xspeed / includes / class-cache.php

class-cache.php in xSpeed Cache: AI-Powered Performance Hub with MCP, Caching & CDN 1.1.6, 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	/**
24	* The `X-XSpeed-Cache` value decided for this request, and — when the
25	* decision was BYPASS — the slug of the gate that made it.
26	*
27	* Recorded as well as sent so unit tests (CLI SAPI, where header() is a
28	* no-op and headers_sent() is meaningless) can assert on the decision.
29	*
30	* @var string
31	*/
32	private static $status_header = '';
33	private static $bypass_reason = '';
34
35	/**
36	* Cache key whose write was deferred to shutdown because a render-time
37	* translation plugin's buffer wraps ours. Null on every ordinary request.
38	*
39	* @var string\|null
40	*/
41	private static $deferred_key = null;
42
43	/**
44	* Translated page HTML captured by the outer buffer, for the deferred
45	* write. Only populated when a translation plugin is active.
46	*
47	* @var string
48	*/
49	private static $translated_output = '';
50
51	/**
52	* Did finalize_buffer() run to completion on this request?
53	*
54	* The deferred translated write runs as a PHP shutdown function, which
55	* fires after a `wp_die()` or a bare `exit()` exactly as it does after a
56	* clean render. Only finalize_buffer() sets this, and only at the point
57	* where it has the full buffer in hand — so an aborted render leaves it
58	* false and the writer declines rather than caching a truncated page
59	* under the real key.
60	*
61	* @var bool
62	*/
63	private static $render_completed = false;
64
65	public function __construct() {
66	/**
67	* When the page-cache output buffer opens.
68	*
69	* Filterable because buffer ORDER decides what gets cached. PHP's
70	* output buffers are LIFO: the last one opened is innermost, and its
71	* callback runs first. A render-time translation plugin that opens
72	* an outer buffer therefore translates AFTER we have already captured
73	* and cached the raw HTML — see translation_buffer_compat().
74	*
75	* @param string $hook Hook to open the buffer on.
76	* @param int $priority Priority for that hook.
77	*/
78	$hook = (string) apply_filters( 'xspeed_cache_buffer_hook', 'template_redirect' );
79	$priority = (int) apply_filters( 'xspeed_cache_buffer_priority', 0 );
80	add_action( $hook, array( $this, 'maybe_start_cache' ), $priority );
81
82	// When a render-time translation plugin is present, open one extra
83	// buffer OUTSIDE its own so we can capture post-translation HTML.
84	// TranslatePress opens on `init` priority 0, so we take a negative
85	// priority to land outside it. This buffer only collects bytes for
86	// the deferred cache write — it never modifies the response.
87	add_action(
88	'init',
89	static function () {
90	if ( ! self::translation_plugin_active() ) {
91	return;
92	}
93	// `init` fires on EVERY request type, and
94	// translation_plugin_active() is a class_exists() check that
95	// is true site-wide — so without this guard the buffer opened
96	// on REST, admin-ajax, cron and WP-CLI too. None of those
97	// reach template_redirect, so $deferred_key stays null and
98	// the collected bytes are never released: a long-running
99	// WP-CLI command copied every byte of its output into a
100	// string that grew for the life of the process.
101	if ( is_admin()
102	\|\| wp_doing_ajax()
103	\|\| wp_doing_cron()
104	\|\| ( defined( 'REST_REQUEST' ) && REST_REQUEST )
105	\|\| ( defined( 'WP_CLI' ) && WP_CLI )
106	\|\| ( defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST ) ) {
107	return;
108	}
109	ob_start(
110	static function ( $chunk ) {
111	self::$translated_output .= $chunk;
112	return $chunk;
113	}
114	);
115	},
116	(int) apply_filters( 'xspeed_translation_outer_buffer_priority', -100 )
117	);
118
119	// Events that should invalidate cached output. Beyond posts/comments,
120	// this covers user and term changes — the REST cache can serve
121	// /wp/v2/users, /wp/v2/categories, /wp/v2/tags, and these also affect
122	// rendered author bylines / term-archive pages. Without them, an edit
123	// left the matching endpoint (and archives) stale for the full TTL.
124	// (FBS-82408)
125	$invalidate_hooks = array(
126	'save_post', 'deleted_post', 'trashed_post',
127	'comment_post', 'wp_set_comment_status',
128	'switch_theme', 'activated_plugin', 'deactivated_plugin',
129	// Users → /wp/v2/users + author archives.
130	'profile_update', 'user_register', 'deleted_user',
131	// Terms → /wp/v2/{taxonomy} + term archives.
132	'created_term', 'edited_term', 'delete_term',
133	);
134	foreach ( $invalidate_hooks as $hook ) {
135	add_action( $hook, array( __CLASS__, 'purge_all' ) );
136	add_action( $hook, array( 'XSpeed\\Minifier', 'purge_minified' ) );
137	}
138
139	add_action( 'update_option_xspeed_options', array( __CLASS__, 'on_settings_change' ), 10, 2 );
140
141	add_action( 'admin_bar_menu', array( $this, 'admin_bar_purge' ), 100 );
142	add_action( 'admin_post_xspeed_purge', array( $this, 'handle_admin_bar_purge' ) );
143	}
144
145	public static function on_settings_change( $old, $new ) {
146	// gzip_enabled moved to xspeed_module_gzip — GzipModule owns the
147	// .htaccess flip via its own update_option_xspeed_module_gzip hook.
148	// Same migration is planned for cache_expiry + excluded_urls
149	// (Cache module). Keep this handler around for whatever still
150	// lives in the legacy blob (cache_enabled is special and goes
151	// through Cache::toggle anyway).
152
153	// Any settings change — purge caches so changes take effect.
154	self::purge_all( 'settings change' );
155	Minifier::purge_minified();
156	}
157
158	/**
159	* Stamp the request's cache decision on the response.
160	*
161	* `X-XSpeed-Cache` was only ever written on the serve-from-cache paths,
162	* so a miss and a deliberate bypass both came back with no header at all
163	* — indistinguishable from a `curl -I`, the first thing anyone reaches
164	* for when a site "isn't caching" (issue #10). The reason slug rides
165	* along on `X-XSpeed-Reason`, but only under WP_DEBUG so production
166	* responses stay clean. Slugs are fixed per gate — never the matched
167	* pattern, cookie or user-agent, which would echo request input back.
168	*
169	* @param string $value HIT (php) \| MISS \| BYPASS.
170	* @param string $reason Fixed slug naming the gate, for BYPASS only.
171	*/
172	private static function mark( string $value, string $reason = '' ): void {
173	self::$status_header = $value;
174	self::$bypass_reason = $reason;
175
176	if ( headers_sent() ) {
177	return;
178	}
179	header( 'X-XSpeed-Cache: ' . $value );
180	if ( '' !== $reason && defined( 'WP_DEBUG' ) && WP_DEBUG ) {
181	header( 'X-XSpeed-Reason: ' . $reason );
182	}
183	}
184
185	/** Record a bypass gate and answer "don't cache" in one statement. */
186	private static function bypass( string $reason ): bool {
187	self::mark( 'BYPASS', $reason );
188	return false;
189	}
190
191	/** The X-XSpeed-Cache value decided for this request ('' if none yet). */
192	public static function status_header(): string {
193	return self::$status_header;
194	}
195
196	/** The bypass gate slug for this request ('' unless BYPASS). */
197	public static function bypass_reason(): string {
198	return self::$bypass_reason;
199	}
200
201	public function maybe_start_cache() {
202	if ( ! self::should_cache() ) {
203	// PHP has just evaluated the FULL exclusion rule list — including
204	// the `~regex` patterns the server config can't express — and
205	// decided this visitor must not be served from cache. Record that
206	// verdict in the conventional bypass cookie so the web server can
207	// enforce it on subsequent requests without starting PHP.
208	//
209	// This is what stops most settings changes from needing an nginx
210	// reload: the config tests one fixed cookie name forever, and the
211	// rule list behind it can change freely.
212	self::sync_bypass_cookie( true );
213	return;
214	}
215
216	// Cacheable: clear any stale bypass cookie, or a visitor who once
217	// had a cart would keep skipping the fast path long after checkout.
218	self::sync_bypass_cookie( false );
219
220	$key = self::cache_key();
221	$file = self::cache_file_for( $key );
222
223	if ( file_exists( $file ) && ! self::is_expired( $file ) ) {
224	Hit_Counter::record_hit();
225	// Emit the HIT marker on THIS path too. The drop-in
226	// (advanced-cache.php) sends "HIT (php)" and the nginx static
227	// rewrite sends "HIT (nginx)", but this template_redirect
228	// serve path — the one that runs when the drop-in isn't loaded
229	// (e.g. WP_CACHE not true) — previously streamed the cached
230	// file with NO marker, so a genuine HIT looked like a MISS in
231	// the response headers. Same header + value as the drop-in.
232	self::mark( 'HIT (php)' );
233	// Replay stored response bits so the HIT matches the original:
234	// a non-HTML Content-Type (cached feeds, sitemaps) and a non-200
235	// status (a cached 404 must serve 404, not 200). No-op for
236	// ordinary pages, which write no .meta.
237	$meta = self::read_meta( $key );
238	if ( ! headers_sent() ) {
239	if ( ! empty( $meta['status'] ) && function_exists( 'http_response_code' ) ) {
240	http_response_code( (int) $meta['status'] );
241	}
242	if ( ! empty( $meta['content_type'] ) && is_string( $meta['content_type'] ) ) {
243	header( 'Content-Type: ' . $meta['content_type'] );
244	}
245	// Conditional GET: emit Last-Modified + ETag and answer a
246	// matching If-Modified-Since / If-None-Match with 304 so
247	// aggregators (and browsers) skip re-downloading an unchanged
248	// cached response — the bandwidth win feeds are about.
249	// (FBS-82407 #5)
250	if ( self::serve_not_modified( $file ) ) {
251	exit; // 304 sent, no body.
252	}
253	}
254	// Serve the precompressed Brotli sibling when the client accepts
255	// it (an add-on, the Pro Brotli module, wrote <file>.br). On this
256	// PHP serve path the web server never sees the .br, so without
257	// this a br-capable client got the plain .html — precompression
258	// did nothing here. Falls through to plain readfile otherwise.
259	$br = self::maybe_serve_brotli( $file );
260	if ( null !== $br ) {
261	// 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.
262	readfile( $br );
263	exit;
264	}
265	// 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.
266	readfile( $file );
267	exit;
268	}
269
270	// Cache miss → render fresh + write cache. On LiteSpeed we send an
271	// explicit "stand down" header so the server's LSCache module does
272	// NOT cache + shadow our response — xSpeed's own .htaccess static
273	// rewrite owns hit serving (and hit accounting) here, exactly as on
274	// Apache. See maybe_emit_lscache_headers() for the full rationale.
275	self::maybe_emit_lscache_headers();
276
277	// We're about to render fresh + cache → miss for this request.
278	// …UNLESS this request is a 404 or a known bot/scanner. Those reach the
279	// render path too, but counting them as cache misses makes the ratio
280	// meaningless — a wave of `/wp-x7.php` scanner 404s reads as a collapsing
281	// cache when nothing is wrong. Runs at template_redirect (priority 0), so
282	// is_404() is already resolved. Excluded requests are tallied separately
283	// for the "you absorbed N scanner hits" line, not dropped. (#118)
284	if ( self::miss_is_excluded() ) {
285	Hit_Counter::record_excluded();
286	} else {
287	Hit_Counter::record_miss();
288	}
289
290	// Stamp it, so "eligible but not cached yet" is visibly different
291	// from "deliberately bypassed" (issue #10). Headers can't be sent
292	// after the body starts, so this has to happen here, not in
293	// finalize_buffer() — nothing has been output at template_redirect.
294	self::mark( 'MISS' );
295
296
297	// WP < 6.9 fallback: ob_start() with a callback, paired with an
298	// explicit shutdown close so the buffer lifecycle is visible to
299	// reviewers and Plugin Check, instead of relying on PHP's implicit
300	// request-end flush. We record our nesting level so close_buffer()
301	// flushes ONLY the buffer we opened.
302	ob_start( array( __CLASS__, 'finalize_buffer' ) );
303	self::$buffer_level = ob_get_level();
304
305	add_action( 'shutdown', array( __CLASS__, 'close_buffer' ), 0 );
306	}
307
308	/**
309	* Close the cache buffer opened by maybe_start_cache().
310	*
311	* Guarded by the recorded buffer level so we never flush a buffer that
312	* another plugin pushed on top of (or under) ours. If something else is
313	* currently on top, we leave the stack alone — PHP's shutdown sequence
314	* will unwind buffers in order and our finalize_buffer() callback will
315	* still run when our level becomes the topmost one.
316	*/
317	public static function close_buffer() {
318	if ( null === self::$buffer_level ) {
319	return;
320	}
321	if ( ob_get_level() === self::$buffer_level ) {
322	ob_end_flush();
323	}
324	self::$buffer_level = null;
325	}
326
327	/**
328	* Are we buffering this request?
329	*
330	* Asked by Css_Combine_Buffer, which needs the finished HTML but must not
331	* open a second buffer when this one is already going to hand it the page
332	* through `xspeed_cache_final_html`. False here means the request is not
333	* cacheable — cache off, excluded URL, logged in — and the combiner has to
334	* provide its own buffer or it silently stops working. (#195)
335	*/
336	public static function is_buffering(): bool {
337	return null !== self::$buffer_level;
338	}
339
340	/**
341	* Is a render-time translation plugin going to wrap our output buffer?
342	*
343	* TranslatePress opens its translation buffer on `init` priority 0. We
344	* open ours on `template_redirect`, which runs much later, so ours nests
345	* INSIDE theirs. PHP unwinds output buffers LIFO — innermost callback
346	* first — so `finalize_buffer()` saw the raw, pre-translation HTML and
347	* cached that, while the live visitor still got the translated bytes from
348	* TRP's outer buffer.
349	*
350	* Result: the first (MISS) visitor to /fr/some-page/ got correct French;
351	* every visitor after got English body text under a `lang="fr-FR"`
352	* document, plus TRP's internal `#TRPLINKPROCESSED` link markers, which
353	* TRP strips at the very end of its own buffer and which therefore leak
354	* into anything captured from inside it.
355	*
356	* Note the ordering cannot be fixed from TRP's side: its
357	* `trp_start_output_buffer_priority` filter only moves the PRIORITY on
358	* `init`, and `init` always fires before `template_redirect` whatever the
359	* priority. The buffer that has to move is ours.
360	*
361	* Detected by main class rather than plugin path, so a renamed directory
362	* or a bundled copy still matches.
363	*/
364	public static function translation_plugin_active(): bool {
365	$active = class_exists( 'TRP_Translate_Press' );
366
367	/**
368	* Whether to treat this request as wrapped by a translation buffer.
369	*
370	* Lets a site add another render-time translation plugin (or opt out)
371	* without patching the engine.
372	*
373	* @param bool $active
374	*/
375	return (bool) apply_filters( 'xspeed_translation_plugin_active', $active );
376	}
377
378	/**
379	* Write the cache file for a request whose output was wrapped by a
380	* render-time translation plugin.
381	*
382	* Registered as a PHP shutdown function (not a WP `shutdown` action) so
383	* it runs after PHP has unwound the output-buffer stack — by which point
384	* the translation plugin's callback has transformed the bytes and its
385	* internal markers are gone.
386	*
387	* finalize_buffer() has already applied the status gate, the
388	* xspeed_cache_final_html filter and HTML minification to the
389	* untranslated copy and then declined to write it. Here we re-run only
390	* what's needed on the translated bytes: minify, write, and fire the
391	* same downstream hooks so Brotli / static-tree listeners behave
392	* identically to the ordinary path.
393	*/
394	public static function write_deferred_translated_cache(): void {
395	$key = self::$deferred_key;
396	self::$deferred_key = null;
397
398	// Release the collected bytes BEFORE the early return, so the static
399	// is cleared on every path rather than only when a key survived.
400	$full = self::$translated_output;
401	self::$translated_output = '';
402
403	$completed = self::$render_completed;
404	self::$render_completed = false;
405
406	if ( null === $key ) {
407	return;
408	}
409
410	// Did the render actually finish?
411	//
412	// This runs as a PHP shutdown function, which fires after a wp_die()
413	// or a bare exit() just as readily as after a clean render — but in
414	// those cases finalize_buffer() never returned, so the bytes we hold
415	// are a page that was cut off partway through. The length and
416	// TRPLINKPROCESSED checks below don't catch that: a fatal after the
417	// footer's translated markup is both over 255 bytes and free of TRP
418	// markers, i.e. truncated but entirely plausible. Caching it would
419	// freeze a half-rendered page under the real key for the full TTL.
420	//
421	// Serving this one URL uncached is the cheap failure; the corrupt
422	// cache entry is the expensive one.
423	if ( ! $completed ) {
424	return;
425	}
426
427	if ( strlen( $full ) < 255 ) {
428	return;
429	}
430
431	// Refuse to cache a copy still carrying the translation plugin's
432	// internal link markers. TRP strips these at the very end of its own
433	// buffer, so their presence means we captured too early — and a
434	// cached page containing them is SEO-visible damage. Better to serve
435	// this URL uncached than to freeze broken markup for the full TTL.
436	if ( false !== strpos( $full, 'TRPLINKPROCESSED' ) ) {
437	return;
438	}
439
440	$minify_opts = Settings_Manager::get( 'minify' );
441	if ( ! empty( $minify_opts['minify_html'] ) ) {
442	$full = Minifier::minify_html( $full );
443	}
444
445	if ( ! file_exists( XSPEED_CACHE_DIR ) ) {
446	wp_mkdir_p( XSPEED_CACHE_DIR );
447	self::write_silence( XSPEED_CACHE_DIR );
448	}
449
450	$file = self::cache_file_for( $key );
451	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents -- WP_Filesystem requires admin context for credentials; this runs on a frontend shutdown where it's unavailable.
452	file_put_contents( $file, $full, LOCK_EX );
453
454	/** This action is documented in includes/class-cache.php */
455	do_action( 'xspeed_flat_file_written', $file, $full );
456
457	self::write_meta( $key );
458
459	// Static tree too, under the same gates finalize_buffer() applies —
460	// otherwise deferring the write would silently cost translated pages
461	// the web-server fast path and leave them on the slower drop-in.
462	if ( self::static_rewrite_allowed() && self::response_is_plain_html() ) {
463	self::store_static( $full );
464	}
465	}
466
467	public static function should_cache() {
468	// Reset first: a single request only reaches this once (the sole
469	// caller is maybe_start_cache()), but tests and any future caller
470	// must never inherit the previous request's verdict.
471	self::$status_header = '';
472	self::$bypass_reason = '';
473
474	$opts = Settings::get();
475	if ( empty( $opts['cache_enabled'] ) ) {
476	return self::bypass( 'cache-disabled' );
477	}
478
479	if ( is_user_logged_in() ) {
480	return self::bypass( 'logged-in' );
481	}
482
483	if ( is_admin() \|\| ( defined( 'DOING_AJAX' ) && DOING_AJAX ) \|\| ( defined( 'DOING_CRON' ) && DOING_CRON ) \|\| ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
484	return self::bypass( 'non-frontend' );
485	}
486
487	if ( defined( 'DONOTCACHEPAGE' ) && DONOTCACHEPAGE ) {
488	return self::bypass( 'donotcachepage' );
489	}
490
491	// All exclusion knobs now owned by CacheModule.
