happy path returns silently.
746	*/
747	private static function store_static( string $html ): void {
748	$host = isset( $_SERVER['HTTP_HOST'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) : '';
749	$uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
750	$host = preg_replace( '/[^a-zA-Z0-9.\-]/', '', $host );
751	$uri = str_replace( "\0", '', $uri );
752	$uri = (string) strtok( $uri, '?' );
753	if ( '' === $host \|\| '' === $uri ) {
754	return;
755	}
756	// Collapse any traversal sequences before path resolution.
757	$uri = preg_replace( '#/+#', '/', $uri );
758	if ( false !== strpos( $uri, '..' ) ) {
759	return;
760	}
761
762	$base = rtrim( XSPEED_CACHE_STATIC_DIR, '/' );
763	$dir = $base . '/' . $host . rtrim( $uri, '/' );
764	$file = $dir . '/index.html';
765
766	// Resolve the parent against the cache root to be sure the
767	// final path is inside our tree even if the OS does anything
768	// funny with multi-byte sequences.
769	$base_real = realpath( WP_CONTENT_DIR );
770	if ( false === $base_real \|\| 0 !== strpos( $base, $base_real ) ) {
771	return;
772	}
773
774	if ( ! file_exists( $dir ) ) {
775	wp_mkdir_p( $dir );
776	}
777	if ( ! is_dir( $dir ) ) {
778	return;
779	}
780	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- Same rationale as the flat-hash cache write above: WP_Filesystem isn't available on frontend requests, and the cache write must happen during shutdown.
781	$written = file_put_contents( $file, $html, LOCK_EX );
782
783	if ( false !== $written ) {
784	/**
785	* Fires after a static cache file (index.html) is written.
786	*
787	* The extension point for serving pre-compressed siblings:
788	* the xspeed-pro Brotli module writes `index.html.br` next to
789	* the file here so the web server's static rewrite can serve a
790	* Brotli copy to clients that advertise `Accept-Encoding: br`,
791	* falling back to GZIP / the plain file otherwise. No core
792	* behavior depends on a listener being present.
793	*
794	* @param string $file Absolute path to the static cache file just written.
795	* @param string $html The HTML written to it.
796	*/
797	do_action( 'xspeed_static_file_written', $file, $html );
798	}
799	}
800
801	/**
802	* Write the .meta sidecar for a cache entry when the response carries
803	* anything the HIT path must replay beyond a plain 200 text/html:
804	* - a non-HTML Content-Type (cached feeds → application/rss+xml,
805	* sitemaps → text/xml, …), and/or
806	* - a non-200 status (a cached 404 must serve 404, not 200).
807	*
808	* Ordinary 200 text/html pages get NO .meta file, so the common path
809	* stays a single write.
810	*
811	* @param string $key Cache key for the current request.
812	*/
813	/**
814	* True only for a plain 200 text/html response — the only kind the
815	* web-server static tree can serve correctly (it streams the .html with
816	* no PHP, so it can't replay a 404 status or a feed Content-Type). Used
817	* to gate store_static() so cached 404s / feeds stay on the replay-capable
818	* drop-in / PHP path. (FBS-82406, FBS-82407)
819	*/
820	private static function response_is_plain_html(): bool {
821	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
822	if ( 200 !== $status && $status > 0 ) {
823	return false;
824	}
825	foreach ( headers_list() as $header ) {
826	if ( 0 === stripos( $header, 'content-type:' ) ) {
827	$ct = trim( substr( $header, strlen( 'content-type:' ) ) );
828	if ( '' !== $ct && false === stripos( $ct, 'text/html' ) ) {
829	return false;
830	}
831	}
832	}
833	return true;
834	}
835
836	private static function write_meta( string $key ): void {
837	$content_type = '';
838	foreach ( headers_list() as $header ) {
839	if ( 0 === stripos( $header, 'content-type:' ) ) {
840	$content_type = trim( substr( $header, strlen( 'content-type:' ) ) );
841	}
842	}
843	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
844
845	$meta = array();
846	$is_default_type = ( '' === $content_type \|\| false !== stripos( $content_type, 'text/html' ) );
847	if ( ! $is_default_type ) {
848	$meta['content_type'] = $content_type;
849	}
850	if ( 200 !== $status && $status > 0 ) {
851	$meta['status'] = $status;
852	}
853
854	// Per-content TTL (seconds). The drop-in and static fast paths can't
855	// call is_expired() / the xspeed_cache_max_age filter (they run before
856	// WP), so persist the resolved max-age here whenever it differs from
857	// the plain page TTL — e.g. the Pro feed cache's 12h vs the 24h page
858	// default. The fast paths read this to expire correctly. (FBS-82407)
859	$opts = Settings_Manager::get( 'cache' );
860	$default_ttl = (int) $opts['cache_expiry'] * HOUR_IN_SECONDS;
861	$ttl = (int) apply_filters( 'xspeed_cache_max_age', $default_ttl );
862	if ( $ttl > 0 && $ttl !== $default_ttl ) {
863	$meta['ttl'] = $ttl;
864	}
865
866	// Nothing to replay → no sidecar.
867	if ( empty( $meta ) ) {
868	return;
869	}
870
871	$payload = wp_json_encode( $meta );
872	if ( false === $payload ) {
873	return;
874	}
875	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- our own cache dir; WP_Filesystem needs admin creds unavailable on a frontend shutdown write.
876	file_put_contents( self::cache_meta_for( $key ), $payload, LOCK_EX );
877	}
878
879	/**
880	* @param string $cause Free-form human reason. Recorded in the
881	* Activity log to give users context (e.g.
882	* 'post saved', 'settings change', 'manual',
883	* 'theme switch').
884	*/
885	/**
886	* Purge the cache entries for ONE URL — every variant of it: the
887	* flat-hash entry (+ .meta / .html.br siblings), both device buckets
888	* (mobile_separate keys them separately), both trailing-slash forms,
889	* and the static-tree index.html (+ .br) the server rewrite serves.
890	* The rest of the cache is untouched — this is the surgical
891	* alternative to purge_all for "I just edited this one page".
892	*
893	* @param string $url Absolute URL, or site-relative path ("/about/").
894	* @param string $cause Who asked, for the purge log. See purge_all().
895	* @return int Number of cache files removed.
896	*/
897	public static function purge_url( string $url, string $cause = 'manual' ): int {
898	$parts = function_exists( 'wp_parse_url' ) ? wp_parse_url( $url ) : parse_url( $url ); // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- fallback for early-boot contexts only.
899	if ( ! is_array( $parts ) ) {
900	return 0;
901	}
902	$host = isset( $parts['host'] ) ? strtolower( (string) $parts['host'] ) : '';
903	if ( '' === $host && function_exists( 'home_url' ) ) {
904	$home = function_exists( 'wp_parse_url' ) ? wp_parse_url( home_url( '/' ) ) : parse_url( home_url( '/' ) ); // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- see above.
905	$host = is_array( $home ) && isset( $home['host'] ) ? strtolower( (string) $home['host'] ) : '';
906	}
907	if ( '' === $host ) {
908	return 0;
909	}
910	$path = isset( $parts['path'] ) ? (string) $parts['path'] : '/';
911	$path = '/' . ltrim( $path, '/' );
912	if ( false !== strpos( $path, '..' ) ) {
913	return 0;
914	}
915
916	// The cache key preserves REQUEST_URI's trailing-slash form, so
917	// purge both. Root stays a single '/'.
918	$forms = array( $path );
919	if ( '/' !== $path ) {
920	$forms[] = rtrim( $path, '/' );
921	$forms[] = rtrim( $path, '/' ) . '/';
922	}
923	$forms = array_unique( $forms );
924
925	$count = 0;
926	foreach ( $forms as $uri ) {
927	// '' = mobile_separate off; '\|m' / '\|d' = the device buckets.
928	foreach ( array( '', '\|m', '\|d' ) as $device ) {
929	$key = md5( $host . $uri . $device );
930	$file = self::cache_file_for( $key );
931	if ( is_file( $file ) ) {
932	wp_delete_file( $file );
933	++$count;
934	}
935	foreach ( array( XSPEED_CACHE_DIR . '/' . $key . '.meta', $file . '.br' ) as $sidecar ) {
936	if ( is_file( $sidecar ) ) {
937	wp_delete_file( $sidecar );
938	}
939	}
940	}
941	}
942
943	// Static tree (served directly by the nginx/.htaccess rewrite).
944	if ( defined( 'XSPEED_CACHE_STATIC_DIR' ) ) {
945	$dir = rtrim( XSPEED_CACHE_STATIC_DIR, '/' ) . '/' . $host . ( '/' === $path ? '' : rtrim( $path, '/' ) );
946	$file = $dir . '/index.html';
947	if ( is_file( $file ) ) {
948	wp_delete_file( $file );
949	++$count;
950	}
951	if ( is_file( $file . '.br' ) ) {
952	wp_delete_file( $file . '.br' );
953	}
954	}
955
956	if ( $count > 0 ) {
957	Cache_Inventory::invalidate();
958	Activity_Log::record(
959	'cache_purge_url',
960	sprintf(
961	/* translators: 1: cause of the purge, 2: URL or path, 3: number of files removed. */
962	__( 'Purged one URL (%1$s) — %2$s, %3$d file(s) removed', 'xspeed' ),
963	$cause,
964	$host . $path,
965	$count
966	),
967	Activity_Log::INFO
968	);
969	}
970
971	return $count;
972	}
973
974	public static function purge_all( string $cause = 'manual' ) {
975	$count = 0;
976	if ( is_dir( XSPEED_CACHE_DIR ) ) {
977	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
978	if ( $files ) {
979	$count = count( $files );
980	foreach ( $files as $f ) {
981	wp_delete_file( $f );
982	}
983	}
984	// Remove the .meta sidecars (content-type for feeds/sitemaps)
985	// alongside their .html entries. Not counted — they're not
986	// cache "pages", just per-entry metadata.
987	$meta = glob( XSPEED_CACHE_DIR . '/*.meta' );
988	if ( $meta ) {
989	foreach ( $meta as $m ) {
990	wp_delete_file( $m );
991	}
992	}
993	// Remove precompressed siblings (e.g. <key>.html.br from the Pro
994	// Brotli module). Not counted — same as .meta. Without this a
995	// purge leaves stale .br bodies behind: disk bloat, and a
996	// staleness window if precompression is later disabled.
997	$br = glob( XSPEED_CACHE_DIR . '/*.br' );
998	if ( $br ) {
999	foreach ( $br as $b ) {
1000	wp_delete_file( $b );
1001	}
1002	}
1003	}
1004	// Static-cache tree purge — recursive because the layout is
1005	// xspeed-static/{host}/{path}/index.html, so a flat glob can't
1006	// reach everything.
