Implement extension registration from an extension.json file

[mediawiki.git] / includes / resourceloader / ResourceLoaderModule.php

<?php
/**
 * Abstraction for resource loader modules.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @author Trevor Parscal
 * @author Roan Kattouw
 */

/**
 * Abstraction for resource loader modules, with name registration and maxage functionality.
 */
abstract class ResourceLoaderModule {
        # Type of resource
        const TYPE_SCRIPTS = 'scripts';
        const TYPE_STYLES = 'styles';
        const TYPE_MESSAGES = 'messages';
        const TYPE_COMBINED = 'combined';

        # sitewide core module like a skin file or jQuery component
        const ORIGIN_CORE_SITEWIDE = 1;

        # per-user module generated by the software
        const ORIGIN_CORE_INDIVIDUAL = 2;

        # sitewide module generated from user-editable files, like MediaWiki:Common.js, or
        # modules accessible to multiple users, such as those generated by the Gadgets extension.
        const ORIGIN_USER_SITEWIDE = 3;

        # per-user module generated from user-editable files, like User:Me/vector.js
        const ORIGIN_USER_INDIVIDUAL = 4;

        # an access constant; make sure this is kept as the largest number in this group
        const ORIGIN_ALL = 10;

        # script and style modules form a hierarchy of trustworthiness, with core modules like
        # skins and jQuery as most trustworthy, and user scripts as least trustworthy.  We can
        # limit the types of scripts and styles we allow to load on, say, sensitive special
        # pages like Special:UserLogin and Special:Preferences
        protected $origin = self::ORIGIN_CORE_SITEWIDE;

        /* Protected Members */

        protected $name = null;
        protected $targets = array( 'desktop' );

        // In-object cache for file dependencies
        protected $fileDeps = array();
        // In-object cache for message blob mtime
        protected $msgBlobMtime = array();

        /**
         * @var Config
         */
        protected $config;

        /* Methods */

        /**
         * Get this module's name. This is set when the module is registered
         * with ResourceLoader::register()
         *
         * @return string|null Name (string) or null if no name was set
         */
        public function getName() {
                return $this->name;
        }

        /**
         * Set this module's name. This is called by ResourceLoader::register()
         * when registering the module. Other code should not call this.
         *
         * @param string $name Name
         */
        public function setName( $name ) {
                $this->name = $name;
        }

        /**
         * Get this module's origin. This is set when the module is registered
         * with ResourceLoader::register()
         *
         * @return int ResourceLoaderModule class constant, the subclass default
         *     if not set manually
         */
        public function getOrigin() {
                return $this->origin;
        }

        /**
         * Set this module's origin. This is called by ResourceLoader::register()
         * when registering the module. Other code should not call this.
         *
         * @param int $origin Origin
         */
        public function setOrigin( $origin ) {
                $this->origin = $origin;
        }

        /**
         * @param ResourceLoaderContext $context
         * @return bool
         */
        public function getFlip( $context ) {
                global $wgContLang;

                return $wgContLang->getDir() !== $context->getDirection();
        }

        /**
         * Get all JS for this module for a given language and skin.
         * Includes all relevant JS except loader scripts.
         *
         * @param ResourceLoaderContext $context
         * @return string JavaScript code
         */
        public function getScript( ResourceLoaderContext $context ) {
                // Stub, override expected
                return '';
        }

        /**
         * Takes named templates by the module and returns an array mapping.
         *
         * @return array of templates mapping template alias to content
         */
        public function getTemplates() {
                // Stub, override expected.
                return array();
        }

        /**
         * @return Config
         * @since 1.24
         */
        public function getConfig() {
                if ( $this->config === null ) {
                        // Ugh, fall back to default
                        $this->config = ConfigFactory::getDefaultInstance()->makeConfig( 'main' );
                }

                return $this->config;
        }

        /**
         * @param Config $config
         * @since 1.24
         */
        public function setConfig( Config $config ) {
                $this->config = $config;
        }

        /**
         * Get the URL or URLs to load for this module's JS in debug mode.
         * The default behavior is to return a load.php?only=scripts URL for
         * the module, but file-based modules will want to override this to
         * load the files directly.
         *
         * This function is called only when 1) we're in debug mode, 2) there
         * is no only= parameter and 3) supportsURLLoading() returns true.
         * #2 is important to prevent an infinite loop, therefore this function
         * MUST return either an only= URL or a non-load.php URL.
         *
         * @param ResourceLoaderContext $context
         * @return array Array of URLs
         */
        public function getScriptURLsForDebug( ResourceLoaderContext $context ) {
                $resourceLoader = $context->getResourceLoader();
                $derivative = new DerivativeResourceLoaderContext( $context );
                $derivative->setModules( array( $this->getName() ) );
                $derivative->setOnly( 'scripts' );
                $derivative->setDebug( true );