492	$cache_opts = Settings_Manager::get( 'cache' );
493
494	$method = isset( $_SERVER['REQUEST_METHOD'] ) ? strtoupper( sanitize_text_field( wp_unslash( $_SERVER['REQUEST_METHOD'] ) ) ) : '';
495	if ( 'GET' !== $method ) {
496	return self::bypass( 'non-get' );
497	}
498
499	// Search-results requests carry a `s` query param, which the
500	// query-string gate below would normally reject as "dynamic". An
501	// add-on (xspeed-pro search cache) can opt them in: when this is a
502	// genuine is_search() and the filter returns true, the `s` param is
503	// treated as cacheable (the search term goes into the cache key so
504	// different searches stay distinct — see cache_key()).
505	$cache_search = self::should_cache_search();
506
507	// Feed opt-in is resolved BEFORE the query-string gate so query-form
508	// feeds (/?feed=rss2, used on plain-permalink sites) aren't rejected
509	// as "dynamic" by that gate — the `feed` param is then allowed through
510	// just like the search `s` param. Feeds are excluded by default (the
511	// `/feed/` pattern in excluded_urls); an add-on (xspeed-pro feed cache)
512	// opts them back in via the filter. (FBS-82407 #4)
513	$is_feed_request = function_exists( 'is_feed' ) && is_feed();
514	/**
515	* Whether to cache the current feed request.
516	*
517	* Default false → feeds fall through to the normal URL-exclusion
518	* rules (so `/feed/` keeps them out). A listener returning true
519	* opts this feed request into caching.
520	*
521	* @param bool $cache_feed Whether to cache this feed request.
522	*/
523	$cache_feed = $is_feed_request && (bool) apply_filters( 'xspeed_should_cache_feed', false );
524
525	// Query string handling: anything OUTSIDE the ignored-params
526	// allow-list (utm_*, fbclid, gclid by default) means a unique
527	// request that we don't want to share with the canonical cache
528	// entry. Skip cache rather than poison the key.
529	//
530	// Parse the RAW query string, NOT a sanitize_text_field() copy:
531	// that filter strips percent-encoded octets (%XX), so `?%73=…`
532	// would lose its `s` key here while WordPress still decodes it to
533	// a search request — the gate would wave the request through and
534	// cache_key() would file the search page under the bare URL,
535	// letting an attacker poison the homepage cache with `/?%73=<spam>`.
536	// parse_str() does its own urldecoding, matching WP's own parse, and
537	// only the KEYS are used below (fed to Glob_Matcher → preg_match,
538	// never echoed or executed), so no sanitization is needed here.
539	$query_raw = isset( $_SERVER['QUERY_STRING'] ) ? wp_unslash( $_SERVER['QUERY_STRING'] ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- see note above: parse_str() urldecodes to match WP; only keys are consumed, via preg_match, never output.
540	if ( '' !== $query_raw ) {
541	$ignored = is_array( $cache_opts['ignored_query_params'] ?? null ) ? $cache_opts['ignored_query_params'] : array();
542	parse_str( $query_raw, $params );
543	foreach ( $params as $key => $_ ) {
544	// Allow the search param through when search caching is on.
545	if ( $cache_search && 's' === $key ) {
546	continue;
547	}
548	// Allow query-form feed params through when feed caching opted
549	// this request in (?feed=rss2 / &withcomments=1 on feeds).
550	if ( $cache_feed && in_array( $key, array( 'feed', 'withcomments', 'withoutcomments' ), true ) ) {
551	continue;
552	}
553	if ( ! self::query_key_is_ignored( (string) $key, $ignored ) ) {
554	// Slug only — never the param name, which is attacker-
555	// controlled and would be reflected into a header.
556	return self::bypass( 'query-param' );
557	}
558	}
559	}
560
561	$request_uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
562	$path = (string) strtok( $request_uri, '?' );
563
564	$excluded_urls = is_array( $cache_opts['excluded_urls'] ?? null ) ? $cache_opts['excluded_urls'] : array();
565	if ( ! $cache_feed && Glob_Matcher::any_match( $excluded_urls, $path ) ) {
566	return self::bypass( 'excluded-url' );
567	}
568
569	// Cookie-based exclusion. We only check cookie NAMES (matching
570	// values would leak content-sensitive logic into the cache key
571	// rules); presence of any matching cookie name skips cache.
572	$excluded_cookies = is_array( $cache_opts['excluded_cookies'] ?? null ) ? $cache_opts['excluded_cookies'] : array();
573	if ( ! empty( $excluded_cookies ) && ! empty( $_COOKIE ) ) {
574	foreach ( array_keys( $_COOKIE ) as $cookie_name ) {
575	if ( Glob_Matcher::any_match( $excluded_cookies, (string) $cookie_name ) ) {
576	return self::bypass( 'excluded-cookie' );
577	}
578	}
579	}
580
581	// User-agent bypass list. Substring match (not glob) since UA
582	// strings have so much variation that glob anchoring rarely
583	// helps and confuses users.
584	$bypass_uas = is_array( $cache_opts['bypass_user_agents'] ?? null ) ? $cache_opts['bypass_user_agents'] : array();
585	if ( ! empty( $bypass_uas ) ) {
586	$ua = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';
587	foreach ( $bypass_uas as $needle ) {
588	if ( '' !== $needle && false !== stripos( $ua, (string) $needle ) ) {
589	return self::bypass( 'user-agent' );
590	}
591	}
592	}
593
594	// Per-post override (Phase 3.4). Honored only on singular
595	// post-context requests — archives / 404s / taxonomies use the
596	// global policy above.
597	if ( Cache_Rules::should_skip_for_post( Cache_Rules::current_post_id() ) ) {
598	return self::bypass( 'post-excluded' );
599	}
600
601	/**
602	* Final say on whether the current request is cacheable.
603	*
604	* Runs at template_redirect (full WP context), so listeners may use
605	* conditional tags (is_search(), is_feed(), is_404(),
606	* wp_is_maintenance_mode(), …). The core engine has already applied
607	* its own exclusion rules and reached `true`; a listener returning
608	* false vetoes caching for this request. This is the documented
609	* extension point add-ons (xspeed-pro) hook to add their own
610	* request-level cache policy without forking the engine.
611	*
612	* Note: this gates the WRITE side. The pre-WP drop-in
613	* (advanced-cache.php) cannot run PHP filters, so request types that
614	* must never be served from a stale file are handled by not
615	* writing them here and/or by purging — see the conflict notes in
616	* advanced-cache.php.
617	*
618	* @param bool $should_cache Whether to cache the current request.
619	*/
620	if ( ! apply_filters( 'xspeed_should_cache', true ) ) {
621	// One slug for every listener — a third-party callback name is
622	// not ours to put in a response header. Which listener vetoed is
623	// a WP_DEBUG-level question the filter itself can answer.
624	return self::bypass( 'filtered' );
625	}
626
627	return true;
628	}
629
630	/**
631	* Whether the current request is a 404 we may cache.
632	*
633	* True only when: it's a genuine main-query is_404(), an add-on opted
634	* in via `xspeed_should_cache_404` (default false), and the request
635	* isn't a transient 404 we must never freeze — maintenance mode or a
636	* 404 emitted while the DB/site is in an error state. The xspeed-pro
637	* 404 cache flips the filter; Free never caches 404s on its own.
638	*/
639	public static function should_cache_404(): bool {
640	if ( ! function_exists( 'is_404' ) \|\| ! is_404() ) {
641	return false;
642	}
643	// Never cache a 404 served because the site is down for
644	// maintenance — that screen disappears the moment maintenance
645	// ends, and a cached copy would outlive it.
646	if ( function_exists( 'wp_is_maintenance_mode' ) && wp_is_maintenance_mode() ) {
647	return false;
648	}
649
650	/**
651	* Whether to cache the current 404 response.
652	*
653	* Default false. A listener returning true opts the (genuine)
654	* 404 into the page cache, served back for any unknown URL under
655	* one generic key. The 404 status is preserved on the HIT.
656	*
657	* @param bool $cache_404 Whether to cache this 404.
658	*/
659	return (bool) apply_filters( 'xspeed_should_cache_404', false );
660	}
661
662	/**
663	* Whether the current request is an internal search-results page we
664	* may cache.
665	*
666	* True only when: it's a genuine main-query is_search() with a
667	* non-empty term, and an add-on opted in via `xspeed_should_cache_search`
668	* (default false). The search term is folded into the cache key (see
669	* search_term() / cache_key()) so different searches stay distinct.
670	* The xspeed-pro search cache flips the filter; Free never caches
671	* search results on its own.
672	*/
673	public static function should_cache_search(): bool {
674	if ( ! function_exists( 'is_search' ) \|\| ! is_search() ) {
675	return false;
676	}
677	// Empty search (`?s=`) renders the same as a normal archive and
678	// carries no term to key on — let it fall through to the usual
679	// rules rather than caching an ambiguous entry.
680	if ( '' === self::search_term() ) {
681	return false;
682	}
683
684	/**
685	* Whether to cache the current search-results request.
686	*
687	* Default false. A listener returning true opts the search page
688	* into the cache, keyed by the normalized search term.
689	*
690	* @param bool $cache_search Whether to cache this search request.
691	*/
692	return (bool) apply_filters( 'xspeed_should_cache_search', false );
693	}
694
695	/**
696	* The current request's normalized search term, or '' if none. Reads
697	* the raw `s` query param (works on the pre-WP drop-in path too, where
698	* get_search_query() isn't available), trims + lowercases so
699	* "WordPress" and "wordpress" share one entry, and collapses internal
700	* whitespace.
701	*/
702	public static function search_term(): string {
703	$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.
704	$raw = trim( $raw );
705	if ( '' === $raw ) {
706	return '';
707	}
708	$raw = preg_replace( '/\s+/', ' ', $raw );
709	return function_exists( 'mb_strtolower' ) ? mb_strtolower( $raw ) : strtolower( $raw );
710	}
711
712	/**
713	* Is this query-string key on the ignored-params allow-list? Supports
714	* trailing-star globs (`utm_*` matches `utm_source`, `utm_medium`,
715	* etc.) so users don't have to enumerate every UTM variant.
716	*/
717	private static function query_key_is_ignored( string $key, array $ignored ): bool {
718	return Glob_Matcher::any_match( $ignored, $key );
719	}
720
721	public static function cache_key() {
722	$host = isset( $_SERVER['HTTP_HOST'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) : 'default';
723
724	// Cacheable 404s share ONE generic per-host entry — keying them by
725	// URL would let a scanner flood (millions of random paths) bloat
726	// the cache with identical 404 bodies. Both the write and the HIT
727	// lookup run through here, so they agree on the key automatically.
728	if ( self::should_cache_404() ) {
729	return md5( $host . '\|404' );
730	}
731
732	$uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '/';
733	// Strip the query string from the key so /post and /post?utm_*=…
734	// share the same cache entry. should_cache() above already
735	// rejected requests with non-ignored params, so by the time we
736	// build the key the only params left are safe to drop.
737	$uri = (string) strtok( $uri, '?' );
738
739	// Optional device bucket: when mobile_separate is on, mobile and
740	// desktop responses live in different cache files so themes that
741	// serve different HTML by device (AMP, WPtouch, Jetpack mobile)
742	// can't poison each other.
743	$device = '';
744	$opts = Settings_Manager::get( 'cache' );
745	if ( ! empty( $opts['mobile_separate'] ) ) {
746	$device = self::is_mobile_request() ? '\|m' : '\|d';
747	}
748
749	// Search-results requests fold the normalized term into the key so
750	// /?s=foo and /?s=bar get distinct entries (the query string is
751	// otherwise stripped above). Only added when search caching opted
752	// in, so non-search URLs are unaffected.
753	$search = self::should_cache_search() ? '\|s=' . self::search_term() : '';
754
755	// Query-form feeds (/?feed=rss2 vs /?feed=atom) share the same path
756	// once the query is stripped, so fold the feed type into the key to
757	// keep the flavors distinct. Pretty-permalink feeds (/feed/rss/) carry
758	// the type in $uri already and are unaffected. (FBS-82407 #4)
759	$feed = '';
760	if ( function_exists( 'is_feed' ) && is_feed() && function_exists( 'get_query_var' ) ) {
761	$feed_type = (string) get_query_var( 'feed' );
762	if ( '' !== $feed_type ) {
763	$feed = '\|feed=' . preg_replace( '/[^a-z0-9]/i', '', $feed_type );
764	}
765	}
766
767	return md5( $host . $uri . $device . $search . $feed );
768	}
769
770	/**
771	* Server-side mobile detection. Prefers WordPress's `wp_is_mobile()`
772	* which uses the same UA tokens as core (so our bucket aligns with
773	* whatever theme-side branching uses). Falls back to a tiny inline
774	* detector if wp_is_mobile() isn't loaded (e.g. the drop-in path).
775	*/
776	private static function is_mobile_request(): bool {
777	if ( function_exists( 'wp_is_mobile' ) ) {
778	return (bool) wp_is_mobile();
779	}
780	// Fallback for the rare context where wp_is_mobile() isn't loaded.
781	// Mirrors core's wp_is_mobile() EXACTLY — including the
782	// Sec-CH-UA-Mobile client hint it checks before UA tokens — so the
783	// bucket this picks matches whatever the engine's primary path (and
784	// the drop-in's own copy of this logic) would pick for the same
785	// request. Drift here re-introduces the cross-path key mismatch.
786	if ( isset( $_SERVER['HTTP_SEC_CH_UA_MOBILE'] ) ) {
787	return '?1' === $_SERVER['HTTP_SEC_CH_UA_MOBILE'];
788	}
789	$ua = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';
790	if ( '' === $ua ) {
791	return false;
792	}
793	return (bool) preg_match( '/(Mobile\|Android\|Silk\/\|Kindle\|BlackBerry\|Opera Mini\|Opera Mobi)/i', $ua );
794	}
795
796	public static function cache_file_for( $key ) {
797	return XSPEED_CACHE_DIR . '/' . $key . '.html';
798	}
799
800	/**
801	* If a precompressed Brotli sibling (`<file>.br`) exists and the client
802	* advertises `Accept-Encoding: br`, emit the Brotli response headers and
803	* return the `.br` path to stream. Returns null to fall through to the
804	* plain file. Keeps the PHP serve path in parity with the web server's
805	* static .br serving (mod_brotli / ngx_brotli rewrite).
806	*
807	* Free has no Brotli logic of its own — this only fires when an add-on
808	* (the Pro Brotli module) actually wrote the .br, so it's a safe no-op
809	* on Free-only installs.
810	*
811	* @param string $file Absolute path to the cached .html file.
812	* @return string\|null The .br path to stream, or null to serve $file.
813	*/
814	public static function maybe_serve_brotli( string $file ): ?string {
815	if ( headers_sent() ) {
816	return null;
817	}
818	$accept = isset( $_SERVER['HTTP_ACCEPT_ENCODING'] )
819	? strtolower( sanitize_text_field( wp_unslash( $_SERVER['HTTP_ACCEPT_ENCODING'] ) ) )
820	: '';
821	// Match `br` as a token (comma/space delimited), not a substring, so
822	// a hypothetical "xbr" encoding can't false-positive.
823	if ( ! preg_match( '/(^\|[\s,])br([\s,;]\|$)/', $accept ) ) {
824	return null;
825	}
826	$br = $file . '.br';
827	if ( ! is_string( $br ) \|\| ! file_exists( $br ) \|\| ! is_readable( $br ) ) {
828	return null;
829	}
830	header( 'Content-Encoding: br' );
831	header( 'Vary: Accept-Encoding', false );
832	// The byte length changes for the compressed body — drop any
833	// Content-Length the caller may have set so the stream isn't
834	// truncated/padded. readfile() lets the SAPI set the right length.
835	header_remove( 'Content-Length' );
836	return $br;
837	}
838
839	/**
840	* Sidecar metadata file for a cache entry. Holds response bits the HIT
841	* path must replay — Content-Type (cached feeds → application/rss+xml,
842	* sitemaps → text/xml) and status (a cached 404 must serve 404, not
843	* 200). JSON, one tiny file per entry, written only when there's
844	* something non-default to replay.
845	*/
846	public static function cache_meta_for( $key ) {
847	return XSPEED_CACHE_DIR . '/' . $key . '.meta';
848	}
849
850	/**
851	* Read the .meta sidecar for a cache entry as an array, or [] if none.
852	* Keys: 'content_type' (string), 'status' (int), 'ttl' (int seconds).
853	* Used on the HIT path to replay content-type/status before streaming
854	* the file, and by Cache_GC to age an entry by its own TTL rather than
855	* the global one — hence public.
856	*/
857	public static function read_meta( $key ): array {
858	$meta_file = self::cache_meta_for( $key );
859	if ( ! file_exists( $meta_file ) ) {
860	return array();
861	}
862	// 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.
863	$raw = file_get_contents( $meta_file );
864	$data = json_decode( (string) $raw, true );
865	return is_array( $data ) ? $data : array();
866	}
867
868	/**
869	* Conditional-GET support for a cache HIT. Emits Last-Modified + ETag
870	* derived from the cache file's mtime, and — when the request's
871	* If-Modified-Since / If-None-Match still match — sends 304 Not Modified
872	* and returns true (caller should exit without a body). Returns false to
873	* proceed with a normal 200 body. Lets aggregators/browsers skip
874	* re-downloading an unchanged cached response. (FBS-82407 #5)
875	*
876	* @param string $file Absolute path to the cache .html file.
877	* @return bool True when a 304 was sent.
878	*/
879	public static function serve_not_modified( string $file ): bool {
880	$mtime = (int) filemtime( $file );
881	if ( $mtime <= 0 ) {
882	return false;
883	}
884	$last_modified = gmdate( 'D, d M Y H:i:s', $mtime ) . ' GMT';
885	$etag = '"' . md5( $file . '\|' . $mtime ) . '"';
886	header( 'Last-Modified: ' . $last_modified );
887	header( 'ETag: ' . $etag );
888
889	$ims = isset( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ? trim( sanitize_text_field( wp_unslash( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) ) : '';
890	$inm = isset( $_SERVER['HTTP_IF_NONE_MATCH'] ) ? trim( sanitize_text_field( wp_unslash( $_SERVER['HTTP_IF_NONE_MATCH'] ) ) ) : '';
891
892	$etag_match = '' !== $inm && false !== strpos( $inm, $etag );
893	$time_match = '' !== $ims && ( strtotime( $ims ) >= $mtime );
894
895	if ( $etag_match \|\| $time_match ) {
896	if ( function_exists( 'http_response_code' ) ) {
897	http_response_code( 304 );
898	}
899	return true;
900	}
901	return false;
902	}
903
904	public static function is_expired( $file ) {
905	// cache_expiry now owned by CacheModule; per-post override
906	// (Phase 3.4) shrinks the TTL further when the editor set one.
907	$opts = Settings_Manager::get( 'cache' );
908	$max_age = (int) $opts['cache_expiry'] * HOUR_IN_SECONDS;
909	$post_override = Cache_Rules::expiry_override_seconds_for_post( Cache_Rules::current_post_id() );
910	if ( null !== $post_override ) {
911	$max_age = $post_override;
912	}
913
914	/**
915	* Filter the max-age (seconds) for the current cache entry.
916	*
917	* Lets an add-on apply a request-type-specific TTL — e.g. the
918	* xspeed-pro feed cache gives feeds a longer expiry than pages,
919	* since aggregators tolerate more staleness. Return seconds.
920	*
921	* @param int $max_age Computed max-age in seconds.
