includes/resourceloader/ResourceLoaderModule.php

   1 <?php
   2 /**
   3  * Abstraction for ResourceLoader modules.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Trevor Parscal
  22  * @author Roan Kattouw
  23  */
  24
  25 use MediaWiki\MediaWikiServices;
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Psr\Log\NullLogger;
  29 use Wikimedia\RelPath;
  30 use Wikimedia\ScopedCallback;
  31
  32 /**
  33  * Abstraction for ResourceLoader modules, with name registration and maxage functionality.
  34  */
  35 abstract class ResourceLoaderModule implements LoggerAwareInterface {
  36         # Type of resource
  37         const TYPE_SCRIPTS = 'scripts';
  38         const TYPE_STYLES = 'styles';
  39         const TYPE_COMBINED = 'combined';
  40
  41         # Desired load type
  42         // Module only has styles (loaded via <style> or <link rel=stylesheet>)
  43         const LOAD_STYLES = 'styles';
  44         // Module may have other resources (loaded via mw.loader from a script)
  45         const LOAD_GENERAL = 'general';
  46
  47         # sitewide core module like a skin file or jQuery component
  48         const ORIGIN_CORE_SITEWIDE = 1;
  49
  50         # per-user module generated by the software
  51         const ORIGIN_CORE_INDIVIDUAL = 2;
  52
  53         # sitewide module generated from user-editable files, like MediaWiki:Common.js, or
  54         # modules accessible to multiple users, such as those generated by the Gadgets extension.
  55         const ORIGIN_USER_SITEWIDE = 3;
  56
  57         # per-user module generated from user-editable files, like User:Me/vector.js
  58         const ORIGIN_USER_INDIVIDUAL = 4;
  59
  60         # an access constant; make sure this is kept as the largest number in this group
  61         const ORIGIN_ALL = 10;
  62
  63         # script and style modules form a hierarchy of trustworthiness, with core modules like
  64         # skins and jQuery as most trustworthy, and user scripts as least trustworthy.  We can
  65         # limit the types of scripts and styles we allow to load on, say, sensitive special
  66         # pages like Special:UserLogin and Special:Preferences
  67         protected $origin = self::ORIGIN_CORE_SITEWIDE;
  68
  69         protected $name = null;
  70         protected $targets = [ 'desktop' ];
  71
  72         // In-object cache for file dependencies
  73         protected $fileDeps = [];
  74         // In-object cache for message blob (keyed by language)
  75         protected $msgBlobs = [];
  76         // In-object cache for version hash
  77         protected $versionHash = [];
  78         // In-object cache for module content
  79         protected $contents = [];
  80
  81         /**
  82          * @var Config
  83          */
  84         protected $config;
  85
  86         /**
  87          * @var array|bool
  88          */
  89         protected $deprecated = false;
  90
  91         /**
  92          * @var LoggerInterface
  93          */
  94         protected $logger;
  95
  96         /**
  97          * Get this module's name. This is set when the module is registered
  98          * with ResourceLoader::register()
  99          *
 100          * @return string|null Name (string) or null if no name was set
 101          */
 102         public function getName() {
 103                 return $this->name;
 104         }
 105
 106         /**
 107          * Set this module's name. This is called by ResourceLoader::register()
 108          * when registering the module. Other code should not call this.
 109          *
 110          * @param string $name
 111          */
 112         public function setName( $name ) {
 113                 $this->name = $name;
 114         }
 115
 116         /**
 117          * Get this module's origin. This is set when the module is registered
 118          * with ResourceLoader::register()
 119          *
 120          * @return int ResourceLoaderModule class constant, the subclass default
 121          *     if not set manually
 122          */
 123         public function getOrigin() {
 124                 return $this->origin;
 125         }
 126
 127         /**
 128          * @param ResourceLoaderContext $context
 129          * @return bool
 130          */
 131         public function getFlip( $context ) {
 132                 return MediaWikiServices::getInstance()->getContentLanguage()->getDir() !==
 133                         $context->getDirection();
 134         }
 135
 136         /**
 137          * Get JS representing deprecation information for the current module if available
 138          *
 139          * @return string JavaScript code
 140          */
 141         public function getDeprecationInformation() {
 142                 $deprecationInfo = $this->deprecated;
 143                 if ( $deprecationInfo ) {
 144                         $name = $this->getName();
 145                         $warning = 'This page is using the deprecated ResourceLoader module "' . $name . '".';
 146                         if ( is_string( $deprecationInfo ) ) {
 147                                 $warning .= "\n" . $deprecationInfo;
 148                         }
 149                         return 'mw.log.warn(' . ResourceLoader::encodeJsonForScript( $warning ) . ');';
 150                 } else {
 151                         return '';
 152                 }
 153         }
 154
 155         /**
 156          * Get all JS for this module for a given language and skin.