1007	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
1008	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1009	}
1010	// REST response cache (cache/xspeed/rest/*.json) — same purge
1011	// triggers (publish, settings change) invalidate it too.
1012	$count += Rest_Cache::purge();
1013
1014	// Minified + combined CSS/JS (cache/xspeed/min/ and min/combined/).
1015	// purge_all is a full filesystem sweep and must clear these too, even
1016	// when the Minify module is currently disabled — orphaned min/ files
1017	// from a feature the user later turned off must still be removed, and
1018	// a stale combined-<hash>.css that the regenerated page no longer
1019	// references otherwise 404s and breaks the frontend. (FBS-83114/83116)
1020	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
1021	Minifier::purge_minified();
1022	}
1023
1024	// Persistent object cache (Redis / Memcached). Flush regardless of
1025	// whether the Object Cache module is currently enabled — a drop-in
1026	// installed earlier keeps serving until flushed.
1027	if ( function_exists( 'wp_cache_flush' ) ) {
1028	wp_cache_flush();
1029	}
1030
1031	self::update_stats( array( 'last_purge' => time() ) );
1032
1033	// Fire AFTER the local sweep so module listeners (Critical CSS,
1034	// Unused CSS, Cloudflare edge purge) run — this action had three
1035	// registered listeners but was never emitted. Treat it as additive
1036	// (CDN / edge invalidation), not the mechanism for clearing local
1037	// files. (FBS-83114)
1038	do_action( 'xspeed_after_purge_all', $cause );
1039
1040	// The list behind the "Cached pages" card is memoized for a minute;
1041	// a purge has to drop it or the drill-down shows pages that no
1042	// longer exist.
1043	Cache_Inventory::invalidate();
1044
1045	// Trigger of WP_CLI / hook / admin-bar purges all hit the same
1046	// path. Record once with the supplied cause so the dashboard
1047	// activity feed reads naturally.
1048	Activity_Log::record(
1049	'cache_purged',
1050	sprintf( 'Cache purged (%s) — %d file%s removed', $cause, $count, 1 === $count ? '' : 's' ),
1051	Activity_Log::INFO
1052	);
1053
1054	return $count;
1055	}
1056
1057	/**
1058	* The per-type purge menu, LiteSpeed-style. Each entry is a cache type
1059	* the user can purge individually from the admin-bar dropdown. `visible`
1060	* controls whether the item shows (active + licensed module only) — it
1061	* NEVER limits Purge All, which always sweeps everything on disk.
1062	*
1063	* Pro registers its own types (Critical CSS, Unused CSS, …) by filtering
1064	* `xspeed_purge_types`, so Free degrades gracefully when Pro is absent.
1065	*
1066	* @return array<string,array{label:string,visible:bool}>
1067	*/
1068	public static function purge_types(): array {
1069	$minify_on = false;
1070	if ( class_exists( '\\XSpeed\\Settings_Manager' ) ) {
1071	$min = Settings_Manager::get( 'minify' );
1072	$minify_on = ! empty( $min['minify_css'] ) \|\| ! empty( $min['minify_js'] ) \|\| ! empty( $min['combine_css'] ) \|\| ! empty( $min['combine_js'] );
1073	}
1074	// Object cache is "active" when an external object-cache drop-in is in
1075	// use — the canonical WP signal, independent of our settings option.
1076	$oc_on = function_exists( 'wp_using_ext_object_cache' ) && wp_using_ext_object_cache();
1077
1078	$types = array(
1079	'all' => array(
1080	'label' => __( 'Purge All', 'xspeed' ),
1081	'visible' => true,
1082	),
1083	'page' => array(
1084	'label' => __( 'Purge Page / Static Cache', 'xspeed' ),
1085	'visible' => true,
1086	),
1087	'assets' => array(
1088	'label' => __( 'Purge CSS / JS Cache', 'xspeed' ),
1089	'visible' => $minify_on,
1090	),
1091	'object' => array(
1092	'label' => __( 'Purge Object Cache', 'xspeed' ),
1093	'visible' => $oc_on,
1094	),
1095	'rest' => array(
1096	'label' => __( 'Purge REST Cache', 'xspeed' ),
1097	'visible' => true,
1098	),
1099	);
1100
1101	/**
1102	* Filter the admin-bar purge-type menu. Pro modules add their own
1103	* (Critical CSS, Unused CSS, CDN). Adding a type here only adds a
1104	* MENU item — purge_type() must know how to handle the same slug.
1105	*
1106	* @param array $types Map of slug => [label, visible].
1107	*/
1108	return (array) apply_filters( 'xspeed_purge_types', $types );
1109	}
1110
1111	/**
1112	* Purge a single cache type by slug. 'all' delegates to purge_all();
1113	* every other slug clears just its own artifacts. Unknown slugs (e.g. a
1114	* Pro type) fan out via the `xspeed_purge_type_{slug}` action so the
1115	* owning module can handle it. Returns the number of items removed where
1116	* countable.
1117	*
1118	* @param string $type Cache type slug.
1119	* @param string $cause Who asked. Threaded through so the purge log can
1120	* tell an AI assistant's purge apart from a click —
1121	* "the cache cleared four times today" is only
1122	* actionable once you know what kept clearing it.
1123	*/
1124	public static function purge_type( string $type, string $cause = 'manual' ): int {
1125	switch ( $type ) {
1126	case 'all':
1127	return self::purge_all( $cause );
1128
1129	case 'page':
1130	$count = 0;
1131	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1132	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.html' ) as $f ) {
1133	wp_delete_file( $f );
1134	++$count;
1135	}
1136	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.meta' ) as $m ) {
1137	wp_delete_file( $m );
1138	}
1139	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.br' ) as $b ) {
1140	wp_delete_file( $b );
1141	}
1142	}
1143	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
1144	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1145	}
1146	self::update_stats( array( 'last_purge' => time() ) );
1147	Cache_Inventory::invalidate();
1148	self::record_partial_purge( 'page', $cause, $count );
1149	return $count;
1150
1151	case 'assets':
1152	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
1153	Minifier::purge_minified();
1154	}
1155	self::record_partial_purge( 'assets', $cause, null );
1156	return 0;
1157
1158	case 'object':
1159	if ( function_exists( 'wp_cache_flush' ) ) {
1160	wp_cache_flush();
1161	}
1162	self::record_partial_purge( 'object cache', $cause, null );
1163	return 0;
1164
1165	case 'rest':
1166	$count = Rest_Cache::purge();
1167	self::record_partial_purge( 'REST responses', $cause, $count );
1168	return $count;
1169
1170	default:
1171	// Pro / third-party type — let the owning module handle it.
1172	do_action( 'xspeed_purge_type_' . $type );
1173	self::record_partial_purge( $type, $cause, null );
1174	return 0;
1175	}
1176	}
1177
1178	/**
1179	* Log a partial purge so the drill-down behind "Last purge" shows every
1180	* clear, not only the full ones. Without this a site whose object cache
1181	* is flushed on a schedule looks, from the log, like nothing happens.
1182	*
1183	* @param string $what Human label for the slice purged.
1184	* @param string $cause Who asked.
1185	* @param int\|null $count Items removed, when countable.
1186	*/
1187	private static function record_partial_purge( string $what, string $cause, ?int $count ): void {
1188	$message = null === $count
1189	? sprintf(
1190	/* translators: 1: what was purged, 2: cause of the purge. */
1191	__( 'Purged %1$s (%2$s)', 'xspeed' ),
1192	$what,
1193	$cause
1194	)
1195	: sprintf(
1196	/* translators: 1: what was purged, 2: cause of the purge, 3: number of files removed. */
1197	__( 'Purged %1$s (%2$s) — %3$d file(s) removed', 'xspeed' ),
1198	$what,
1199	$cause,
1200	$count
1201	);
1202
1203	Activity_Log::record( 'cache_purged', $message, Activity_Log::INFO );
1204	}
1205
1206	/**
1207	* Recursively delete every `index.html` (and its precompressed
1208	* `index.html.br` sibling, if the Pro Brotli module wrote one) plus
1209	* empty directories inside the static-cache tree. Used by purge_all().
1210	* Returns the number of .html files removed so purge stats stay accurate
1211	* across the flat + static caches — .br siblings are not counted
1212	* (they're encodings of a page, not pages).
1213	*/
1214	private static function rmtree_html( string $dir ): int {
1215	if ( ! is_dir( $dir ) ) {
1216	return 0;
1217	}
1218	$removed = 0;
1219	// SCANDIR_SORT_NONE skips alphabetic sort — we're going to walk
1220	// the whole tree regardless of order.
1221	$entries = @scandir( $dir, SCANDIR_SORT_NONE ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
1222	if ( false === $entries ) {
1223	return 0;
1224	}
1225	foreach ( $entries as $entry ) {
1226	if ( '.' === $entry \|\| '..' === $entry ) {
1227	continue;
1228	}
1229	$path = $dir . '/' . $entry;
1230	if ( is_dir( $path ) ) {
1231	$removed += self::rmtree_html( $path );
1232	// Best-effort empty-dir cleanup; ignore failures (a
1233	// foreign file inside would block rmdir, which is fine).
1234	// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged, WordPress.WP.AlternativeFunctions.file_system_operations_rmdir -- Best-effort empty-dir cleanup; WP_Filesystem needs admin credentials we don't have during a normal purge.
1235	@rmdir( $path );
1236	continue;
1237	}
1238	if ( substr( $entry, -5 ) === '.html' ) {
1239	wp_delete_file( $path );
1240	++$removed;
1241	} elseif ( substr( $entry, -3 ) === '.br' ) {
1242	// Precompressed sibling (index.html.br). Remove it too so a
1243	// purge doesn't orphan stale Brotli bodies. Not counted.
1244	wp_delete_file( $path );
1245	}
1246	}
1247	return $removed;
1248	}
1249
1250	/**
1251	* Drop a "silence is golden" index.php into a directory so apaches/nginx
1252	* with directory listing enabled don't expose cache contents.
1253	*/
1254	public static function write_silence( $dir ) {
1255	$file = trailingslashit( $dir ) . 'index.php';
1256	if ( ! file_exists( $file ) ) {
1257	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- WP_Filesystem requires admin context for credentials; cache dir setup may run during a frontend page render.
1258	file_put_contents( $file, "<?php\n// Silence is golden.\n" );
1259	}
1260	}
1261
1262	/**
1263	* Persist stats with autoload disabled — stats are only read in admin
1264	* contexts, so there is no reason to inflate every frontend request's
1265	* `wp_load_alloptions()` payload.
