xspeed / includes / class-cache.php

class-cache.php in xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN 1.0.9, 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	public static function purge_all( string $cause = 'manual' ) {
886	$count = 0;
887	if ( is_dir( XSPEED_CACHE_DIR ) ) {
888	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
889	if ( $files ) {
890	$count = count( $files );
891	foreach ( $files as $f ) {
892	wp_delete_file( $f );
893	}
894	}
895	// Remove the .meta sidecars (content-type for feeds/sitemaps)
896	// alongside their .html entries. Not counted — they're not
897	// cache "pages", just per-entry metadata.
898	$meta = glob( XSPEED_CACHE_DIR . '/*.meta' );
899	if ( $meta ) {
900	foreach ( $meta as $m ) {
901	wp_delete_file( $m );
902	}
903	}
904	// Remove precompressed siblings (e.g. <key>.html.br from the Pro
905	// Brotli module). Not counted — same as .meta. Without this a
906	// purge leaves stale .br bodies behind: disk bloat, and a
907	// staleness window if precompression is later disabled.
908	$br = glob( XSPEED_CACHE_DIR . '/*.br' );
909	if ( $br ) {
910	foreach ( $br as $b ) {
911	wp_delete_file( $b );
912	}
913	}
914	}
915	// Static-cache tree purge — recursive because the layout is
916	// xspeed-static/{host}/{path}/index.html, so a flat glob can't
917	// reach everything.
918	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
919	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
920	}
921	// REST response cache (cache/xspeed/rest/*.json) — same purge
922	// triggers (publish, settings change) invalidate it too.
923	$count += Rest_Cache::purge();
924
925	// Minified + combined CSS/JS (cache/xspeed/min/ and min/combined/).
926	// purge_all is a full filesystem sweep and must clear these too, even
927	// when the Minify module is currently disabled — orphaned min/ files
928	// from a feature the user later turned off must still be removed, and
929	// a stale combined-<hash>.css that the regenerated page no longer
930	// references otherwise 404s and breaks the frontend. (FBS-83114/83116)
931	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
932	Minifier::purge_minified();
933	}
934
935	// Persistent object cache (Redis / Memcached). Flush regardless of
936	// whether the Object Cache module is currently enabled — a drop-in
937	// installed earlier keeps serving until flushed.
938	if ( function_exists( 'wp_cache_flush' ) ) {
939	wp_cache_flush();
940	}
941
942	self::update_stats( array( 'last_purge' => time() ) );
943
944	// Fire AFTER the local sweep so module listeners (Critical CSS,
945	// Unused CSS, Cloudflare edge purge) run — this action had three
946	// registered listeners but was never emitted. Treat it as additive
947	// (CDN / edge invalidation), not the mechanism for clearing local
948	// files. (FBS-83114)
949	do_action( 'xspeed_after_purge_all', $cause );
950
951	// Trigger of WP_CLI / hook / admin-bar purges all hit the same
952	// path. Record once with the supplied cause so the dashboard
953	// activity feed reads naturally.
954	Activity_Log::record(
955	'cache_purged',
956	sprintf( 'Cache purged (%s) — %d file%s removed', $cause, $count, 1 === $count ? '' : 's' ),
957	Activity_Log::INFO
958	);
959
960	return $count;
961	}
962
963	/**
964	* The per-type purge menu, LiteSpeed-style. Each entry is a cache type
965	* the user can purge individually from the admin-bar dropdown. `visible`
966	* controls whether the item shows (active + licensed module only) — it
967	* NEVER limits Purge All, which always sweeps everything on disk.
968	*
969	* Pro registers its own types (Critical CSS, Unused CSS, …) by filtering
970	* `xspeed_purge_types`, so Free degrades gracefully when Pro is absent.
971	*
972	* @return array<string,array{label:string,visible:bool}>
973	*/
974	public static function purge_types(): array {
975	$minify_on = false;
976	if ( class_exists( '\\XSpeed\\Settings_Manager' ) ) {
977	$min = Settings_Manager::get( 'minify' );
978	$minify_on = ! empty( $min['minify_css'] ) \|\| ! empty( $min['minify_js'] ) \|\| ! empty( $min['combine_css'] ) \|\| ! empty( $min['combine_js'] );
979	}
980	// Object cache is "active" when an external object-cache drop-in is in
981	// use — the canonical WP signal, independent of our settings option.
982	$oc_on = function_exists( 'wp_using_ext_object_cache' ) && wp_using_ext_object_cache();
983
984	$types = array(
985	'all' => array(
986	'label' => __( 'Purge All', 'xspeed' ),
987	'visible' => true,
988	),
989	'page' => array(
990	'label' => __( 'Purge Page / Static Cache', 'xspeed' ),
991	'visible' => true,
992	),
993	'assets' => array(
994	'label' => __( 'Purge CSS / JS Cache', 'xspeed' ),
995	'visible' => $minify_on,
996	),
997	'object' => array(
998	'label' => __( 'Purge Object Cache', 'xspeed' ),
999	'visible' => $oc_on,
1000	),
1001	'rest' => array(
1002	'label' => __( 'Purge REST Cache', 'xspeed' ),
1003	'visible' => true,
1004	),
1005	);
1006
1007	/**
1008	* Filter the admin-bar purge-type menu. Pro modules add their own
1009	* (Critical CSS, Unused CSS, CDN). Adding a type here only adds a
1010	* MENU item — purge_type() must know how to handle the same slug.
1011	*
1012	* @param array $types Map of slug => [label, visible].
1013	*/
1014	return (array) apply_filters( 'xspeed_purge_types', $types );
1015	}
1016
1017	/**
1018	* Purge a single cache type by slug. 'all' delegates to purge_all();
1019	* every other slug clears just its own artifacts. Unknown slugs (e.g. a
1020	* Pro type) fan out via the `xspeed_purge_type_{slug}` action so the
1021	* owning module can handle it. Returns the number of items removed where
1022	* countable.
1023	*/
1024	public static function purge_type( string $type ): int {
1025	switch ( $type ) {
1026	case 'all':
1027	return self::purge_all( 'manual' );
1028
1029	case 'page':
1030	$count = 0;
1031	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1032	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.html' ) as $f ) {
1033	wp_delete_file( $f );
1034	++$count;
1035	}
1036	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.meta' ) as $m ) {
1037	wp_delete_file( $m );
1038	}
1039	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.br' ) as $b ) {
1040	wp_delete_file( $b );
1041	}
1042	}
1043	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
1044	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1045	}
1046	self::update_stats( array( 'last_purge' => time() ) );
1047	return $count;
1048
1049	case 'assets':
1050	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
1051	Minifier::purge_minified();
1052	}
1053	return 0;
1054
1055	case 'object':
1056	if ( function_exists( 'wp_cache_flush' ) ) {
1057	wp_cache_flush();
1058	}
1059	return 0;
1060
1061	case 'rest':
1062	return Rest_Cache::purge();
1063
1064	default:
1065	// Pro / third-party type — let the owning module handle it.
1066	do_action( 'xspeed_purge_type_' . $type );
1067	return 0;
1068	}
1069	}
1070
1071	/**
1072	* Recursively delete every `index.html` (and its precompressed
1073	* `index.html.br` sibling, if the Pro Brotli module wrote one) plus
1074	* empty directories inside the static-cache tree. Used by purge_all().
1075	* Returns the number of .html files removed so purge stats stay accurate
1076	* across the flat + static caches — .br siblings are not counted
1077	* (they're encodings of a page, not pages).
1078	*/
1079	private static function rmtree_html( string $dir ): int {
1080	if ( ! is_dir( $dir ) ) {
1081	return 0;
1082	}
1083	$removed = 0;
1084	// SCANDIR_SORT_NONE skips alphabetic sort — we're going to walk
1085	// the whole tree regardless of order.
1086	$entries = @scandir( $dir, SCANDIR_SORT_NONE ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
1087	if ( false === $entries ) {
1088	return 0;
1089	}
1090	foreach ( $entries as $entry ) {
1091	if ( '.' === $entry \|\| '..' === $entry ) {
1092	continue;
1093	}
1094	$path = $dir . '/' . $entry;
1095	if ( is_dir( $path ) ) {
1096	$removed += self::rmtree_html( $path );
1097	// Best-effort empty-dir cleanup; ignore failures (a
1098	// foreign file inside would block rmdir, which is fine).
1099	// 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.
1100	@rmdir( $path );
1101	continue;
1102	}
1103	if ( substr( $entry, -5 ) === '.html' ) {
1104	wp_delete_file( $path );
1105	++$removed;
1106	} elseif ( substr( $entry, -3 ) === '.br' ) {
1107	// Precompressed sibling (index.html.br). Remove it too so a
1108	// purge doesn't orphan stale Brotli bodies. Not counted.