 157          * Includes all relevant JS except loader scripts.
 158          *
 159          * For "plain" script modules, this should return a string with JS code. For multi-file modules
 160          * where require() is used to load one file from another file, this should return an array
 161          * structured as follows:
 162          * [
 163          *     'files' => [
 164          *         'file1.js' => [ 'type' => 'script', 'content' => 'JS code' ],
 165          *         'file2.js' => [ 'type' => 'script', 'content' => 'JS code' ],
 166          *         'data.json' => [ 'type' => 'data', 'content' => array ]
 167          *     ],
 168          *     'main' => 'file1.js'
 169          * ]
 170          *
 171          * @param ResourceLoaderContext $context
 172          * @return string|array JavaScript code (string), or multi-file structure described above (array)
 173          */
 174         public function getScript( ResourceLoaderContext $context ) {
 175                 // Stub, override expected
 176                 return '';
 177         }
 178
 179         /**
 180          * Takes named templates by the module and returns an array mapping.
 181          *
 182          * @return string[] Array of templates mapping template alias to content
 183          */
 184         public function getTemplates() {
 185                 // Stub, override expected.
 186                 return [];
 187         }
 188
 189         /**
 190          * @return Config
 191          * @since 1.24
 192          */
 193         public function getConfig() {
 194                 if ( $this->config === null ) {
 195                         // Ugh, fall back to default
 196                         $this->config = MediaWikiServices::getInstance()->getMainConfig();
 197                 }
 198
 199                 return $this->config;
 200         }
 201
 202         /**
 203          * @param Config $config
 204          * @since 1.24
 205          */
 206         public function setConfig( Config $config ) {
 207                 $this->config = $config;
 208         }
 209
 210         /**
 211          * @since 1.27
 212          * @param LoggerInterface $logger
 213          * @return null
 214          */
 215         public function setLogger( LoggerInterface $logger ) {
 216                 $this->logger = $logger;
 217         }
 218
 219         /**
 220          * @since 1.27
 221          * @return LoggerInterface
 222          */
 223         protected function getLogger() {
 224                 if ( !$this->logger ) {
 225                         $this->logger = new NullLogger();
 226                 }
 227                 return $this->logger;
 228         }
 229
 230         /**
 231          * Get the URL or URLs to load for this module's JS in debug mode.
 232          * The default behavior is to return a load.php?only=scripts URL for
 233          * the module, but file-based modules will want to override this to
 234          * load the files directly.
 235          *
 236          * This function is called only when 1) we're in debug mode, 2) there
 237          * is no only= parameter and 3) supportsURLLoading() returns true.
 238          * #2 is important to prevent an infinite loop, therefore this function
 239          * MUST return either an only= URL or a non-load.php URL.
 240          *
 241          * @param ResourceLoaderContext $context
 242          * @return array Array of URLs
 243          */
 244         public function getScriptURLsForDebug( ResourceLoaderContext $context ) {
 245                 $resourceLoader = $context->getResourceLoader();
 246                 $derivative = new DerivativeResourceLoaderContext( $context );
 247                 $derivative->setModules( [ $this->getName() ] );
 248                 $derivative->setOnly( 'scripts' );
 249                 $derivative->setDebug( true );
 250
 251                 $url = $resourceLoader->createLoaderURL(
 252                         $this->getSource(),
 253                         $derivative
 254                 );
 255
 256                 return [ $url ];
 257         }
 258
 259         /**
 260          * Whether this module supports URL loading. If this function returns false,
 261          * getScript() will be used even in cases (debug mode, no only param) where
 262          * getScriptURLsForDebug() would normally be used instead.
 263          * @return bool
 264          */
 265         public function supportsURLLoading() {
 266                 return true;
 267         }
 268
 269         /**
 270          * Get all CSS for this module for a given skin.
 271          *
 272          * @param ResourceLoaderContext $context
 273          * @return array List of CSS strings or array of CSS strings keyed by media type.
 274          *  like [ 'screen' => '.foo { width: 0 }' ];
 275          *  or [ 'screen' => [ '.foo { width: 0 }' ] ];
 276          */
 277         public function getStyles( ResourceLoaderContext $context ) {
 278                 // Stub, override expected
 279                 return [];
 280         }
 281
 282         /**
 283          * Get the URL or URLs to load for this module's CSS in debug mode.