1266	*/
1267	private static function update_stats( array $stats ) {
1268	if ( false === get_option( 'xspeed_stats' ) ) {
1269	add_option( 'xspeed_stats', $stats, '', 'no' );
1270	return;
1271	}
1272	update_option( 'xspeed_stats', $stats );
1273	}
1274
1275	public static function get_stats() {
1276	$count = 0;
1277	$size = 0;
1278	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1279	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
1280	if ( $files ) {
1281	$count = count( $files );
1282	foreach ( $files as $f ) {
1283	$size += filesize( $f );
1284	}
1285	}
1286	}
1287	// Drain the HIT-log file BEFORE reading totals. Two serve paths that
1288	// bypass the normal in-PHP record_hit() append one line per HIT here:
1289	// the nginx server-level rewrite (see nginx_snippet(), never reaches
1290	// PHP) and the advanced-cache.php drop-in (runs pre-WordPress, can't
1291	// reach Hit_Counter). Without this drain both look like a 0% hit-ratio
1292	// on a perfectly working cache.
1293	Hit_Counter::collect_nginx_log_hits();
1294
1295	// Apache/LiteSpeed static-rewrite HITs are served straight from disk
1296	// by .htaccess and never reach PHP either — but there's no .htaccess
1297	// equivalent of nginx's access_log directive, so we count them by
1298	// scanning the web server's own access log incrementally. No-op when
1299	// the log isn't readable (managed hosts) — see the method docblock.
1300	Hit_Counter::collect_server_log_hits();
1301
1302	$stats = get_option( 'xspeed_stats', array() );
1303	$totals = Hit_Counter::totals_24h();
1304	return array(
1305	'cached_pages' => $count,
1306	'cache_size' => $size,
1307	'last_purge' => isset( $stats['last_purge'] ) ? (int) $stats['last_purge'] : 0,
1308	// Rolling 24h cache performance — sourced from Hit_Counter's
1309	// hourly buckets. The frontend uses hit_ratio to drive the
1310	// CacheHero stat grid + the Health module's panel.
1311	'hits_24h' => $totals['hits'],
1312	'misses_24h' => $totals['misses'],
1313	'hit_ratio' => $totals['ratio'],
1314	);
1315	}
1316
1317	/**
1318	* Apply the user's enable/disable choice. Called only from the REST
1319	* toggle endpoint, which is gated by current_user_can( 'manage_options' )
1320	* and a verified REST nonce. This is the only place the drop-in and
1321	* the WP_CACHE constant are written — they MUST NOT happen on
1322	* register_activation_hook (WordPress.org review requirement).
1323	*
1324	* @param bool $enable User's choice.
1325	* @return array{
1326	* enabled: bool,
1327	* dropin_installed: bool,
1328	* wp_cache_constant: bool,
1329	* wp_config_writable: bool,
1330	* manual_snippet: ?string
1331	* }
1332	*/
1333	public static function toggle( $enable ) {
1334	$enable = (bool) $enable;
1335
1336	if ( $enable ) {
1337	$dropin_ok = self::install_dropin();
1338	$wp_config_ok = self::set_wp_cache_constant( true );
1339	$rewrite_ok = self::install_rewrite();
1340	self::ensure_hits_log_file();
1341	self::sync_mobile_flag();
1342	$snippet = $wp_config_ok ? null : "define( 'WP_CACHE', true );";
1343
1344	Activity_Log::record(
1345	'cache_enabled_event',
1346	$wp_config_ok
1347	? 'Cache enabled. Drop-in installed, WP_CACHE constant set.'
1348	: 'Cache enabled. Drop-in installed; wp-config.php not writable — add the WP_CACHE snippet manually.',
1349	$wp_config_ok ? Activity_Log::SUCCESS : Activity_Log::WARN
1350	);
1351
1352	return array(
1353	'enabled' => true,
1354	'dropin_installed' => (bool) $dropin_ok,
1355	'wp_cache_constant' => (bool) $wp_config_ok,
1356	'rewrite_installed' => (bool) $rewrite_ok,
1357	'wp_config_writable' => self::wp_config_writable(),
1358	'manual_snippet' => $snippet,
1359	'nginx_snippet' => self::nginx_snippet(),
1360	// Unified server-block snippet aggregating every enabled
1361	// module's directives — the same value the dashboard and
1362	// Health insight render. The wizard shows this so all three
1363	// surfaces stay in lockstep. Null on non-nginx hosts.
1364	'nginx_server_block' => self::full_nginx_server_block(),
1365	);
1366	}
1367
1368	self::remove_dropin();
1369	self::set_wp_cache_constant( false );
1370	self::remove_rewrite();
1371	// Drop the device-bucket marker too — with the drop-in gone there's
1372	// nothing left to read it, and leaving it behind would dirty a fresh
1373	// re-enable (and leaks across test runs).
1374	self::sync_mobile_flag( false );
1375
1376	Activity_Log::record(
1377	'cache_disabled_event',
1378	'Cache disabled. Drop-in removed.',
1379	Activity_Log::INFO
1380	);
1381
1382	return array(
1383	'enabled' => false,
1384	'dropin_installed' => false,
1385	'wp_cache_constant' => false,
1386	'rewrite_installed' => false,
1387	'wp_config_writable' => self::wp_config_writable(),
1388	'manual_snippet' => null,
1389	'nginx_snippet' => self::nginx_snippet(),
1390	'nginx_server_block' => self::full_nginx_server_block(),
1391	);
1392	}
1393
1394	/**
1395	* Check wp-config.php writability via WP_Filesystem. Plugin Check flags
1396	* direct is_writable() under WordPress.WP.AlternativeFunctions.
1397	*/
1398	private static function wp_config_writable() {
1399	global $wp_filesystem;
1400	if ( ! function_exists( 'WP_Filesystem' ) ) {
1401	require_once ABSPATH . 'wp-admin/includes/file.php';
1402	}
1403	WP_Filesystem();
1404
1405	return $wp_filesystem ? (bool) $wp_filesystem->is_writable( ABSPATH . 'wp-config.php' ) : false;
1406	}
1407
1408	/**
1409	* Nginx server-block snippet mirroring the Apache rewrite block.
1410	* We never auto-write nginx config — it sits outside the WordPress
1411	* root and is owned by the server admin — but the dashboard
1412	* surfaces this snippet when nginx is detected so the admin can
1413	* paste it once and unlock the same PHP-bypass speedup we get on
1414	* Apache / LiteSpeed via .htaccess.
1415	*
1416	* Returns null when the server isn't nginx (no point showing it).
1417	*/
1418	/**
1419	* Create wp-content/cache/xspeed/hits.log as an empty file so the
1420	* server-level rewrite's `access_log` directive has somewhere to
1421	* write on first request. Idempotent — touches an existing file
1422	* without disturbing accumulated lines. Called from Cache::toggle()
1423	* on enable and from auto_heal() when the file is missing.
1424	*
1425	* Permissions matter here. The file is created by PHP-FPM (often uid
1426	* www-data), but the nginx process that appends HIT lines may run as a
1427	* DIFFERENT uid — on multi-container hosts (e.g. xclude/Kinsta: nginx in
1428	* its own container as uid `nginx`, PHP-FPM in another as `www-data`)
1429	* they don't share a user at all. A default-umask 0644 file is then
1430	* unwritable by nginx, the access_log write silently fails, and the
1431	* dashboard shows a 0% hit ratio even though static HITs are serving.
1432	* So we widen the dir to 0777 and the file to 0666 — group/other write —
1433	* so whatever uid nginx runs as can append. (The file holds only HIT
1434	* request lines, no secrets.)
1435	*/
1436	/**
1437	* Directory holding the nginx hit log. Lives under uploads/, NOT the
1438	* cache dir — uninstall.php and a cache purge both delete the cache
1439	* dir, which would orphan the pasted nginx `access_log` directive's
1440	* parent directory and make `nginx -t` fail [emerg], taking down every
1441	* vhost on the host (FBS-82478). uploads/ always exists, isn't a
1442	* plugin-managed cache dir, and is never deleted on uninstall — so the
1443	* directive's target dir survives both, and nginx (which creates a
1444	* missing log FILE but not a missing DIR) can always open it.
1445	*
1446	* Falls back to the cache dir only if uploads is somehow unavailable.
1447	*/
1448	public static function hits_log_dir(): string {
1449	if ( function_exists( 'wp_upload_dir' ) ) {
1450	$uploads = wp_upload_dir( null, false );
1451	if ( is_array( $uploads ) && empty( $uploads['error'] ) && ! empty( $uploads['basedir'] ) ) {
1452	return rtrim( (string) $uploads['basedir'], '/' ) . '/xspeed';
1453	}
1454	}
1455	return XSPEED_CACHE_DIR;
1456	}
1457
1458	/** Absolute path to the nginx hit log file. */
1459	public static function hits_log_path(): string {
1460	return self::hits_log_dir() . '/hits.log';
1461	}
1462
1463	/**
1464	* Sync the drop-in's mobile-bucket flag file with the `mobile_separate`
1465	* setting. The drop-in (advanced-cache.php) runs before WordPress loads,
1466	* so it can't read the option — instead it checks for a zero-byte
1467	* `.mobile-separate` marker next to the cache files. When the setting is
1468	* on we touch the marker; when off we remove it. The drop-in's cache_key
1469	* computation keys off the marker's presence so its '\|m'/'\|d' device
1470	* bucket stays in lockstep with Cache::cache_key().
1471	*
1472	* Without this, turning on mobile_separate made Cache::store() write keys
1473	* with a '\|d'/'\|m' suffix the drop-in never reproduced — so the drop-in's
1474	* file_exists() always missed, every HIT fell through to a full WP boot,
1475	* and the fast pre-WP path was silently dead.
1476	*
1477	* @param bool\|null $enabled Force a state; null reads the current setting.
1478	*/
1479	public static function sync_mobile_flag( $enabled = null ): void {
1480	if ( null === $enabled ) {
1481	$opts = Settings_Manager::get( 'cache' );
1482	$enabled = ! empty( $opts['mobile_separate'] );
1483	}
1484	$dir = XSPEED_CACHE_DIR;
1485	$flag = $dir . '/.mobile-separate';
1486	if ( $enabled ) {
1487	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1488	return;
1489	}
1490	if ( ! file_exists( $flag ) ) {
1491	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch, WordPress.PHP.NoSilencedErrors.Discouraged -- read by the pre-WP drop-in via file_exists(); must be a plain marker, not WP_Filesystem.