1109	wp_delete_file( $path );
1110	}
1111	}
1112	return $removed;
1113	}
1114
1115	/**
1116	* Drop a "silence is golden" index.php into a directory so apaches/nginx
1117	* with directory listing enabled don't expose cache contents.
1118	*/
1119	public static function write_silence( $dir ) {
1120	$file = trailingslashit( $dir ) . 'index.php';
1121	if ( ! file_exists( $file ) ) {
1122	// 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.
1123	file_put_contents( $file, "<?php\n// Silence is golden.\n" );
1124	}
1125	}
1126
1127	/**
1128	* Persist stats with autoload disabled — stats are only read in admin
1129	* contexts, so there is no reason to inflate every frontend request's
1130	* `wp_load_alloptions()` payload.
1131	*/
1132	private static function update_stats( array $stats ) {
1133	if ( false === get_option( 'xspeed_stats' ) ) {
1134	add_option( 'xspeed_stats', $stats, '', 'no' );
1135	return;
1136	}
1137	update_option( 'xspeed_stats', $stats );
1138	}
1139
1140	public static function get_stats() {
1141	$count = 0;
1142	$size = 0;
1143	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1144	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
1145	if ( $files ) {
1146	$count = count( $files );
1147	foreach ( $files as $f ) {
1148	$size += filesize( $f );
1149	}
1150	}
1151	}
1152	// Drain the HIT-log file BEFORE reading totals. Two serve paths that
1153	// bypass the normal in-PHP record_hit() append one line per HIT here:
1154	// the nginx server-level rewrite (see nginx_snippet(), never reaches
1155	// PHP) and the advanced-cache.php drop-in (runs pre-WordPress, can't
1156	// reach Hit_Counter). Without this drain both look like a 0% hit-ratio
1157	// on a perfectly working cache.
1158	Hit_Counter::collect_nginx_log_hits();
1159
1160	// Apache/LiteSpeed static-rewrite HITs are served straight from disk
1161	// by .htaccess and never reach PHP either — but there's no .htaccess
1162	// equivalent of nginx's access_log directive, so we count them by
1163	// scanning the web server's own access log incrementally. No-op when
1164	// the log isn't readable (managed hosts) — see the method docblock.
1165	Hit_Counter::collect_server_log_hits();
1166
1167	$stats = get_option( 'xspeed_stats', array() );
1168	$totals = Hit_Counter::totals_24h();
1169	return array(
1170	'cached_pages' => $count,
1171	'cache_size' => $size,
1172	'last_purge' => isset( $stats['last_purge'] ) ? (int) $stats['last_purge'] : 0,
1173	// Rolling 24h cache performance — sourced from Hit_Counter's
1174	// hourly buckets. The frontend uses hit_ratio to drive the
1175	// CacheHero stat grid + the Health module's panel.
1176	'hits_24h' => $totals['hits'],
1177	'misses_24h' => $totals['misses'],
1178	'hit_ratio' => $totals['ratio'],
1179	);
1180	}
1181
1182	/**
1183	* Apply the user's enable/disable choice. Called only from the REST
1184	* toggle endpoint, which is gated by current_user_can( 'manage_options' )
1185	* and a verified REST nonce. This is the only place the drop-in and
1186	* the WP_CACHE constant are written — they MUST NOT happen on
1187	* register_activation_hook (WordPress.org review requirement).
1188	*
1189	* @param bool $enable User's choice.
1190	* @return array{
1191	* enabled: bool,
1192	* dropin_installed: bool,
1193	* wp_cache_constant: bool,
1194	* wp_config_writable: bool,
1195	* manual_snippet: ?string
1196	* }
1197	*/
1198	public static function toggle( $enable ) {
1199	$enable = (bool) $enable;
1200
1201	if ( $enable ) {
1202	$dropin_ok = self::install_dropin();
1203	$wp_config_ok = self::set_wp_cache_constant( true );
1204	$rewrite_ok = self::install_rewrite();
1205	self::ensure_hits_log_file();
1206	self::sync_mobile_flag();
1207	$snippet = $wp_config_ok ? null : "define( 'WP_CACHE', true );";
1208
1209	Activity_Log::record(
1210	'cache_enabled_event',
1211	$wp_config_ok
1212	? 'Cache enabled. Drop-in installed, WP_CACHE constant set.'
1213	: 'Cache enabled. Drop-in installed; wp-config.php not writable — add the WP_CACHE snippet manually.',
1214	$wp_config_ok ? Activity_Log::SUCCESS : Activity_Log::WARN
1215	);
1216
1217	return array(
1218	'enabled' => true,
1219	'dropin_installed' => (bool) $dropin_ok,
1220	'wp_cache_constant' => (bool) $wp_config_ok,
1221	'rewrite_installed' => (bool) $rewrite_ok,
1222	'wp_config_writable' => self::wp_config_writable(),
1223	'manual_snippet' => $snippet,
1224	'nginx_snippet' => self::nginx_snippet(),
1225	// Unified server-block snippet aggregating every enabled
1226	// module's directives — the same value the dashboard and
1227	// Health insight render. The wizard shows this so all three
1228	// surfaces stay in lockstep. Null on non-nginx hosts.
1229	'nginx_server_block' => self::full_nginx_server_block(),
1230	);
1231	}
1232
1233	self::remove_dropin();
1234	self::set_wp_cache_constant( false );
1235	self::remove_rewrite();
1236	// Drop the device-bucket marker too — with the drop-in gone there's
1237	// nothing left to read it, and leaving it behind would dirty a fresh
1238	// re-enable (and leaks across test runs).
1239	self::sync_mobile_flag( false );
1240
1241	Activity_Log::record(
1242	'cache_disabled_event',
1243	'Cache disabled. Drop-in removed.',
1244	Activity_Log::INFO
1245	);
1246
1247	return array(
1248	'enabled' => false,
1249	'dropin_installed' => false,
1250	'wp_cache_constant' => false,
1251	'rewrite_installed' => false,
1252	'wp_config_writable' => self::wp_config_writable(),
1253	'manual_snippet' => null,
1254	'nginx_snippet' => self::nginx_snippet(),
1255	'nginx_server_block' => self::full_nginx_server_block(),
1256	);
1257	}
1258
1259	/**
1260	* Check wp-config.php writability via WP_Filesystem. Plugin Check flags
1261	* direct is_writable() under WordPress.WP.AlternativeFunctions.
1262	*/
1263	private static function wp_config_writable() {
1264	global $wp_filesystem;
1265	if ( ! function_exists( 'WP_Filesystem' ) ) {
1266	require_once ABSPATH . 'wp-admin/includes/file.php';
1267	}
1268	WP_Filesystem();
1269
1270	return $wp_filesystem ? (bool) $wp_filesystem->is_writable( ABSPATH . 'wp-config.php' ) : false;
1271	}
1272
1273	/**
1274	* Nginx server-block snippet mirroring the Apache rewrite block.
1275	* We never auto-write nginx config — it sits outside the WordPress
1276	* root and is owned by the server admin — but the dashboard
1277	* surfaces this snippet when nginx is detected so the admin can
1278	* paste it once and unlock the same PHP-bypass speedup we get on
1279	* Apache / LiteSpeed via .htaccess.
1280	*
1281	* Returns null when the server isn't nginx (no point showing it).
1282	*/
1283	/**
1284	* Create wp-content/cache/xspeed/hits.log as an empty file so the
1285	* server-level rewrite's `access_log` directive has somewhere to
1286	* write on first request. Idempotent — touches an existing file
1287	* without disturbing accumulated lines. Called from Cache::toggle()
1288	* on enable and from auto_heal() when the file is missing.
1289	*
1290	* Permissions matter here. The file is created by PHP-FPM (often uid
1291	* www-data), but the nginx process that appends HIT lines may run as a
1292	* DIFFERENT uid — on multi-container hosts (e.g. xclude/Kinsta: nginx in
1293	* its own container as uid `nginx`, PHP-FPM in another as `www-data`)
1294	* they don't share a user at all. A default-umask 0644 file is then
1295	* unwritable by nginx, the access_log write silently fails, and the
1296	* dashboard shows a 0% hit ratio even though static HITs are serving.
1297	* So we widen the dir to 0777 and the file to 0666 — group/other write —
1298	* so whatever uid nginx runs as can append. (The file holds only HIT
1299	* request lines, no secrets.)
1300	*/
1301	/**
1302	* Directory holding the nginx hit log. Lives under uploads/, NOT the
1303	* cache dir — uninstall.php and a cache purge both delete the cache
1304	* dir, which would orphan the pasted nginx `access_log` directive's
1305	* parent directory and make `nginx -t` fail [emerg], taking down every
1306	* vhost on the host (FBS-82478). uploads/ always exists, isn't a
1307	* plugin-managed cache dir, and is never deleted on uninstall — so the
1308	* directive's target dir survives both, and nginx (which creates a
1309	* missing log FILE but not a missing DIR) can always open it.