 284          * The default behavior is to return a load.php?only=styles URL for
 285          * the module, but file-based modules will want to override this to
 286          * load the files directly. See also getScriptURLsForDebug()
 287          *
 288          * @param ResourceLoaderContext $context
 289          * @return array [ mediaType => [ URL1, URL2, ... ], ... ]
 290          */
 291         public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
 292                 $resourceLoader = $context->getResourceLoader();
 293                 $derivative = new DerivativeResourceLoaderContext( $context );
 294                 $derivative->setModules( [ $this->getName() ] );
 295                 $derivative->setOnly( 'styles' );
 296                 $derivative->setDebug( true );
 297
 298                 $url = $resourceLoader->createLoaderURL(
 299                         $this->getSource(),
 300                         $derivative
 301                 );
 302
 303                 return [ 'all' => [ $url ] ];
 304         }
 305
 306         /**
 307          * Get the messages needed for this module.
 308          *
 309          * To get a JSON blob with messages, use MessageBlobStore::get()
 310          *
 311          * @return array List of message keys. Keys may occur more than once
 312          */
 313         public function getMessages() {
 314                 // Stub, override expected
 315                 return [];
 316         }
 317
 318         /**
 319          * Get the group this module is in.
 320          *
 321          * @return string Group name
 322          */
 323         public function getGroup() {
 324                 // Stub, override expected
 325                 return null;
 326         }
 327
 328         /**
 329          * Get the source of this module. Should only be overridden for foreign modules.
 330          *
 331          * @return string Source name, 'local' for local modules
 332          */
 333         public function getSource() {
 334                 // Stub, override expected
 335                 return 'local';
 336         }
 337
 338         /**
 339          * Whether this module's JS expects to work without the client-side ResourceLoader module.
 340          * Returning true from this function will prevent mw.loader.state() call from being
 341          * appended to the bottom of the script.
 342          *
 343          * @return bool
 344          */
 345         public function isRaw() {
 346                 return false;
 347         }
 348
 349         /**
 350          * Get a list of modules this module depends on.
 351          *
 352          * Dependency information is taken into account when loading a module
 353          * on the client side.
 354          *
 355          * Note: It is expected that $context will be made non-optional in the near
 356          * future.
 357          *
 358          * @param ResourceLoaderContext|null $context
 359          * @return array List of module names as strings
 360          */
 361         public function getDependencies( ResourceLoaderContext $context = null ) {
 362                 // Stub, override expected
 363                 return [];
 364         }
 365
 366         /**
 367          * Get target(s) for the module, eg ['desktop'] or ['desktop', 'mobile']
 368          *
 369          * @return array Array of strings
 370          */
 371         public function getTargets() {
 372                 return $this->targets;
 373         }
 374
 375         /**
 376          * Get the module's load type.
 377          *
 378          * @since 1.28
 379          * @return string ResourceLoaderModule LOAD_* constant
 380          */
 381         public function getType() {
 382                 return self::LOAD_GENERAL;
 383         }
 384
 385         /**
 386          * Get the skip function.
 387          *
 388          * Modules that provide fallback functionality can provide a "skip function". This
 389          * function, if provided, will be passed along to the module registry on the client.
 390          * When this module is loaded (either directly or as a dependency of another module),
 391          * then this function is executed first. If the function returns true, the module will
 392          * instantly be considered "ready" without requesting the associated module resources.
 393          *
 394          * The value returned here must be valid javascript for execution in a private function.
 395          * It must not contain the "function () {" and "}" wrapper though.
 396          *
 397          * @return string|null A JavaScript function body returning a boolean value, or null
 398          */
 399         public function getSkipFunction() {
 400                 return null;
 401         }
 402
 403         /**
 404          * Get the files this module depends on indirectly for a given skin.
 405          *
 406          * These are only image files referenced by the module's stylesheet.
 407          *
 408          * @param ResourceLoaderContext $context
 409          * @return array List of files
 410          */
 411         protected function getFileDependencies( ResourceLoaderContext $context ) {
 412                 $vary = self::getVary( $context );
 413
 414                 // Try in-object cache first
 415                 if ( !isset( $this->fileDeps[$vary] ) ) {
 416                         $dbr = wfGetDB( DB_REPLICA );
 417                         $deps = $dbr->selectField( 'module_deps',
 418                                 'md_deps',
 419                                 [
 420                                         'md_module' => $this->getName(),
 421                                         'md_skin' => $vary,
 422                                 ],
 423                                 __METHOD__
 424                         );
 425
 426                         if ( !is_null( $deps ) ) {
 427                                 $this->fileDeps[$vary] = self::expandRelativePaths(
 428                                         (array)json_decode( $deps, true )
 429                                 );
 430                         } else {
 431                                 $this->fileDeps[$vary] = [];
 432                         }
 433                 }
 434                 return $this->fileDeps[$vary];
 435         }
 436
 437         /**
 438          * Set in-object cache for file dependencies.