1492	@touch( $flag );
1493	}
1494	return;
1495	}
1496	if ( file_exists( $flag ) ) {
1497	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1498	@unlink( $flag );
1499	}
1500	}
1501
1502	/**
1503	* Write / remove the `.maintenance-active` sentinel next to the cache
1504	* files. The pre-WP drop-in checks for this marker and bails when present,
1505	* so a page cached while the site was live is NOT served during
1506	* maintenance / coming-soon mode — WordPress loads and renders the
1507	* maintenance screen instead. The Pro Maintenance-Cache module drives this
1508	* on the maintenance on/off transition. (FBS-82409 B1)
1509	*
1510	* @param bool $active True to arm the sentinel (entering maintenance),
1511	* false to clear it (site recovered).
1512	*/
1513	public static function sync_maintenance_flag( bool $active ): void {
1514	$dir = XSPEED_CACHE_DIR;
1515	$flag = $dir . '/.maintenance-active';
1516	if ( $active ) {
1517	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1518	return;
1519	}
1520	if ( ! file_exists( $flag ) ) {
1521	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch, WordPress.PHP.NoSilencedErrors.Discouraged -- read by the pre-WP drop-in via file_exists(); must be a plain marker, not WP_Filesystem.
1522	@touch( $flag );
1523	}
1524	return;
1525	}
1526	if ( file_exists( $flag ) ) {
1527	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1528	@unlink( $flag );
1529	}
1530	}
1531
1532	/**
1533	* Reconcile every mobile_separate-dependent artifact to the current
1534	* setting. Called on boot and whenever the cache settings are saved, so
1535	* flipping mobile_separate at runtime can't leave the install in a
1536	* half-converted state.
1537	*
1538	* Three things must agree with the setting:
1539	* 1. the drop-in's `.mobile-separate` flag (sync_mobile_flag()),
1540	* 2. the device-blind server rewrite — present only when OFF
1541	* (static_rewrite_allowed()),
1542	* 3. the now-stale static-cache tree + page cache, which were keyed
1543	* under the old scheme and would serve wrong-device HTML.
1544	*
1545	* No-ops when the cache is disabled — there's nothing installed to
1546	* reconcile, and toggle() handles install/teardown itself.
1547	*/
1548	public static function reconcile_mobile_separate(): void {
1549	self::sync_mobile_flag();
1550
1551	// The rewrite/static reconciliation below needs the plugin's path
1552	// constants. They're absent in early-boot / unit-test contexts where
1553	// only the drop-in flag matters — bail to the flag-only behavior then.
1554	if ( ! defined( 'XSPEED_CACHE_STATIC_DIR' ) ) {
1555	return;
1556	}
1557
1558	// Only touch the rewrite + caches when caching is actually on.
1559	$opts = get_option( 'xspeed_options', array() );
1560	if ( empty( $opts['cache_enabled'] ) ) {
1561	return;
1562	}
1563
1564	$rewrite_present = self::rewrite_installed();
1565	$rewrite_wanted = self::static_rewrite_allowed();
1566
1567	if ( $rewrite_present === $rewrite_wanted ) {
1568	// Already consistent — nothing flipped, leave caches intact so a
1569	// plain settings save (e.g. expiry change) doesn't blow the cache.
1570	return;
1571	}
1572
1573	// The setting flipped. Bring the rewrite into line and purge the
1574	// now-misbucketed cache so the next request re-primes under the new
1575	// device scheme.
1576	if ( $rewrite_wanted ) {
1577	self::install_rewrite();
1578	} else {
1579	self::remove_rewrite();
1580	}
1581	self::purge_all( 'mobile_separate changed' );
1582	}
1583
1584	/**
1585	* Whether the server-level static-rewrite fast path may be used.
1586	*
1587	* The rewrite serves `{host}{path}/index.html` straight from the web
1588	* server, keyed only by host + path — it has no way to run our PHP
1589	* device detection, so it can't tell mobile from desktop. When
1590	* `mobile_separate` is on, a single static file would be shared across
1591	* devices and whoever primed it wins (mobile visitors could get desktop
1592	* HTML, or vice-versa). Rather than duplicate a wp_is_mobile()-equivalent
1593	* UA matcher into .htaccess AND the nginx snippet (three copies that
1594	* would inevitably drift), we simply DON'T engage the static rewrite when
1595	* mobile_separate is on. Requests then fall through to the PHP drop-in,
1596	* which buckets correctly — a small TTFB cost (~85ms vs ~30ms) paid only
1597	* on mobile-separate sites, in exchange for guaranteed correctness.
1598	*
1599	* LiteSpeed exclusion (2026-06-16): on LiteSpeed — OpenLiteSpeed in
1600	* particular — `.htaccess` CAN run our RewriteRule to serve the static
1601	* file, but its `.htaccess` engine ignores `mod_headers`, so we cannot
1602	* stamp the served response with `X-XSpeed-Cache: HIT`, AND there is no
1603	* `.htaccess` equivalent of nginx's per-location `access_log` to record
1604	* the hit. The result was a cache that worked but was invisible: no HIT
1605	* header and a hit-ratio frozen near 0%. Every OTHER server gives the
1606	* user a visible HIT header + a counted hit (nginx via add_header +
1607	* access_log in its snippet; Apache via .htaccess mod_headers, which it
1608	* honors). To keep LiteSpeed CONSISTENT with the rest, we route its hits
1609	* through the PHP drop-in instead — the drop-in emits
1610	* `X-XSpeed-Cache: HIT (php)` and calls Hit_Counter inline, exactly the
1611	* observable behavior the other servers get. The cost is the drop-in's
1612	* ~30ms TTFB vs the static path's ~10ms, paid only on LiteSpeed; in
1613	* exchange the dashboard hit-ratio and the response header finally tell
1614	* the truth there. (Apache keeps the static fast path — it honors the
1615	* header.) See maybe_emit_lscache_headers() for the paired LSCache
1616	* stand-down that stops LiteSpeed's own module from shadowing the
1617	* drop-in.
1618	*/
1619	public static function static_rewrite_allowed(): bool {
1620	// LiteSpeed: drop-in serves hits (visible + counted) — see docblock.
1621	if ( Server::LITESPEED === Server::type() ) {
1622	return false;
1623	}
1624	$opts = Settings_Manager::get( 'cache' );
1625	return empty( $opts['mobile_separate'] );
1626	}
1627
1628	/**
1629	* Why the device-blind static rewrite is NOT installed, when it isn't.
1630	* Returns 'mobile_separate' when Separate Mobile Cache is the blocker
1631	* (the static file is one-per-URL, so it can't coexist with per-device
1632	* buckets), '' otherwise. Lets the dashboard explain the slow path
1633	* instead of silently falling back to PHP serving. (FBS-83145)
1634	*/
1635	public static function static_rewrite_block_reason(): string {
1636	if ( Server::LITESPEED === Server::type() ) {
1637	return ''; // Intended on LiteSpeed — not a "block".
1638	}
1639	$opts = Settings_Manager::get( 'cache' );
1640	return ! empty( $opts['mobile_separate'] ) ? 'mobile_separate' : '';
1641	}
1642
1643	/**
1644	* Whether migration flagged Separate Mobile Cache for user review. Set by
1645	* Migration::map_mobile_separate() when a source plugin (WP Rocket / WP
1646	* Super Cache / LiteSpeed) had its "separate mobile cache" option on: we
1647	* import it as OFF (to keep the device-blind static fast path) but record
1648	* this flag so the dashboard can invite the user to turn it back on only
1649	* if their site genuinely serves different HTML per device. (FBS-83145)
1650	*/
1651	public static function mobile_separate_needs_review(): bool {
1652	$opts = Settings_Manager::get( 'cache' );
1653	return ! empty( $opts['mobile_separate_review'] );
1654	}
1655
1656	/**
1657	* Clear the review flag — called when the user has acted on the prompt
1658	* (dismissed it, or turned Separate Mobile Cache on/off deliberately) so
1659	* the dashboard callout doesn't nag forever. Writes the option directly
1660	* (bypassing Settings_Manager) so it never touches schema fields.
1661	*/
1662	public static function clear_mobile_separate_review(): void {
1663	$stored = get_option( 'xspeed_module_cache', array() );
1664	if ( ! is_array( $stored ) \|\| empty( $stored['mobile_separate_review'] ) ) {
1665	return;
1666	}
1667	unset( $stored['mobile_separate_review'] );
1668	update_option( 'xspeed_module_cache', $stored );
1669	}
1670
1671	/**
1672	* On-demand probe: does the homepage serve materially the same HTML to a
1673	* desktop and a mobile browser? Fetches home_url() twice over loopback —
1674	* once with a desktop User-Agent, once with a mobile one — strips
1675	* per-request noise (nonces, CSRF tokens, session ids, inline timestamps),
1676	* and compares. When identical, Separate Mobile Cache is almost certainly
1677	* unnecessary and the user can turn it off to regain the static fast path.
1678	*
1679	* NEVER run automatically (no page-load cost) — only from the dashboard
1680	* "Check now" button. Result is cached for 10 minutes so a double-click or
1681	* a re-render doesn't fire two more self-requests. (FBS-83145)
1682	*
1683	* @return array{ identical:bool, checked:bool, reason?:string, desktop_bytes?:int, mobile_bytes?:int }
1684	*/
1685	public static function probe_mobile_equality(): array {
1686	$cached = get_transient( 'xspeed_mobile_equality_probe' );
1687	if ( is_array( $cached ) ) {
1688	return $cached;
1689	}
1690
1691	$home = home_url( '/' );
1692	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
1693	if ( '' === $host ) {
1694	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'home_url has no host' );
1695	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
1696	return $result;
1697	}
1698
1699	// Match WP core's own mobile detection (wp_is_mobile) so the probe
1700	// reflects what the site would actually branch on. iPhone Safari for
1701	// mobile; a current desktop Chrome UA for desktop.
1702	$desktop_ua = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36';
1703	$mobile_ua = 'Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Mobile/15E148 Safari/604.1';
1704
1705	$is_local = function_exists( 'wp_get_environment_type' )
1706	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
1707
1708	$fetch = static function ( string $ua ) use ( $home, $is_local ) {
1709	$resp = wp_remote_get(
1710	$home,
1711	array(
1712	'timeout' => 5,
1713	'sslverify' => ! $is_local,
1714	'redirection' => 2,
1715	// Bust any per-device cache so we compare freshly-rendered
1716	// HTML, and pass the device UA the site would branch on.