1310	*
1311	* Falls back to the cache dir only if uploads is somehow unavailable.
1312	*/
1313	public static function hits_log_dir(): string {
1314	if ( function_exists( 'wp_upload_dir' ) ) {
1315	$uploads = wp_upload_dir( null, false );
1316	if ( is_array( $uploads ) && empty( $uploads['error'] ) && ! empty( $uploads['basedir'] ) ) {
1317	return rtrim( (string) $uploads['basedir'], '/' ) . '/xspeed';
1318	}
1319	}
1320	return XSPEED_CACHE_DIR;
1321	}
1322
1323	/** Absolute path to the nginx hit log file. */
1324	public static function hits_log_path(): string {
1325	return self::hits_log_dir() . '/hits.log';
1326	}
1327
1328	/**
1329	* Sync the drop-in's mobile-bucket flag file with the `mobile_separate`
1330	* setting. The drop-in (advanced-cache.php) runs before WordPress loads,
1331	* so it can't read the option — instead it checks for a zero-byte
1332	* `.mobile-separate` marker next to the cache files. When the setting is
1333	* on we touch the marker; when off we remove it. The drop-in's cache_key
1334	* computation keys off the marker's presence so its '\|m'/'\|d' device
1335	* bucket stays in lockstep with Cache::cache_key().
1336	*
1337	* Without this, turning on mobile_separate made Cache::store() write keys
1338	* with a '\|d'/'\|m' suffix the drop-in never reproduced — so the drop-in's
1339	* file_exists() always missed, every HIT fell through to a full WP boot,
1340	* and the fast pre-WP path was silently dead.
1341	*
1342	* @param bool\|null $enabled Force a state; null reads the current setting.
1343	*/
1344	public static function sync_mobile_flag( $enabled = null ): void {
1345	if ( null === $enabled ) {
1346	$opts = Settings_Manager::get( 'cache' );
1347	$enabled = ! empty( $opts['mobile_separate'] );
1348	}
1349	$dir = XSPEED_CACHE_DIR;
1350	$flag = $dir . '/.mobile-separate';
1351	if ( $enabled ) {
1352	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1353	return;
1354	}
1355	if ( ! file_exists( $flag ) ) {
1356	// 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.
1357	@touch( $flag );
1358	}
1359	return;
1360	}
1361	if ( file_exists( $flag ) ) {
1362	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1363	@unlink( $flag );
1364	}
1365	}
1366
1367	/**
1368	* Write / remove the `.maintenance-active` sentinel next to the cache
1369	* files. The pre-WP drop-in checks for this marker and bails when present,
1370	* so a page cached while the site was live is NOT served during
1371	* maintenance / coming-soon mode — WordPress loads and renders the
1372	* maintenance screen instead. The Pro Maintenance-Cache module drives this
1373	* on the maintenance on/off transition. (FBS-82409 B1)
1374	*
1375	* @param bool $active True to arm the sentinel (entering maintenance),
1376	* false to clear it (site recovered).
1377	*/
1378	public static function sync_maintenance_flag( bool $active ): void {
1379	$dir = XSPEED_CACHE_DIR;
1380	$flag = $dir . '/.maintenance-active';
1381	if ( $active ) {
1382	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1383	return;
1384	}
1385	if ( ! file_exists( $flag ) ) {
1386	// 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.
1387	@touch( $flag );
1388	}
1389	return;
1390	}
1391	if ( file_exists( $flag ) ) {
1392	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1393	@unlink( $flag );
1394	}
1395	}
1396
1397	/**
1398	* Reconcile every mobile_separate-dependent artifact to the current
1399	* setting. Called on boot and whenever the cache settings are saved, so
1400	* flipping mobile_separate at runtime can't leave the install in a
1401	* half-converted state.
1402	*
1403	* Three things must agree with the setting:
1404	* 1. the drop-in's `.mobile-separate` flag (sync_mobile_flag()),
1405	* 2. the device-blind server rewrite — present only when OFF
1406	* (static_rewrite_allowed()),
1407	* 3. the now-stale static-cache tree + page cache, which were keyed
1408	* under the old scheme and would serve wrong-device HTML.
1409	*
1410	* No-ops when the cache is disabled — there's nothing installed to
1411	* reconcile, and toggle() handles install/teardown itself.
1412	*/
1413	public static function reconcile_mobile_separate(): void {
1414	self::sync_mobile_flag();
1415
1416	// The rewrite/static reconciliation below needs the plugin's path
1417	// constants. They're absent in early-boot / unit-test contexts where
1418	// only the drop-in flag matters — bail to the flag-only behavior then.
1419	if ( ! defined( 'XSPEED_CACHE_STATIC_DIR' ) ) {
1420	return;
1421	}
1422
1423	// Only touch the rewrite + caches when caching is actually on.
1424	$opts = get_option( 'xspeed_options', array() );
1425	if ( empty( $opts['cache_enabled'] ) ) {
1426	return;
1427	}
1428
1429	$rewrite_present = self::rewrite_installed();
1430	$rewrite_wanted = self::static_rewrite_allowed();
1431
1432	if ( $rewrite_present === $rewrite_wanted ) {
1433	// Already consistent — nothing flipped, leave caches intact so a
1434	// plain settings save (e.g. expiry change) doesn't blow the cache.
1435	return;
1436	}
1437
1438	// The setting flipped. Bring the rewrite into line and purge the
1439	// now-misbucketed cache so the next request re-primes under the new
1440	// device scheme.
1441	if ( $rewrite_wanted ) {
1442	self::install_rewrite();
1443	} else {
1444	self::remove_rewrite();
1445	}
1446	self::purge_all( 'mobile_separate changed' );
1447	}
1448
1449	/**
1450	* Whether the server-level static-rewrite fast path may be used.
1451	*
1452	* The rewrite serves `{host}{path}/index.html` straight from the web
1453	* server, keyed only by host + path — it has no way to run our PHP
1454	* device detection, so it can't tell mobile from desktop. When
1455	* `mobile_separate` is on, a single static file would be shared across
1456	* devices and whoever primed it wins (mobile visitors could get desktop
1457	* HTML, or vice-versa). Rather than duplicate a wp_is_mobile()-equivalent
1458	* UA matcher into .htaccess AND the nginx snippet (three copies that
1459	* would inevitably drift), we simply DON'T engage the static rewrite when
1460	* mobile_separate is on. Requests then fall through to the PHP drop-in,
1461	* which buckets correctly — a small TTFB cost (~85ms vs ~30ms) paid only
1462	* on mobile-separate sites, in exchange for guaranteed correctness.
1463	*
1464	* LiteSpeed exclusion (2026-06-16): on LiteSpeed — OpenLiteSpeed in
1465	* particular — `.htaccess` CAN run our RewriteRule to serve the static
1466	* file, but its `.htaccess` engine ignores `mod_headers`, so we cannot
1467	* stamp the served response with `X-XSpeed-Cache: HIT`, AND there is no
1468	* `.htaccess` equivalent of nginx's per-location `access_log` to record
1469	* the hit. The result was a cache that worked but was invisible: no HIT
1470	* header and a hit-ratio frozen near 0%. Every OTHER server gives the
1471	* user a visible HIT header + a counted hit (nginx via add_header +
1472	* access_log in its snippet; Apache via .htaccess mod_headers, which it
1473	* honors). To keep LiteSpeed CONSISTENT with the rest, we route its hits
1474	* through the PHP drop-in instead — the drop-in emits
1475	* `X-XSpeed-Cache: HIT (php)` and calls Hit_Counter inline, exactly the
1476	* observable behavior the other servers get. The cost is the drop-in's
1477	* ~30ms TTFB vs the static path's ~10ms, paid only on LiteSpeed; in
1478	* exchange the dashboard hit-ratio and the response header finally tell
1479	* the truth there. (Apache keeps the static fast path — it honors the
1480	* header.) See maybe_emit_lscache_headers() for the paired LSCache
1481	* stand-down that stops LiteSpeed's own module from shadowing the
1482	* drop-in.
1483	*/
1484	public static function static_rewrite_allowed(): bool {
1485	// LiteSpeed: drop-in serves hits (visible + counted) — see docblock.
1486	if ( Server::LITESPEED === Server::type() ) {
1487	return false;
1488	}
1489	$opts = Settings_Manager::get( 'cache' );
1490	return empty( $opts['mobile_separate'] );
1491	}
1492
1493	/**
1494	* Why the device-blind static rewrite is NOT installed, when it isn't.
1495	* Returns 'mobile_separate' when Separate Mobile Cache is the blocker
1496	* (the static file is one-per-URL, so it can't coexist with per-device
1497	* buckets), '' otherwise. Lets the dashboard explain the slow path
1498	* instead of silently falling back to PHP serving. (FBS-83145)
1499	*/
1500	public static function static_rewrite_block_reason(): string {
1501	if ( Server::LITESPEED === Server::type() ) {
1502	return ''; // Intended on LiteSpeed — not a "block".