 439          *
 440          * This is used to retrieve data in batches. See ResourceLoader::preloadModuleInfo().
 441          * To save the data, use saveFileDependencies().
 442          *
 443          * @param ResourceLoaderContext $context
 444          * @param string[] $files Array of file names
 445          */
 446         public function setFileDependencies( ResourceLoaderContext $context, $files ) {
 447                 $vary = self::getVary( $context );
 448                 $this->fileDeps[$vary] = $files;
 449         }
 450
 451         /**
 452          * Set the files this module depends on indirectly for a given skin.
 453          *
 454          * @since 1.27
 455          * @param ResourceLoaderContext $context
 456          * @param array $localFileRefs List of files
 457          */
 458         protected function saveFileDependencies( ResourceLoaderContext $context, $localFileRefs ) {
 459                 try {
 460                         // Related bugs and performance considerations:
 461                         // 1. Don't needlessly change the database value with the same list in a
 462                         //    different order or with duplicates.
 463                         // 2. Use relative paths to avoid ghost entries when $IP changes. (T111481)
 464                         // 3. Don't needlessly replace the database with the same value
 465                         //    just because $IP changed (e.g. when upgrading a wiki).
 466                         // 4. Don't create an endless replace loop on every request for this
 467                         //    module when '../' is used anywhere. Even though both are expanded
 468                         //    (one expanded by getFileDependencies from the DB, the other is
 469                         //    still raw as originally read by RL), the latter has not
 470                         //    been normalized yet.
 471
 472                         // Normalise
 473                         $localFileRefs = array_values( array_unique( $localFileRefs ) );
 474                         sort( $localFileRefs );
 475                         $localPaths = self::getRelativePaths( $localFileRefs );
 476                         $storedPaths = self::getRelativePaths( $this->getFileDependencies( $context ) );
 477
 478                         if ( $localPaths === $storedPaths ) {
 479                                 // Unchanged. Avoid needless database query (especially master conn!).
 480                                 return;
 481                         }
 482
 483                         // The file deps list has changed, we want to update it.
 484                         $vary = self::getVary( $context );
 485                         $cache = ObjectCache::getLocalClusterInstance();
 486                         $key = $cache->makeKey( __METHOD__, $this->getName(), $vary );
 487                         $scopeLock = $cache->getScopedLock( $key, 0 );
 488                         if ( !$scopeLock ) {
 489                                 // Another request appears to be doing this update already.
 490                                 // Avoid write slams (T124649).
 491                                 return;
 492                         }
 493
 494                         // No needless escaping as this isn't HTML output.
 495                         // Only stored in the database and parsed in PHP.
 496                         $deps = json_encode( $localPaths, JSON_UNESCAPED_SLASHES );
 497                         $dbw = wfGetDB( DB_MASTER );
 498                         $dbw->upsert( 'module_deps',
 499                                 [
 500                                         'md_module' => $this->getName(),
 501                                         'md_skin' => $vary,
 502                                         'md_deps' => $deps,
 503                                 ],
 504                                 [ [ 'md_module', 'md_skin' ] ],
 505                                 [
 506                                         'md_deps' => $deps,
 507                                 ],
 508                                 __METHOD__
 509                         );
 510
 511                         if ( $dbw->trxLevel() ) {
 512                                 $dbw->onTransactionResolution(
 513                                         function () use ( &$scopeLock ) {
 514                                                 ScopedCallback::consume( $scopeLock ); // release after commit
 515                                         },
 516                                         __METHOD__
 517                                 );
 518                         }
 519                 } catch ( Exception $e ) {
 520                         // Probably a DB failure. Either the read query from getFileDependencies(),
 521                         // or the write query above.
 522                         wfDebugLog( 'resourceloader', __METHOD__ . ": failed to update DB: $e" );
 523                 }
 524         }
 525
 526         /**
 527          * Make file paths relative to MediaWiki directory.
 528          *
 529          * This is used to make file paths safe for storing in a database without the paths
 530          * becoming stale or incorrect when MediaWiki is moved or upgraded (T111481).
 531          *
 532          * @since 1.27
 533          * @param array $filePaths
 534          * @return array
 535          */
 536         public static function getRelativePaths( array $filePaths ) {
 537                 global $IP;
 538                 return array_map( function ( $path ) use ( $IP ) {
 539                         return RelPath::getRelativePath( $path, $IP );
 540                 }, $filePaths );
 541         }
 542
 543         /**
 544          * Expand directories relative to $IP.
 545          *
 546          * @since 1.27
 547          * @param array $filePaths
 548          * @return array
 549          */
 550         public static function expandRelativePaths( array $filePaths ) {
 551                 global $IP;
 552                 return array_map( function ( $path ) use ( $IP ) {
 553                         return RelPath::joinPath( $IP, $path );
 554                 }, $filePaths );
 555         }
 556
 557         /**
 558          * Get the hash of the message blob.