1717	'user-agent' => $ua,
1718	'headers' => array( 'Cache-Control' => 'no-cache' ),
1719	)
1720	);
1721	if ( is_wp_error( $resp ) \|\| 200 !== (int) wp_remote_retrieve_response_code( $resp ) ) {
1722	return null;
1723	}
1724	return (string) wp_remote_retrieve_body( $resp );
1725	};
1726
1727	$desktop = $fetch( $desktop_ua );
1728	$mobile = $fetch( $mobile_ua );
1729
1730	if ( null === $desktop \|\| null === $mobile ) {
1731	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'could not fetch homepage twice' );
1732	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
1733	return $result;
1734	}
1735
1736	$identical = self::normalize_html_for_diff( $desktop ) === self::normalize_html_for_diff( $mobile );
1737
1738	$result = array(
1739	'identical' => $identical,
1740	'checked' => true,
1741	'desktop_bytes' => strlen( $desktop ),
1742	'mobile_bytes' => strlen( $mobile ),
1743	);
1744	set_transient( 'xspeed_mobile_equality_probe', $result, 10 * MINUTE_IN_SECONDS );
1745	return $result;
1746	}
1747
1748	/**
1749	* Strip per-request noise from HTML so a desktop-vs-mobile diff reflects
1750	* real structural differences, not nonces / session ids / timestamps that
1751	* change on every render. Deliberately conservative: it normalizes the
1752	* handful of well-known noise sources and collapses whitespace, so a site
1753	* that truly serves different markup per device still compares as different.
1754	*/
1755	private static function normalize_html_for_diff( string $html ): string {
1756	$patterns = array(
1757	// WP nonces (data-nonce="...", _wpnonce=..., "nonce":"...").
1758	'/(_wpnonce\|nonce\|_ajax_nonce)["\']?\s[:=]\s["\']?[a-f0-9]{10}/i',
1759	// Generic 10+ hex tokens (CSRF, cache-buster hashes, session ids).
1760	'/\b[a-f0-9]{16,}\b/i',
1761	// wp-generated unique ids (e.g. wp-block ids, aria ids).
1762	'/(id\|for\|aria-[a-z]+)="[^"]*-[0-9]{3,}"/i',
1763	// ISO-ish timestamps + epoch-looking numbers in query strings.
1764	'/\?ver=[0-9.]+/',
1765	'/[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9:.+Z-]+/',
1766	);
1767	$html = (string) preg_replace( $patterns, 'X', $html );
1768	// Collapse all whitespace so trivial formatting differences don't count.
1769	return trim( (string) preg_replace( '/\s+/', ' ', $html ) );
1770	}
1771
1772	public static function ensure_hits_log_file(): bool {
1773	// The HITs log exists ONLY so a server-level nginx `access_log`
1774	// directive has a world-writable file to append to (see nginx_snippet()
1775	// + Hit_Counter::collect_nginx_log_hits()). On Apache/LiteSpeed/managed
1776	// hosts nothing writes it, so creating it — and, worse, chmod()-ing it
1777	// world-writable — is pointless AND fails with "Operation not permitted"
1778	// when PHP can't chmod files it doesn't own (a warning that surfaces in
1779	// logs that capture @-suppressed errors). Skip the whole thing off nginx.
1780	if ( Server::NGINX !== Server::type() ) {
1781	return false;
1782	}
1783	$dir = self::hits_log_dir();
1784	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1785	return false;
1786	}
1787	// Ensure the dir is traversable + writable by a different-uid nginx.
1788	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_chmod -- nginx (a separate uid in multi-container setups) must be able to create/append the log; WP_Filesystem layers ownership overrides that defeat that intent.
1789	@chmod( $dir, 0777 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort; the access_log just stays empty if it fails.
1790	$path = self::hits_log_path();
1791	if ( ! file_exists( $path ) ) {
1792	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch -- See docblock: must be a plain touch, not WP_Filesystem.
1793	@touch( $path ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-fatal helper; failures already covered by the dir check.
1794	}
1795	// World-writable so a different-uid nginx can append HIT lines.
1796	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_chmod -- See docblock.
1797	@chmod( $path, 0666 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort.
1798	return file_exists( $path );
1799	}
1800
1801	public static function nginx_snippet(): ?string {
1802	if ( Server::NGINX !== Server::type() ) {
1803	return null;
1804	}
1805	$rel = '/' . ltrim( str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR ), '/' );
1806	$rel = rtrim( $rel, '/' );
1807
1808	// WP-Rocket-canonical pattern: every condition lives at
1809	// SERVER level (outside any location block). Each one appends
1810	// a tag to $xspeed_no_cache; the final check is a single
1811	// string-equality against the unmodified default "no-cache".
1812	// Only when ALL conditions pass does the rewrite fire,
1813	// jumping the request to the static file's URL. nginx then
1814	// restarts location matching against the new path, where
1815	// regular static-file serving takes over.
1816	//
1817	// Why server-level + a single rewrite (instead of try_files
1818	// inside `location /`): nginx's well-documented "if is evil"
1819	// quirk silently disables `try_files`'s last fallback when
1820	// any `if` in the same location is true. Moving the `if`s
1821	// outside any location dodges the trap completely, because
1822	// server-level rewrite is the documented stable path.
1823	//
1824	// `last` (not `break`) restarts location matching — required
1825	// so the rewritten static-file URI gets served via the normal
1826	// static-file location, not re-matched against `location /`
1827	// where our own rewrite would loop.
1828	//
1829	// The cache existence check is the LAST condition in the
1830	// chain so when the file isn't cached, $xspeed_no_cache
1831	// gets a "-nofile" tag and the rewrite is skipped — the
1832	// request falls through to whatever `location /` the user
1833	// already had (typically `try_files $uri $uri/ /index.php?$args;`).
1834	// Absolute path to the hit-log file from the nginx process's
1835	// filesystem view. Nginx's `access_log buffer=N flush=Ns` form
1836	// requires a literal path — `$document_root` variables are
1837	// rejected — so PHP computes it. Lives under uploads/ (NOT the
1838	// cache dir): a cache purge or uninstall deletes the cache dir,
1839	// which would orphan this directive's parent directory and make
1840	// `nginx -t` fail [emerg] for EVERY vhost on the host
1841	// (FBS-82478). uploads/ survives both, so the directive can
1842	// never take nginx down. Works on every topology where the nginx
1843	// process shares a filesystem with PHP (container or host).
1844	$hits_abs = self::hits_log_path();
1845
1846	$lines = array();
1847	$lines[] = '# xSpeed static cache — paste at server level, above location / { }.';
1848	// Cache host must match the on-disk dir PHP writes: store_static() /
1849	// static_host() take HTTP_HOST and strip every char outside
1850	// [a-zA-Z0-9.\-] — i.e. it removes the colon but KEEPS the port digits
1851	// (localhost:8192 → localhost8192). nginx's own $host can't reproduce
1852	// that: $host has the port already stripped ENTIRELY (→ localhost), so
1853	// the -f check looks for localhost/... while PHP wrote localhost8192/...
1854	// and the rewrite never fires on a non-standard port. Derive
1855	// $xspeed_host from $http_host (which keeps the port) and drop just the
1856	// colon, so it equals the PHP dir on every port. On standard ports
1857	// $http_host has no colon, so $xspeed_host == $host == the bare domain.
1858	$lines[] = 'set $xspeed_host $http_host;'; // default: no port → unchanged (e.g. example.com)
1859	$lines[] = 'if ($http_host ~ "^([^:]+):(\\d+)$") { set $xspeed_host $1$2; }'; // host:port → hostport (matches PHP static_host())
1860	$lines[] = 'set $xspeed_no_cache "no-cache";';
1861	$lines[] = 'if ($request_method != GET) { set $xspeed_no_cache "$xspeed_no_cache-method"; }';
1862	$lines[] = 'if ($args) { set $xspeed_no_cache "$xspeed_no_cache-args"; }';
1863	$lines[] = 'if ($http_cookie ~* "(wordpress_logged_in\|comment_author\|wp-postpass_)") { set $xspeed_no_cache "$xspeed_no_cache-cookie"; }';
1864	$lines[] = 'if (!-f "$document_root' . $rel . '/$xspeed_host$uri/index.html") { set $xspeed_no_cache "$xspeed_no_cache-nofile"; }';
1865	// Neither `add_header` nor `access_log` is allowed inside an `if{}`
1866	// at server level (nginx rejects with "directive is not allowed
1867	// here"). The logging therefore lives in a `location` block that
1868	// matches the rewritten URI after `rewrite … last;` restarts
1869	// location matching. Every HIT lands there exactly once, every
1870	// MISS / PHP-served request never matches it.
1871	$lines[] = 'if ($xspeed_no_cache = "no-cache") {';
1872	$lines[] = ' rewrite ^ ' . $rel . '/$xspeed_host$uri/index.html last;';
1873	$lines[] = '}';
1874	$lines[] = '';
1875	$lines[] = '# Serve + log the cached HIT — `^~` is required so this beats any regex location.';
1876	$lines[] = 'location ^~ ' . $rel . '/ {';
1877	$lines[] = ' internal;';
1878	// LITERAL log path (not `set $var; access_log $var`). The variable form
1879	// makes nginx open the log lazily per-request and SILENTLY drop the
1880	// line if the open fails — so on a working host hits were served
1881	// (X-XSpeed-Cache fires regardless) but nothing was ever written and
1882	// the hit ratio sat at 0%. A literal path makes nginx open the file at
1883	// config load and actually log every hit.
1884	//
1885	// Deleting the log FILE is still safe with a literal path: nginx
1886	// recreates it on the next write/reload and `nginx -t` stays green
1887	// (verified). The only thing that [emerg]s `nginx -t` is a missing
1888	// parent DIRECTORY — and the log lives under uploads/xspeed/, which
1889	// survives cache purge + uninstall, and which ensure_hits_log_file()
1890	// (run on every admin_init via auto_heal) recreates if it ever goes
1891	// missing. So: hits are logged, and a user deleting the log can't take
1892	// nginx down.
1893	$lines[] = ' access_log ' . $hits_abs . ' combined buffer=16k flush=5s;';
1894	$lines[] = ' add_header X-XSpeed-Cache "HIT (nginx)" always;';
1895	$lines[] = '}';
1896	return implode( "\n", $lines );
1897	}
1898
1899	/**
1900	* Aggregate every enabled module's nginx_directives() into one
1901	* pasteable server-block snippet. Replaces the per-module "paste
1902	* this snippet" notices with a single consolidated paste — every
1903	* future feature toggle just regenerates this output.
1904	*
1905	* Returns null on non-nginx hosts (nothing to paste).
1906	*
1907	* Sections render in module-registration order so the layout stays
1908	* predictable; each module gets a comment header `# <slug>`.