1503	}
1504	$opts = Settings_Manager::get( 'cache' );
1505	return ! empty( $opts['mobile_separate'] ) ? 'mobile_separate' : '';
1506	}
1507
1508	/**
1509	* Whether migration flagged Separate Mobile Cache for user review. Set by
1510	* Migration::map_mobile_separate() when a source plugin (WP Rocket / WP
1511	* Super Cache / LiteSpeed) had its "separate mobile cache" option on: we
1512	* import it as OFF (to keep the device-blind static fast path) but record
1513	* this flag so the dashboard can invite the user to turn it back on only
1514	* if their site genuinely serves different HTML per device. (FBS-83145)
1515	*/
1516	public static function mobile_separate_needs_review(): bool {
1517	$opts = Settings_Manager::get( 'cache' );
1518	return ! empty( $opts['mobile_separate_review'] );
1519	}
1520
1521	/**
1522	* Clear the review flag — called when the user has acted on the prompt
1523	* (dismissed it, or turned Separate Mobile Cache on/off deliberately) so
1524	* the dashboard callout doesn't nag forever. Writes the option directly
1525	* (bypassing Settings_Manager) so it never touches schema fields.
1526	*/
1527	public static function clear_mobile_separate_review(): void {
1528	$stored = get_option( 'xspeed_module_cache', array() );
1529	if ( ! is_array( $stored ) \|\| empty( $stored['mobile_separate_review'] ) ) {
1530	return;
1531	}
1532	unset( $stored['mobile_separate_review'] );
1533	update_option( 'xspeed_module_cache', $stored );
1534	}
1535
1536	/**
1537	* On-demand probe: does the homepage serve materially the same HTML to a
1538	* desktop and a mobile browser? Fetches home_url() twice over loopback —
1539	* once with a desktop User-Agent, once with a mobile one — strips
1540	* per-request noise (nonces, CSRF tokens, session ids, inline timestamps),
1541	* and compares. When identical, Separate Mobile Cache is almost certainly
1542	* unnecessary and the user can turn it off to regain the static fast path.
1543	*
1544	* NEVER run automatically (no page-load cost) — only from the dashboard
1545	* "Check now" button. Result is cached for 10 minutes so a double-click or
1546	* a re-render doesn't fire two more self-requests. (FBS-83145)
1547	*
1548	* @return array{ identical:bool, checked:bool, reason?:string, desktop_bytes?:int, mobile_bytes?:int }
1549	*/
1550	public static function probe_mobile_equality(): array {
1551	$cached = get_transient( 'xspeed_mobile_equality_probe' );
1552	if ( is_array( $cached ) ) {
1553	return $cached;
1554	}
1555
1556	$home = home_url( '/' );
1557	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
1558	if ( '' === $host ) {
1559	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'home_url has no host' );
1560	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
1561	return $result;
1562	}
1563
1564	// Match WP core's own mobile detection (wp_is_mobile) so the probe
1565	// reflects what the site would actually branch on. iPhone Safari for
1566	// mobile; a current desktop Chrome UA for desktop.
1567	$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';
1568	$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';
1569
1570	$is_local = function_exists( 'wp_get_environment_type' )
1571	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
1572
1573	$fetch = static function ( string $ua ) use ( $home, $is_local ) {
1574	$resp = wp_remote_get(
1575	$home,
1576	array(
1577	'timeout' => 5,
1578	'sslverify' => ! $is_local,
1579	'redirection' => 2,
1580	// Bust any per-device cache so we compare freshly-rendered
1581	// HTML, and pass the device UA the site would branch on.
1582	'user-agent' => $ua,
1583	'headers' => array( 'Cache-Control' => 'no-cache' ),
1584	)
1585	);
1586	if ( is_wp_error( $resp ) \|\| 200 !== (int) wp_remote_retrieve_response_code( $resp ) ) {
1587	return null;
1588	}
1589	return (string) wp_remote_retrieve_body( $resp );
1590	};
1591
1592	$desktop = $fetch( $desktop_ua );
1593	$mobile = $fetch( $mobile_ua );
1594
1595	if ( null === $desktop \|\| null === $mobile ) {
1596	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'could not fetch homepage twice' );
1597	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
1598	return $result;
1599	}
1600
1601	$identical = self::normalize_html_for_diff( $desktop ) === self::normalize_html_for_diff( $mobile );
1602
1603	$result = array(
1604	'identical' => $identical,
1605	'checked' => true,
1606	'desktop_bytes' => strlen( $desktop ),
1607	'mobile_bytes' => strlen( $mobile ),
1608	);
1609	set_transient( 'xspeed_mobile_equality_probe', $result, 10 * MINUTE_IN_SECONDS );
1610	return $result;
1611	}
1612
1613	/**
1614	* Strip per-request noise from HTML so a desktop-vs-mobile diff reflects
1615	* real structural differences, not nonces / session ids / timestamps that
1616	* change on every render. Deliberately conservative: it normalizes the
1617	* handful of well-known noise sources and collapses whitespace, so a site
1618	* that truly serves different markup per device still compares as different.
1619	*/
1620	private static function normalize_html_for_diff( string $html ): string {
1621	$patterns = array(
1622	// WP nonces (data-nonce="...", _wpnonce=..., "nonce":"...").
1623	'/(_wpnonce\|nonce\|_ajax_nonce)["\']?\s[:=]\s["\']?[a-f0-9]{10}/i',
1624	// Generic 10+ hex tokens (CSRF, cache-buster hashes, session ids).
1625	'/\b[a-f0-9]{16,}\b/i',
1626	// wp-generated unique ids (e.g. wp-block ids, aria ids).
1627	'/(id\|for\|aria-[a-z]+)="[^"]*-[0-9]{3,}"/i',
1628	// ISO-ish timestamps + epoch-looking numbers in query strings.
1629	'/\?ver=[0-9.]+/',
1630	'/[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9:.+Z-]+/',
1631	);
1632	$html = (string) preg_replace( $patterns, 'X', $html );
1633	// Collapse all whitespace so trivial formatting differences don't count.
1634	return trim( (string) preg_replace( '/\s+/', ' ', $html ) );
1635	}
1636
1637	public static function ensure_hits_log_file(): bool {
1638	// The HITs log exists ONLY so a server-level nginx `access_log`
1639	// directive has a world-writable file to append to (see nginx_snippet()
1640	// + Hit_Counter::collect_nginx_log_hits()). On Apache/LiteSpeed/managed
1641	// hosts nothing writes it, so creating it — and, worse, chmod()-ing it
1642	// world-writable — is pointless AND fails with "Operation not permitted"
1643	// when PHP can't chmod files it doesn't own (a warning that surfaces in
1644	// logs that capture @-suppressed errors). Skip the whole thing off nginx.
1645	if ( Server::NGINX !== Server::type() ) {
1646	return false;
1647	}
1648	$dir = self::hits_log_dir();
1649	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1650	return false;
1651	}
1652	// Ensure the dir is traversable + writable by a different-uid nginx.
1653	// 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.
1654	@chmod( $dir, 0777 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort; the access_log just stays empty if it fails.
1655	$path = self::hits_log_path();
1656	if ( ! file_exists( $path ) ) {
1657	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch -- See docblock: must be a plain touch, not WP_Filesystem.
1658	@touch( $path ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-fatal helper; failures already covered by the dir check.
1659	}
1660	// World-writable so a different-uid nginx can append HIT lines.
1661	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_chmod -- See docblock.
1662	@chmod( $path, 0666 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort.
1663	return file_exists( $path );
1664	}
1665
1666	public static function nginx_snippet(): ?string {
1667	if ( Server::NGINX !== Server::type() ) {
1668	return null;
1669	}
1670	$rel = '/' . ltrim( str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR ), '/' );
1671	$rel = rtrim( $rel, '/' );
1672
1673	// WP-Rocket-canonical pattern: every condition lives at
1674	// SERVER level (outside any location block). Each one appends
1675	// a tag to $xspeed_no_cache; the final check is a single
1676	// string-equality against the unmodified default "no-cache".
1677	// Only when ALL conditions pass does the rewrite fire,
1678	// jumping the request to the static file's URL. nginx then
1679	// restarts location matching against the new path, where
1680	// regular static-file serving takes over.
1681	//
1682	// Why server-level + a single rewrite (instead of try_files
1683	// inside `location /`): nginx's well-documented "if is evil"
1684	// quirk silently disables `try_files`'s last fallback when
1685	// any `if` in the same location is true. Moving the `if`s
1686	// outside any location dodges the trap completely, because
1687	// server-level rewrite is the documented stable path.
1688	//
1689	// `last` (not `break`) restarts location matching — required
1690	// so the rewritten static-file URI gets served via the normal
1691	// static-file location, not re-matched against `location /`
1692	// where our own rewrite would loop.