                $url = $resourceLoader->createLoaderURL(
                        $this->getSource(),
                        $derivative
                );

                return array( $url );
        }

        /**
         * Whether this module supports URL loading. If this function returns false,
         * getScript() will be used even in cases (debug mode, no only param) where
         * getScriptURLsForDebug() would normally be used instead.
         * @return bool
         */
        public function supportsURLLoading() {
                return true;
        }

        /**
         * Get all CSS for this module for a given skin.
         *
         * @param ResourceLoaderContext $context
         * @return array List of CSS strings or array of CSS strings keyed by media type.
         *  like array( 'screen' => '.foo { width: 0 }' );
         *  or array( 'screen' => array( '.foo { width: 0 }' ) );
         */
        public function getStyles( ResourceLoaderContext $context ) {
                // Stub, override expected
                return array();
        }

        /**
         * Get the URL or URLs to load for this module's CSS in debug mode.
         * The default behavior is to return a load.php?only=styles URL for
         * the module, but file-based modules will want to override this to
         * load the files directly. See also getScriptURLsForDebug()
         *
         * @param ResourceLoaderContext $context
         * @return array Array( mediaType => array( URL1, URL2, ... ), ... )
         */
        public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
                $resourceLoader = $context->getResourceLoader();
                $derivative = new DerivativeResourceLoaderContext( $context );
                $derivative->setModules( array( $this->getName() ) );
                $derivative->setOnly( 'styles' );
                $derivative->setDebug( true );

                $url = $resourceLoader->createLoaderURL(
                        $this->getSource(),
                        $derivative
                );

                return array( 'all' => array( $url ) );
        }

        /**
         * Get the messages needed for this module.
         *
         * To get a JSON blob with messages, use MessageBlobStore::get()
         *
         * @return array List of message keys. Keys may occur more than once
         */
        public function getMessages() {
                // Stub, override expected
                return array();
        }

        /**
         * Get the group this module is in.
         *
         * @return string Group name
         */
        public function getGroup() {
                // Stub, override expected
                return null;
        }

        /**
         * Get the origin of this module. Should only be overridden for foreign modules.
         *
         * @return string Origin name, 'local' for local modules
         */
        public function getSource() {
                // Stub, override expected
                return 'local';
        }

        /**
         * Where on the HTML page should this module's JS be loaded?
         *  - 'top': in the "<head>"
         *  - 'bottom': at the bottom of the "<body>"
         *
         * @return string
         */
        public function getPosition() {
                return 'bottom';
        }

        /**
         * Whether this module's JS expects to work without the client-side ResourceLoader module.
         * Returning true from this function will prevent mw.loader.state() call from being
         * appended to the bottom of the script.
         *
         * @return bool
         */
        public function isRaw() {
                return false;
        }

        /**
         * Get the loader JS for this module, if set.
         *
         * @return mixed JavaScript loader code as a string or boolean false if no custom loader set
         */
        public function getLoaderScript() {
                // Stub, override expected
                return false;
        }

        /**
         * Get a list of modules this module depends on.
         *
         * Dependency information is taken into account when loading a module
         * on the client side.
         *
         * To add dependencies dynamically on the client side, use a custom
         * loader script, see getLoaderScript()
         * @return array List of module names as strings
         */
        public function getDependencies() {
                // Stub, override expected
                return array();
        }

        /**
         * Get target(s) for the module, eg ['desktop'] or ['desktop', 'mobile']
         *
         * @return array Array of strings
         */
        public function getTargets() {
                return $this->targets;
        }

        /**
         * Get the skip function.
         *
         * Modules that provide fallback functionality can provide a "skip function". This
         * function, if provided, will be passed along to the module registry on the client.
         * When this module is loaded (either directly or as a dependency of another module),
         * then this function is executed first. If the function returns true, the module will
         * instantly be considered "ready" without requesting the associated module resources.
         *
         * The value returned here must be valid javascript for execution in a private function.
         * It must not contain the "function () {" and "}" wrapper though.
         *
         * @return string|null A JavaScript function body returning a boolean value, or null
         */
        public function getSkipFunction() {
                return null;
        }