1909	*/
1910	public static function full_nginx_server_block(): ?string {
1911	if ( Server::NGINX !== Server::type() ) {
1912	return null;
1913	}
1914
1915	$blocks = array();
1916	foreach ( Module_Registry::all() as $module ) {
1917	$directives = $module->nginx_directives();
1918	if ( ! is_string( $directives ) \|\| '' === trim( $directives ) ) {
1919	continue;
1920	}
1921	$blocks[] = "# === " . $module->slug() . " ===\n" . rtrim( $directives );
1922	}
1923
1924	if ( empty( $blocks ) ) {
1925	return null;
1926	}
1927
1928	$header = "# xSpeed unified nginx config — paste into `server { }`, above `location / { }`; re-paste after toggling features.\n";
1929
1930	return $header . "\n" . implode( "\n\n", $blocks ) . "\n";
1931	}
1932
1933	/**
1934	* Tell LiteSpeed's LSCache module to stand down on the cache-miss
1935	* render path.
1936	*
1937	* History: this method used to emit X-LiteSpeed-Cache-Control:
1938	* public,max-age=N + X-LiteSpeed-Tag, handing caching to the server's
1939	* LSCache store. That delegation backfired — once LSCache cached a
1940	* page it served every subsequent request from its OWN store and
1941	* intercepted the request before our site-root .htaccess static
1942	* rewrite could run. Net effect on LiteSpeed hosts: no X-XSpeed-Cache
1943	* header, our static-cache tree never served, the HIT log never
1944	* written (hit ratio frozen at 0%), and the Health probe reporting a
1945	* false "cache running on PHP fallback" because it never saw an
1946	* xSpeed-served response.
1947	*
1948	* xSpeed now owns the cache on LiteSpeed exactly as it does on Apache:
1949	* our `.htaccess` mod_rewrite block serves hits straight from the
1950	* static-cache tree (with the X-XSpeed-Cache header + access-log HIT
1951	* accounting), and PHP/the drop-in is the fallback. To guarantee
1952	* LSCache doesn't shadow that with its own copy — some LiteSpeed
1953	* configs cache by default — we send an explicit `no-cache` control so
1954	* the server defers to our rewrite. Skipped when the LiteSpeed Cache
1955	* plugin is active (it owns its own header policy; our Conflict
1956	* registry handles that coexistence separately).
1957	*/
1958	public static function maybe_emit_lscache_headers(): void {
1959	if ( headers_sent() ) {
1960	return;
1961	}
1962	if ( Server::LITESPEED !== Server::type() ) {
1963	return;
1964	}
1965	// is_plugin_active() lives in wp-admin/includes/plugin.php which
1966	// isn't auto-loaded on front-end requests. Use the option layer
1967	// directly to avoid pulling in admin code from a render path.
1968	$active = (array) get_option( 'active_plugins', array() );
1969	if ( in_array( 'litespeed-cache/litespeed-cache.php', $active, true ) ) {
1970	return;
1971	}
1972
1973	// Explicitly opt this response OUT of LSCache so the server can't
1974	// shadow our static-rewrite cache with its own internal copy.
1975	header( 'X-LiteSpeed-Cache-Control: no-cache' );
1976	}
1977
1978	/**
1979	* Reconcile drop-in + WP_CACHE + rewrite block with the user's
1980	* saved choice. Runs on admin_init. Cheap when nothing's wrong
1981	* (one option read + a handful of file_exists / defined checks);
1982	* writes only when state has drifted (typical cause: plugin
1983	* upgrade wiped the drop-in, foreign plugin removed our WP_CACHE
1984	* define, or someone hand-edited .htaccess).
1985	*
1986	* Skipped during the WP plugin updater run so we don't race
1987	* the upgrader's own filesystem operations.
1988	*/
1989	public static function auto_heal(): void {
1990	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
1991	return;
1992	}
1993	if ( wp_doing_ajax() \|\| wp_doing_cron() ) {
1994	return;
1995	}
1996
1997	$opts = get_option( 'xspeed_options', array() );
1998	if ( empty( $opts['cache_enabled'] ) ) {
1999	return;
2000	}
2001
2002	$dropin_target = WP_CONTENT_DIR . '/advanced-cache.php';
2003	$dropin_ours = false;
2004	$dropin_stale = false;
2005	if ( file_exists( $dropin_target ) ) {
2006	$contents = @file_get_contents( $dropin_target ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2007	$dropin_ours = is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' );
2008	// Reinstall when OUR drop-in is an older version than the source —
2009	// the marker alone can't distinguish an old copy from a new one, so
2010	// a serve-logic change (e.g. the .meta read for 404s/feeds) would
2011	// otherwise never reach existing cache-enabled sites until a manual
2012	// cache toggle. (FBS-82406/82407)
2013	if ( $dropin_ours ) {
2014	$dropin_stale = self::dropin_version( (string) $contents ) < self::dropin_version( @file_get_contents( XSPEED_DIR . 'includes/advanced-cache.php' ) ?: '' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2015	}
2016	}
2017
2018	if ( ! $dropin_ours \|\| $dropin_stale ) {
2019	self::install_dropin();
2020	}
2021
2022	if ( ! defined( 'WP_CACHE' ) \|\| ! WP_CACHE ) {
2023	self::set_wp_cache_constant( true );
2024	}
2025
2026	// Rewrite block goes last. It's what turns the static-cache
2027	// tree into a PHP-bypass — every cache hit served by the web
2028	// server directly. Without it we still cache, just at drop-in
2029	// speed (~85ms TTFB) instead of static-file speed (~25-40ms).
2030	//
2031	// Reconcile against mobile_separate: the rewrite is device-blind, so
2032	// it must be ABSENT when mobile_separate is on and PRESENT otherwise.
2033	// auto_heal() runs periodically, so it also repairs a rewrite that
2034	// was left installed before mobile_separate was switched on.
2035	if ( self::static_rewrite_allowed() ) {
2036	if ( ! self::rewrite_installed() ) {
2037	self::install_rewrite();
2038	}
2039	} elseif ( self::rewrite_installed() ) {
2040	self::remove_rewrite();
2041	}
2042
2043	// HITs log file — nginx writes one line per HIT served directly
2044	// (see nginx_snippet()), Cache::get_stats() drains the file via
2045	// Hit_Counter::collect_nginx_log_hits(). If the file vanishes
2046	// (plugin upgrade wiped wp-content/cache/), nginx errors silently
2047	// on the access_log directive and the counter stays at 0.
2048	self::ensure_hits_log_file();
2049	}
2050
2051	/**
2052	* Build the .htaccess rules that map cacheable requests to the
2053	* static-cache tree. Conditions are deliberately strict: GET only,
2054	* empty query string, no session/comment-author/post-password
2055	* cookie, and the static file must exist on disk. Anything that
2056	* fails one of these falls through to PHP and the drop-in / full
2057	* WordPress path.
2058	*
2059	* @return string[] Lines for insert_with_markers().
2060	*/
2061	public static function rewrite_block_lines(): array {
2062	// Path relative to ABSPATH so the rule lives in the site-root
2063	// .htaccess regardless of where wp-content sits. WP_CONTENT_DIR
2064	// can be moved, so we compute the document-root-relative form
2065	// at install time and bake it into the rule.
2066	$rel = str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR );
2067	$rel = '/' . ltrim( $rel, '/' );
2068	$rel = rtrim( $rel, '/' );
2069
2070	return array(
2071	'<IfModule mod_rewrite.c>',
2072	' RewriteEngine On',
2073	' RewriteCond %{REQUEST_METHOD} ^GET$',
2074	' RewriteCond %{QUERY_STRING} ^$',
2075	' RewriteCond %{HTTP_COOKIE} !(wordpress_logged_in\|comment_author\|wp-postpass_) [NC]',
2076	// Capture REQUEST_URI without its trailing slash into %1.
2077	// store_static() writes `{host}{uri-without-trailing-slash}/index.html`,
2078	// so this normalization lets `/blog/` and `/blog` both hit
2079	// the same cache file without producing the double-slash
2080	// path that would skip the -f check below.
2081	' RewriteCond %{REQUEST_URI} ^(.*?)/?$',
2082	' RewriteCond %{DOCUMENT_ROOT}' . $rel . '/%{HTTP_HOST}%1/index.html -f',
2083	// Pattern is `^`, NOT `.`. The per-directory rewrite engine
2084	// strips the leading slash before matching, so the HOMEPAGE
2085	// request `/` arrives here as an EMPTY path. `.` requires at
2086	// least one character and therefore never matches the homepage
2087	// — on LiteSpeed (which honors this strictly) the front page
2088	// fell through to PHP while every inner page rewrote fine.
2089	// `^` matches the empty string AND any non-empty path, so it
2090	// covers `/` and `/blog` alike. (Confirmed on OpenLiteSpeed
2091	// 1.8: `.` → homepage served by PHP drop-in; `^` → served
2092	// directly from the static file.)
2093	' RewriteRule ^ ' . $rel . '/%{HTTP_HOST}%1/index.html [L]',
2094	'</IfModule>',
2095	);
2096	}
2097
2098	/**
2099	* Active probe that confirms the web-server static-rewrite path is
2100	* actually serving cached files. Writes a probe file with a random
2101	* nonce, fetches it over HTTP at its public URL, and checks whether
2102	* the response was served directly by the web server (Last-Modified
2103	* + ETag headers + no X-Powered-By: PHP).
2104	*
2105	* Server-agnostic: same probe works for nginx (snippet pasted) and
2106	* Apache / LiteSpeed (.htaccess block installed). If the rewrite
2107	* isn't engaged, the request falls through to WordPress and PHP
2108	* adds its own headers, which the probe detects and reports.
2109	*
2110	* Throttled via a 5-minute transient — we never want this running
2111	* on every Health card paint.
2112	*
2113	* @return array{active:bool, reason:string, code?:int, php?:bool, expires?:int}
2114	*/
2115	/**
2116	* @param bool $allow_probe When false (the default), return ONLY a cached
2117	* result and never make an HTTP request — so admin page loads are never
2118	* blocked by the loopback probe. The actual HTTP probe only runs when a
2119	* caller explicitly opts in (the Health tab / cron). Previously this ran
2120	* synchronously on every dashboard bootstrap, so a slow/timing-out
2121	* loopback request added up to `timeout` seconds to admin page loads on
2122	* hosts that block self-requests. (FBS-82142)
2123	*/
2124	/**
2125	* Discard the cached probe result and run a fresh one.
2126	*
2127	* Without this there was no way to re-check: the result sat in a transient
2128	* for five minutes and nothing ever deleted it, so a user who fixed their
2129	* nginx config kept seeing "nginx detected — configure for max cache speed"
2130	* with no means of confirming the fix worked. (FBS-84012)
2131	*/
2132	public static function recheck_static_rewrite(): array {
2133	delete_transient( 'xspeed_rewrite_probe' );
2134	return self::probe_static_rewrite( true );
2135	}
2136
2137	public static function probe_static_rewrite( bool $allow_probe = false ): array {
2138	$cached = get_transient( 'xspeed_rewrite_probe' );
2139	if ( is_array( $cached ) ) {
2140	return $cached;
2141	}
2142	// No cached result yet and the caller doesn't want to pay for a live
2143	// HTTP probe (e.g. the admin bootstrap): report "pending" without
2144	// blocking. The Health tab will run the real probe on demand.