922	*/
923	$max_age = (int) apply_filters( 'xspeed_cache_max_age', $max_age );
924
925	// A missing file is "expired" — the caller should re-render. Guard
926	// filemtime() rather than letting it warn: callers legitimately ask
927	// about a file that isn't there (Pro's predictive warmer probes for
928	// freshness, and Cache_GC can collect an entry between the check and
929	// the read), and on a site with WP_DEBUG the warning is noise.
930	$mtime = file_exists( $file ) ? filemtime( $file ) : false;
931	if ( false === $mtime ) {
932	return true;
933	}
934
935	return ( time() - (int) $mtime ) > $max_age;
936	}
937
938	/**
939	* Accumulator for the full response body across all output-handler phases.
940	*
941	* PHP invokes an ob_start() callback once per flush, and each invocation
942	* only receives the chunk produced since the previous flush. If anything
943	* during the render calls `ob_flush()` or `flush()` (some themes, lazy-
944	* load plugins, AMP, etc. do), the final-phase call would otherwise only
945	* see the tail of the page — and we'd cache a truncated response that
946	* gets served repeatedly until purge. We accumulate every chunk here so
947	* the cache file always reflects the complete page.
948	*
949	* @var string
950	*/
951	private static $accumulated = '';
952
953	public static function finalize_buffer( $buffer, $phase = PHP_OUTPUT_HANDLER_FINAL ) {
954	self::$accumulated .= $buffer;
955
956	// On non-final phases (mid-request flushes), pass the current chunk
957	// through to the client unmodified and keep collecting. The WP 6.9
958	// filter path always passes the full body in one shot with the
959	// default $phase, so it falls straight through to the final block.
960	$is_final = ( $phase & ( PHP_OUTPUT_HANDLER_FINAL \| PHP_OUTPUT_HANDLER_END ) ) !== 0;
961	if ( ! $is_final ) {
962	return $buffer;
963	}
964
965	$full = self::$accumulated;
966	self::$accumulated = '';
967
968	if ( strlen( $full ) < 255 ) {
969	return $buffer;
970	}
971
972	// Status gate. We cache 200 by default. A 404 may be cached too,
973	// but only when an add-on (xspeed-pro 404 cache) opts in for a
974	// genuine is_404() — never a transient 404 (maintenance screen,
975	// DB error, or a 404 emitted outside the main query), which would
976	// otherwise be frozen until purge. Any other status is skipped.
977	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
978	if ( 200 !== $status ) {
979	if ( 404 !== $status \|\| ! self::should_cache_404() ) {
980	return $buffer;
981	}
982	}
983
984	// If no mid-request flush happened, $buffer === $full and we can
985	// safely minify the on-wire bytes too. Otherwise earlier chunks have
986	// already been sent unminified, so we minify only what goes to disk —
987	// the first visitor sees unminified HTML, every cache hit after that
988	// is minified.
989	$single_chunk = ( $buffer === $full );
990
991	/**
992	* Filter: xspeed_cache_final_html
993	*
994	* Last chance to transform the fully-rendered page HTML before it is
995	* minified and written to the cache file. Runs on cache MISS only, so
996	* whatever a listener injects here is baked into the cached HTML and
997	* replayed on every subsequent HIT (the drop-in short-circuits before
998	* PHP on a HIT — a wp_head hook would never fire there).
999	*
1000	* The Preload module uses this to inject the LCP-image <link rel=preload>
1001	* + preconnect hints and add fetchpriority="high" to the hero <img>.
1002	* Keep listeners fast and idempotent; this is the on-wire body.
1003	*
1004	* @param string $full Complete page HTML.
1005	*/
1006	$full = (string) apply_filters( 'xspeed_cache_final_html', $full );
1007	if ( $single_chunk ) {
1008	$buffer = $full;
1009	}
1010
1011	// minify_html now owned by the Minify module; read through the
1012	// module's storage so this stays consistent with the engine that
1013	// applies CSS/JS minification.
1014	$minify_opts = Settings_Manager::get( 'minify' );
1015	if ( ! empty( $minify_opts['minify_html'] ) ) {
1016	$full = Minifier::minify_html( $full );
1017	if ( $single_chunk ) {
1018	$buffer = $full;
1019	}
1020	}
1021
1022	if ( ! file_exists( XSPEED_CACHE_DIR ) ) {
1023	wp_mkdir_p( XSPEED_CACHE_DIR );
1024	self::write_silence( XSPEED_CACHE_DIR );
1025	}
1026
1027	// Path safety: cache_file_for() builds `XSPEED_CACHE_DIR . '/' . $key . '.html'`
1028	// where $key comes from md5() — guaranteed to be exactly 32 lowercase
1029	// hex chars, so no traversal sequence ('..', '/', null byte, etc.)
1030	// can appear. The write is therefore always inside XSPEED_CACHE_DIR.
1031	$key = self::cache_key();
1032	$file = self::cache_file_for( $key );
1033
1034	// A render-time translation plugin (TranslatePress) wraps our buffer,
1035	// so the bytes we hold here are still UNTRANSLATED — its callback has
1036	// not run yet, and writing now would cache English under a French URL
1037	// and bake in its internal #TRPLINKPROCESSED markers. Hand off to
1038	// shutdown, where the outer buffer has already translated, and let
1039	// the pass-through below deliver this request untouched.
1040	if ( self::translation_plugin_active() ) {
1041	self::$deferred_key = $key;
1042	// Reaching here means finalize_buffer() ran to completion: the
1043	// status gate passed, should_cache() said yes, and PHP handed us
1044	// the whole buffer. A wp_die() or exit() mid-render unwinds the
1045	// buffer stack WITHOUT calling this callback, so the flag stays
1046	// false and the shutdown writer declines — see the guard there.
1047	self::$render_completed = true;
1048	// A PHP shutdown function, not a WP `shutdown` action: this must
1049	// run after the output-buffer stack has unwound, and WP's
1050	// shutdown action fires while our outer buffer is still open.
1051	register_shutdown_function( array( __CLASS__, 'write_deferred_translated_cache' ) );
1052	return $buffer;
1053	}
1054
1055	// 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.
1056	file_put_contents( $file, $full, LOCK_EX );
1057
1058	/**
1059	* Fires after the flat hash cache file ({md5}.html) is written.
1060	*
1061	* Mirror of `xspeed_static_file_written` for the flat cache. The PHP
1062	* serve path (Cache::maybe_serve_brotli / the drop-in) serves THIS
1063	* file and looks for a `{md5}.html.br` sibling — which only the Pro
1064	* Brotli listener on this hook writes. Without it the .br sibling was
1065	* never created and the PHP path could never serve Brotli (FBS-83039,
1066	* Blocker 2): the static-tree .br (written on xspeed_static_file_written)
1067	* lives in a different cache layout the PHP path never reads.
1068	*
1069	* @param string $file Absolute path to the flat cache file just written.
1070	* @param string $full The HTML written to it.
1071	*/
1072	do_action( 'xspeed_flat_file_written', $file, $full );
1073
1074	// Persist a non-default Content-Type so the HIT path can replay it
1075	// (cached feeds must serve application/rss+xml, not text/html).
1076	// Only written when the response set a content-type other than
1077	// the HTML default — pages don't pay for an extra file.
1078	self::write_meta( $key );
1079
1080	// Static-cache tree (xspeed-static/{host}{path}/index.html). The
1081	// .htaccess rewrite block serves this file directly via the web
1082	// server, bypassing PHP for ~3-5× lower TTFB vs the drop-in path.
1083	// store_static() returns silently on any path/permission issue —
1084	// the drop-in remains the safety net.
1085	//
1086	// Skip it entirely when mobile_separate is on: the rewrite is
1087	// disabled in that mode (static_rewrite_allowed()), so a static file
1088	// would only be dead weight — and a device-blind one at that.
1089	// Skip the static-tree write for responses the web server can't replay
1090	// correctly: a non-200 status (a cached 404 would be served as a soft
1091	// 200, FBS-82406) or a non-HTML content-type (a cached feed would go
1092	// out as text/html, FBS-82407). The web server serves these .html files
1093	// directly with no PHP, so there's no .meta replay — keep them on the
1094	// drop-in / PHP path instead, which DOES replay status + content-type.
1095	if ( self::static_rewrite_allowed() && self::response_is_plain_html() ) {
1096	self::store_static( $full );
1097	}
1098
1099	return $buffer;
1100	}
1101
1102	/**
1103	* Write the current response to the static-cache tree at
1104	* `xspeed-static/{host}{request_uri}/index.html`. The web-server
1105	* rewrite block points at this path so cache hits skip PHP
1106	* entirely. Caller already minified/finalized $html.
1107	*
1108	* Path safety: $host is restricted to a `[a-zA-Z0-9.\-]` allowlist;
1109	* $uri has its query string stripped, null bytes removed, '..'
1110	* sequences collapsed, and after concatenation we verify the
1111	* resolved real path stays inside XSPEED_CACHE_STATIC_DIR before
1112	* any write. Anything off the happy path returns silently.
1113	*
1114	* INVARIANT — the static tree is keyed by `{host}{path}` and NOTHING
1115	* else, and both generated rewrites refuse any request that carries a
1116	* query string at all (`RewriteCond %{QUERY_STRING} ^$` on Apache,
1117	* `if ($args)` in nginx_snippet()). So a response may only be stored
1118	* here when cache_key() adds no discriminator beyond `{host}{path}`:
1119	* a query-keyed entry can never be served from here, only mis-served
1120	* as the bare path. Any future opt-in that folds a query param into the
1121	* key needs a guard below, exactly like the search one.
1122	*/
1123	private static function store_static( string $html ): void {
1124	// Search results are keyed by term in cache_key() (`\|s=<term>`) but
1125	// carry the path of whatever URL was searched from — for the usual
1126	// `/?s=<term>` that path is `/`. Writing them here would file the
1127	// results page as `{host}/index.html` and the web server would serve
1128	// it to every visitor as the homepage: an unauthenticated visitor
1129	// poisons the front page with one request. Searches stay on the
1130	// drop-in, which replays the term-keyed entry correctly. (#191)
1131	//
1132	// This is a superset of the query-string check the exclusion gate
1133	// does: it also covers `/?%73=<term>`, which decodes to the same
1134	// search (the shape #109 fixed on the gate side).
1135	if ( self::should_cache_search() ) {
1136	return;
1137	}
1138
1139	$host = isset( $_SERVER['HTTP_HOST'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) : '';
1140	$uri = isset( $_SERVER['REQUEST_URI'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
1141	$host = preg_replace( '/[^a-zA-Z0-9.\-]/', '', $host );
1142	$uri = str_replace( "\0", '', $uri );
1143	$uri = (string) strtok( $uri, '?' );
1144	if ( '' === $host \|\| '' === $uri ) {
1145	return;
1146	}
1147	// Collapse any traversal sequences before path resolution.
1148	$uri = preg_replace( '#/+#', '/', $uri );
1149	if ( false !== strpos( $uri, '..' ) ) {
1150	return;
1151	}
1152
1153	$base = rtrim( XSPEED_CACHE_STATIC_DIR, '/' );
1154	$dir = $base . '/' . $host . rtrim( $uri, '/' );
1155	$file = $dir . '/index.html';
1156
1157	// Resolve the parent against the cache root to be sure the
1158	// final path is inside our tree even if the OS does anything
1159	// funny with multi-byte sequences.
1160	$base_real = realpath( WP_CONTENT_DIR );
1161	if ( false === $base_real \|\| 0 !== strpos( $base, $base_real ) ) {
1162	return;
1163	}
1164
1165	if ( ! file_exists( $dir ) ) {
1166	wp_mkdir_p( $dir );
1167	}
1168	if ( ! is_dir( $dir ) ) {
1169	return;
1170	}
1171	// 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.
1172	$written = file_put_contents( $file, $html, LOCK_EX );
1173
1174	if ( false !== $written ) {
1175	/**
1176	* Fires after a static cache file (index.html) is written.
1177	*
1178	* The extension point for serving pre-compressed siblings:
1179	* the xspeed-pro Brotli module writes `index.html.br` next to
1180	* the file here so the web server's static rewrite can serve a
1181	* Brotli copy to clients that advertise `Accept-Encoding: br`,
1182	* falling back to GZIP / the plain file otherwise. No core
1183	* behavior depends on a listener being present.
1184	*
1185	* @param string $file Absolute path to the static cache file just written.
1186	* @param string $html The HTML written to it.
1187	*/
1188	do_action( 'xspeed_static_file_written', $file, $html );
1189	}
1190	}
1191
1192	/**
1193	* Write the .meta sidecar for a cache entry when the response carries
1194	* anything the HIT path must replay beyond a plain 200 text/html:
1195	* - a non-HTML Content-Type (cached feeds → application/rss+xml,
1196	* sitemaps → text/xml, …), and/or
1197	* - a non-200 status (a cached 404 must serve 404, not 200).
1198	*
1199	* Ordinary 200 text/html pages get NO .meta file, so the common path
1200	* stays a single write.
1201	*
1202	* @param string $key Cache key for the current request.
1203	*/
1204	/**
1205	* True only for a plain 200 text/html response — the only kind the
1206	* web-server static tree can serve correctly (it streams the .html with
1207	* no PHP, so it can't replay a 404 status or a feed Content-Type). Used
1208	* to gate store_static() so cached 404s / feeds stay on the replay-capable
1209	* drop-in / PHP path. (FBS-82406, FBS-82407)
1210	*/
1211	private static function response_is_plain_html(): bool {
1212	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
1213	if ( 200 !== $status && $status > 0 ) {
1214	return false;
1215	}
1216	foreach ( headers_list() as $header ) {
1217	if ( 0 === stripos( $header, 'content-type:' ) ) {
1218	$ct = trim( substr( $header, strlen( 'content-type:' ) ) );
1219	if ( '' !== $ct && false === stripos( $ct, 'text/html' ) ) {
1220	return false;
1221	}
1222	}
1223	}
1224	return true;
1225	}
1226
1227	private static function write_meta( string $key ): void {
1228	$content_type = '';
1229	foreach ( headers_list() as $header ) {
1230	if ( 0 === stripos( $header, 'content-type:' ) ) {
1231	$content_type = trim( substr( $header, strlen( 'content-type:' ) ) );
1232	}
1233	}
1234	$status = function_exists( 'http_response_code' ) ? (int) http_response_code() : 200;
1235
1236	$meta = array();
1237	$is_default_type = ( '' === $content_type \|\| false !== stripos( $content_type, 'text/html' ) );
1238	if ( ! $is_default_type ) {
1239	$meta['content_type'] = $content_type;
1240	}
1241	if ( 200 !== $status && $status > 0 ) {
1242	$meta['status'] = $status;
1243	}
1244
1245	// Per-content TTL (seconds). The drop-in and static fast paths can't
1246	// call is_expired() / the xspeed_cache_max_age filter (they run before
1247	// WP), so persist the resolved max-age here whenever it differs from
1248	// the plain page TTL — e.g. the Pro feed cache's 12h vs the 24h page
1249	// default. The fast paths read this to expire correctly. (FBS-82407)
1250	$opts = Settings_Manager::get( 'cache' );
1251	$default_ttl = (int) $opts['cache_expiry'] * HOUR_IN_SECONDS;
1252	$ttl = (int) apply_filters( 'xspeed_cache_max_age', $default_ttl );
1253	if ( $ttl > 0 && $ttl !== $default_ttl ) {
1254	$meta['ttl'] = $ttl;
1255	}
1256
1257	// Nothing to replay → no sidecar.
1258	if ( empty( $meta ) ) {
1259	return;
1260	}
1261
1262	$payload = wp_json_encode( $meta );
1263	if ( false === $payload ) {
1264	return;
1265	}
1266	// 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.
1267	file_put_contents( self::cache_meta_for( $key ), $payload, LOCK_EX );
1268	}
1269
1270	/**
1271	* @param string $cause Free-form human reason. Recorded in the
1272	* Activity log to give users context (e.g.
1273	* 'post saved', 'settings change', 'manual',
1274	* 'theme switch').
1275	*/
1276	/**
1277	* Purge the cache entries for ONE URL — every variant of it: the
1278	* flat-hash entry (+ .meta / .html.br siblings), both device buckets
1279	* (mobile_separate keys them separately), both trailing-slash forms,
1280	* and the static-tree index.html (+ .br) the server rewrite serves.
1281	* The rest of the cache is untouched — this is the surgical
1282	* alternative to purge_all for "I just edited this one page".
1283	*
1284	* @param string $url Absolute URL, or site-relative path ("/about/").
1285	* @param string $cause Who asked, for the purge log. See purge_all().
1286	* @return int Number of cache files removed.
1287	*/
1288	public static function purge_url( string $url, string $cause = 'manual' ): int {
1289	$parts = function_exists( 'wp_parse_url' ) ? wp_parse_url( $url ) : parse_url( $url ); // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- fallback for early-boot contexts only.
1290	if ( ! is_array( $parts ) ) {
1291	return 0;
1292	}
1293	$host = isset( $parts['host'] ) ? strtolower( (string) $parts['host'] ) : '';
1294	if ( '' === $host && function_exists( 'home_url' ) ) {
1295	$home = function_exists( 'wp_parse_url' ) ? wp_parse_url( home_url( '/' ) ) : parse_url( home_url( '/' ) ); // phpcs:ignore WordPress.WP.AlternativeFunctions.parse_url_parse_url -- see above.
1296	$host = is_array( $home ) && isset( $home['host'] ) ? strtolower( (string) $home['host'] ) : '';
1297	}
1298	if ( '' === $host ) {
1299	return 0;
1300	}
1301	$path = isset( $parts['path'] ) ? (string) $parts['path'] : '/';
1302	$path = '/' . ltrim( $path, '/' );
1303	if ( false !== strpos( $path, '..' ) ) {
1304	return 0;
1305	}
1306
1307	// The cache key preserves REQUEST_URI's trailing-slash form, so
1308	// purge both. Root stays a single '/'.
1309	$forms = array( $path );
1310	if ( '/' !== $path ) {
1311	$forms[] = rtrim( $path, '/' );
1312	$forms[] = rtrim( $path, '/' ) . '/';
1313	}
1314	$forms = array_unique( $forms );
1315
1316	$count = 0;
1317	foreach ( $forms as $uri ) {
1318	// '' = mobile_separate off; '\|m' / '\|d' = the device buckets.
1319	foreach ( array( '', '\|m', '\|d' ) as $device ) {
1320	$key = md5( $host . $uri . $device );
1321	$file = self::cache_file_for( $key );
1322	if ( is_file( $file ) ) {
1323	wp_delete_file( $file );
1324	++$count;
1325	}
1326	foreach ( array( XSPEED_CACHE_DIR . '/' . $key . '.meta', $file . '.br' ) as $sidecar ) {
1327	if ( is_file( $sidecar ) ) {
1328	wp_delete_file( $sidecar );
1329	}
1330	}
1331	}
1332	}
1333
1334	// Static tree (served directly by the nginx/.htaccess rewrite).
1335	if ( defined( 'XSPEED_CACHE_STATIC_DIR' ) ) {
1336	$dir = rtrim( XSPEED_CACHE_STATIC_DIR, '/' ) . '/' . $host . ( '/' === $path ? '' : rtrim( $path, '/' ) );
1337	$file = $dir . '/index.html';
1338	if ( is_file( $file ) ) {
1339	wp_delete_file( $file );
1340	++$count;
1341	}
1342	if ( is_file( $file . '.br' ) ) {
1343	wp_delete_file( $file . '.br' );
1344	}
1345	}
1346
1347	if ( $count > 0 ) {
1348	Cache_Inventory::invalidate();
1349	Activity_Log::record(
1350	'cache_purge_url',
1351	sprintf(
1352	/* translators: 1: cause of the purge, 2: URL or path, 3: number of files removed. */
1353	__( 'Purged one URL (%1$s) — %2$s, %3$d file(s) removed', 'xspeed' ),
1354	$cause,
1355	$host . $path,
1356	$count
1357	),
1358	Activity_Log::INFO
1359	);
1360	}
1361
1362	return $count;
1363	}
1364
1365	public static function purge_all( string $cause = 'manual' ) {
1366	$count = 0;
1367	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1368	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
1369	if ( $files ) {
1370	$count = count( $files );
1371	foreach ( $files as $f ) {
1372	wp_delete_file( $f );
1373	}
1374	}
1375	// Remove the .meta sidecars (content-type for feeds/sitemaps)
1376	// alongside their .html entries. Not counted — they're not
1377	// cache "pages", just per-entry metadata.