 559          *
 560          * @since 1.27
 561          * @param ResourceLoaderContext $context
 562          * @return string|null JSON blob or null if module has no messages
 563          */
 564         protected function getMessageBlob( ResourceLoaderContext $context ) {
 565                 if ( !$this->getMessages() ) {
 566                         // Don't bother consulting MessageBlobStore
 567                         return null;
 568                 }
 569                 // Message blobs may only vary language, not by context keys
 570                 $lang = $context->getLanguage();
 571                 if ( !isset( $this->msgBlobs[$lang] ) ) {
 572                         $this->getLogger()->warning( 'Message blob for {module} should have been preloaded', [
 573                                 'module' => $this->getName(),
 574                         ] );
 575                         $store = $context->getResourceLoader()->getMessageBlobStore();
 576                         $this->msgBlobs[$lang] = $store->getBlob( $this, $lang );
 577                 }
 578                 return $this->msgBlobs[$lang];
 579         }
 580
 581         /**
 582          * Set in-object cache for message blobs.
 583          *
 584          * Used to allow fetching of message blobs in batches. See ResourceLoader::preloadModuleInfo().
 585          *
 586          * @since 1.27
 587          * @param string|null $blob JSON blob or null
 588          * @param string $lang Language code
 589          */
 590         public function setMessageBlob( $blob, $lang ) {
 591                 $this->msgBlobs[$lang] = $blob;
 592         }
 593
 594         /**
 595          * Get headers to send as part of a module web response.
 596          *
 597          * It is not supported to send headers through this method that are
 598          * required to be unique or otherwise sent once in an HTTP response
 599          * because clients may make batch requests for multiple modules (as
 600          * is the default behaviour for ResourceLoader clients).
 601          *
 602          * For exclusive or aggregated headers, see ResourceLoader::sendResponseHeaders().
 603          *
 604          * @since 1.30
 605          * @param ResourceLoaderContext $context
 606          * @return string[] Array of HTTP response headers
 607          */
 608         final public function getHeaders( ResourceLoaderContext $context ) {
 609                 $headers = [];
 610
 611                 $formattedLinks = [];
 612                 foreach ( $this->getPreloadLinks( $context ) as $url => $attribs ) {
 613                         $link = "<{$url}>;rel=preload";
 614                         foreach ( $attribs as $key => $val ) {
 615                                 $link .= ";{$key}={$val}";
 616                         }
 617                         $formattedLinks[] = $link;
 618                 }
 619                 if ( $formattedLinks ) {
 620                         $headers[] = 'Link: ' . implode( ',', $formattedLinks );
 621                 }
 622
 623                 return $headers;
 624         }
 625
 626         /**
 627          * Get a list of resources that web browsers may preload.
 628          *
 629          * Behaviour of rel=preload link is specified at <https://www.w3.org/TR/preload/>.
 630          *
 631          * Use case for ResourceLoader originally part of T164299.
 632          *
 633          * @par Example
 634          * @code
 635          *     protected function getPreloadLinks() {
 636          *         return [
 637          *             'https://example.org/script.js' => [ 'as' => 'script' ],
 638          *             'https://example.org/image.png' => [ 'as' => 'image' ],
 639          *         ];
 640          *     }
 641          * @endcode
 642          *
 643          * @par Example using HiDPI image variants
 644          * @code
 645          *     protected function getPreloadLinks() {
 646          *         return [
 647          *             'https://example.org/logo.png' => [
 648          *                 'as' => 'image',
 649          *                 'media' => 'not all and (min-resolution: 2dppx)',
 650          *             ],
 651          *             'https://example.org/logo@2x.png' => [
 652          *                 'as' => 'image',
 653          *                 'media' => '(min-resolution: 2dppx)',
 654          *             ],
 655          *         ];
 656          *     }
 657          * @endcode
 658          *
 659          * @see ResourceLoaderModule::getHeaders
 660          * @since 1.30
 661          * @param ResourceLoaderContext $context
 662          * @return array Keyed by url, values must be an array containing
 663          *  at least an 'as' key. Optionally a 'media' key as well.
 664          */
 665         protected function getPreloadLinks( ResourceLoaderContext $context ) {
 666                 return [];
 667         }
 668
 669         /**
 670          * Get module-specific LESS variables, if any.
 671          *
 672          * @since 1.27
 673          * @param ResourceLoaderContext $context
 674          * @return array Module-specific LESS variables.
 675          */
 676         protected function getLessVars( ResourceLoaderContext $context ) {
 677                 return [];
 678         }
 679
 680         /**
 681          * Get an array of this module's resources. Ready for serving to the web.