1693	//
1694	// The cache existence check is the LAST condition in the
1695	// chain so when the file isn't cached, $xspeed_no_cache
1696	// gets a "-nofile" tag and the rewrite is skipped — the
1697	// request falls through to whatever `location /` the user
1698	// already had (typically `try_files $uri $uri/ /index.php?$args;`).
1699	// Absolute path to the hit-log file from the nginx process's
1700	// filesystem view. Nginx's `access_log buffer=N flush=Ns` form
1701	// requires a literal path — `$document_root` variables are
1702	// rejected — so PHP computes it. Lives under uploads/ (NOT the
1703	// cache dir): a cache purge or uninstall deletes the cache dir,
1704	// which would orphan this directive's parent directory and make
1705	// `nginx -t` fail [emerg] for EVERY vhost on the host
1706	// (FBS-82478). uploads/ survives both, so the directive can
1707	// never take nginx down. Works on every topology where the nginx
1708	// process shares a filesystem with PHP (container or host).
1709	$hits_abs = self::hits_log_path();
1710
1711	$lines = array();
1712	$lines[] = '# xSpeed static cache — paste at server level, above location / { }.';
1713	// Cache host must match the on-disk dir PHP writes: store_static() /
1714	// static_host() take HTTP_HOST and strip every char outside
1715	// [a-zA-Z0-9.\-] — i.e. it removes the colon but KEEPS the port digits
1716	// (localhost:8192 → localhost8192). nginx's own $host can't reproduce
1717	// that: $host has the port already stripped ENTIRELY (→ localhost), so
1718	// the -f check looks for localhost/... while PHP wrote localhost8192/...
1719	// and the rewrite never fires on a non-standard port. Derive
1720	// $xspeed_host from $http_host (which keeps the port) and drop just the
1721	// colon, so it equals the PHP dir on every port. On standard ports
1722	// $http_host has no colon, so $xspeed_host == $host == the bare domain.
1723	$lines[] = 'set $xspeed_host $http_host;'; // default: no port → unchanged (e.g. example.com)
1724	$lines[] = 'if ($http_host ~ "^([^:]+):(\\d+)$") { set $xspeed_host $1$2; }'; // host:port → hostport (matches PHP static_host())
1725	$lines[] = 'set $xspeed_no_cache "no-cache";';
1726	$lines[] = 'if ($request_method != GET) { set $xspeed_no_cache "$xspeed_no_cache-method"; }';
1727	$lines[] = 'if ($args) { set $xspeed_no_cache "$xspeed_no_cache-args"; }';
1728	$lines[] = 'if ($http_cookie ~* "(wordpress_logged_in\|comment_author\|wp-postpass_)") { set $xspeed_no_cache "$xspeed_no_cache-cookie"; }';
1729	$lines[] = 'if (!-f "$document_root' . $rel . '/$xspeed_host$uri/index.html") { set $xspeed_no_cache "$xspeed_no_cache-nofile"; }';
1730	// Neither `add_header` nor `access_log` is allowed inside an `if{}`
1731	// at server level (nginx rejects with "directive is not allowed
1732	// here"). The logging therefore lives in a `location` block that
1733	// matches the rewritten URI after `rewrite … last;` restarts
1734	// location matching. Every HIT lands there exactly once, every
1735	// MISS / PHP-served request never matches it.
1736	$lines[] = 'if ($xspeed_no_cache = "no-cache") {';
1737	$lines[] = ' rewrite ^ ' . $rel . '/$xspeed_host$uri/index.html last;';
1738	$lines[] = '}';
1739	$lines[] = '';
1740	$lines[] = '# Serve + log the cached HIT — `^~` is required so this beats any regex location.';
1741	$lines[] = 'location ^~ ' . $rel . '/ {';
1742	$lines[] = ' internal;';
1743	// LITERAL log path (not `set $var; access_log $var`). The variable form
1744	// makes nginx open the log lazily per-request and SILENTLY drop the
1745	// line if the open fails — so on a working host hits were served
1746	// (X-XSpeed-Cache fires regardless) but nothing was ever written and
1747	// the hit ratio sat at 0%. A literal path makes nginx open the file at
1748	// config load and actually log every hit.
1749	//
1750	// Deleting the log FILE is still safe with a literal path: nginx
1751	// recreates it on the next write/reload and `nginx -t` stays green
1752	// (verified). The only thing that [emerg]s `nginx -t` is a missing
1753	// parent DIRECTORY — and the log lives under uploads/xspeed/, which
1754	// survives cache purge + uninstall, and which ensure_hits_log_file()
1755	// (run on every admin_init via auto_heal) recreates if it ever goes
1756	// missing. So: hits are logged, and a user deleting the log can't take
1757	// nginx down.
1758	$lines[] = ' access_log ' . $hits_abs . ' combined buffer=16k flush=5s;';
1759	$lines[] = ' add_header X-XSpeed-Cache "HIT (nginx)" always;';
1760	$lines[] = '}';
1761	return implode( "\n", $lines );
1762	}
1763
1764	/**
1765	* Aggregate every enabled module's nginx_directives() into one
1766	* pasteable server-block snippet. Replaces the per-module "paste
1767	* this snippet" notices with a single consolidated paste — every
1768	* future feature toggle just regenerates this output.
1769	*
1770	* Returns null on non-nginx hosts (nothing to paste).
1771	*
1772	* Sections render in module-registration order so the layout stays
1773	* predictable; each module gets a comment header `# <slug>`.
1774	*/
1775	public static function full_nginx_server_block(): ?string {
1776	if ( Server::NGINX !== Server::type() ) {
1777	return null;
1778	}
1779
1780	$blocks = array();
1781	foreach ( Module_Registry::all() as $module ) {
1782	$directives = $module->nginx_directives();
1783	if ( ! is_string( $directives ) \|\| '' === trim( $directives ) ) {
1784	continue;
1785	}
1786	$blocks[] = "# === " . $module->slug() . " ===\n" . rtrim( $directives );
1787	}
1788
1789	if ( empty( $blocks ) ) {
1790	return null;
1791	}
1792
1793	$header = "# xSpeed unified nginx config — paste into `server { }`, above `location / { }`; re-paste after toggling features.\n";
1794
1795	return $header . "\n" . implode( "\n\n", $blocks ) . "\n";
1796	}
1797
1798	/**
1799	* Tell LiteSpeed's LSCache module to stand down on the cache-miss
1800	* render path.
1801	*
1802	* History: this method used to emit X-LiteSpeed-Cache-Control:
1803	* public,max-age=N + X-LiteSpeed-Tag, handing caching to the server's
1804	* LSCache store. That delegation backfired — once LSCache cached a
1805	* page it served every subsequent request from its OWN store and
1806	* intercepted the request before our site-root .htaccess static
1807	* rewrite could run. Net effect on LiteSpeed hosts: no X-XSpeed-Cache
1808	* header, our static-cache tree never served, the HIT log never
1809	* written (hit ratio frozen at 0%), and the Health probe reporting a
1810	* false "cache running on PHP fallback" because it never saw an
1811	* xSpeed-served response.
1812	*
1813	* xSpeed now owns the cache on LiteSpeed exactly as it does on Apache:
1814	* our `.htaccess` mod_rewrite block serves hits straight from the
1815	* static-cache tree (with the X-XSpeed-Cache header + access-log HIT
1816	* accounting), and PHP/the drop-in is the fallback. To guarantee
1817	* LSCache doesn't shadow that with its own copy — some LiteSpeed
1818	* configs cache by default — we send an explicit `no-cache` control so
1819	* the server defers to our rewrite. Skipped when the LiteSpeed Cache
1820	* plugin is active (it owns its own header policy; our Conflict
1821	* registry handles that coexistence separately).
1822	*/
1823	public static function maybe_emit_lscache_headers(): void {
1824	if ( headers_sent() ) {
1825	return;
1826	}
1827	if ( Server::LITESPEED !== Server::type() ) {
1828	return;
1829	}
1830	// is_plugin_active() lives in wp-admin/includes/plugin.php which
1831	// isn't auto-loaded on front-end requests. Use the option layer
1832	// directly to avoid pulling in admin code from a render path.
1833	$active = (array) get_option( 'active_plugins', array() );
1834	if ( in_array( 'litespeed-cache/litespeed-cache.php', $active, true ) ) {
1835	return;
1836	}
1837
1838	// Explicitly opt this response OUT of LSCache so the server can't
1839	// shadow our static-rewrite cache with its own internal copy.
1840	header( 'X-LiteSpeed-Cache-Control: no-cache' );
1841	}
1842
1843	/**
1844	* Reconcile drop-in + WP_CACHE + rewrite block with the user's
1845	* saved choice. Runs on admin_init. Cheap when nothing's wrong
1846	* (one option read + a handful of file_exists / defined checks);
1847	* writes only when state has drifted (typical cause: plugin
1848	* upgrade wiped the drop-in, foreign plugin removed our WP_CACHE
1849	* define, or someone hand-edited .htaccess).