1378	$meta = glob( XSPEED_CACHE_DIR . '/*.meta' );
1379	if ( $meta ) {
1380	foreach ( $meta as $m ) {
1381	wp_delete_file( $m );
1382	}
1383	}
1384	// Remove precompressed siblings (e.g. <key>.html.br from the Pro
1385	// Brotli module). Not counted — same as .meta. Without this a
1386	// purge leaves stale .br bodies behind: disk bloat, and a
1387	// staleness window if precompression is later disabled.
1388	$br = glob( XSPEED_CACHE_DIR . '/*.br' );
1389	if ( $br ) {
1390	foreach ( $br as $b ) {
1391	wp_delete_file( $b );
1392	}
1393	}
1394	}
1395	// Static-cache tree purge — recursive because the layout is
1396	// xspeed-static/{host}/{path}/index.html, so a flat glob can't
1397	// reach everything.
1398	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
1399	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1400	}
1401	// REST response cache (cache/xspeed/rest/*.json) — same purge
1402	// triggers (publish, settings change) invalidate it too.
1403	$count += Rest_Cache::purge();
1404
1405	// Minified + combined CSS/JS (cache/xspeed/min/ and min/combined/).
1406	// purge_all is a full filesystem sweep and must clear these too, even
1407	// when the Minify module is currently disabled — orphaned min/ files
1408	// from a feature the user later turned off must still be removed, and
1409	// a stale combined-<hash>.css that the regenerated page no longer
1410	// references otherwise 404s and breaks the frontend. (FBS-83114/83116)
1411	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
1412	Minifier::purge_minified();
1413	}
1414
1415	// Persistent object cache (Redis / Memcached). Flush regardless of
1416	// whether the Object Cache module is currently enabled — a drop-in
1417	// installed earlier keeps serving until flushed.
1418	if ( function_exists( 'wp_cache_flush' ) ) {
1419	wp_cache_flush();
1420	}
1421
1422	self::update_stats( array( 'last_purge' => time() ) );
1423
1424	// Fire AFTER the local sweep so module listeners (Critical CSS,
1425	// Unused CSS, Cloudflare edge purge) run — this action had three
1426	// registered listeners but was never emitted. Treat it as additive
1427	// (CDN / edge invalidation), not the mechanism for clearing local
1428	// files. (FBS-83114)
1429	do_action( 'xspeed_after_purge_all', $cause );
1430
1431	// The list behind the "Cached pages" card is memoized for a minute;
1432	// a purge has to drop it or the drill-down shows pages that no
1433	// longer exist.
1434	Cache_Inventory::invalidate();
1435
1436	// Trigger of WP_CLI / hook / admin-bar purges all hit the same
1437	// path. Record once with the supplied cause so the dashboard
1438	// activity feed reads naturally.
1439	Activity_Log::record(
1440	'cache_purged',
1441	sprintf( 'Cache purged (%s) — %d file%s removed', $cause, $count, 1 === $count ? '' : 's' ),
1442	Activity_Log::INFO
1443	);
1444
1445	return $count;
1446	}
1447
1448	/**
1449	* The per-type purge menu, LiteSpeed-style. Each entry is a cache type
1450	* the user can purge individually from the admin-bar dropdown. `visible`
1451	* controls whether the item shows (active + licensed module only) — it
1452	* NEVER limits Purge All, which always sweeps everything on disk.
1453	*
1454	* Pro registers its own types (Critical CSS, Unused CSS, …) by filtering
1455	* `xspeed_purge_types`, so Free degrades gracefully when Pro is absent.
1456	*
1457	* @return array<string,array{label:string,visible:bool}>
1458	*/
1459	public static function purge_types(): array {
1460	$minify_on = false;
1461	if ( class_exists( '\\XSpeed\\Settings_Manager' ) ) {
1462	$min = Settings_Manager::get( 'minify' );
1463	$minify_on = ! empty( $min['minify_css'] ) \|\| ! empty( $min['minify_js'] ) \|\| ! empty( $min['combine_css'] ) \|\| ! empty( $min['combine_js'] );
1464	}
1465	// Object cache is "active" when an external object-cache drop-in is in
1466	// use — the canonical WP signal, independent of our settings option.
1467	$oc_on = function_exists( 'wp_using_ext_object_cache' ) && wp_using_ext_object_cache();
1468
1469	$types = array(
1470	'all' => array(
1471	'label' => __( 'Purge All', 'xspeed' ),
1472	'visible' => true,
1473	),
1474	'page' => array(
1475	'label' => __( 'Purge Page / Static Cache', 'xspeed' ),
1476	'visible' => true,
1477	),
1478	'assets' => array(
1479	'label' => __( 'Purge CSS / JS Cache', 'xspeed' ),
1480	'visible' => $minify_on,
1481	),
1482	'object' => array(
1483	'label' => __( 'Purge Object Cache', 'xspeed' ),
1484	'visible' => $oc_on,
1485	),
1486	'rest' => array(
1487	'label' => __( 'Purge REST Cache', 'xspeed' ),
1488	'visible' => true,
1489	),
1490	);
1491
1492	/**
1493	* Filter the admin-bar purge-type menu. Pro modules add their own
1494	* (Critical CSS, Unused CSS, CDN). Adding a type here only adds a
1495	* MENU item — purge_type() must know how to handle the same slug.
1496	*
1497	* @param array $types Map of slug => [label, visible].
1498	*/
1499	return (array) apply_filters( 'xspeed_purge_types', $types );
1500	}
1501
1502	/**
1503	* Purge a single cache type by slug. 'all' delegates to purge_all();
1504	* every other slug clears just its own artifacts. Unknown slugs (e.g. a
1505	* Pro type) fan out via the `xspeed_purge_type_{slug}` action so the
1506	* owning module can handle it. Returns the number of items removed where
1507	* countable.
1508	*
1509	* @param string $type Cache type slug.
1510	* @param string $cause Who asked. Threaded through so the purge log can
1511	* tell an AI assistant's purge apart from a click —
1512	* "the cache cleared four times today" is only
1513	* actionable once you know what kept clearing it.
1514	*/
1515	public static function purge_type( string $type, string $cause = 'manual' ): int {
1516	switch ( $type ) {
1517	case 'all':
1518	return self::purge_all( $cause );
1519
1520	case 'page':
1521	$count = 0;
1522	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1523	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.html' ) as $f ) {
1524	wp_delete_file( $f );
1525	++$count;
1526	}
1527	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.meta' ) as $m ) {
1528	wp_delete_file( $m );
1529	}
1530	foreach ( (array) glob( XSPEED_CACHE_DIR . '/*.br' ) as $b ) {
1531	wp_delete_file( $b );
1532	}
1533	}
1534	if ( is_dir( XSPEED_CACHE_STATIC_DIR ) ) {
1535	$count += self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1536	}
1537	self::update_stats( array( 'last_purge' => time() ) );
1538	Cache_Inventory::invalidate();
1539	self::record_partial_purge( 'page', $cause, $count );
1540	return $count;
1541
1542	case 'assets':
1543	if ( class_exists( '\\XSpeed\\Minifier' ) ) {
1544	Minifier::purge_minified();
1545	}
1546	self::record_partial_purge( 'assets', $cause, null );
1547	return 0;
1548
1549	case 'object':
1550	if ( function_exists( 'wp_cache_flush' ) ) {
1551	wp_cache_flush();
1552	}
1553	self::record_partial_purge( 'object cache', $cause, null );
1554	return 0;
1555
1556	case 'rest':
1557	$count = Rest_Cache::purge();
1558	self::record_partial_purge( 'REST responses', $cause, $count );
1559	return $count;
1560
1561	default:
1562	// Pro / third-party type — let the owning module handle it.
1563	do_action( 'xspeed_purge_type_' . $type );
1564	self::record_partial_purge( $type, $cause, null );
1565	return 0;
1566	}
1567	}
1568
1569	/**
1570	* Log a partial purge so the drill-down behind "Last purge" shows every
1571	* clear, not only the full ones. Without this a site whose object cache
1572	* is flushed on a schedule looks, from the log, like nothing happens.
1573	*
1574	* @param string $what Human label for the slice purged.
1575	* @param string $cause Who asked.
1576	* @param int\|null $count Items removed, when countable.
1577	*/
1578	private static function record_partial_purge( string $what, string $cause, ?int $count ): void {
1579	$message = null === $count
1580	? sprintf(
1581	/* translators: 1: what was purged, 2: cause of the purge. */
1582	__( 'Purged %1$s (%2$s)', 'xspeed' ),
1583	$what,
1584	$cause
1585	)
1586	: sprintf(
1587	/* translators: 1: what was purged, 2: cause of the purge, 3: number of files removed. */
1588	__( 'Purged %1$s (%2$s) — %3$d file(s) removed', 'xspeed' ),
1589	$what,
1590	$cause,
1591	$count
1592	);
1593
1594	Activity_Log::record( 'cache_purged', $message, Activity_Log::INFO );
1595	}
1596
1597	/**
1598	* Clear the static tree only, leaving the flat cache in place.
1599	*
1600	* A narrower purge_all() for the case where only the web-server tree can
1601	* be wrong: its files are keyed by `{host}{path}` and nothing else, so a
1602	* response filed under the wrong path poisons it while the flat cache —
1603	* keyed by cache_key(), discriminators included — stays correct. Avoids
1604	* throwing away Critical CSS, minified bundles and the object cache to
1605	* fix a static-only problem.
1606	*
1607	* @return int Number of index.html files removed.
1608	*/
1609	public static function purge_static_tree(): int {
1610	return self::rmtree_html( XSPEED_CACHE_STATIC_DIR );
1611	}
1612
1613	/**
1614	* Recursively delete every `index.html` (and its precompressed
1615	* `index.html.br` sibling, if the Pro Brotli module wrote one) plus
1616	* empty directories inside the static-cache tree. Used by purge_all().
1617	* Returns the number of .html files removed so purge stats stay accurate
1618	* across the flat + static caches — .br siblings are not counted
1619	* (they're encodings of a page, not pages).
1620	*/
1621	private static function rmtree_html( string $dir ): int {
1622	if ( ! is_dir( $dir ) ) {
1623	return 0;
1624	}
1625	$removed = 0;
1626	// SCANDIR_SORT_NONE skips alphabetic sort — we're going to walk
1627	// the whole tree regardless of order.
1628	$entries = @scandir( $dir, SCANDIR_SORT_NONE ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
1629	if ( false === $entries ) {
1630	return 0;
1631	}
1632	foreach ( $entries as $entry ) {
1633	if ( '.' === $entry \|\| '..' === $entry ) {
1634	continue;
1635	}
1636	$path = $dir . '/' . $entry;
1637	if ( is_dir( $path ) ) {
1638	$removed += self::rmtree_html( $path );
1639	// Best-effort empty-dir cleanup; ignore failures (a
1640	// foreign file inside would block rmdir, which is fine).
1641	// 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.
1642	@rmdir( $path );
1643	continue;
1644	}
1645	if ( substr( $entry, -5 ) === '.html' ) {
1646	wp_delete_file( $path );
1647	++$removed;
1648	} elseif ( substr( $entry, -3 ) === '.br' ) {
1649	// Precompressed sibling (index.html.br). Remove it too so a
1650	// purge doesn't orphan stale Brotli bodies. Not counted.
1651	wp_delete_file( $path );
1652	}
1653	}
1654	return $removed;
1655	}
1656
1657	/**
1658	* Drop a "silence is golden" index.php into a directory so apaches/nginx
1659	* with directory listing enabled don't expose cache contents.
1660	*/
1661	public static function write_silence( $dir ) {
1662	$file = trailingslashit( $dir ) . 'index.php';
1663	if ( ! file_exists( $file ) ) {
1664	// 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.
1665	file_put_contents( $file, "<?php\n// Silence is golden.\n" );
1666	}
1667	}
1668
1669	/**
1670	* The raw xspeed_stats option as an array. Keys currently in use:
1671	* 'last_purge', 'last_gc', 'gc_removed', 'gc_removed_total'.
1672	*/
1673	public static function get_stats_option(): array {
1674	$stats = get_option( 'xspeed_stats', array() );
1675	return is_array( $stats ) ? $stats : array();
1676	}
1677
1678	/**
1679	* Persist stats with autoload disabled — stats are only read in admin
1680	* contexts, so there is no reason to inflate every frontend request's
1681	* `wp_load_alloptions()` payload.
1682	*
1683	* MERGES into whatever is already stored. It used to overwrite, which
1684	* was harmless while `last_purge` was the only key — with the GC keys
1685	* alongside it, a purge would have wiped the GC history and vice versa.
1686	*/
1687	public static function update_stats( array $stats ) {
1688	if ( false === get_option( 'xspeed_stats', false ) ) {
1689	add_option( 'xspeed_stats', $stats, '', 'no' );
1690	return;
1691	}
1692	update_option( 'xspeed_stats', array_merge( self::get_stats_option(), $stats ) );
1693	}
1694
1695	public static function get_stats() {
1696	$count = 0;
1697	$size = 0;
1698	if ( is_dir( XSPEED_CACHE_DIR ) ) {
1699	$files = glob( XSPEED_CACHE_DIR . '/*.html' );
1700	if ( $files ) {
1701	$count = count( $files );
1702	foreach ( $files as $f ) {
1703	$size += filesize( $f );
1704	}
1705	}
1706	}
1707	// Drain the HIT-log file BEFORE reading totals. Two serve paths that
1708	// bypass the normal in-PHP record_hit() append one line per HIT here:
1709	// the nginx server-level rewrite (see nginx_snippet(), never reaches
1710	// PHP) and the advanced-cache.php drop-in (runs pre-WordPress, can't
1711	// reach Hit_Counter). Without this drain both look like a 0% hit-ratio
1712	// on a perfectly working cache.
1713	Hit_Counter::collect_nginx_log_hits();
1714
1715	// Apache/LiteSpeed static-rewrite HITs are served straight from disk
1716	// by .htaccess and never reach PHP either — but there's no .htaccess
1717	// equivalent of nginx's access_log directive, so we count them by
1718	// scanning the web server's own access log incrementally. No-op when
1719	// the log isn't readable (managed hosts) — see the method docblock.
1720	Hit_Counter::collect_server_log_hits();
1721
1722	$stats = get_option( 'xspeed_stats', array() );
1723	$totals = Hit_Counter::totals_24h();
1724	return array(
1725	'cached_pages' => $count,
1726	'cache_size' => $size,
1727	'last_purge' => isset( $stats['last_purge'] ) ? (int) $stats['last_purge'] : 0,
1728	// Rolling 24h cache performance — sourced from Hit_Counter's
1729	// hourly buckets. The frontend uses hit_ratio to drive the
1730	// CacheHero stat grid + the Health module's panel.
1731	'hits_24h' => $totals['hits'],
1732	'misses_24h' => $totals['misses'],
1733	'hit_ratio' => $totals['ratio'],
1734	// Requests kept OUT of the ratio (404s + bots) — surfaced as its own
1735	// "absorbed N scanner/bot requests" line rather than distorting the
1736	// cache-performance number. (#118)
1737	'excluded_24h' => $totals['excluded'],
1738	// True when an edge cache (Cloudflare) fronts the origin, so hits are
1739	// absorbed before reaching PHP. The dashboard labels the ratio
1740	// "origin-layer only" instead of implying it's the full picture. (#118)
1741	'edge_cache' => self::edge_cache_detected(),
1742	);
1743	}
1744
1745	/**
1746	* Whether the current request should be kept OUT of the cache hit/miss
1747	* ratio: a genuine 404, or a known bot / scanner. Runs at template_redirect
1748	* time, so is_404() is resolved. (#118)
1749	*/
1750	private static function miss_is_excluded(): bool {
1751	if ( function_exists( 'is_404' ) && is_404() ) {
1752	return true;
1753	}
1754	$ua = isset( $_SERVER['HTTP_USER_AGENT'] )
1755	? sanitize_text_field( wp_unslash( (string) $_SERVER['HTTP_USER_AGENT'] ) )
1756	: '';
1757	return Hit_Counter::is_bot_ua( $ua );
1758	}
1759
1760	/**
1761	* Whether an edge cache fronts this origin. Today: the Cloudflare
1762	* integration is connected — so an unknown share of hits is served at the
1763	* edge and never counted here, making the origin ratio a partial view the
1764	* dashboard must label as such. (#118)
1765	*/
1766	private static function edge_cache_detected(): bool {
1767	$cf = get_option( 'xspeed_module_cloudflare', array() );
1768	return is_array( $cf ) && ! empty( $cf['enabled'] );
1769	}
1770
1771	/**
1772	* Apply the user's enable/disable choice. Called from the REST toggle
1773	* endpoint, which is gated by current_user_can( 'manage_options' ) and
1774	* a verified REST nonce.
1775	*
1776	* This is the only path that ENABLES caching — a drop-in is never
1777	* created for a user who hasn't opted in, which is the guideline that
1778	* matters (a plugin must not install drop-ins or edit wp-config.php
1779	* on a fresh activation). RESTORING the drop-in for a site that
1780	* already has cache_enabled = true is a different act and is handled
1781	* by restore_dropin_if_enabled() on activation and auto_heal() at
1782	* runtime; without it every plugin update silently un-caches the site.
1783	*
1784	* @param bool $enable User's choice.
1785	* @return array{
1786	* enabled: bool,
1787	* dropin_installed: bool,
1788	* wp_cache_constant: bool,
1789	* wp_config_writable: bool,
1790	* manual_snippet: ?string
1791	* }
1792	*/
1793	public static function toggle( $enable ) {
1794	$enable = (bool) $enable;
1795
1796	if ( $enable ) {
1797	$dropin_ok = self::install_dropin();
1798	$wp_config_ok = self::set_wp_cache_constant( true );
1799	$rewrite_ok = self::install_rewrite();
1800	self::ensure_hits_log_file();
1801	self::sync_mobile_flag();
1802	$snippet = $wp_config_ok ? null : "define( 'WP_CACHE', true );";
1803
1804	Activity_Log::record(
1805	'cache_enabled_event',
1806	$wp_config_ok
1807	? 'Cache enabled. Drop-in installed, WP_CACHE constant set.'
1808	: 'Cache enabled. Drop-in installed; wp-config.php not writable — add the WP_CACHE snippet manually.',
1809	$wp_config_ok ? Activity_Log::SUCCESS : Activity_Log::WARN
1810	);
1811
1812	return array(
1813	'enabled' => true,
1814	'dropin_installed' => (bool) $dropin_ok,
1815	'wp_cache_constant' => (bool) $wp_config_ok,
1816	'rewrite_installed' => (bool) $rewrite_ok,
1817	'wp_config_writable' => self::wp_config_writable(),
1818	'manual_snippet' => $snippet,
1819	'nginx_snippet' => self::nginx_snippet(),
1820	// Unified server-block snippet aggregating every enabled
1821	// module's directives — the same value the dashboard and
1822	// Health insight render. The wizard shows this so all three
1823	// surfaces stay in lockstep. Null on non-nginx hosts.