 682          *
 683          * @since 1.26
 684          * @param ResourceLoaderContext $context
 685          * @return array
 686          */
 687         public function getModuleContent( ResourceLoaderContext $context ) {
 688                 $contextHash = $context->getHash();
 689                 // Cache this expensive operation. This calls builds the scripts, styles, and messages
 690                 // content which typically involves filesystem and/or database access.
 691                 if ( !array_key_exists( $contextHash, $this->contents ) ) {
 692                         $this->contents[$contextHash] = $this->buildContent( $context );
 693                 }
 694                 return $this->contents[$contextHash];
 695         }
 696
 697         /**
 698          * Bundle all resources attached to this module into an array.
 699          *
 700          * @since 1.26
 701          * @param ResourceLoaderContext $context
 702          * @return array
 703          */
 704         final protected function buildContent( ResourceLoaderContext $context ) {
 705                 $rl = $context->getResourceLoader();
 706                 $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
 707                 $statStart = microtime( true );
 708
 709                 // This MUST build both scripts and styles, regardless of whether $context->getOnly()
 710                 // is 'scripts' or 'styles' because the result is used by getVersionHash which
 711                 // must be consistent regardless of the 'only' filter on the current request.
 712                 // Also, when introducing new module content resources (e.g. templates, headers),
 713                 // these should only be included in the array when they are non-empty so that
 714                 // existing modules not using them do not get their cache invalidated.
 715                 $content = [];
 716
 717                 // Scripts
 718                 // If we are in debug mode, we'll want to return an array of URLs if possible
 719                 // However, we can't do this if the module doesn't support it.
 720                 // We also can't do this if there is an only= parameter, because we have to give
 721                 // the module a way to return a load.php URL without causing an infinite loop
 722                 if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 723                         $scripts = $this->getScriptURLsForDebug( $context );
 724                 } else {
 725                         $scripts = $this->getScript( $context );
 726                         // Make the script safe to concatenate by making sure there is at least one
 727                         // trailing new line at the end of the content. Previously, this looked for
 728                         // a semi-colon instead, but that breaks concatenation if the semicolon
 729                         // is inside a comment like "// foo();". Instead, simply use a
 730                         // line break as separator which matches JavaScript native logic for implicitly
 731                         // ending statements even if a semi-colon is missing.
 732                         // Bugs: T29054, T162719.
 733                         if ( is_string( $scripts )
 734                                 && strlen( $scripts )
 735                                 && substr( $scripts, -1 ) !== "\n"
 736                         ) {
 737                                 $scripts .= "\n";
 738                         }
 739                 }
 740                 $content['scripts'] = $scripts;
 741
 742                 $styles = [];
 743                 // Don't create empty stylesheets like [ '' => '' ] for modules
 744                 // that don't *have* any stylesheets (T40024).
 745                 $stylePairs = $this->getStyles( $context );
 746                 if ( count( $stylePairs ) ) {
 747                         // If we are in debug mode without &only= set, we'll want to return an array of URLs
 748                         // See comment near shouldIncludeScripts() for more details
 749                         if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 750                                 $styles = [
 751                                         'url' => $this->getStyleURLsForDebug( $context )
 752                                 ];
 753                         } else {
 754                                 // Minify CSS before embedding in mw.loader.implement call
 755                                 // (unless in debug mode)
 756                                 if ( !$context->getDebug() ) {
 757                                         foreach ( $stylePairs as $media => $style ) {
 758                                                 // Can be either a string or an array of strings.
 759                                                 if ( is_array( $style ) ) {
 760                                                         $stylePairs[$media] = [];
 761                                                         foreach ( $style as $cssText ) {
 762                                                                 if ( is_string( $cssText ) ) {
 763                                                                         $stylePairs[$media][] =
 764                                                                                 ResourceLoader::filter( 'minify-css', $cssText );
 765                                                                 }
 766                                                         }
 767                                                 } elseif ( is_string( $style ) ) {
 768                                                         $stylePairs[$media] = ResourceLoader::filter( 'minify-css', $style );
 769                                                 }
 770                                         }
 771                                 }
 772                                 // Wrap styles into @media groups as needed and flatten into a numerical array
 773                                 $styles = [
 774                                         'css' => $rl->makeCombinedStyles( $stylePairs )
 775                                 ];
 776                         }
 777                 }
 778                 $content['styles'] = $styles;
 779
 780                 // Messages
 781                 $blob = $this->getMessageBlob( $context );
 782                 if ( $blob ) {
 783                         $content['messagesBlob'] = $blob;
 784                 }
 785
 786                 $templates = $this->getTemplates();
 787                 if ( $templates ) {
 788                         $content['templates'] = $templates;
 789                 }
 790
 791                 $headers = $this->getHeaders( $context );
 792                 if ( $headers ) {
 793                         $content['headers'] = $headers;
 794                 }
 795
 796                 $statTiming = microtime( true ) - $statStart;
 797                 $statName = strtr( $this->getName(), '.', '_' );
 798                 $stats->timing( "resourceloader_build.all", 1000 * $statTiming );
 799                 $stats->timing( "resourceloader_build.$statName", 1000 * $statTiming );
 800
 801                 return $content;
 802         }
 803
 804         /**
 805          * Get a string identifying the current version of this module in a given context.
