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