1824	'nginx_server_block' => self::full_nginx_server_block(),
1825	);
1826	}
1827
1828	self::remove_dropin();
1829	self::set_wp_cache_constant( false );
1830	self::remove_rewrite();
1831	// Drop the device-bucket marker too — with the drop-in gone there's
1832	// nothing left to read it, and leaving it behind would dirty a fresh
1833	// re-enable (and leaks across test runs).
1834	self::sync_mobile_flag( false );
1835
1836	Activity_Log::record(
1837	'cache_disabled_event',
1838	'Cache disabled. Drop-in removed.',
1839	Activity_Log::INFO
1840	);
1841
1842	return array(
1843	'enabled' => false,
1844	'dropin_installed' => false,
1845	'wp_cache_constant' => false,
1846	'rewrite_installed' => false,
1847	'wp_config_writable' => self::wp_config_writable(),
1848	'manual_snippet' => null,
1849	'nginx_snippet' => self::nginx_snippet(),
1850	'nginx_server_block' => self::full_nginx_server_block(),
1851	);
1852	}
1853
1854	/**
1855	* Check wp-config.php writability via WP_Filesystem. Plugin Check flags
1856	* direct is_writable() under WordPress.WP.AlternativeFunctions.
1857	*/
1858	private static function wp_config_writable() {
1859	global $wp_filesystem;
1860	if ( ! function_exists( 'WP_Filesystem' ) ) {
1861	require_once ABSPATH . 'wp-admin/includes/file.php';
1862	}
1863	WP_Filesystem();
1864
1865	return $wp_filesystem ? (bool) $wp_filesystem->is_writable( ABSPATH . 'wp-config.php' ) : false;
1866	}
1867
1868	/**
1869	* Nginx server-block snippet mirroring the Apache rewrite block.
1870	* We never auto-write nginx config — it sits outside the WordPress
1871	* root and is owned by the server admin — but the dashboard
1872	* surfaces this snippet when nginx is detected so the admin can
1873	* paste it once and unlock the same PHP-bypass speedup we get on
1874	* Apache / LiteSpeed via .htaccess.
1875	*
1876	* Returns null when the server isn't nginx (no point showing it).
1877	*/
1878	/**
1879	* Create wp-content/cache/xspeed/hits.log as an empty file so the
1880	* server-level rewrite's `access_log` directive has somewhere to
1881	* write on first request. Idempotent — touches an existing file
1882	* without disturbing accumulated lines. Called from Cache::toggle()
1883	* on enable and from auto_heal() when the file is missing.
1884	*
1885	* Permissions matter here. The file is created by PHP-FPM (often uid
1886	* www-data), but the nginx process that appends HIT lines may run as a
1887	* DIFFERENT uid — on multi-container hosts (e.g. xclude/Kinsta: nginx in
1888	* its own container as uid `nginx`, PHP-FPM in another as `www-data`)
1889	* they don't share a user at all. A default-umask 0644 file is then
1890	* unwritable by nginx, the access_log write silently fails, and the
1891	* dashboard shows a 0% hit ratio even though static HITs are serving.
1892	* So we widen the dir to 0777 and the file to 0666 — group/other write —
1893	* so whatever uid nginx runs as can append. (The file holds only HIT
1894	* request lines, no secrets.)
1895	*/
1896	/**
1897	* Directory holding the nginx hit log. Lives under uploads/, NOT the
1898	* cache dir — uninstall.php and a cache purge both delete the cache
1899	* dir, which would orphan the pasted nginx `access_log` directive's
1900	* parent directory and make `nginx -t` fail [emerg], taking down every
1901	* vhost on the host (FBS-82478). uploads/ always exists, isn't a
1902	* plugin-managed cache dir, and is never deleted on uninstall — so the
1903	* directive's target dir survives both, and nginx (which creates a
1904	* missing log FILE but not a missing DIR) can always open it.
1905	*
1906	* Falls back to the cache dir only if uploads is somehow unavailable.
1907	*/
1908	public static function hits_log_dir(): string {
1909	if ( function_exists( 'wp_upload_dir' ) ) {
1910	$uploads = wp_upload_dir( null, false );
1911	if ( is_array( $uploads ) && empty( $uploads['error'] ) && ! empty( $uploads['basedir'] ) ) {
1912	return rtrim( (string) $uploads['basedir'], '/' ) . '/xspeed';
1913	}
1914	}
1915	return XSPEED_CACHE_DIR;
1916	}
1917
1918	/** Absolute path to the nginx hit log file. */
1919	public static function hits_log_path(): string {
1920	return self::hits_log_dir() . '/hits.log';
1921	}
1922
1923	/**
1924	* Sync the drop-in's mobile-bucket flag file with the `mobile_separate`
1925	* setting. The drop-in (advanced-cache.php) runs before WordPress loads,
1926	* so it can't read the option — instead it checks for a zero-byte
1927	* `.mobile-separate` marker next to the cache files. When the setting is
1928	* on we touch the marker; when off we remove it. The drop-in's cache_key
1929	* computation keys off the marker's presence so its '\|m'/'\|d' device
1930	* bucket stays in lockstep with Cache::cache_key().
1931	*
1932	* Without this, turning on mobile_separate made Cache::store() write keys
1933	* with a '\|d'/'\|m' suffix the drop-in never reproduced — so the drop-in's
1934	* file_exists() always missed, every HIT fell through to a full WP boot,
1935	* and the fast pre-WP path was silently dead.
1936	*
1937	* @param bool\|null $enabled Force a state; null reads the current setting.
1938	*/
1939	public static function sync_mobile_flag( $enabled = null ): void {
1940	if ( null === $enabled ) {
1941	$opts = Settings_Manager::get( 'cache' );
1942	$enabled = ! empty( $opts['mobile_separate'] );
1943	}
1944	$dir = XSPEED_CACHE_DIR;
1945	$flag = $dir . '/.mobile-separate';
1946	if ( $enabled ) {
1947	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1948	return;
1949	}
1950	if ( ! file_exists( $flag ) ) {
1951	// 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.
1952	@touch( $flag );
1953	}
1954	return;
1955	}
1956	if ( file_exists( $flag ) ) {
1957	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1958	@unlink( $flag );
1959	}
1960	}
1961
1962	/**
1963	* Write / remove the `.maintenance-active` sentinel next to the cache
1964	* files. The pre-WP drop-in checks for this marker and bails when present,
1965	* so a page cached while the site was live is NOT served during
1966	* maintenance / coming-soon mode — WordPress loads and renders the
1967	* maintenance screen instead. The Pro Maintenance-Cache module drives this
1968	* on the maintenance on/off transition. (FBS-82409 B1)
1969	*
1970	* @param bool $active True to arm the sentinel (entering maintenance),
1971	* false to clear it (site recovered).
1972	*/
1973	public static function sync_maintenance_flag( bool $active ): void {
1974	$dir = XSPEED_CACHE_DIR;
1975	$flag = $dir . '/.maintenance-active';
1976	if ( $active ) {
1977	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
1978	return;
1979	}
1980	if ( ! file_exists( $flag ) ) {
1981	// 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.
1982	@touch( $flag );
1983	}
1984	return;
1985	}
1986	if ( file_exists( $flag ) ) {
1987	// phpcs:ignore WordPress.WP.AlternativeFunctions.unlink_unlink, WordPress.PHP.NoSilencedErrors.Discouraged -- plain marker removal; non-fatal.
1988	@unlink( $flag );
1989	}
1990	}
1991
1992	/**
1993	* Reconcile every mobile_separate-dependent artifact to the current
1994	* setting. Called on boot and whenever the cache settings are saved, so
1995	* flipping mobile_separate at runtime can't leave the install in a
1996	* half-converted state.
1997	*
1998	* Three things must agree with the setting:
1999	* 1. the drop-in's `.mobile-separate` flag (sync_mobile_flag()),
2000	* 2. the device-blind server rewrite — present only when OFF
2001	* (static_rewrite_allowed()),
2002	* 3. the now-stale static-cache tree + page cache, which were keyed
2003	* under the old scheme and would serve wrong-device HTML.
2004	*
2005	* No-ops when the cache is disabled — there's nothing installed to
2006	* reconcile, and toggle() handles install/teardown itself.
2007	*/
2008	public static function reconcile_mobile_separate(): void {
2009	self::sync_mobile_flag();
2010
2011	// The rewrite/static reconciliation below needs the plugin's path
2012	// constants. They're absent in early-boot / unit-test contexts where
2013	// only the drop-in flag matters — bail to the flag-only behavior then.
2014	if ( ! defined( 'XSPEED_CACHE_STATIC_DIR' ) ) {
2015	return;
2016	}
2017
2018	// Only touch the rewrite + caches when caching is actually on.
2019	$opts = get_option( 'xspeed_options', array() );
2020	if ( empty( $opts['cache_enabled'] ) ) {
2021	return;
2022	}
2023
2024	$rewrite_present = self::rewrite_installed();
2025	$rewrite_wanted = self::static_rewrite_allowed();
2026
2027	// Did the thing that actually invalidates cache KEYS change?
2028	// mobile_separate buckets entries as \|d / \|m, so flipping it makes
2029	// stored entries mis-bucketed and they must go. A rewrite-state
2030	// mismatch from anything else (e.g. mod_headers detection, a hand-
2031	// edited .htaccess) changes no key at all — the same files are still
2032	// valid, they're just served by PHP instead of by the web server.
2033	// Purging there is what let one WP-CLI call wipe the whole cache on
2034	// every bootstrap. (#138)
2035	//
2036	// Read the setting from the SAME place static_rewrite_allowed() and
2037	// sync_mobile_flag() do — the cache module's settings, not the
2038	// top-level xspeed_options — or this marker would track a key that
2039	// never changes and a real flip would go unnoticed.
2040	$cache_opts = Settings_Manager::get( 'cache' );
2041	$mobile_now = ! empty( $cache_opts['mobile_separate'] );
2042	$mobile_last = get_option( 'xspeed_last_mobile_separate', null );
2043	$mobile_flipped = ( null !== $mobile_last && (bool) (int) $mobile_last !== $mobile_now );
2044
2045	if ( (string) (int) $mobile_now !== (string) $mobile_last ) {
2046	update_option( 'xspeed_last_mobile_separate', $mobile_now ? '1' : '0', false );
2047	}
2048
2049	if ( $rewrite_present === $rewrite_wanted ) {
2050	// Already consistent — nothing flipped, leave caches intact so a
2051	// plain settings save (e.g. expiry change) doesn't blow the cache.
2052	return;
2053	}
2054
2055	// Bring the rewrite into line with what this server actually supports.
2056	if ( $rewrite_wanted ) {
2057	self::install_rewrite();
2058	} else {
2059	self::remove_rewrite();
2060	}
2061
2062	// Only discard cache contents when the device bucketing changed.
2063	if ( $mobile_flipped ) {
2064	self::purge_all( 'mobile_separate changed' );
2065	}
2066	}
2067
2068	/**
2069	* Whether the server-level static-rewrite fast path may be used.
2070	*
2071	* The rewrite serves `{host}{path}/index.html` straight from the web
2072	* server, keyed only by host + path — it has no way to run our PHP
2073	* device detection, so it can't tell mobile from desktop. When
2074	* `mobile_separate` is on, a single static file would be shared across
2075	* devices and whoever primed it wins (mobile visitors could get desktop
2076	* HTML, or vice-versa). Rather than duplicate a wp_is_mobile()-equivalent
2077	* UA matcher into .htaccess AND the nginx snippet (three copies that
2078	* would inevitably drift), we simply DON'T engage the static rewrite when
2079	* mobile_separate is on. Requests then fall through to the PHP drop-in,
2080	* which buckets correctly — a small TTFB cost (~85ms vs ~30ms) paid only
2081	* on mobile-separate sites, in exchange for guaranteed correctness.
2082	*
2083	* LiteSpeed exclusion (2026-06-16): on LiteSpeed — OpenLiteSpeed in
2084	* particular — `.htaccess` CAN run our RewriteRule to serve the static
2085	* file, but its `.htaccess` engine ignores `mod_headers`, so we cannot
2086	* stamp the served response with `X-XSpeed-Cache: HIT`, AND there is no
2087	* `.htaccess` equivalent of nginx's per-location `access_log` to record
2088	* the hit. The result was a cache that worked but was invisible: no HIT
2089	* header and a hit-ratio frozen near 0%. Every OTHER server gives the
2090	* user a visible HIT header + a counted hit (nginx via add_header +
2091	* access_log in its snippet; Apache via the `<IfModule mod_headers.c>`
2092	* block in rewrite_block_lines(), WHEN that module is loaded — when it is
2093	* not, Apache takes this same drop-in fallback). To keep LiteSpeed
2094	* CONSISTENT with the rest, we route its hits
2095	* through the PHP drop-in instead — the drop-in emits
2096	* `X-XSpeed-Cache: HIT (php)` and calls Hit_Counter inline, exactly the
2097	* observable behavior the other servers get. The cost is the drop-in's
2098	* ~30ms TTFB vs the static path's ~10ms, paid only on LiteSpeed; in
2099	* exchange the dashboard hit-ratio and the response header finally tell
2100	* the truth there. (Apache keeps the static fast path — it honors the
2101	* header.) See maybe_emit_lscache_headers() for the paired LSCache
2102	* stand-down that stops LiteSpeed's own module from shadowing the
2103	* drop-in.
2104	*/
2105	public static function static_rewrite_allowed(): bool {
2106	// LiteSpeed: drop-in serves hits (visible + counted) — see docblock.
2107	if ( Server::LITESPEED === Server::type() ) {
2108	return false;
2109	}
2110	// Apache without mod_headers is in EXACTLY the position LiteSpeed
2111	// is in above: it can run the RewriteRule and serve the static
2112	// file, but it cannot stamp `X-XSpeed-Cache` on the response, so
2113	// the hit is invisible to the user and uncountable by
2114	// Hit_Counter. The docblock above used to assert Apache "honors
2115	// mod_headers" and left it on the fast path unconditionally —
2116	// true only when the module is actually loaded. Fall back to the
2117	// drop-in when it isn't, trading ~10ms of TTFB for a hit that
2118	// shows up in the header and the ratio. (Field report: hit ratio
2119	// pinned at 0% on a working Apache cache.)
2120	if ( Server::APACHE === Server::type() && ! Server::apache_has_mod_headers() ) {
2121	return false;
2122	}
2123	$opts = Settings_Manager::get( 'cache' );
2124	return empty( $opts['mobile_separate'] );
2125	}
2126
2127	/**
2128	* Why the device-blind static rewrite is NOT installed, when it isn't.
2129	* Returns 'mobile_separate' when Separate Mobile Cache is the blocker
2130	* (the static file is one-per-URL, so it can't coexist with per-device
2131	* buckets), 'no_mod_headers' when Apache can't stamp the HIT header,
2132	* '' otherwise. Lets the dashboard explain the slow path instead of
2133	* silently falling back to PHP serving. (FBS-83145)
2134	*
2135	* Every refusal in static_rewrite_allowed() that is NOT self-explanatory
2136	* must have a branch here. Otherwise the Health card falls through to
2137	* "Block missing — toggle Enable Cache off and on to reinstall it",
2138	* advice that cannot work: the same condition that suppressed the write
2139	* suppresses the reinstall, and auto_heal() strips the block again on
2140	* the next admin page load. (Field report: Apache host with mod_headers
2141	* unloaded sat on the slow path with no way to find out why.)
2142	*/
2143	/**
2144	* Qualify a raw probe result with what we already KNOW about config.
2145	*
2146	* probe_static_rewrite() writes its own file under the static-cache tree
2147	* and fetches that, which succeeds whenever the web server can serve a
2148	* static file at all — including when static_rewrite_allowed() is false
2149	* and no real page is on the static path. So `active: true` on its own is
2150	* not evidence that pages are being served statically.
2151	*
2152	* The reachable case is nginx with Separate Mobile Cache on: the snippet
2153	* lives in the server block and we cannot remove it, pages are
2154	* deliberately routed to the PHP drop-in, but the probe file is still
2155	* served directly.
2156	*
2157	* The Health panel learned this in 88b4b50; the CLI, REST and MCP paths
2158	* did not, so they kept reporting "active" in exactly that configuration.
2159	* Rather than repeat the reasoning at each call site, they now all come
2160	* through here.
2161	*
2162	* Deliberately does NOT consult rewrite_installed(): on nginx the fast
2163	* path is the pasted snippet and there is no .htaccess marker to find, so
2164	* requiring one would report every correctly-configured nginx site as
2165	* broken.
2166	*
2167	* @param array $probe Raw result from probe_static_rewrite().
2168	* @return array{active:bool,inconclusive:bool,reason:string,block_reason:string}
2169	*/
2170	public static function qualify_rewrite_probe( array $probe ): array {
2171	$active = (bool) ( $probe['active'] ?? false );
2172	$inconclusive = (bool) ( $probe['inconclusive'] ?? false );
2173	$reason = (string) ( $probe['reason'] ?? '' );
2174	$block_reason = self::static_rewrite_block_reason();
2175
2176	// A known refusal outranks the probe, and also outranks
2177	// "inconclusive" — a blocked rewrite whose probe merely failed to
2178	// complete is still definitely blocked.
2179	if ( '' !== $block_reason ) {
2180	$active = false;
2181	$inconclusive = false;
2182	$reason = self::block_reason_text( $block_reason );
2183	}
2184
2185	return array(
2186	'active' => $active,
2187	'inconclusive' => $inconclusive,
2188	'reason' => $reason,
2189	'block_reason' => $block_reason,
2190	);
2191	}
2192
2193	/**
2194	* Human-readable explanation for a static_rewrite_block_reason() code.
2195	*
2196	* Each one has to say what to DO about it: "mobile_separate" alone tells
2197	* a user nothing, and the whole point of surfacing a refusal instead of
2198	* the probe verdict is that it is actionable.
2199	*/
2200	public static function block_reason_text( string $code ): string {
2201	switch ( $code ) {
2202	case 'mobile_separate':
2203	return 'Separate Mobile Cache is on, which disables the device-blind static rewrite. Cache hits are served by PHP instead. If your site serves the same HTML to every device, turn it off in Cache settings for much faster hits.';
2204	case 'no_mod_headers':
2205	return "Apache's mod_headers is not loaded, so the static rewrite cannot mark its responses as cache hits. Enable mod_headers, or leave hits on the PHP path.";
2206	default:
2207	return sprintf( 'The static rewrite is disabled (%s).', $code );
2208	}
2209	}
2210
2211	public static function static_rewrite_block_reason(): string {
2212	if ( Server::LITESPEED === Server::type() ) {
2213	return ''; // Intended on LiteSpeed — not a "block".
2214	}
2215	if ( Server::APACHE === Server::type() && ! Server::apache_has_mod_headers() ) {
2216	return 'no_mod_headers';
2217	}
2218	$opts = Settings_Manager::get( 'cache' );
2219	return ! empty( $opts['mobile_separate'] ) ? 'mobile_separate' : '';
2220	}
2221
2222	/**
2223	* Whether migration flagged Separate Mobile Cache for user review. Set by
2224	* Migration::map_mobile_separate() when a source plugin (WP Rocket / WP
2225	* Super Cache / LiteSpeed) had its "separate mobile cache" option on: we
2226	* import it as OFF (to keep the device-blind static fast path) but record
2227	* this flag so the dashboard can invite the user to turn it back on only
2228	* if their site genuinely serves different HTML per device. (FBS-83145)
2229	*/
2230	public static function mobile_separate_needs_review(): bool {
2231	$opts = Settings_Manager::get( 'cache' );
2232	return ! empty( $opts['mobile_separate_review'] );
2233	}
2234
2235	/**
2236	* Clear the review flag — called when the user has acted on the prompt
2237	* (dismissed it, or turned Separate Mobile Cache on/off deliberately) so
2238	* the dashboard callout doesn't nag forever. Writes the option directly
2239	* (bypassing Settings_Manager) so it never touches schema fields.