1850	*
1851	* Skipped during the WP plugin updater run so we don't race
1852	* the upgrader's own filesystem operations.
1853	*/
1854	public static function auto_heal(): void {
1855	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
1856	return;
1857	}
1858	if ( wp_doing_ajax() \|\| wp_doing_cron() ) {
1859	return;
1860	}
1861
1862	$opts = get_option( 'xspeed_options', array() );
1863	if ( empty( $opts['cache_enabled'] ) ) {
1864	return;
1865	}
1866
1867	$dropin_target = WP_CONTENT_DIR . '/advanced-cache.php';
1868	$dropin_ours = false;
1869	$dropin_stale = false;
1870	if ( file_exists( $dropin_target ) ) {
1871	$contents = @file_get_contents( $dropin_target ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
1872	$dropin_ours = is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' );
1873	// Reinstall when OUR drop-in is an older version than the source —
1874	// the marker alone can't distinguish an old copy from a new one, so
1875	// a serve-logic change (e.g. the .meta read for 404s/feeds) would
1876	// otherwise never reach existing cache-enabled sites until a manual
1877	// cache toggle. (FBS-82406/82407)
1878	if ( $dropin_ours ) {
1879	$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
1880	}
1881	}
1882
1883	if ( ! $dropin_ours \|\| $dropin_stale ) {
1884	self::install_dropin();
1885	}
1886
1887	if ( ! defined( 'WP_CACHE' ) \|\| ! WP_CACHE ) {
1888	self::set_wp_cache_constant( true );
1889	}
1890
1891	// Rewrite block goes last. It's what turns the static-cache
1892	// tree into a PHP-bypass — every cache hit served by the web
1893	// server directly. Without it we still cache, just at drop-in
1894	// speed (~85ms TTFB) instead of static-file speed (~25-40ms).
1895	//
1896	// Reconcile against mobile_separate: the rewrite is device-blind, so
1897	// it must be ABSENT when mobile_separate is on and PRESENT otherwise.
1898	// auto_heal() runs periodically, so it also repairs a rewrite that
1899	// was left installed before mobile_separate was switched on.
1900	if ( self::static_rewrite_allowed() ) {
1901	if ( ! self::rewrite_installed() ) {
1902	self::install_rewrite();
1903	}
1904	} elseif ( self::rewrite_installed() ) {
1905	self::remove_rewrite();
1906	}
1907
1908	// HITs log file — nginx writes one line per HIT served directly
1909	// (see nginx_snippet()), Cache::get_stats() drains the file via
1910	// Hit_Counter::collect_nginx_log_hits(). If the file vanishes
1911	// (plugin upgrade wiped wp-content/cache/), nginx errors silently
1912	// on the access_log directive and the counter stays at 0.
1913	self::ensure_hits_log_file();
1914	}
1915
1916	/**
1917	* Build the .htaccess rules that map cacheable requests to the
1918	* static-cache tree. Conditions are deliberately strict: GET only,
1919	* empty query string, no session/comment-author/post-password
1920	* cookie, and the static file must exist on disk. Anything that
1921	* fails one of these falls through to PHP and the drop-in / full
1922	* WordPress path.
1923	*
1924	* @return string[] Lines for insert_with_markers().
1925	*/
1926	public static function rewrite_block_lines(): array {
1927	// Path relative to ABSPATH so the rule lives in the site-root
1928	// .htaccess regardless of where wp-content sits. WP_CONTENT_DIR
1929	// can be moved, so we compute the document-root-relative form
1930	// at install time and bake it into the rule.
1931	$rel = str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR );
1932	$rel = '/' . ltrim( $rel, '/' );
1933	$rel = rtrim( $rel, '/' );
1934
1935	return array(
1936	'<IfModule mod_rewrite.c>',
1937	' RewriteEngine On',
1938	' RewriteCond %{REQUEST_METHOD} ^GET$',
1939	' RewriteCond %{QUERY_STRING} ^$',
1940	' RewriteCond %{HTTP_COOKIE} !(wordpress_logged_in\|comment_author\|wp-postpass_) [NC]',
1941	// Capture REQUEST_URI without its trailing slash into %1.
1942	// store_static() writes `{host}{uri-without-trailing-slash}/index.html`,
1943	// so this normalization lets `/blog/` and `/blog` both hit
1944	// the same cache file without producing the double-slash
1945	// path that would skip the -f check below.
1946	' RewriteCond %{REQUEST_URI} ^(.*?)/?$',
1947	' RewriteCond %{DOCUMENT_ROOT}' . $rel . '/%{HTTP_HOST}%1/index.html -f',
1948	// Pattern is `^`, NOT `.`. The per-directory rewrite engine
1949	// strips the leading slash before matching, so the HOMEPAGE
1950	// request `/` arrives here as an EMPTY path. `.` requires at
1951	// least one character and therefore never matches the homepage
1952	// — on LiteSpeed (which honors this strictly) the front page
1953	// fell through to PHP while every inner page rewrote fine.
1954	// `^` matches the empty string AND any non-empty path, so it
1955	// covers `/` and `/blog` alike. (Confirmed on OpenLiteSpeed
1956	// 1.8: `.` → homepage served by PHP drop-in; `^` → served
1957	// directly from the static file.)
1958	' RewriteRule ^ ' . $rel . '/%{HTTP_HOST}%1/index.html [L]',
1959	'</IfModule>',
1960	);
1961	}
1962
1963	/**
1964	* Active probe that confirms the web-server static-rewrite path is
1965	* actually serving cached files. Writes a probe file with a random
1966	* nonce, fetches it over HTTP at its public URL, and checks whether
1967	* the response was served directly by the web server (Last-Modified
1968	* + ETag headers + no X-Powered-By: PHP).
1969	*
1970	* Server-agnostic: same probe works for nginx (snippet pasted) and
1971	* Apache / LiteSpeed (.htaccess block installed). If the rewrite
1972	* isn't engaged, the request falls through to WordPress and PHP
1973	* adds its own headers, which the probe detects and reports.
1974	*
1975	* Throttled via a 5-minute transient — we never want this running
1976	* on every Health card paint.
1977	*
1978	* @return array{active:bool, reason:string, code?:int, php?:bool, expires?:int}
1979	*/
1980	/**
1981	* @param bool $allow_probe When false (the default), return ONLY a cached
1982	* result and never make an HTTP request — so admin page loads are never
1983	* blocked by the loopback probe. The actual HTTP probe only runs when a
1984	* caller explicitly opts in (the Health tab / cron). Previously this ran
1985	* synchronously on every dashboard bootstrap, so a slow/timing-out
1986	* loopback request added up to `timeout` seconds to admin page loads on
1987	* hosts that block self-requests. (FBS-82142)
1988	*/
1989	public static function probe_static_rewrite( bool $allow_probe = false ): array {
1990	$cached = get_transient( 'xspeed_rewrite_probe' );
1991	if ( is_array( $cached ) ) {
1992	return $cached;
1993	}
1994	// No cached result yet and the caller doesn't want to pay for a live
1995	// HTTP probe (e.g. the admin bootstrap): report "pending" without
1996	// blocking. The Health tab will run the real probe on demand.
1997	if ( ! $allow_probe ) {
1998	return array( 'active' => false, 'reason' => 'probe pending', 'pending' => true );
1999	}
2000
2001	$home = home_url( '/' );
2002	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
2003	if ( '' === $host ) {
2004	$result = array( 'active' => false, 'reason' => 'home_url has no host' );
2005	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2006	return $result;
2007	}
2008
2009	// Use a randomised path AND nonce so a stale CDN cache entry
2010	// from a prior probe can never make a broken install look
2011	// healthy. Path is namespaced under __xspeed_probe__ so the
2012	// directory listing stays obvious if cleanup misfires.
2013	$slug = wp_generate_password( 12, false, false );
2014	$nonce = wp_generate_password( 24, false, false );
2015	$probe_dir = XSPEED_CACHE_STATIC_DIR . '/' . $host . '/__xspeed_probe__/' . $slug;
2016	$probe_file = $probe_dir . '/index.html';
2017	$probe_url = trailingslashit( $home ) . '__xspeed_probe__/' . $slug . '/';
2018
2019	if ( ! file_exists( $probe_dir ) ) {
2020	wp_mkdir_p( $probe_dir );
2021	}
2022	if ( ! is_dir( $probe_dir ) ) {
2023	$result = array( 'active' => false, 'reason' => 'cannot create probe dir' );
2024	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2025	return $result;
2026	}
2027	// 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.