2145	if ( ! $allow_probe ) {
2146	return array( 'active' => false, 'reason' => 'probe pending', 'pending' => true );
2147	}
2148
2149	$home = home_url( '/' );
2150	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
2151	if ( '' === $host ) {
2152	$result = array( 'active' => false, 'reason' => 'home_url has no host' );
2153	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2154	return $result;
2155	}
2156
2157	// Use a randomised path AND nonce so a stale CDN cache entry
2158	// from a prior probe can never make a broken install look
2159	// healthy. Path is namespaced under __xspeed_probe__ so the
2160	// directory listing stays obvious if cleanup misfires.
2161	$slug = wp_generate_password( 12, false, false );
2162	$nonce = wp_generate_password( 24, false, false );
2163	$probe_dir = XSPEED_CACHE_STATIC_DIR . '/' . $host . '/__xspeed_probe__/' . $slug;
2164	$probe_file = $probe_dir . '/index.html';
2165	$probe_url = trailingslashit( $home ) . '__xspeed_probe__/' . $slug . '/';
2166
2167	if ( ! file_exists( $probe_dir ) ) {
2168	wp_mkdir_p( $probe_dir );
2169	}
2170	if ( ! is_dir( $probe_dir ) ) {
2171	$result = array( 'active' => false, 'reason' => 'cannot create probe dir' );
2172	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2173	return $result;
2174	}
2175	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- WP_Filesystem requires admin credentials we may not have here; the file is in our own cache dir.
2176	file_put_contents( $probe_file, $nonce, LOCK_EX );
2177
2178	// Verify TLS by default — disabling it site-wide is a needless MITM
2179	// exposure (FBS-82142). Only relax verification in local/dev
2180	// environments, where self-signed certs are common and there's no
2181	// real attacker in the loop.
2182	$is_local = function_exists( 'wp_get_environment_type' )
2183	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
2184	$resp = wp_remote_get(
2185	$probe_url,
2186	array(
2187	// 3s cap so a host that hangs on loopback self-requests can't
2188	// stall the caller for long; the result/error is cached so we
2189	// don't repeat the wait every minute.
2190	'timeout' => 3,
2191	'sslverify' => ! $is_local,
2192	'redirection' => 0,
2193	'headers' => array( 'Cache-Control' => 'no-cache' ),
2194	)
2195	);
2196
2197	// Best-effort cleanup so we don't accumulate probe dirs even
2198	// if subsequent calls all hit the transient.
2199	if ( file_exists( $probe_file ) ) {
2200	wp_delete_file( $probe_file );
2201	}
2202	if ( is_dir( $probe_dir ) ) {
2203	// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged, WordPress.WP.AlternativeFunctions.file_system_operations_rmdir -- Best-effort probe-dir cleanup; WP_Filesystem needs admin credentials we don't have here.
2204	@rmdir( $probe_dir );
2205	}
2206
2207	if ( is_wp_error( $resp ) ) {
2208	$result = array(
2209	'active' => false,
2210	// The request never completed, so we learned NOTHING about the
2211	// rewrite. Flagged inconclusive so the UI doesn't tell the user
2212	// to configure a server that may already be configured — a
2213	// blocked loopback, a self-signed cert, or a timeout is a probe
2214	// failure, not a missing rewrite. (FBS-84012)
2215	'inconclusive' => true,
2216	'reason' => 'http error: ' . $resp->get_error_message(),
2217	);
2218	// Cache the failure for the full 5 minutes (not 1) so a host that
2219	// times out on the loopback probe isn't re-probed — and re-stalled
2220	// — on every page load within the window. (FBS-82142)
2221	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
2222	return $result;
2223	}
2224
2225	$code = (int) wp_remote_retrieve_response_code( $resp );
2226	$body = (string) wp_remote_retrieve_body( $resp );
2227	$ua_php = '' !== (string) wp_remote_retrieve_header( $resp, 'x-powered-by' );
2228	$has_etag = '' !== (string) wp_remote_retrieve_header( $resp, 'etag' )
2229	\|\| '' !== (string) wp_remote_retrieve_header( $resp, 'last-modified' );
2230	$match = trim( $body ) === $nonce;
2231
2232	// "Active" = the web server served our raw nonce bytes back
2233	// AND emitted the static-serve markers (ETag / Last-Modified)
2234	// AND didn't add an X-Powered-By: PHP header. All three are
2235	// individually noisy; together they're conclusive.
2236	$active = $match && $has_etag && ! $ua_php && 200 === $code;
2237
2238	/*
2239	* `inconclusive` separates "we proved the rewrite isn't serving" from
2240	* "the probe couldn't tell". Only the former should drive a
2241	* configure-your-server banner; the latter previously rendered the
2242	* same alarming copy at a user who had already configured nginx
2243	* correctly, and there was no way to clear it. (FBS-84012)
2244	*/
2245	$inconclusive = false;
2246	if ( $active ) {
2247	$reason = 'static-served';
2248	} elseif ( 200 === $code && $match && $ua_php ) {
2249	$reason = 'php served the file instead of nginx/Apache (rewrite block missing)';
2250	} elseif ( 200 === $code && ! $match ) {
2251	// Something answered 200 with content that isn't our nonce — a CDN,
2252	// a proxy, a security plugin. That tells us nothing about the
2253	// origin's rewrite.
2254	$reason = 'unexpected body (CDN cached an older response?)';
2255	$inconclusive = true;
2256	} elseif ( 404 === $code ) {
2257	$reason = 'probe URL returned 404 (rewrite block missing or wrong path)';
2258	} else {
2259	// Redirects, 403s from a WAF, 5xx — the probe never reached a
2260	// verdict about the rewrite itself.
2261	$reason = sprintf( 'unexpected response (HTTP %d, body %d B, php=%s)', $code, strlen( $body ), $ua_php ? 'yes' : 'no' );
2262	$inconclusive = true;
2263	}
2264
2265	$result = array(
2266	'active' => $active,
2267	'inconclusive' => $inconclusive,
2268	'reason' => $reason,
2269	'code' => $code,
2270	'php' => $ua_php,
2271	);
2272	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
2273	return $result;
2274	}
2275
2276	public static function rewrite_installed(): bool {
2277	$htaccess = ABSPATH . '.htaccess';
2278	if ( ! file_exists( $htaccess ) ) {
2279	return false;
2280	}
2281	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2282	if ( ! is_string( $existing ) ) {
2283	return false;
2284	}
2285	return false !== strpos( $existing, '# BEGIN xSpeed Static Cache' );
2286	}
2287
2288	/**
2289	* Install the static-cache rewrite block at the TOP of .htaccess.
2290	*
2291	* Position matters: WordPress's own block ends with
2292	* `RewriteRule . /index.php [L]` which routes every non-file
2293	* request to PHP. The [L] flag stops the current rewrite pass,
2294	* but Apache restarts the cycle; on the second pass REQUEST_URI
2295	* is /index.php and no static-file check can match. The only
2296	* reliable position for a "serve static if it exists" rule is
2297	* before WordPress's block.
2298	*
2299	* WP's insert_with_markers() always appends, so we manage the
2300	* block manually: strip any prior xSpeed Static Cache markers,
2301	* then write our block followed by the rest of the file.
2302	*/
2303	public static function install_rewrite(): bool {
2304	// The static rewrite is device-blind; never install it when
2305	// mobile_separate is on (see static_rewrite_allowed()).
2306	if ( ! self::static_rewrite_allowed() ) {
2307	return false;
2308	}
2309	$htaccess = ABSPATH . '.htaccess';
2310	$existing = file_exists( $htaccess ) ? @file_get_contents( $htaccess ) : ''; // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2311	if ( false === $existing ) {
2312	$existing = '';
2313	}
2314	// Apache/LiteSpeed only. nginx hosts: rule won't fire, drop-in
2315	// covers; we skip the write so we don't litter their root.
2316	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- Pre-flight check before file_put_contents; WP_Filesystem requires admin credentials we don't have inside a manage_options REST request.
2317	if ( file_exists( $htaccess ) && ! is_writable( $htaccess ) ) {
2318	return false;
2319	}
2320	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See above.
2321	if ( ! file_exists( $htaccess ) && ! is_writable( ABSPATH ) ) {
2322	return false;
2323	}
2324
2325	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
2326	$block = self::marker_block( 'xSpeed Static Cache', self::rewrite_block_lines() );
2327	$next = $block . ( '' === $cleaned ? '' : "\n" . $cleaned );
2328
2329	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents, PluginCheck.CodeAnalysis.WriteFile.ABSPATHDetected -- WP_Filesystem requires admin credentials we don't have here; toggle() runs in a REST request authorized by manage_options nonce. The target is the site's .htaccess (configuration file managed by WP core itself), not user data — wp_upload_dir() doesn't apply.
2330	return false !== file_put_contents( $htaccess, $next, LOCK_EX );
2331	}
2332
2333	public static function remove_rewrite(): bool {
2334	$htaccess = ABSPATH . '.htaccess';
2335	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See install_rewrite() rationale.
2336	if ( ! file_exists( $htaccess ) \|\| ! is_writable( $htaccess ) ) {
2337	return false;
2338	}
2339	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2340	if ( false === $existing ) {
2341	return false;
2342	}
2343	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
2344	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents, PluginCheck.CodeAnalysis.WriteFile.ABSPATHDetected -- See install_rewrite() rationale.
2345	return false !== file_put_contents( $htaccess, $cleaned, LOCK_EX );
2346	}
2347
2348	/**
2349	* Strip a `# BEGIN <marker>` ... `# END <marker>` block from a
2350	* .htaccess-style file, including any blank line that immediately
2351	* follows it. Idempotent — returns the input unchanged if the
2352	* marker isn't present.
2353	*/
2354	private static function strip_marker_block( string $contents, string $marker ): string {
2355	$pattern = '/# BEGIN ' . preg_quote( $marker, '/' ) . '\b.?# END ' . preg_quote( $marker, '/' ) . "\b[^\n]\n?\n?/s";
2356	$out = preg_replace( $pattern, '', $contents );
2357	return is_string( $out ) ? $out : $contents;
2358	}
2359
2360	private static function marker_block( string $marker, array $lines ): string {
2361	$header = "# BEGIN $marker\n";
2362	$header .= "# The directives (lines) between \"BEGIN $marker\" and \"END $marker\" are\n";
2363	$header .= "# dynamically generated, and should only be modified via WordPress filters.\n";
2364	$header .= "# Any changes to the directives between these markers will be overwritten.\n";
2365	$footer = "# END $marker\n";
2366	return $header . implode( "\n", $lines ) . "\n" . $footer;
2367	}
2368
2369	/**
2370	* Parse the `XSPEED_DROPIN_VERSION: N` stamp out of a drop-in's source.