2240	*/
2241	public static function clear_mobile_separate_review(): void {
2242	$stored = get_option( 'xspeed_module_cache', array() );
2243	if ( ! is_array( $stored ) \|\| empty( $stored['mobile_separate_review'] ) ) {
2244	return;
2245	}
2246	unset( $stored['mobile_separate_review'] );
2247	update_option( 'xspeed_module_cache', $stored );
2248	}
2249
2250	/**
2251	* On-demand probe: does the homepage serve materially the same HTML to a
2252	* desktop and a mobile browser? Fetches home_url() twice over loopback —
2253	* once with a desktop User-Agent, once with a mobile one — strips
2254	* per-request noise (nonces, CSRF tokens, session ids, inline timestamps),
2255	* and compares. When identical, Separate Mobile Cache is almost certainly
2256	* unnecessary and the user can turn it off to regain the static fast path.
2257	*
2258	* NEVER run automatically (no page-load cost) — only from the dashboard
2259	* "Check now" button. Result is cached for 10 minutes so a double-click or
2260	* a re-render doesn't fire two more self-requests. (FBS-83145)
2261	*
2262	* @return array{ identical:bool, checked:bool, reason?:string, desktop_bytes?:int, mobile_bytes?:int }
2263	*/
2264	public static function probe_mobile_equality(): array {
2265	$cached = get_transient( 'xspeed_mobile_equality_probe' );
2266	if ( is_array( $cached ) ) {
2267	return $cached;
2268	}
2269
2270	$home = home_url( '/' );
2271	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
2272	if ( '' === $host ) {
2273	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'home_url has no host' );
2274	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
2275	return $result;
2276	}
2277
2278	// Match WP core's own mobile detection (wp_is_mobile) so the probe
2279	// reflects what the site would actually branch on. iPhone Safari for
2280	// mobile; a current desktop Chrome UA for desktop.
2281	$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';
2282	$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';
2283
2284	$is_local = function_exists( 'wp_get_environment_type' )
2285	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
2286
2287	$fetch = static function ( string $ua ) use ( $home, $is_local ) {
2288	$resp = wp_remote_get(
2289	$home,
2290	array(
2291	'timeout' => 5,
2292	'sslverify' => ! $is_local,
2293	'redirection' => 2,
2294	// Bust any per-device cache so we compare freshly-rendered
2295	// HTML, and pass the device UA the site would branch on.
2296	'user-agent' => $ua,
2297	'headers' => array( 'Cache-Control' => 'no-cache' ),
2298	)
2299	);
2300	if ( is_wp_error( $resp ) \|\| 200 !== (int) wp_remote_retrieve_response_code( $resp ) ) {
2301	return null;
2302	}
2303	return (string) wp_remote_retrieve_body( $resp );
2304	};
2305
2306	$desktop = $fetch( $desktop_ua );
2307	$mobile = $fetch( $mobile_ua );
2308
2309	if ( null === $desktop \|\| null === $mobile ) {
2310	$result = array( 'identical' => false, 'checked' => false, 'reason' => 'could not fetch homepage twice' );
2311	set_transient( 'xspeed_mobile_equality_probe', $result, MINUTE_IN_SECONDS );
2312	return $result;
2313	}
2314
2315	$identical = self::normalize_html_for_diff( $desktop ) === self::normalize_html_for_diff( $mobile );
2316
2317	$result = array(
2318	'identical' => $identical,
2319	'checked' => true,
2320	'desktop_bytes' => strlen( $desktop ),
2321	'mobile_bytes' => strlen( $mobile ),
2322	);
2323	set_transient( 'xspeed_mobile_equality_probe', $result, 10 * MINUTE_IN_SECONDS );
2324	return $result;
2325	}
2326
2327	/**
2328	* Strip per-request noise from HTML so a desktop-vs-mobile diff reflects
2329	* real structural differences, not nonces / session ids / timestamps that
2330	* change on every render. Deliberately conservative: it normalizes the
2331	* handful of well-known noise sources and collapses whitespace, so a site
2332	* that truly serves different markup per device still compares as different.
2333	*/
2334	private static function normalize_html_for_diff( string $html ): string {
2335	$patterns = array(
2336	// WP nonces (data-nonce="...", _wpnonce=..., "nonce":"...").
2337	'/(_wpnonce\|nonce\|_ajax_nonce)["\']?\s[:=]\s["\']?[a-f0-9]{10}/i',
2338	// Generic 10+ hex tokens (CSRF, cache-buster hashes, session ids).
2339	'/\b[a-f0-9]{16,}\b/i',
2340	// wp-generated unique ids (e.g. wp-block ids, aria ids).
2341	'/(id\|for\|aria-[a-z]+)="[^"]*-[0-9]{3,}"/i',
2342	// ISO-ish timestamps + epoch-looking numbers in query strings.
2343	'/\?ver=[0-9.]+/',
2344	'/[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9:.+Z-]+/',
2345	);
2346	$html = (string) preg_replace( $patterns, 'X', $html );
2347	// Collapse all whitespace so trivial formatting differences don't count.
2348	return trim( (string) preg_replace( '/\s+/', ' ', $html ) );
2349	}
2350
2351	public static function ensure_hits_log_file(): bool {
2352	// TWO writers append to this log, and an earlier fix conflated them:
2353	//
2354	// 1. nginx, via the server-level `access_log` directive in
2355	// nginx_snippet() — a DIFFERENT uid, which is why the file needs
2356	// to be world-writable there.
2357	// 2. the PHP drop-in (advanced-cache.php), on EVERY server. A hit it
2358	// serves bypasses WordPress entirely, so it can't call
2359	// Hit_Counter::record_hit() — appending here is the only way that
2360	// hit is ever counted.
2361	//
2362	// The nginx-only early return that used to sit at the top of this
2363	// method was fixing something real: chmod() on a file PHP doesn't own
2364	// raises "Operation not permitted", and off nginx that chmod buys
2365	// nothing. But it took directory creation with it, so on LiteSpeed
2366	// (which always serves via the drop-in), on Apache without mod_headers,
2367	// and anywhere mobile_separate forces the drop-in path, writer 2 was
2368	// appending to a file whose parent directory did not exist. The append
2369	// is @-suppressed and documented as non-fatal, so every one of those
2370	// hits vanished and the dashboard ratio sat at 0% forever.
2371	//
2372	// So: create the dir + file everywhere, and keep only the chmod gated
2373	// to nginx.
2374	$dir = self::hits_log_dir();
2375	if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) {
2376	return false;
2377	}
2378
2379	$is_nginx = ( Server::NGINX === Server::type() );
2380
2381	if ( $is_nginx ) {
2382	// Ensure the dir is traversable + writable by a different-uid nginx.
2383	// 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.
2384	@chmod( $dir, 0777 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort; the access_log just stays empty if it fails.
2385	}
2386
2387	$path = self::hits_log_path();
2388	if ( ! file_exists( $path ) ) {
2389	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_touch -- See docblock: must be a plain touch, not WP_Filesystem.
2390	@touch( $path ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- non-fatal helper; failures already covered by the dir check.
2391	}
2392
2393	if ( $is_nginx ) {
2394	// World-writable so a different-uid nginx can append HIT lines.
2395	// Off nginx the drop-in appends as the same uid that owns the file,
2396	// so this is unnecessary — and would emit the "Operation not
2397	// permitted" warnings the old early return was added to silence.
2398	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_chmod -- See docblock.
2399	@chmod( $path, 0666 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort.
2400	}
2401
2402	return file_exists( $path );
2403	}
2404
2405	public static function nginx_snippet(): ?string {
2406	if ( Server::NGINX !== Server::type() ) {
2407	return null;
2408	}
2409	$rel = '/' . ltrim( str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR ), '/' );
2410	$rel = rtrim( $rel, '/' );
2411
2412	// WP-Rocket-canonical pattern: every condition lives at
2413	// SERVER level (outside any location block). Each one appends
2414	// a tag to $xspeed_no_cache; the final check is a single
2415	// string-equality against the unmodified default "no-cache".
2416	// Only when ALL conditions pass does the rewrite fire,
2417	// jumping the request to the static file's URL. nginx then
2418	// restarts location matching against the new path, where
2419	// regular static-file serving takes over.
2420	//
2421	// Why server-level + a single rewrite (instead of try_files
2422	// inside `location /`): nginx's well-documented "if is evil"
2423	// quirk silently disables `try_files`'s last fallback when
2424	// any `if` in the same location is true. Moving the `if`s
2425	// outside any location dodges the trap completely, because
2426	// server-level rewrite is the documented stable path.
2427	//
2428	// `last` (not `break`) restarts location matching — required
2429	// so the rewritten static-file URI gets served via the normal
2430	// static-file location, not re-matched against `location /`
2431	// where our own rewrite would loop.
2432	//
2433	// The cache existence check is the LAST condition in the
2434	// chain so when the file isn't cached, $xspeed_no_cache
2435	// gets a "-nofile" tag and the rewrite is skipped — the
2436	// request falls through to whatever `location /` the user
2437	// already had (typically `try_files $uri $uri/ /index.php?$args;`).
2438	// Absolute path to the hit-log file from the nginx process's
2439	// filesystem view. Nginx's `access_log buffer=N flush=Ns` form
2440	// requires a literal path — `$document_root` variables are
2441	// rejected — so PHP computes it. Lives under uploads/ (NOT the
2442	// cache dir): a cache purge or uninstall deletes the cache dir,
2443	// which would orphan this directive's parent directory and make
2444	// `nginx -t` fail [emerg] for EVERY vhost on the host
2445	// (FBS-82478). uploads/ survives both, so the directive can
2446	// never take nginx down. Works on every topology where the nginx
2447	// process shares a filesystem with PHP (container or host).
2448	$hits_abs = self::hits_log_path();
2449
2450	$lines = array();
2451	$lines[] = '# xSpeed static cache — paste at server level, above location / { }.';
2452	// Cache host must match the on-disk dir PHP writes: store_static() /
2453	// static_host() take HTTP_HOST and strip every char outside
2454	// [a-zA-Z0-9.\-] — i.e. it removes the colon but KEEPS the port digits
2455	// (localhost:8192 → localhost8192). nginx's own $host can't reproduce
2456	// that: $host has the port already stripped ENTIRELY (→ localhost), so
2457	// the -f check looks for localhost/... while PHP wrote localhost8192/...
2458	// and the rewrite never fires on a non-standard port. Derive
2459	// $xspeed_host from $http_host (which keeps the port) and drop just the
2460	// colon, so it equals the PHP dir on every port. On standard ports
2461	// $http_host has no colon, so $xspeed_host == $host == the bare domain.
2462	$lines[] = 'set $xspeed_host $http_host;'; // default: no port → unchanged (e.g. example.com)
2463	$lines[] = 'if ($http_host ~ "^([^:]+):(\\d+)$") { set $xspeed_host $1$2; }'; // host:port → hostport (matches PHP static_host())
2464	$lines[] = 'set $xspeed_no_cache "no-cache";';
2465	$lines[] = 'if ($request_method != GET) { set $xspeed_no_cache "$xspeed_no_cache-method"; }';
2466	$lines[] = 'if ($args) { set $xspeed_no_cache "$xspeed_no_cache-args"; }';
2467	// Cookie + user-agent exclusions, generated from the user's actual
2468	// settings rather than a hardcoded list. Before this, the rule
2469	// tested three fixed cookie names and no user agent at all, so
2470	// every excluded_cookies / bypass_user_agents entry applied only
2471	// while a page was cold — on a warm page nginx served the shared
2472	// anonymous copy to carts, members and bypassed bots alike. The
2473	// three historical names survive as a floor inside cookie_rule().
2474	// `~*` is case-insensitive, matching PHP's stripos()/glob checks.
2475	$cache_opts = Settings_Manager::get( 'cache' );
2476	$cookie_rule = Server_Rules::cookie_rule(
2477	is_array( $cache_opts['excluded_cookies'] ?? null ) ? $cache_opts['excluded_cookies'] : array()
2478	);
2479	$lines[] = 'if ($http_cookie ~* "(' . $cookie_rule['regex'] . ')") { set $xspeed_no_cache "$xspeed_no_cache-cookie"; }';
2480
2481	$ua_rule = Server_Rules::user_agent_rule(
2482	is_array( $cache_opts['bypass_user_agents'] ?? null ) ? $cache_opts['bypass_user_agents'] : array()
2483	);
2484	// Emitted only when the list is non-empty — an empty alternation
2485	// would compile to `(...)` matching every request and disable the
2486	// fast path entirely.
2487	if ( '' !== $ua_rule['regex'] ) {
2488	$lines[] = 'if ($http_user_agent ~* "(' . $ua_rule['regex'] . ')") { set $xspeed_no_cache "$xspeed_no_cache-ua"; }';
2489	}
2490	$lines[] = 'if (!-f "$document_root' . $rel . '/$xspeed_host$uri/index.html") { set $xspeed_no_cache "$xspeed_no_cache-nofile"; }';
2491	// Neither `add_header` nor `access_log` is allowed inside an `if{}`
2492	// at server level (nginx rejects with "directive is not allowed
2493	// here"). The logging therefore lives in a `location` block that
2494	// matches the rewritten URI after `rewrite … last;` restarts
2495	// location matching. Every HIT lands there exactly once, every
2496	// MISS / PHP-served request never matches it.
2497	$lines[] = 'if ($xspeed_no_cache = "no-cache") {';
2498	$lines[] = ' rewrite ^ ' . $rel . '/$xspeed_host$uri/index.html last;';
2499	$lines[] = '}';
2500	$lines[] = '';
2501	$lines[] = '# Serve + log the cached HIT — `^~` is required so this beats any regex location.';
2502	$lines[] = 'location ^~ ' . $rel . '/ {';
2503	$lines[] = ' internal;';
2504	// LITERAL log path (not `set $var; access_log $var`). The variable form
2505	// makes nginx open the log lazily per-request and SILENTLY drop the
2506	// line if the open fails — so on a working host hits were served
2507	// (X-XSpeed-Cache fires regardless) but nothing was ever written and
2508	// the hit ratio sat at 0%. A literal path makes nginx open the file at
2509	// config load and actually log every hit.
2510	//
2511	// Deleting the log FILE is still safe with a literal path: nginx
2512	// recreates it on the next write/reload and `nginx -t` stays green
2513	// (verified). The only thing that [emerg]s `nginx -t` is a missing
2514	// parent DIRECTORY — and the log lives under uploads/xspeed/, which
2515	// survives cache purge + uninstall, and which ensure_hits_log_file()
2516	// (run on every admin_init via auto_heal) recreates if it ever goes
2517	// missing. So: hits are logged, and a user deleting the log can't take
2518	// nginx down.
2519	$lines[] = ' access_log ' . $hits_abs . ' combined buffer=16k flush=5s;';
2520	$lines[] = ' add_header X-XSpeed-Cache "HIT (nginx)" always;';
2521	$lines[] = '}';
2522	return implode( "\n", $lines );
2523	}
2524
2525	/**
2526	* Aggregate every enabled module's nginx_directives() into one
2527	* pasteable server-block snippet. Replaces the per-module "paste
2528	* this snippet" notices with a single consolidated paste — every
2529	* future feature toggle just regenerates this output.
2530	*
2531	* Returns null on non-nginx hosts (nothing to paste).
2532	*
2533	* Sections render in module-registration order so the layout stays
2534	* predictable; each module gets a comment header `# <slug>`.
2535	*/
2536	public static function full_nginx_server_block(): ?string {
2537	if ( Server::NGINX !== Server::type() ) {
2538	return null;
2539	}
2540
2541	$blocks = array();
2542	foreach ( Module_Registry::all() as $module ) {
2543	$directives = $module->nginx_directives();
2544	if ( ! is_string( $directives ) \|\| '' === trim( $directives ) ) {
2545	continue;
2546	}
2547	$blocks[] = "# === " . $module->slug() . " ===\n" . rtrim( $directives );
2548	}
2549
2550	if ( empty( $blocks ) ) {
2551	return null;
2552	}
2553
2554	$header = "# xSpeed unified nginx config — paste into `server { }`, above `location / { }`; re-paste after toggling features.\n";
2555
2556	return $header . "\n" . implode( "\n\n", $blocks ) . "\n";
2557	}
2558
2559	/**
2560	* Tell LiteSpeed's LSCache module to stand down on the cache-miss
2561	* render path.
2562	*
2563	* History: this method used to emit X-LiteSpeed-Cache-Control:
2564	* public,max-age=N + X-LiteSpeed-Tag, handing caching to the server's
2565	* LSCache store. That delegation backfired — once LSCache cached a
2566	* page it served every subsequent request from its OWN store and
2567	* intercepted the request before our site-root .htaccess static
2568	* rewrite could run. Net effect on LiteSpeed hosts: no X-XSpeed-Cache
2569	* header, our static-cache tree never served, the HIT log never
2570	* written (hit ratio frozen at 0%), and the Health probe reporting a
2571	* false "cache running on PHP fallback" because it never saw an
2572	* xSpeed-served response.
2573	*
2574	* xSpeed now owns the cache on LiteSpeed exactly as it does on Apache:
2575	* our `.htaccess` mod_rewrite block serves hits straight from the
2576	* static-cache tree (with the X-XSpeed-Cache header + access-log HIT
2577	* accounting), and PHP/the drop-in is the fallback. To guarantee
2578	* LSCache doesn't shadow that with its own copy — some LiteSpeed
2579	* configs cache by default — we send an explicit `no-cache` control so
2580	* the server defers to our rewrite. Skipped when the LiteSpeed Cache
2581	* plugin is active (it owns its own header policy; our Conflict
2582	* registry handles that coexistence separately).
2583	*/
2584	public static function maybe_emit_lscache_headers(): void {
2585	if ( headers_sent() ) {
2586	return;
2587	}
2588	if ( Server::LITESPEED !== Server::type() ) {
2589	return;
2590	}
2591	// is_plugin_active() lives in wp-admin/includes/plugin.php which
2592	// isn't auto-loaded on front-end requests. Use the option layer
2593	// directly to avoid pulling in admin code from a render path.
2594	$active = (array) get_option( 'active_plugins', array() );
2595	if ( in_array( 'litespeed-cache/litespeed-cache.php', $active, true ) ) {
2596	return;
2597	}
2598
2599	// Explicitly opt this response OUT of LSCache so the server can't
2600	// shadow our static-rewrite cache with its own internal copy.
2601	header( 'X-LiteSpeed-Cache-Control: no-cache' );
2602	}
2603
2604	/**
2605	* Restore the drop-in + WP_CACHE constant for a site that had caching
2606	* ON before this activation — and ONLY for such a site.
2607	*
2608	* WordPress runs an upgrade as deactivate → wipe plugin files →
2609	* install → activate. The wipe takes advanced-cache.php with it, so
2610	* without this the site serves 100% uncached from the moment the
2611	* update finishes until the next authenticated wp-admin page load
2612	* (auto_heal() is on admin_init). On a site whose admin logs in
2613	* rarely that window is hours or days of silent cache loss, while
2614	* the dashboard still reports cache_enabled = true. (FBS field
2615	* report against 1.1.2 / Pro 1.0.5.)