2028	file_put_contents( $probe_file, $nonce, LOCK_EX );
2029
2030	// Verify TLS by default — disabling it site-wide is a needless MITM
2031	// exposure (FBS-82142). Only relax verification in local/dev
2032	// environments, where self-signed certs are common and there's no
2033	// real attacker in the loop.
2034	$is_local = function_exists( 'wp_get_environment_type' )
2035	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
2036	$resp = wp_remote_get(
2037	$probe_url,
2038	array(
2039	// 3s cap so a host that hangs on loopback self-requests can't
2040	// stall the caller for long; the result/error is cached so we
2041	// don't repeat the wait every minute.
2042	'timeout' => 3,
2043	'sslverify' => ! $is_local,
2044	'redirection' => 0,
2045	'headers' => array( 'Cache-Control' => 'no-cache' ),
2046	)
2047	);
2048
2049	// Best-effort cleanup so we don't accumulate probe dirs even
2050	// if subsequent calls all hit the transient.
2051	if ( file_exists( $probe_file ) ) {
2052	wp_delete_file( $probe_file );
2053	}
2054	if ( is_dir( $probe_dir ) ) {
2055	// 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.
2056	@rmdir( $probe_dir );
2057	}
2058
2059	if ( is_wp_error( $resp ) ) {
2060	$result = array(
2061	'active' => false,
2062	'reason' => 'http error: ' . $resp->get_error_message(),
2063	);
2064	// Cache the failure for the full 5 minutes (not 1) so a host that
2065	// times out on the loopback probe isn't re-probed — and re-stalled
2066	// — on every page load within the window. (FBS-82142)
2067	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
2068	return $result;
2069	}
2070
2071	$code = (int) wp_remote_retrieve_response_code( $resp );
2072	$body = (string) wp_remote_retrieve_body( $resp );
2073	$ua_php = '' !== (string) wp_remote_retrieve_header( $resp, 'x-powered-by' );
2074	$has_etag = '' !== (string) wp_remote_retrieve_header( $resp, 'etag' )
2075	\|\| '' !== (string) wp_remote_retrieve_header( $resp, 'last-modified' );
2076	$match = trim( $body ) === $nonce;
2077
2078	// "Active" = the web server served our raw nonce bytes back
2079	// AND emitted the static-serve markers (ETag / Last-Modified)
2080	// AND didn't add an X-Powered-By: PHP header. All three are
2081	// individually noisy; together they're conclusive.
2082	$active = $match && $has_etag && ! $ua_php && 200 === $code;
2083
2084	if ( $active ) {
2085	$reason = 'static-served';
2086	} elseif ( 200 === $code && $match && $ua_php ) {
2087	$reason = 'php served the file instead of nginx/Apache (rewrite block missing)';
2088	} elseif ( 200 === $code && ! $match ) {
2089	$reason = 'unexpected body (CDN cached an older response?)';
2090	} elseif ( 404 === $code ) {
2091	$reason = 'probe URL returned 404 (rewrite block missing or wrong path)';
2092	} else {
2093	$reason = sprintf( 'unexpected response (HTTP %d, body %d B, php=%s)', $code, strlen( $body ), $ua_php ? 'yes' : 'no' );
2094	}
2095
2096	$result = array(
2097	'active' => $active,
2098	'reason' => $reason,
2099	'code' => $code,
2100	'php' => $ua_php,
2101	);
2102	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
2103	return $result;
2104	}
2105
2106	public static function rewrite_installed(): bool {
2107	$htaccess = ABSPATH . '.htaccess';
2108	if ( ! file_exists( $htaccess ) ) {
2109	return false;
2110	}
2111	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2112	if ( ! is_string( $existing ) ) {
2113	return false;
2114	}
2115	return false !== strpos( $existing, '# BEGIN xSpeed Static Cache' );
2116	}
2117
2118	/**
2119	* Install the static-cache rewrite block at the TOP of .htaccess.
2120	*
2121	* Position matters: WordPress's own block ends with
2122	* `RewriteRule . /index.php [L]` which routes every non-file
2123	* request to PHP. The [L] flag stops the current rewrite pass,
2124	* but Apache restarts the cycle; on the second pass REQUEST_URI
2125	* is /index.php and no static-file check can match. The only
2126	* reliable position for a "serve static if it exists" rule is
2127	* before WordPress's block.
2128	*
2129	* WP's insert_with_markers() always appends, so we manage the
2130	* block manually: strip any prior xSpeed Static Cache markers,
2131	* then write our block followed by the rest of the file.
2132	*/
2133	public static function install_rewrite(): bool {
2134	// The static rewrite is device-blind; never install it when
2135	// mobile_separate is on (see static_rewrite_allowed()).
2136	if ( ! self::static_rewrite_allowed() ) {
2137	return false;
2138	}
2139	$htaccess = ABSPATH . '.htaccess';
2140	$existing = file_exists( $htaccess ) ? @file_get_contents( $htaccess ) : ''; // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2141	if ( false === $existing ) {
2142	$existing = '';
2143	}
2144	// Apache/LiteSpeed only. nginx hosts: rule won't fire, drop-in
2145	// covers; we skip the write so we don't litter their root.
2146	// 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.
2147	if ( file_exists( $htaccess ) && ! is_writable( $htaccess ) ) {
2148	return false;
2149	}
2150	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See above.
2151	if ( ! file_exists( $htaccess ) && ! is_writable( ABSPATH ) ) {
2152	return false;
2153	}
2154
2155	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
2156	$block = self::marker_block( 'xSpeed Static Cache', self::rewrite_block_lines() );
2157	$next = $block . ( '' === $cleaned ? '' : "\n" . $cleaned );
2158
2159	// 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.
2160	return false !== file_put_contents( $htaccess, $next, LOCK_EX );
2161	}
2162
2163	public static function remove_rewrite(): bool {
2164	$htaccess = ABSPATH . '.htaccess';
2165	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See install_rewrite() rationale.
2166	if ( ! file_exists( $htaccess ) \|\| ! is_writable( $htaccess ) ) {
2167	return false;
2168	}
2169	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2170	if ( false === $existing ) {
2171	return false;
2172	}
2173	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
2174	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents, PluginCheck.CodeAnalysis.WriteFile.ABSPATHDetected -- See install_rewrite() rationale.
2175	return false !== file_put_contents( $htaccess, $cleaned, LOCK_EX );
2176	}
2177
2178	/**
2179	* Strip a `# BEGIN <marker>` ... `# END <marker>` block from a
2180	* .htaccess-style file, including any blank line that immediately
2181	* follows it. Idempotent — returns the input unchanged if the
2182	* marker isn't present.
2183	*/
2184	private static function strip_marker_block( string $contents, string $marker ): string {
2185	$pattern = '/# BEGIN ' . preg_quote( $marker, '/' ) . '\b.?# END ' . preg_quote( $marker, '/' ) . "\b[^\n]\n?\n?/s";
2186	$out = preg_replace( $pattern, '', $contents );
2187	return is_string( $out ) ? $out : $contents;
2188	}
2189
2190	private static function marker_block( string $marker, array $lines ): string {
2191	$header = "# BEGIN $marker\n";
2192	$header .= "# The directives (lines) between \"BEGIN $marker\" and \"END $marker\" are\n";
2193	$header .= "# dynamically generated, and should only be modified via WordPress filters.\n";
2194	$header .= "# Any changes to the directives between these markers will be overwritten.\n";
2195	$footer = "# END $marker\n";
2196	return $header . implode( "\n", $lines ) . "\n" . $footer;
2197	}
2198
2199	/**
2200	* Parse the `XSPEED_DROPIN_VERSION: N` stamp out of a drop-in's source.
2201	* Returns 0 when absent (an un-stamped older copy reinstalls). Used to
2202	* detect a stale installed drop-in vs the bundled source.
2203	*/
2204	private static function dropin_version( string $contents ): int {
2205	if ( preg_match( '/XSPEED_DROPIN_VERSION:\s*(\d+)/', $contents, $m ) ) {
2206	return (int) $m[1];
2207	}
2208	return 0;
2209	}
2210
2211	public static function install_dropin() {
2212	$source = XSPEED_DIR . 'includes/advanced-cache.php';
2213	$target = WP_CONTENT_DIR . '/advanced-cache.php';
2214	if ( ! file_exists( $source ) ) {
2215	return false;
2216	}
2217
2218	global $wp_filesystem;
2219	if ( ! function_exists( 'WP_Filesystem' ) ) {
2220	require_once ABSPATH . 'wp-admin/includes/file.php';
2221	}
2222	WP_Filesystem();
2223	if ( ! $wp_filesystem ) {
2224	return false;
2225	}
2226
2227	$source_contents = $wp_filesystem->get_contents( $source );
2228	if ( ! is_string( $source_contents ) ) {
2229	return false;
2230	}
2231
2232	// Bake the absolute hit-log path into the drop-in. It runs before
2233	// WordPress loads, so it can't resolve wp_upload_dir() itself — we
2234	// substitute the @@XSPEED_HITS_LOG@@ token with the real uploads path
2235	// (never the cache dir; see hits_log_dir() / FBS-82478). Use a single
2236	// quoted PHP string literal so the installed file stays valid PHP.