        /**
         * Get the files this module depends on indirectly for a given skin.
         * Currently these are only image files referenced by the module's CSS.
         *
         * @param string $skin Skin name
         * @return array List of files
         */
        public function getFileDependencies( $skin ) {
                // Try in-object cache first
                if ( isset( $this->fileDeps[$skin] ) ) {
                        return $this->fileDeps[$skin];
                }

                $dbr = wfGetDB( DB_SLAVE );
                $deps = $dbr->selectField( 'module_deps', 'md_deps', array(
                                'md_module' => $this->getName(),
                                'md_skin' => $skin,
                        ), __METHOD__
                );
                if ( !is_null( $deps ) ) {
                        $this->fileDeps[$skin] = (array)FormatJson::decode( $deps, true );
                } else {
                        $this->fileDeps[$skin] = array();
                }
                return $this->fileDeps[$skin];
        }

        /**
         * Set preloaded file dependency information. Used so we can load this
         * information for all modules at once.
         * @param string $skin Skin name
         * @param array $deps Array of file names
         */
        public function setFileDependencies( $skin, $deps ) {
                $this->fileDeps[$skin] = $deps;
        }

        /**
         * Get the last modification timestamp of the message blob for this
         * module in a given language.
         * @param string $lang Language code
         * @return int UNIX timestamp
         */
        public function getMsgBlobMtime( $lang ) {
                if ( !isset( $this->msgBlobMtime[$lang] ) ) {
                        if ( !count( $this->getMessages() ) ) {
                                return 1;
                        }

                        $dbr = wfGetDB( DB_SLAVE );
                        $msgBlobMtime = $dbr->selectField( 'msg_resource', 'mr_timestamp', array(
                                        'mr_resource' => $this->getName(),
                                        'mr_lang' => $lang
                                ), __METHOD__
                        );
                        // If no blob was found, but the module does have messages, that means we need
                        // to regenerate it. Return NOW
                        if ( $msgBlobMtime === false ) {
                                $msgBlobMtime = wfTimestampNow();
                        }
                        $this->msgBlobMtime[$lang] = wfTimestamp( TS_UNIX, $msgBlobMtime );
                }
                return $this->msgBlobMtime[$lang];
        }

        /**
         * Set a preloaded message blob last modification timestamp. Used so we
         * can load this information for all modules at once.
         * @param string $lang Language code
         * @param int $mtime UNIX timestamp
         */
        public function setMsgBlobMtime( $lang, $mtime ) {
                $this->msgBlobMtime[$lang] = $mtime;
        }

        /* Abstract Methods */

        /**
         * Get this module's last modification timestamp for a given
         * combination of language, skin and debug mode flag. This is typically
         * the highest of each of the relevant components' modification
         * timestamps. Whenever anything happens that changes the module's
         * contents for these parameters, the mtime should increase.
         *
         * NOTE: The mtime of the module's messages is NOT automatically included.
         * If you want this to happen, you'll need to call getMsgBlobMtime()
         * yourself and take its result into consideration.
         *
         * NOTE: The mtime of the module's hash is NOT automatically included.
         * If your module provides a getModifiedHash() method, you'll need to call getHashMtime()
         * yourself and take its result into consideration.
         *
         * @param ResourceLoaderContext $context Context object
         * @return int UNIX timestamp
         */
        public function getModifiedTime( ResourceLoaderContext $context ) {
                return 1;
        }

        /**
         * Helper method for calculating when the module's hash (if it has one) changed.
         *
         * @param ResourceLoaderContext $context
         * @return int UNIX timestamp
         */
        public function getHashMtime( ResourceLoaderContext $context ) {
                $hash = $this->getModifiedHash( $context );
                if ( !is_string( $hash ) ) {
                        return 1;
                }

                $cache = wfGetCache( CACHE_ANYTHING );
                $key = wfMemcKey( 'resourceloader', 'modulemodifiedhash', $this->getName(), $hash );

                $data = $cache->get( $key );
                if ( is_array( $data ) && $data['hash'] === $hash ) {
                        // Hash is still the same, re-use the timestamp of when we first saw this hash.
                        return $data['timestamp'];
                }

                $timestamp = time();
                $cache->set( $key, array(
                        'hash' => $hash,
                        'timestamp' => $timestamp,
                ) );

                return $timestamp;
        }

        /**
         * Get the hash for whatever this module may contain.
         *
         * This is the method subclasses should implement if they want to make
         * use of getHashMTime() inside getModifiedTime().
         *
         * @param ResourceLoaderContext $context
         * @return string|null Hash
         */
        public function getModifiedHash( ResourceLoaderContext $context ) {
                return null;
        }