2616	*
2617	* The `cache_enabled` guard is the whole contract: a FRESH install
2618	* has the option unset, so activation writes nothing and the user
2619	* still opts in explicitly through Cache::toggle() via the
2620	* /cache/toggle REST endpoint. We only ever put back state the user
2621	* already chose — repair, never a new install path. This is what
2622	* keeps us on the right side of the "don't create drop-ins the user
2623	* didn't ask for" guideline while matching what WP Rocket, W3 Total
2624	* Cache and WP Super Cache all do on activation.
2625	*
2626	* @return bool True when a restore was performed.
2627	*/
2628	public static function restore_dropin_if_enabled(): bool {
2629	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
2630	return false;
2631	}
2632
2633	// The user's saved choice. Absent/false on a fresh install => no
2634	// drop-in is written and nothing touches wp-config.php.
2635	$opts = get_option( 'xspeed_options', array() );
2636	if ( empty( $opts['cache_enabled'] ) ) {
2637	return false;
2638	}
2639
2640	$restored = false;
2641
2642	// Only (re)install when the drop-in is missing, foreign, or an
2643	// older version of ours — never rewrite a current, healthy file.
2644	$target = WP_CONTENT_DIR . '/advanced-cache.php';
2645	$needs = true;
2646	if ( file_exists( $target ) ) {
2647	$contents = @file_get_contents( $target ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Best-effort read; a failure just means we reinstall.
2648	if ( is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' ) ) {
2649	$source = @file_get_contents( XSPEED_DIR . 'includes/advanced-cache.php' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Same.
2650	$needs = self::dropin_version( $contents ) < self::dropin_version( is_string( $source ) ? $source : '' );
2651	}
2652	}
2653	if ( $needs && self::install_dropin() ) {
2654	$restored = true;
2655	}
2656
2657	// WP_CACHE lives in wp-config.php, which the upgrade doesn't touch —
2658	// but a foreign cache plugin or a hand-edit can drop it, and without
2659	// it core never loads the drop-in at all.
2660	if ( ! defined( 'WP_CACHE' ) \|\| ! WP_CACHE ) {
2661	if ( self::set_wp_cache_constant( true ) ) {
2662	$restored = true;
2663	}
2664	}
2665
2666	if ( $restored ) {
2667	Activity_Log::record(
2668	'cache_dropin_restored',
2669	'Cache drop-in restored after a plugin update — caching was already enabled.',
2670	Activity_Log::SUCCESS
2671	);
2672	}
2673
2674	return $restored;
2675	}
2676
2677	/**
2678	* Reconcile drop-in + WP_CACHE + rewrite block with the user's
2679	* saved choice. Runs on admin_init. Cheap when nothing's wrong
2680	* (one option read + a handful of file_exists / defined checks);
2681	* writes only when state has drifted (typical cause: plugin
2682	* upgrade wiped the drop-in, foreign plugin removed our WP_CACHE
2683	* define, or someone hand-edited .htaccess).
2684	*
2685	* Skipped during the WP plugin updater run so we don't race
2686	* the upgrader's own filesystem operations.
2687	*/
2688	public static function auto_heal(): void {
2689	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
2690	return;
2691	}
2692	if ( wp_doing_ajax() \|\| wp_doing_cron() ) {
2693	return;
2694	}
2695
2696	$opts = get_option( 'xspeed_options', array() );
2697	if ( empty( $opts['cache_enabled'] ) ) {
2698	return;
2699	}
2700
2701	$dropin_target = WP_CONTENT_DIR . '/advanced-cache.php';
2702	$dropin_ours = false;
2703	$dropin_stale = false;
2704	if ( file_exists( $dropin_target ) ) {
2705	$contents = @file_get_contents( $dropin_target ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
2706	$dropin_ours = is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' );
2707	// Reinstall when OUR drop-in is an older version than the source —
2708	// the marker alone can't distinguish an old copy from a new one, so
2709	// a serve-logic change (e.g. the .meta read for 404s/feeds) would
2710	// otherwise never reach existing cache-enabled sites until a manual
2711	// cache toggle. (FBS-82406/82407)
2712	if ( $dropin_ours ) {
2713	$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
2714	}
2715	}
2716
2717	if ( ! $dropin_ours \|\| $dropin_stale ) {
2718	self::install_dropin();
2719	}
2720
2721	if ( ! defined( 'WP_CACHE' ) \|\| ! WP_CACHE ) {
2722	self::set_wp_cache_constant( true );
2723	}
2724
2725	// Rewrite block goes last. It's what turns the static-cache
2726	// tree into a PHP-bypass — every cache hit served by the web
2727	// server directly. Without it we still cache, just at drop-in
2728	// speed (~85ms TTFB) instead of static-file speed (~25-40ms).
2729	//
2730	// Reconcile against mobile_separate: the rewrite is device-blind, so
2731	// it must be ABSENT when mobile_separate is on and PRESENT otherwise.
2732	// auto_heal() runs periodically, so it also repairs a rewrite that
2733	// was left installed before mobile_separate was switched on.
2734	if ( self::static_rewrite_allowed() ) {
2735	if ( ! self::rewrite_installed() ) {
2736	self::install_rewrite();
2737	}
2738	} elseif ( self::rewrite_installed() ) {
2739	self::remove_rewrite();
2740	}
2741
2742	// HITs log file — nginx writes one line per HIT served directly
2743	// (see nginx_snippet()), Cache::get_stats() drains the file via
2744	// Hit_Counter::collect_nginx_log_hits(). If the file vanishes
2745	// (plugin upgrade wiped wp-content/cache/), nginx errors silently
2746	// on the access_log directive and the counter stays at 0.
2747	self::ensure_hits_log_file();
2748	}
2749
2750	/**
2751	* Keep the generic bypass cookie in sync with PHP's caching verdict.
2752	*
2753	* The server config tests exactly one cookie name (Server_Rules::
2754	* BYPASS_COOKIE) forever, and PHP decides what that name means. Adding
2755	* a new excluded cookie therefore needs no config change and no nginx
2756	* reload — the reason this exists.
2757	*
2758	* Session cookie (expiry 0) so it dies with the browser session, and
2759	* deliberately NOT HttpOnly-sensitive: it carries no identity, only the
2760	* boolean "don't serve this visitor a shared cached page".
2761	*
2762	* Honest limit: this can only ever help a visitor PHP has already seen
2763	* once. A bot's first request to a warm page never reaches PHP, which
2764	* is why user-agent rules are still written into the server config
2765	* rather than relying on this.
2766	*
2767	* @param bool $bypass Whether this visitor must skip the cache.
2768	*/
2769	private static function sync_bypass_cookie( bool $bypass ): void {
2770	if ( headers_sent() ) {
2771	return;
2772	}
2773
2774	$name = Server_Rules::BYPASS_COOKIE;
2775	$has = isset( $_COOKIE[ $name ] );
2776
2777	// Only touch the header when the state actually changes — a
2778	// Set-Cookie on every request would make the response uncacheable
2779	// for intermediary caches and add noise to every hit.
2780	if ( $bypass === $has ) {
2781	return;
2782	}
2783
2784	$path = defined( 'COOKIEPATH' ) && COOKIEPATH ? COOKIEPATH : '/';
2785	$domain = defined( 'COOKIE_DOMAIN' ) ? COOKIE_DOMAIN : '';
2786
2787	if ( $bypass ) {
2788	setcookie( $name, '1', 0, $path, (string) $domain, is_ssl(), false );
2789	$_COOKIE[ $name ] = '1';
2790	} else {
2791	setcookie( $name, '', time() - 3600, $path, (string) $domain, is_ssl(), false );
2792	unset( $_COOKIE[ $name ] );
2793	}
2794	}
2795
2796	/**
2797	* Build the .htaccess rules that map cacheable requests to the
2798	* static-cache tree. Conditions are deliberately strict: GET only,
2799	* empty query string, no session/comment-author/post-password
2800	* cookie, and the static file must exist on disk. Anything that
2801	* fails one of these falls through to PHP and the drop-in / full
2802	* WordPress path.
2803	*
2804	* @return string[] Lines for insert_with_markers().
2805	*/
2806	public static function rewrite_block_lines(): array {
2807	// Path relative to ABSPATH so the rule lives in the site-root
2808	// .htaccess regardless of where wp-content sits. WP_CONTENT_DIR
2809	// can be moved, so we compute the document-root-relative form
2810	// at install time and bake it into the rule.
2811	$rel = str_replace( ABSPATH, '/', XSPEED_CACHE_STATIC_DIR );
2812	$rel = '/' . ltrim( $rel, '/' );
2813	$rel = rtrim( $rel, '/' );
2814
2815	// Cookie + user-agent exclusions generated from the live settings.
2816	// See the matching block in nginx_snippet() — same generator, same
2817	// floor, so both servers enforce an identical policy. Apache reads
2818	// .htaccess on every request and we already self-heal this file, so
2819	// Apache/LiteSpeed users get the fix on upgrade with no action.
2820	$cache_opts = Settings_Manager::get( 'cache' );
2821	$cookie_rule = Server_Rules::cookie_rule(
2822	is_array( $cache_opts['excluded_cookies'] ?? null ) ? $cache_opts['excluded_cookies'] : array()
2823	);
2824	$ua_rule = Server_Rules::user_agent_rule(
2825	is_array( $cache_opts['bypass_user_agents'] ?? null ) ? $cache_opts['bypass_user_agents'] : array()
2826	);
2827
2828	$lines = array(
2829	'<IfModule mod_rewrite.c>',
2830	' RewriteEngine On',
2831	' RewriteCond %{REQUEST_METHOD} ^GET$',
2832	' RewriteCond %{QUERY_STRING} ^$',
2833	' RewriteCond %{HTTP_COOKIE} !(' . $cookie_rule['regex'] . ') [NC]',
2834	);
2835
2836	// Only emit the UA condition when there's something to match —
2837	// `!()` would negate an always-true empty match and refuse every
2838	// request, silently disabling the static path.
2839	if ( '' !== $ua_rule['regex'] ) {
2840	// Quoted, because RewriteCond is whitespace-delimited and real
2841	// user-agent fragments contain spaces ("Mozilla/5.0 (compatible").
2842	// Unquoted, a space adds an argument and Apache answers every
2843	// request with a 500 — and because .htaccess is parsed per
2844	// request, `httpd -t` still reports Syntax OK. Server_Rules has
2845	// already excluded quotes and backslashes from the alternation,
2846	// so the closing quote here cannot be escaped away.
2847	$lines[] = ' RewriteCond %{HTTP_USER_AGENT} "!(' . $ua_rule['regex'] . ')" [NC]';
2848	}
2849
2850	return array_merge(
2851	$lines,
2852	array(
2853	// Capture REQUEST_URI without its trailing slash into %1.
2854	// store_static() writes `{host}{uri-without-trailing-slash}/index.html`,
2855	// so this normalization lets `/blog/` and `/blog` both hit
2856	// the same cache file without producing the double-slash
2857	// path that would skip the -f check below.
2858	' RewriteCond %{REQUEST_URI} ^(.*?)/?$',
2859	' RewriteCond %{DOCUMENT_ROOT}' . $rel . '/%{HTTP_HOST}%1/index.html -f',
2860	// Pattern is `^`, NOT `.`. The per-directory rewrite engine
2861	// strips the leading slash before matching, so the HOMEPAGE
2862	// request `/` arrives here as an EMPTY path. `.` requires at
2863	// least one character and therefore never matches the homepage
2864	// — on LiteSpeed (which honors this strictly) the front page
2865	// fell through to PHP while every inner page rewrote fine.
2866	// `^` matches the empty string AND any non-empty path, so it
2867	// covers `/` and `/blog` alike. (Confirmed on OpenLiteSpeed
2868	// 1.8: `.` → homepage served by PHP drop-in; `^` → served
2869	// directly from the static file.)
2870	' RewriteRule ^ ' . $rel . '/%{HTTP_HOST}%1/index.html [L]',
2871	'</IfModule>',
2872	// Mark the statically-served response as a cache HIT.
2873	//
2874	// A file served by the rewrite above bypasses PHP entirely, so
2875	// this directive is the ONLY thing that can identify it as
2876	// cached — both for the user reading response headers and for
2877	// Hit_Counter, which reconciles static hits from the access
2878	// log. Without it the cache works perfectly and reports a 0%
2879	// hit ratio, which reads as "the plugin is broken". (Field
2880	// report against 1.1.2: homepage served byte-identical from
2881	// the static tree, no X-XSpeed-Cache header on any response.)
2882	//
2883	// `always` so the header is set on the 200 from the rewritten
2884	// file, not only on the successful-response table. The
2885	// <IfModule> guard keeps a server without mod_headers from
2886	// 500ing on an unknown directive — on such a host the header
2887	// is silently dropped, which is exactly why
2888	// static_rewrite_allowed() refuses the static path there and
2889	// routes hits through the drop-in instead.
2890	'<IfModule mod_headers.c>',
2891	' <FilesMatch "\\.html$">',
2892	' Header always set X-XSpeed-Cache "HIT (static)"',
2893	' </FilesMatch>',
2894	'</IfModule>',
2895	)
2896	);
2897	}
2898
2899	/**
2900	* Active probe that confirms the web-server static-rewrite path is
2901	* actually serving cached files. Writes a probe file with a random
2902	* nonce, fetches it over HTTP at its public URL, and checks whether
2903	* the response was served directly by the web server (Last-Modified
2904	* + ETag headers + no X-Powered-By: PHP).
2905	*
2906	* Server-agnostic: same probe works for nginx (snippet pasted) and
2907	* Apache / LiteSpeed (.htaccess block installed). If the rewrite
2908	* isn't engaged, the request falls through to WordPress and PHP
2909	* adds its own headers, which the probe detects and reports.
2910	*
2911	* Throttled via a 5-minute transient — we never want this running
2912	* on every Health card paint.
2913	*
2914	* @return array{active:bool, reason:string, code?:int, php?:bool, expires?:int}
2915	*/
2916	/**
2917	* @param bool $allow_probe When false (the default), return ONLY a cached
2918	* result and never make an HTTP request — so admin page loads are never
2919	* blocked by the loopback probe. The actual HTTP probe only runs when a
2920	* caller explicitly opts in (the Health tab / cron). Previously this ran
2921	* synchronously on every dashboard bootstrap, so a slow/timing-out
2922	* loopback request added up to `timeout` seconds to admin page loads on
2923	* hosts that block self-requests. (FBS-82142)
2924	*/
2925	/**
2926	* Discard the cached probe result and run a fresh one.
2927	*
2928	* Without this there was no way to re-check: the result sat in a transient
2929	* for five minutes and nothing ever deleted it, so a user who fixed their
2930	* nginx config kept seeing "nginx detected — configure for max cache speed"
2931	* with no means of confirming the fix worked. (FBS-84012)
2932	*/
2933	public static function recheck_static_rewrite(): array {
2934	delete_transient( 'xspeed_rewrite_probe' );
2935	return self::probe_static_rewrite( true );
2936	}
2937
2938	public static function probe_static_rewrite( bool $allow_probe = false ): array {
2939	$cached = get_transient( 'xspeed_rewrite_probe' );
2940	if ( is_array( $cached ) ) {
2941	return $cached;
2942	}
2943	// No cached result yet and the caller doesn't want to pay for a live
2944	// HTTP probe (e.g. the admin bootstrap): report "pending" without
2945	// blocking. The Health tab will run the real probe on demand.
2946	if ( ! $allow_probe ) {
2947	return array( 'active' => false, 'reason' => 'probe pending', 'pending' => true );
2948	}
2949
2950	$home = home_url( '/' );
2951	$host = (string) wp_parse_url( $home, PHP_URL_HOST );
2952	if ( '' === $host ) {
2953	$result = array( 'active' => false, 'reason' => 'home_url has no host' );
2954	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2955	return $result;
2956	}
2957
2958	// Use a randomised path AND nonce so a stale CDN cache entry
2959	// from a prior probe can never make a broken install look
2960	// healthy. Path is namespaced under __xspeed_probe__ so the
2961	// directory listing stays obvious if cleanup misfires.
2962	$slug = wp_generate_password( 12, false, false );
2963	$nonce = wp_generate_password( 24, false, false );
2964	$probe_dir = XSPEED_CACHE_STATIC_DIR . '/' . $host . '/__xspeed_probe__/' . $slug;
2965	$probe_file = $probe_dir . '/index.html';
2966	$probe_url = trailingslashit( $home ) . '__xspeed_probe__/' . $slug . '/';
2967
2968	if ( ! file_exists( $probe_dir ) ) {
2969	wp_mkdir_p( $probe_dir );
2970	}
2971	if ( ! is_dir( $probe_dir ) ) {
2972	$result = array( 'active' => false, 'reason' => 'cannot create probe dir' );
2973	set_transient( 'xspeed_rewrite_probe', $result, MINUTE_IN_SECONDS );
2974	return $result;
2975	}
2976	// 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.
2977	file_put_contents( $probe_file, $nonce, LOCK_EX );
2978
2979	// Verify TLS by default — disabling it site-wide is a needless MITM
2980	// exposure (FBS-82142). Only relax verification in local/dev
2981	// environments, where self-signed certs are common and there's no
2982	// real attacker in the loop.
2983	$is_local = function_exists( 'wp_get_environment_type' )
2984	&& in_array( wp_get_environment_type(), array( 'local', 'development' ), true );
2985	$resp = wp_remote_get(
2986	$probe_url,
2987	array(
2988	// 3s cap so a host that hangs on loopback self-requests can't
2989	// stall the caller for long; the result/error is cached so we
2990	// don't repeat the wait every minute.
2991	'timeout' => 3,
2992	'sslverify' => ! $is_local,
2993	'redirection' => 0,
2994	'headers' => array( 'Cache-Control' => 'no-cache' ),
2995	)
2996	);
2997
2998	// Best-effort cleanup so we don't accumulate probe dirs even
2999	// if subsequent calls all hit the transient.
3000	if ( file_exists( $probe_file ) ) {
3001	wp_delete_file( $probe_file );
3002	}
3003	if ( is_dir( $probe_dir ) ) {
3004	// 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.
3005	@rmdir( $probe_dir );
3006	}
3007
3008	if ( is_wp_error( $resp ) ) {
3009	$result = array(
3010	'active' => false,
3011	// The request never completed, so we learned NOTHING about the
3012	// rewrite. Flagged inconclusive so the UI doesn't tell the user
3013	// to configure a server that may already be configured — a
3014	// blocked loopback, a self-signed cert, or a timeout is a probe
3015	// failure, not a missing rewrite. (FBS-84012)
3016	'inconclusive' => true,
3017	'reason' => 'http error: ' . $resp->get_error_message(),
3018	);
3019	// Cache the failure for the full 5 minutes (not 1) so a host that
3020	// times out on the loopback probe isn't re-probed — and re-stalled
3021	// — on every page load within the window. (FBS-82142)
3022	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
3023	return $result;
3024	}
3025
3026	$code = (int) wp_remote_retrieve_response_code( $resp );
3027	$body = (string) wp_remote_retrieve_body( $resp );
3028	$ua_php = '' !== (string) wp_remote_retrieve_header( $resp, 'x-powered-by' );
3029	$has_etag = '' !== (string) wp_remote_retrieve_header( $resp, 'etag' )
3030	\|\| '' !== (string) wp_remote_retrieve_header( $resp, 'last-modified' );
3031	$match = trim( $body ) === $nonce;
3032
3033	// "Active" = the web server served our raw nonce bytes back
3034	// AND emitted the static-serve markers (ETag / Last-Modified)
3035	// AND didn't add an X-Powered-By: PHP header. All three are
3036	// individually noisy; together they're conclusive.