 806          *
 807          * Whenever anything happens that changes the module's response (e.g. scripts, styles, and
 808          * messages) this value must change. This value is used to store module responses in cache.
 809          * (Both client-side and server-side.)
 810          *
 811          * It is not recommended to override this directly. Use getDefinitionSummary() instead.
 812          * If overridden, one must call the parent getVersionHash(), append data and re-hash.
 813          *
 814          * This method should be quick because it is frequently run by ResourceLoaderStartUpModule to
 815          * propagate changes to the client and effectively invalidate cache.
 816          *
 817          * @since 1.26
 818          * @param ResourceLoaderContext $context
 819          * @return string Hash (should use ResourceLoader::makeHash)
 820          */
 821         public function getVersionHash( ResourceLoaderContext $context ) {
 822                 // Cache this somewhat expensive operation. Especially because some classes
 823                 // (e.g. startup module) iterate more than once over all modules to get versions.
 824                 $contextHash = $context->getHash();
 825                 if ( !array_key_exists( $contextHash, $this->versionHash ) ) {
 826                         if ( $this->enableModuleContentVersion() ) {
 827                                 // Detect changes directly by hashing the module contents.
 828                                 $str = json_encode( $this->getModuleContent( $context ) );
 829                         } else {
 830                                 // Infer changes based on definition and other metrics
 831                                 $summary = $this->getDefinitionSummary( $context );
 832                                 if ( !isset( $summary['_class'] ) ) {
 833                                         throw new LogicException( 'getDefinitionSummary must call parent method' );
 834                                 }
 835                                 $str = json_encode( $summary );
 836                         }
 837
 838                         $this->versionHash[$contextHash] = ResourceLoader::makeHash( $str );
 839                 }
 840                 return $this->versionHash[$contextHash];
 841         }
 842
 843         /**
 844          * Whether to generate version hash based on module content.
 845          *
 846          * If a module requires database or file system access to build the module
 847          * content, consider disabling this in favour of manually tracking relevant
 848          * aspects in getDefinitionSummary(). See getVersionHash() for how this is used.
 849          *
 850          * @return bool
 851          */
 852         public function enableModuleContentVersion() {
 853                 return false;
 854         }
 855
 856         /**
 857          * Get the definition summary for this module.
 858          *
 859          * This is the method subclasses are recommended to use to track values in their
 860          * version hash. Call this in getVersionHash() and pass it to e.g. json_encode.
 861          *
 862          * Subclasses must call the parent getDefinitionSummary() and build on that.
 863          * It is recommended that each subclass appends its own new array. This prevents
 864          * clashes or accidental overwrites of existing keys and gives each subclass
 865          * its own scope for simple array keys.
 866          *
 867          * @code
 868          *     $summary = parent::getDefinitionSummary( $context );
 869          *     $summary[] = [
 870          *         'foo' => 123,
 871          *         'bar' => 'quux',
 872          *     ];
 873          *     return $summary;
 874          * @endcode
 875          *
 876          * Return an array containing values from all significant properties of this
 877          * module's definition.
 878          *
 879          * Be careful not to normalise too much. Especially preserve the order of things
 880          * that carry significance in getScript and getStyles (T39812).
 881          *
 882          * Avoid including things that are insiginificant (e.g. order of message keys is
 883          * insignificant and should be sorted to avoid unnecessary cache invalidation).
 884          *
 885          * This data structure must exclusively contain arrays and scalars as values (avoid
 886          * object instances) to allow simple serialisation using json_encode.
 887          *
 888          * If modules have a hash or timestamp from another source, that may be incuded as-is.
 889          *
 890          * A number of utility methods are available to help you gather data. These are not
 891          * called by default and must be included by the subclass' getDefinitionSummary().
 892          *
 893          * - getMessageBlob()
 894          *
 895          * @since 1.23
 896          * @param ResourceLoaderContext $context
 897          * @return array|null
 898          */
 899         public function getDefinitionSummary( ResourceLoaderContext $context ) {
 900                 return [
 901                         '_class' => static::class,
 902                         // Make sure that when filter cache for minification is invalidated,
 903                         // we also change the HTTP urls and mw.loader.store keys (T176884).