2371	* Returns 0 when absent (an un-stamped older copy reinstalls). Used to
2372	* detect a stale installed drop-in vs the bundled source.
2373	*/
2374	private static function dropin_version( string $contents ): int {
2375	if ( preg_match( '/XSPEED_DROPIN_VERSION:\s*(\d+)/', $contents, $m ) ) {
2376	return (int) $m[1];
2377	}
2378	return 0;
2379	}
2380
2381	public static function install_dropin() {
2382	$source = XSPEED_DIR . 'includes/advanced-cache.php';
2383	$target = WP_CONTENT_DIR . '/advanced-cache.php';
2384	if ( ! file_exists( $source ) ) {
2385	return false;
2386	}
2387
2388	global $wp_filesystem;
2389	if ( ! function_exists( 'WP_Filesystem' ) ) {
2390	require_once ABSPATH . 'wp-admin/includes/file.php';
2391	}
2392	WP_Filesystem();
2393	if ( ! $wp_filesystem ) {
2394	return false;
2395	}
2396
2397	$source_contents = $wp_filesystem->get_contents( $source );
2398	if ( ! is_string( $source_contents ) ) {
2399	return false;
2400	}
2401
2402	// Bake the absolute hit-log path into the drop-in. It runs before
2403	// WordPress loads, so it can't resolve wp_upload_dir() itself — we
2404	// substitute the @@XSPEED_HITS_LOG@@ token with the real uploads path
2405	// (never the cache dir; see hits_log_dir() / FBS-82478). Use a single
2406	// quoted PHP string literal so the installed file stays valid PHP.
2407	$source_contents = str_replace(
2408	'@@XSPEED_HITS_LOG@@',
2409	str_replace( "'", "\\'", self::hits_log_path() ),
2410	$source_contents
2411	);
2412
2413	if ( file_exists( $target ) ) {
2414	$existing = $wp_filesystem->get_contents( $target );
2415	$is_xspeed = is_string( $existing ) && false !== strpos( $existing, 'XSPEED_DROPIN' );
2416
2417	if ( $is_xspeed ) {
2418	if ( $existing === $source_contents ) {
2419	return true;
2420	}
2421	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
2422	}
2423
2424	// Foreign drop-in (e.g. left over from another cache plugin) — back it up
2425	// before overwriting so the user can recover if needed. Uploads dir
2426	// (not wp-content root) keeps the backup out of WordPress's reserved
2427	// drop-in location.
2428	$upload = wp_upload_dir( null, false );
2429	$basedir = isset( $upload['basedir'] ) ? trailingslashit( $upload['basedir'] ) . 'xspeed-backups' : false;
2430	if ( $basedir ) {
2431	if ( ! file_exists( $basedir ) ) {
2432	wp_mkdir_p( $basedir );
2433	self::write_silence( $basedir );
2434	}
2435	$backup = $basedir . '/advanced-cache.foreign-' . gmdate( 'Ymd-His' ) . '.php.bak';
2436	$wp_filesystem->move( $target, $backup, true );
2437	} else {
2438	$wp_filesystem->delete( $target );
2439	}
2440	}
2441
2442	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
2443	}
2444
2445	public static function remove_dropin() {
2446	$target = WP_CONTENT_DIR . '/advanced-cache.php';
2447	if ( ! file_exists( $target ) ) {
2448	return;
2449	}
2450
2451	global $wp_filesystem;
2452	if ( ! function_exists( 'WP_Filesystem' ) ) {
2453	require_once ABSPATH . 'wp-admin/includes/file.php';
2454	}
2455	WP_Filesystem();
2456	if ( ! $wp_filesystem ) {
2457	return;
2458	}
2459
2460	$contents = $wp_filesystem->get_contents( $target );
2461	if ( is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' ) ) {
2462	wp_delete_file( $target );
2463	}
2464	}
2465
2466	public static function set_wp_cache_constant( $enable ) {
2467	$wp_config = ABSPATH . 'wp-config.php';
2468	if ( ! file_exists( $wp_config ) ) {
2469	return false;
2470	}
2471
2472	global $wp_filesystem;
2473	if ( ! function_exists( 'WP_Filesystem' ) ) {
2474	require_once ABSPATH . 'wp-admin/includes/file.php';
2475	}
2476	WP_Filesystem();
2477	if ( ! $wp_filesystem \|\| ! $wp_filesystem->is_writable( $wp_config ) ) {
2478	return false;
2479	}
2480
2481	$config = $wp_filesystem->get_contents( $wp_config );
2482
2483	if ( $enable ) {
2484	// Own the constant. A previous caching plugin (e.g. WP Rocket sets
2485	// it false on deactivate) can leave `define( 'WP_CACHE', false );`
2486	// behind — presence alone is not enough, the VALUE must be true or
2487	// WordPress never loads advanced-cache.php and our drop-in is dead.
2488	if ( preg_match( "/define\\(\\s['\"]WP_CACHE['\"]\\s,/", $config ) ) {
2489	$rewritten = preg_replace(
2490	"/define\$\\s['\"]WP_CACHE['\"]\\s,\\s[^)]\$\\s*;/",
2491	"define( 'WP_CACHE', true );",
2492	$config,
2493	1
2494	);
2495	// If an existing define was already `true`, the rewrite is a
2496	// no-op string-wise; either way we end on WP_CACHE === true.
2497	if ( null !== $rewritten ) {
2498	$config = $rewritten;
2499	}
2500	} else {
2501	$config = preg_replace( '/(<\?php)/', "$1\ndefine( 'WP_CACHE', true );", $config, 1 );
2502	}
2503	} else {
2504	$config = preg_replace( "/define\$\\s['\"]WP_CACHE['\"]\\s,\\strue\\s\$;\\s*\\n?/", '', $config );
2505	}
2506
2507	return (bool) $wp_filesystem->put_contents( $wp_config, $config, FS_CHMOD_FILE );
2508	}
2509
2510	/**
2511	* Admin-bar purge menu — a parent node plus one child per visible cache
2512	* type (LiteSpeed-style), instead of a single "Purge All" link. Each
2513	* child posts to the same admin-post handler with its type slug. The
2514	* per-type items only appear for active/licensed modules; "Purge All"
2515	* always shows and always sweeps everything. (FBS-83114)
2516	*
2517	* The parent node links to the settings page rather than a purge URL —
2518	* clicking the top-level item used to wipe the whole cache instantly with
2519	* no confirmation, which is far too destructive for a stray click. Purging
2520	* stays available (and explicit) through the child items. (FBS-84068)
2521	*/
2522	public function admin_bar_purge( $wp_admin_bar ) {
2523	if ( ! current_user_can( 'manage_options' ) ) {
2524	return;
2525	}
2526
2527	$wp_admin_bar->add_node(
2528	array(
2529	'id' => 'xspeed-purge',
2530	'title' => __( 'xSpeed Cache', 'xspeed' ),
2531	'href' => admin_url( 'admin.php?page=' . Admin::PAGE_SLUG ),
2532	)
2533	);
2534
2535	foreach ( self::purge_types() as $slug => $type ) {
2536	if ( empty( $type['visible'] ) ) {
2537	continue;
2538	}
2539	$wp_admin_bar->add_node(
2540	array(
2541	'id' => 'xspeed-purge-' . $slug,
2542	'parent' => 'xspeed-purge',
2543	'title' => esc_html( $type['label'] ),
2544	'href' => self::purge_type_url( $slug ),
2545	)
2546	);
2547	}
2548	}
2549
2550	/**
2551	* Nonce-protected admin-post URL for purging a single type. The nonce
2552	* action is per-type so a leaked URL can't be replayed for a different
2553	* scope.
2554	*/
2555	private static function purge_type_url( string $type ): string {
2556	return wp_nonce_url(
2557	admin_url( 'admin-post.php?action=xspeed_purge&type=' . rawurlencode( $type ) ),
2558	'xspeed_purge_' . $type
2559	);
2560	}
2561
2562	public function handle_admin_bar_purge() {
2563	if ( ! current_user_can( 'manage_options' ) ) {
2564	wp_die( esc_html__( 'Unauthorized.', 'xspeed' ), 403 );
2565	}
2566	$type = isset( $_GET['type'] ) ? sanitize_key( wp_unslash( $_GET['type'] ) ) : 'all';
2567	check_admin_referer( 'xspeed_purge_' . $type );
2568
2569	// Only honour known types; anything else falls back to a full purge.
2570	if ( ! array_key_exists( $type, self::purge_types() ) ) {
2571	$type = 'all';
2572	}
2573	self::purge_type( $type );
2574
2575	wp_safe_redirect( self::safe_purge_redirect( wp_get_referer() ) );
2576	exit;
2577	}
2578
2579	/**
2580	* Resolve a safe redirect target for an admin-bar purge.
2581	*
2582	* The purge sends the admin back where they came from — but the referer
2583	* can be a ONE-SHOT action URL (e.g. update.php?action=upload-plugin from
2584	* installing a plugin zip, or any *.php?action=… that consumed a POST /
2585	* temp upload). Redirecting there re-runs the action with nothing to act
2586	* on, so WordPress dies — the classic "Please select a file" from
2587	* File_Upload_Upgrader. Strip the transient action args so we return to a
2588	* safe, re-GET-able view of the same page; fall back to the dashboard when
2589	* there is no usable referer.
2590	*
2591	* @param string\|false $referer Raw wp_get_referer() value.
2592	* @return string Safe URL to redirect to.
2593	*/
2594	public static function safe_purge_redirect( $referer ): string {
2595	$referer = is_string( $referer ) ? $referer : '';
2596	if ( '' === $referer ) {
2597	return admin_url();
2598	}
2599
2600	// A referer that lands on an action-processing endpoint (update.php,
2601	// update-core.php, plugin/theme install/upload flows) can't be safely
2602	// re-requested — send them to the dashboard instead of replaying it.
2603	$path = (string) wp_parse_url( $referer, PHP_URL_PATH );
2604	if ( preg_match( '#/wp-admin/(update\|update-core)\.php$#', $path ) ) {
2605	return admin_url();
2606	}
2607
2608	// Otherwise keep them on the same page but drop the query args that
2609	// would re-trigger a form action or upload on load.
2610	return remove_query_arg(
2611	array( 'action', 'action2', 'package', 'overwrite', 'plugin', 'theme', 'file', '_wpnonce', '_ajax_nonce' ),
2612	$referer
2613	);
2614	}
2615	}
2616