3037	$active = $match && $has_etag && ! $ua_php && 200 === $code;
3038
3039	/*
3040	* `inconclusive` separates "we proved the rewrite isn't serving" from
3041	* "the probe couldn't tell". Only the former should drive a
3042	* configure-your-server banner; the latter previously rendered the
3043	* same alarming copy at a user who had already configured nginx
3044	* correctly, and there was no way to clear it. (FBS-84012)
3045	*/
3046	$inconclusive = false;
3047	if ( $active ) {
3048	$reason = 'static-served';
3049	} elseif ( 200 === $code && $match && $ua_php ) {
3050	$reason = 'php served the file instead of nginx/Apache (rewrite block missing)';
3051	} elseif ( 200 === $code && ! $match ) {
3052	// Something answered 200 with content that isn't our nonce — a CDN,
3053	// a proxy, a security plugin. That tells us nothing about the
3054	// origin's rewrite.
3055	$reason = 'unexpected body (CDN cached an older response?)';
3056	$inconclusive = true;
3057	} elseif ( 404 === $code ) {
3058	$reason = 'probe URL returned 404 (rewrite block missing or wrong path)';
3059	} else {
3060	// Redirects, 403s from a WAF, 5xx — the probe never reached a
3061	// verdict about the rewrite itself.
3062	$reason = sprintf( 'unexpected response (HTTP %d, body %d B, php=%s)', $code, strlen( $body ), $ua_php ? 'yes' : 'no' );
3063	$inconclusive = true;
3064	}
3065
3066	$result = array(
3067	'active' => $active,
3068	'inconclusive' => $inconclusive,
3069	'reason' => $reason,
3070	'code' => $code,
3071	'php' => $ua_php,
3072	);
3073	set_transient( 'xspeed_rewrite_probe', $result, 5 * MINUTE_IN_SECONDS );
3074	return $result;
3075	}
3076
3077	public static function rewrite_installed(): bool {
3078	$htaccess = ABSPATH . '.htaccess';
3079	if ( ! file_exists( $htaccess ) ) {
3080	return false;
3081	}
3082	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
3083	if ( ! is_string( $existing ) ) {
3084	return false;
3085	}
3086	return false !== strpos( $existing, '# BEGIN xSpeed Static Cache' );
3087	}
3088
3089	/**
3090	* Install the static-cache rewrite block at the TOP of .htaccess.
3091	*
3092	* Position matters: WordPress's own block ends with
3093	* `RewriteRule . /index.php [L]` which routes every non-file
3094	* request to PHP. The [L] flag stops the current rewrite pass,
3095	* but Apache restarts the cycle; on the second pass REQUEST_URI
3096	* is /index.php and no static-file check can match. The only
3097	* reliable position for a "serve static if it exists" rule is
3098	* before WordPress's block.
3099	*
3100	* WP's insert_with_markers() always appends, so we manage the
3101	* block manually: strip any prior xSpeed Static Cache markers,
3102	* then write our block followed by the rest of the file.
3103	*/
3104	public static function install_rewrite(): bool {
3105	// The static rewrite is device-blind; never install it when
3106	// mobile_separate is on (see static_rewrite_allowed()).
3107	if ( ! self::static_rewrite_allowed() ) {
3108	return false;
3109	}
3110	$htaccess = ABSPATH . '.htaccess';
3111	$existing = file_exists( $htaccess ) ? @file_get_contents( $htaccess ) : ''; // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
3112	if ( false === $existing ) {
3113	$existing = '';
3114	}
3115	// Apache/LiteSpeed only. nginx hosts: rule won't fire, drop-in
3116	// covers; we skip the write so we don't litter their root.
3117	// 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.
3118	if ( file_exists( $htaccess ) && ! is_writable( $htaccess ) ) {
3119	return false;
3120	}
3121	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See above.
3122	if ( ! file_exists( $htaccess ) && ! is_writable( ABSPATH ) ) {
3123	return false;
3124	}
3125
3126	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
3127	$block = self::marker_block( 'xSpeed Static Cache', self::rewrite_block_lines() );
3128	$next = $block . ( '' === $cleaned ? '' : "\n" . $cleaned );
3129
3130	// 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.
3131	return false !== file_put_contents( $htaccess, $next, LOCK_EX );
3132	}
3133
3134	/**
3135	* Rewrite the .htaccess block in place when — and only when — one is
3136	* already installed.
3137	*
3138	* The block embeds the generated cookie / user-agent exclusion rules,
3139	* so it goes stale the moment those settings change. install_rewrite()
3140	* regenerates it from the live settings, but calling that unconditionally
3141	* on every save would CREATE a block on sites that never enabled the
3142	* static path — silently turning on server-level serving nobody asked
3143	* for. So we refresh only what's already there.
3144	*
3145	* @return bool True when a block was present and rewritten.
3146	*/
3147	public static function refresh_rewrite_if_installed(): bool {
3148	$htaccess = ABSPATH . '.htaccess';
3149	if ( ! file_exists( $htaccess ) ) {
3150	return false;
3151	}
3152	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Best-effort read; an unreadable file simply means nothing to refresh.
3153	if ( ! is_string( $existing ) \|\| false === strpos( $existing, '# BEGIN xSpeed Static Cache' ) ) {
3154	return false;
3155	}
3156	return self::install_rewrite();
3157	}
3158
3159	public static function remove_rewrite(): bool {
3160	$htaccess = ABSPATH . '.htaccess';
3161	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable -- See install_rewrite() rationale.
3162	if ( ! file_exists( $htaccess ) \|\| ! is_writable( $htaccess ) ) {
3163	return false;
3164	}
3165	$existing = @file_get_contents( $htaccess ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
3166	if ( false === $existing ) {
3167	return false;
3168	}
3169	$cleaned = self::strip_marker_block( $existing, 'xSpeed Static Cache' );
3170	// phpcs:ignore WordPress.WP.AlternativeFunctions.file_put_contents_file_put_contents, PluginCheck.CodeAnalysis.WriteFile.ABSPATHDetected -- See install_rewrite() rationale.
3171	return false !== file_put_contents( $htaccess, $cleaned, LOCK_EX );
3172	}
3173
3174	/**
3175	* Strip a `# BEGIN <marker>` ... `# END <marker>` block from a
3176	* .htaccess-style file, including any blank line that immediately
3177	* follows it. Idempotent — returns the input unchanged if the
3178	* marker isn't present.
3179	*/
3180	private static function strip_marker_block( string $contents, string $marker ): string {
3181	$pattern = '/# BEGIN ' . preg_quote( $marker, '/' ) . '\b.?# END ' . preg_quote( $marker, '/' ) . "\b[^\n]\n?\n?/s";
3182	$out = preg_replace( $pattern, '', $contents );
3183	return is_string( $out ) ? $out : $contents;
3184	}
3185
3186	private static function marker_block( string $marker, array $lines ): string {
3187	$header = "# BEGIN $marker\n";
3188	$header .= "# The directives (lines) between \"BEGIN $marker\" and \"END $marker\" are\n";
3189	$header .= "# dynamically generated, and should only be modified via WordPress filters.\n";
3190	$header .= "# Any changes to the directives between these markers will be overwritten.\n";
3191	$footer = "# END $marker\n";
3192	return $header . implode( "\n", $lines ) . "\n" . $footer;
3193	}
3194
3195	/**
3196	* Parse the `XSPEED_DROPIN_VERSION: N` stamp out of a drop-in's source.
3197	* Returns 0 when absent (an un-stamped older copy reinstalls). Used to
3198	* detect a stale installed drop-in vs the bundled source.
3199	*/
3200	private static function dropin_version( string $contents ): int {
3201	if ( preg_match( '/XSPEED_DROPIN_VERSION:\s*(\d+)/', $contents, $m ) ) {
3202	return (int) $m[1];
3203	}
3204	return 0;
3205	}
3206
3207	public static function install_dropin() {
3208	$source = XSPEED_DIR . 'includes/advanced-cache.php';
3209	$target = WP_CONTENT_DIR . '/advanced-cache.php';
3210	if ( ! file_exists( $source ) ) {
3211	return false;
3212	}
3213
3214	global $wp_filesystem;
3215	if ( ! function_exists( 'WP_Filesystem' ) ) {
3216	require_once ABSPATH . 'wp-admin/includes/file.php';
3217	}
3218	WP_Filesystem();
3219	if ( ! $wp_filesystem ) {
3220	return false;
3221	}
3222
3223	$source_contents = $wp_filesystem->get_contents( $source );
3224	if ( ! is_string( $source_contents ) ) {
3225	return false;
3226	}
3227
3228	// Bake the absolute hit-log path into the drop-in. It runs before
3229	// WordPress loads, so it can't resolve wp_upload_dir() itself — we
3230	// substitute the @@XSPEED_HITS_LOG@@ token with the real uploads path
3231	// (never the cache dir; see hits_log_dir() / FBS-82478). Use a single
3232	// quoted PHP string literal so the installed file stays valid PHP.
3233	$source_contents = str_replace(
3234	'@@XSPEED_HITS_LOG@@',
3235	str_replace( "'", "\\'", self::hits_log_path() ),
3236	$source_contents
3237	);
3238
3239	// Bake the cookie + user-agent exclusion rules in too. The drop-in
3240	// runs before WordPress loads, so it cannot read the settings — and
3241	// without them it served the shared anonymous page to any visitor
3242	// PHP had not yet seen (a first-time cart visitor, a bypassed bot).
3243	// The generic bypass cookie only covers repeat visitors; these two
3244	// regexes are what make the FIRST request correct.
3245	//
3246	// Both are already fully escaped by Server_Rules, and each is
3247	// embedded as a single-quoted PHP literal, so a settings value can
3248	// neither break the drop-in's syntax nor execute.
3249	$cache_opts = Settings_Manager::get( 'cache' );
3250	$cookie_rule = Server_Rules::cookie_rule(
3251	is_array( $cache_opts['excluded_cookies'] ?? null ) ? $cache_opts['excluded_cookies'] : array()
3252	);
3253	$ua_rule = Server_Rules::user_agent_rule(
3254	is_array( $cache_opts['bypass_user_agents'] ?? null ) ? $cache_opts['bypass_user_agents'] : array()
3255	);
3256
3257	$source_contents = str_replace(
3258	'@@XSPEED_COOKIE_RE@@',
3259	str_replace( "'", "\\'", $cookie_rule['regex'] ),
3260	$source_contents
3261	);
3262	$source_contents = str_replace(
3263	'@@XSPEED_UA_RE@@',
3264	str_replace( "'", "\\'", $ua_rule['regex'] ),
3265	$source_contents
3266	);
3267
3268	if ( file_exists( $target ) ) {
3269	$existing = $wp_filesystem->get_contents( $target );
3270	$is_xspeed = is_string( $existing ) && false !== strpos( $existing, 'XSPEED_DROPIN' );
3271
3272	if ( $is_xspeed ) {
3273	if ( $existing === $source_contents ) {
3274	return true;
3275	}
3276	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
3277	}
3278
3279	// Foreign drop-in (e.g. left over from another cache plugin) — back it up
3280	// before overwriting so the user can recover if needed. Uploads dir
3281	// (not wp-content root) keeps the backup out of WordPress's reserved
3282	// drop-in location.
3283	$upload = wp_upload_dir( null, false );
3284	$basedir = isset( $upload['basedir'] ) ? trailingslashit( $upload['basedir'] ) . 'xspeed-backups' : false;
3285	if ( $basedir ) {
3286	if ( ! file_exists( $basedir ) ) {
3287	wp_mkdir_p( $basedir );
3288	self::write_silence( $basedir );
3289	}
3290	$backup = $basedir . '/advanced-cache.foreign-' . gmdate( 'Ymd-His' ) . '.php.bak';
3291	$wp_filesystem->move( $target, $backup, true );
3292	} else {
3293	$wp_filesystem->delete( $target );
3294	}
3295	}
3296
3297	return (bool) $wp_filesystem->put_contents( $target, $source_contents, FS_CHMOD_FILE );
3298	}
3299
3300	public static function remove_dropin() {
3301	$target = WP_CONTENT_DIR . '/advanced-cache.php';
3302	if ( ! file_exists( $target ) ) {
3303	return;
3304	}
3305
3306	global $wp_filesystem;
3307	if ( ! function_exists( 'WP_Filesystem' ) ) {
3308	require_once ABSPATH . 'wp-admin/includes/file.php';
3309	}
3310	WP_Filesystem();
3311	if ( ! $wp_filesystem ) {
3312	return;
3313	}
3314
3315	$contents = $wp_filesystem->get_contents( $target );
3316	if ( is_string( $contents ) && false !== strpos( $contents, 'XSPEED_DROPIN' ) ) {
3317	wp_delete_file( $target );
3318	}
3319	}
3320
3321	public static function set_wp_cache_constant( $enable ) {
3322	$wp_config = ABSPATH . 'wp-config.php';
3323	if ( ! file_exists( $wp_config ) ) {
3324	return false;
3325	}
3326
3327	global $wp_filesystem;
3328	if ( ! function_exists( 'WP_Filesystem' ) ) {
3329	require_once ABSPATH . 'wp-admin/includes/file.php';
3330	}
3331	WP_Filesystem();
3332	if ( ! $wp_filesystem \|\| ! $wp_filesystem->is_writable( $wp_config ) ) {
3333	return false;
3334	}
3335
3336	$config = $wp_filesystem->get_contents( $wp_config );
3337
3338	if ( $enable ) {
3339	// Own the constant. A previous caching plugin (e.g. WP Rocket sets
3340	// it false on deactivate) can leave `define( 'WP_CACHE', false );`
3341	// behind — presence alone is not enough, the VALUE must be true or
3342	// WordPress never loads advanced-cache.php and our drop-in is dead.
3343	if ( preg_match( "/define\\(\\s['\"]WP_CACHE['\"]\\s,/", $config ) ) {
3344	$rewritten = preg_replace(
3345	"/define\$\\s['\"]WP_CACHE['\"]\\s,\\s[^)]\$\\s*;/",
3346	"define( 'WP_CACHE', true );",
3347	$config,
3348	1
3349	);
3350	// If an existing define was already `true`, the rewrite is a
3351	// no-op string-wise; either way we end on WP_CACHE === true.
3352	if ( null !== $rewritten ) {
3353	$config = $rewritten;
3354	}
3355	} else {
3356	$config = preg_replace( '/(<\?php)/', "$1\ndefine( 'WP_CACHE', true );", $config, 1 );
3357	}
3358	} else {
3359	// Shared with uninstall.php so the two removal paths can't drift
3360	// — they already had, which is why every non-lowercase spelling
3361	// of the value survived a disable. (#9)
3362	require_once XSPEED_DIR . 'includes/wp-cache-constant.php';
3363	$config = xspeed_strip_wp_cache_define( $config );
3364	}
3365
3366	return (bool) $wp_filesystem->put_contents( $wp_config, $config, FS_CHMOD_FILE );
3367	}
3368
3369	/**
3370	* Admin-bar purge menu — a parent node plus one child per visible cache
3371	* type (LiteSpeed-style), instead of a single "Purge All" link. Each
3372	* child posts to the same admin-post handler with its type slug. The
3373	* per-type items only appear for active/licensed modules; "Purge All"
3374	* always shows and always sweeps everything. (FBS-83114)
3375	*
3376	* The parent node links to the settings page rather than a purge URL —
3377	* clicking the top-level item used to wipe the whole cache instantly with
3378	* no confirmation, which is far too destructive for a stray click. Purging
3379	* stays available (and explicit) through the child items. (FBS-84068)
3380	*/
3381	public function admin_bar_purge( $wp_admin_bar ) {
3382	if ( ! current_user_can( 'manage_options' ) ) {
3383	return;
3384	}
3385
3386	$wp_admin_bar->add_node(
3387	array(
3388	'id' => 'xspeed-purge',
3389	'title' => __( 'xSpeed Cache', 'xspeed' ),
3390	'href' => admin_url( 'admin.php?page=' . Admin::PAGE_SLUG ),
3391	)
3392	);
3393
3394	foreach ( self::purge_types() as $slug => $type ) {
3395	if ( empty( $type['visible'] ) ) {
3396	continue;
3397	}
3398	$wp_admin_bar->add_node(
3399	array(
3400	'id' => 'xspeed-purge-' . $slug,
3401	'parent' => 'xspeed-purge',
3402	'title' => esc_html( $type['label'] ),
3403	'href' => self::purge_type_url( $slug ),
3404	)
3405	);
3406	}
3407	}
3408
3409	/**
3410	* Nonce-protected admin-post URL for purging a single type. The nonce
3411	* action is per-type so a leaked URL can't be replayed for a different
3412	* scope.
3413	*/
3414	private static function purge_type_url( string $type ): string {
3415	return wp_nonce_url(
3416	admin_url( 'admin-post.php?action=xspeed_purge&type=' . rawurlencode( $type ) ),
3417	'xspeed_purge_' . $type
3418	);
3419	}
3420
3421	public function handle_admin_bar_purge() {
3422	if ( ! current_user_can( 'manage_options' ) ) {
3423	wp_die( esc_html__( 'Unauthorized.', 'xspeed' ), 403 );
3424	}
3425	$type = isset( $_GET['type'] ) ? sanitize_key( wp_unslash( $_GET['type'] ) ) : 'all';
3426	check_admin_referer( 'xspeed_purge_' . $type );
3427
3428	// Only honour known types; anything else falls back to a full purge.
3429	if ( ! array_key_exists( $type, self::purge_types() ) ) {
3430	$type = 'all';
3431	}
3432	self::purge_type( $type );
3433
3434	wp_safe_redirect( self::safe_purge_redirect( wp_get_referer() ) );
3435	exit;
3436	}
3437
3438	/**
3439	* Resolve a safe redirect target for an admin-bar purge.
3440	*
3441	* The purge sends the admin back where they came from — but the referer
3442	* can be a ONE-SHOT action URL (e.g. update.php?action=upload-plugin from
3443	* installing a plugin zip, or any *.php?action=… that consumed a POST /
3444	* temp upload). Redirecting there re-runs the action with nothing to act
3445	* on, so WordPress dies — the classic "Please select a file" from
3446	* File_Upload_Upgrader. Strip the transient action args so we return to a
3447	* safe, re-GET-able view of the same page; fall back to the dashboard when
3448	* there is no usable referer.
3449	*
3450	* @param string\|false $referer Raw wp_get_referer() value.
3451	* @return string Safe URL to redirect to.
3452	*/
3453	public static function safe_purge_redirect( $referer ): string {
3454	$referer = is_string( $referer ) ? $referer : '';
3455	if ( '' === $referer ) {
3456	return admin_url();
3457	}
3458
3459	// A referer that lands on an action-processing endpoint (update.php,
3460	// update-core.php, plugin/theme install/upload flows) can't be safely
3461	// re-requested — send them to the dashboard instead of replaying it.
3462	$path = (string) wp_parse_url( $referer, PHP_URL_PATH );
3463	if ( preg_match( '#/wp-admin/(update\|update-core)\.php$#', $path ) ) {
3464	return admin_url();
3465	}
3466
3467	// Otherwise keep them on the same page but drop the query args that
3468	// would re-trigger a form action or upload on load.
3469	return remove_query_arg(
3470	array( 'action', 'action2', 'package', 'overwrite', 'plugin', 'theme', 'file', '_wpnonce', '_ajax_nonce' ),
3471	$referer
3472	);
3473	}
3474	}
3475