 904                         '_cacheVersion' => ResourceLoader::CACHE_VERSION,
 905                 ];
 906         }
 907
 908         /**
 909          * Check whether this module is known to be empty. If a child class
 910          * has an easy and cheap way to determine that this module is
 911          * definitely going to be empty, it should override this method to
 912          * return true in that case. Callers may optimize the request for this
 913          * module away if this function returns true.
 914          * @param ResourceLoaderContext $context
 915          * @return bool
 916          */
 917         public function isKnownEmpty( ResourceLoaderContext $context ) {
 918                 return false;
 919         }
 920
 921         /**
 922          * Check whether this module should be embeded rather than linked
 923          *
 924          * Modules returning true here will be embedded rather than loaded by
 925          * ResourceLoaderClientHtml.
 926          *
 927          * @since 1.30
 928          * @param ResourceLoaderContext $context
 929          * @return bool
 930          */
 931         public function shouldEmbedModule( ResourceLoaderContext $context ) {
 932                 return $this->getGroup() === 'private';
 933         }
 934
 935         /** @var JSParser Lazy-initialized; use self::javaScriptParser() */
 936         private static $jsParser;
 937         private static $parseCacheVersion = 1;
 938
 939         /**
 940          * Validate a given script file; if valid returns the original source.
 941          * If invalid, returns replacement JS source that throws an exception.
 942          *
 943          * @param string $fileName
 944          * @param string $contents
 945          * @return string JS with the original, or a replacement error
 946          */
 947         protected function validateScriptFile( $fileName, $contents ) {
 948                 if ( !$this->getConfig()->get( 'ResourceLoaderValidateJS' ) ) {
 949                         return $contents;
 950                 }
 951                 $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
 952                 return $cache->getWithSetCallback(
 953                         $cache->makeGlobalKey(
 954                                 'resourceloader-jsparse',
 955                                 self::$parseCacheVersion,
 956                                 md5( $contents ),
 957                                 $fileName
 958                         ),
 959                         $cache::TTL_WEEK,
 960                         function () use ( $contents, $fileName ) {
 961                                 $parser = self::javaScriptParser();
 962                                 $err = null;
 963                                 try {
 964                                         Wikimedia\suppressWarnings();
 965                                         $parser->parse( $contents, $fileName, 1 );
 966                                 } catch ( Exception $e ) {
 967                                         $err = $e;
 968                                 } finally {
 969                                         Wikimedia\restoreWarnings();
 970                                 }
 971                                 if ( $err ) {
 972                                         // Send the error to the browser console client-side.
 973                                         // By returning this as replacement for the actual script,
 974                                         // we ensure modules are safe to load in a batch request,
 975                                         // without causing other unrelated modules to break.
 976                                         return 'mw.log.error(' .
 977                                                 Xml::encodeJsVar( 'JavaScript parse error: ' . $err->getMessage() ) .
 978                                                 ');';
 979                                 }
 980                                 return $contents;
 981                         }
 982                 );
 983         }
 984
 985         /**
 986          * @return JSParser
 987          */
 988         protected static function javaScriptParser() {
 989                 if ( !self::$jsParser ) {
 990                         self::$jsParser = new JSParser();
 991                 }
 992                 return self::$jsParser;
 993         }
 994
 995         /**
 996          * Safe version of filemtime(), which doesn't throw a PHP warning if the file doesn't exist.
 997          * Defaults to 1.
 998          *
 999          * @param string $filePath File path
1000          * @return int UNIX timestamp
1001          */
1002         protected static function safeFilemtime( $filePath ) {
1003                 Wikimedia\suppressWarnings();
1004                 $mtime = filemtime( $filePath ) ?: 1;
1005                 Wikimedia\restoreWarnings();
1006                 return $mtime;
1007         }
1008
1009         /**
1010          * Compute a non-cryptographic string hash of a file's contents.
1011          * If the file does not exist or cannot be read, returns an empty string.
1012          *
1013          * @since 1.26 Uses MD4 instead of SHA1.
1014          * @param string $filePath File path
1015          * @return string Hash
1016          */
1017         protected static function safeFileHash( $filePath ) {
1018                 return FileContentsHasher::getFileContentsHash( $filePath );
1019         }
1020
1021         /**
1022          * Get vary string.
1023          *
1024          * @internal For internal use only.
1025          * @param ResourceLoaderContext $context
1026          * @return string Vary string
1027          */
1028         public static function getVary( ResourceLoaderContext $context ) {
1029                 return implode( '|', [
1030                         $context->getSkin(),
1031                         $context->getLanguage(),
1032                 ] );
1033         }
1034 }