2237	$source_contents = str_replace(
2238	'@@XSPEED_HITS_LOG@@',
2239	str_replace( "'", "\\'", self::hits_log_path() ),
2240	$source_contents
2241	);
2242
2243	if ( file_exists( $target ) ) {
2244	$existing = $wp_filesystem->get_contents( $target );
2245	$is_xspeed = is_string( $existing ) && false !== strpos( $existing, 'XSPEED_DROPIN' );
2246
2247	if ( $is_xspeed ) {
2248	if ( $existing === $source_contents ) {
2249	return true;
2250	}
2251	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
2252	}
2253
2254	// Foreign drop-in (e.g. left over from another cache plugin) — back it up
2255	// before overwriting so the user can recover if needed. Uploads dir
2256	// (not wp-content root) keeps the backup out of WordPress's reserved
2257	// drop-in location.
2258	$upload = wp_upload_dir( null, false );
2259	$basedir = isset( $upload['basedir'] ) ? trailingslashit( $upload['basedir'] ) . 'xspeed-backups' : false;
2260	if ( $basedir ) {
2261	if ( ! file_exists( $basedir ) ) {
2262	wp_mkdir_p( $basedir );
2263	self::write_silence( $basedir );
2264	}
2265	$backup = $basedir . '/advanced-cache.foreign-' . gmdate( 'Ymd-His' ) . '.php.bak';
2266	$wp_filesystem->move( $target, $backup, true );
2267	} else {
2268	$wp_filesystem->delete( $target );
2269	}
2270	}
2271
2272	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
2273	}
2274
2275	public static function remove_dropin() {
2276	$target = WP_CONTENT_DIR . '/advanced-cache.php';
2277	if ( ! file_exists( $target ) ) {
2278	return;
2279	}
2280
2281	global $wp_filesystem;
2282	if ( ! function_exists( 'WP_Filesystem' ) ) {
2283	require_once ABSPATH . 'wp-admin/includes/file.php';
2284	}
2285	WP_Filesystem();
2286	if ( ! $wp_filesystem ) {
2287	return;
2288	}
2289
2290	$contents = $wp_filesystem->get_contents( $target );
2291	if ( is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' ) ) {
2292	wp_delete_file( $target );
2293	}
2294	}
2295
2296	public static function set_wp_cache_constant( $enable ) {
2297	$wp_config = ABSPATH . 'wp-config.php';
2298	if ( ! file_exists( $wp_config ) ) {
2299	return false;
2300	}
2301
2302	global $wp_filesystem;
2303	if ( ! function_exists( 'WP_Filesystem' ) ) {
2304	require_once ABSPATH . 'wp-admin/includes/file.php';
2305	}
2306	WP_Filesystem();
2307	if ( ! $wp_filesystem \|\| ! $wp_filesystem->is_writable( $wp_config ) ) {
2308	return false;
2309	}
2310
2311	$config = $wp_filesystem->get_contents( $wp_config );
2312
2313	if ( $enable ) {
2314	// Own the constant. A previous caching plugin (e.g. WP Rocket sets
2315	// it false on deactivate) can leave `define( 'WP_CACHE', false );`
2316	// behind — presence alone is not enough, the VALUE must be true or
2317	// WordPress never loads advanced-cache.php and our drop-in is dead.
2318	if ( preg_match( "/define\\(\\s['\"]WP_CACHE['\"]\\s,/", $config ) ) {
2319	$rewritten = preg_replace(
2320	"/define\$\\s['\"]WP_CACHE['\"]\\s,\\s[^)]\$\\s*;/",
2321	"define( 'WP_CACHE', true );",
2322	$config,
2323	1
2324	);
2325	// If an existing define was already `true`, the rewrite is a
2326	// no-op string-wise; either way we end on WP_CACHE === true.
2327	if ( null !== $rewritten ) {
2328	$config = $rewritten;
2329	}
2330	} else {
2331	$config = preg_replace( '/(<\?php)/', "$1\ndefine( 'WP_CACHE', true );", $config, 1 );
2332	}
2333	} else {
2334	$config = preg_replace( "/define\$\\s['\"]WP_CACHE['\"]\\s,\\strue\\s\$;\\s*\\n?/", '', $config );
2335	}
2336
2337	return (bool) $wp_filesystem->put_contents( $wp_config, $config, FS_CHMOD_FILE );
2338	}
2339
2340	/**
2341	* Admin-bar purge menu — a parent node plus one child per visible cache
2342	* type (LiteSpeed-style), instead of a single "Purge All" link. Each
2343	* child posts to the same admin-post handler with its type slug. The
2344	* per-type items only appear for active/licensed modules; "Purge All"
2345	* always shows and always sweeps everything. (FBS-83114)
2346	*/
2347	public function admin_bar_purge( $wp_admin_bar ) {
2348	if ( ! current_user_can( 'manage_options' ) ) {
2349	return;
2350	}
2351
2352	$wp_admin_bar->add_node(
2353	array(
2354	'id' => 'xspeed-purge',
2355	'title' => __( 'xSpeed Cache', 'xspeed' ),
2356	'href' => self::purge_type_url( 'all' ),
2357	)
2358	);
2359
2360	foreach ( self::purge_types() as $slug => $type ) {
2361	if ( empty( $type['visible'] ) ) {
2362	continue;
2363	}
2364	$wp_admin_bar->add_node(
2365	array(
2366	'id' => 'xspeed-purge-' . $slug,
2367	'parent' => 'xspeed-purge',
2368	'title' => esc_html( $type['label'] ),
2369	'href' => self::purge_type_url( $slug ),
2370	)
2371	);
2372	}
2373	}
2374
2375	/**
2376	* Nonce-protected admin-post URL for purging a single type. The nonce
2377	* action is per-type so a leaked URL can't be replayed for a different
2378	* scope.
2379	*/
2380	private static function purge_type_url( string $type ): string {
2381	return wp_nonce_url(
2382	admin_url( 'admin-post.php?action=xspeed_purge&type=' . rawurlencode( $type ) ),
2383	'xspeed_purge_' . $type
2384	);
2385	}
2386
2387	public function handle_admin_bar_purge() {
2388	if ( ! current_user_can( 'manage_options' ) ) {
2389	wp_die( esc_html__( 'Unauthorized.', 'xspeed' ), 403 );
2390	}
2391	$type = isset( $_GET['type'] ) ? sanitize_key( wp_unslash( $_GET['type'] ) ) : 'all';
2392	check_admin_referer( 'xspeed_purge_' . $type );
2393
2394	// Only honour known types; anything else falls back to a full purge.
2395	if ( ! array_key_exists( $type, self::purge_types() ) ) {
2396	$type = 'all';
2397	}
2398	self::purge_type( $type );
2399
2400	wp_safe_redirect( self::safe_purge_redirect( wp_get_referer() ) );
2401	exit;
2402	}
2403
2404	/**
2405	* Resolve a safe redirect target for an admin-bar purge.
2406	*
2407	* The purge sends the admin back where they came from — but the referer
2408	* can be a ONE-SHOT action URL (e.g. update.php?action=upload-plugin from
2409	* installing a plugin zip, or any *.php?action=… that consumed a POST /
2410	* temp upload). Redirecting there re-runs the action with nothing to act
2411	* on, so WordPress dies — the classic "Please select a file" from
2412	* File_Upload_Upgrader. Strip the transient action args so we return to a
2413	* safe, re-GET-able view of the same page; fall back to the dashboard when
2414	* there is no usable referer.
2415	*
2416	* @param string\|false $referer Raw wp_get_referer() value.
2417	* @return string Safe URL to redirect to.
2418	*/
2419	public static function safe_purge_redirect( $referer ): string {
2420	$referer = is_string( $referer ) ? $referer : '';
2421	if ( '' === $referer ) {
2422	return admin_url();
2423	}
2424
2425	// A referer that lands on an action-processing endpoint (update.php,
2426	// update-core.php, plugin/theme install/upload flows) can't be safely
2427	// re-requested — send them to the dashboard instead of replaying it.
2428	$path = (string) wp_parse_url( $referer, PHP_URL_PATH );
2429	if ( preg_match( '#/wp-admin/(update\|update-core)\.php$#', $path ) ) {
2430	return admin_url();
2431	}
2432
2433	// Otherwise keep them on the same page but drop the query args that
2434	// would re-trigger a form action or upload on load.
2435	return remove_query_arg(
2436	array( 'action', 'action2', 'package', 'overwrite', 'plugin', 'theme', 'file', '_wpnonce', '_ajax_nonce' ),
2437	$referer
2438	);
2439	}
2440	}
2441