        /**
         * Helper method for calculating when this module's definition summary was last changed.
         *
         * @since 1.23
         *
         * @param ResourceLoaderContext $context
         * @return int UNIX timestamp
         */
        public function getDefinitionMtime( ResourceLoaderContext $context ) {
                $summary = $this->getDefinitionSummary( $context );
                if ( $summary === null ) {
                        return 1;
                }

                $hash = md5( json_encode( $summary ) );

                $cache = wfGetCache( CACHE_ANYTHING );

                // Embed the hash itself in the cache key. This allows for a few nifty things:
                // - During deployment, servers with old and new versions of the code communicating
                //   with the same memcached will not override the same key repeatedly increasing
                //   the timestamp.
                // - In case of the definition changing and then changing back in a short period of time
                //   (e.g. in case of a revert or a corrupt server) the old timestamp and client-side cache
                //   url will be re-used.
                // - If different context-combinations (e.g. same skin, same language or some combination
                //   thereof) result in the same definition, they will use the same hash and timestamp.
                $key = wfMemcKey( 'resourceloader', 'moduledefinition', $this->getName(), $hash );

                $data = $cache->get( $key );
                if ( is_int( $data ) && $data > 0 ) {
                        // We've seen this hash before, re-use the timestamp of when we first saw it.
                        return $data;
                }

                wfDebugLog( 'resourceloader', __METHOD__ . ": New definition hash for module "
                        . "{$this->getName()} in context {$context->getHash()}: $hash." );

                $timestamp = time();
                $cache->set( $key, $timestamp );

                return $timestamp;
        }

        /**
         * Get the definition summary for this module.
         *
         * This is the method subclasses should implement if they want to make
         * use of getDefinitionMTime() inside getModifiedTime().
         *
         * Return an array containing values from all significant properties of this
         * module's definition. Be sure to include things that are explicitly ordered,
         * in their actaul order (bug 37812).
         *
         * Avoid including things that are insiginificant (e.g. order of message
         * keys is insignificant and should be sorted to avoid unnecessary cache
         * invalidation).
         *
         * Avoid including things already considered by other methods inside your
         * getModifiedTime(), such as file mtime timestamps.
         *
         * Serialisation is done using json_encode, which means object state is not
         * taken into account when building the hash. This data structure must only
         * contain arrays and scalars as values (avoid object instances) which means
         * it requires abstraction.
         *
         * @since 1.23
         *
         * @param ResourceLoaderContext $context
         * @return array|null
         */
        public function getDefinitionSummary( ResourceLoaderContext $context ) {
                return array(
                        'class' => get_class( $this ),
                );
        }

        /**
         * Check whether this module is known to be empty. If a child class
         * has an easy and cheap way to determine that this module is
         * definitely going to be empty, it should override this method to
         * return true in that case. Callers may optimize the request for this
         * module away if this function returns true.
         * @param ResourceLoaderContext $context
         * @return bool
         */
        public function isKnownEmpty( ResourceLoaderContext $context ) {
                return false;
        }

        /** @var JSParser Lazy-initialized; use self::javaScriptParser() */
        private static $jsParser;
        private static $parseCacheVersion = 1;

        /**
         * Validate a given script file; if valid returns the original source.
         * If invalid, returns replacement JS source that throws an exception.
         *
         * @param string $fileName
         * @param string $contents
         * @return string JS with the original, or a replacement error
         */
        protected function validateScriptFile( $fileName, $contents ) {
                if ( $this->getConfig()->get( 'ResourceLoaderValidateJS' ) ) {
                        // Try for cache hit
                        // Use CACHE_ANYTHING since filtering is very slow compared to DB queries
                        $key = wfMemcKey( 'resourceloader', 'jsparse', self::$parseCacheVersion, md5( $contents ) );
                        $cache = wfGetCache( CACHE_ANYTHING );
                        $cacheEntry = $cache->get( $key );
                        if ( is_string( $cacheEntry ) ) {
                                return $cacheEntry;
                        }

                        $parser = self::javaScriptParser();
                        try {
                                $parser->parse( $contents, $fileName, 1 );
                                $result = $contents;
                        } catch ( Exception $e ) {
                                // We'll save this to cache to avoid having to validate broken JS over and over...
                                $err = $e->getMessage();
                                $result = "throw new Error(" . Xml::encodeJsVar( "JavaScript parse error: $err" ) . ");";
                        }

                        $cache->set( $key, $result );
                        return $result;
                } else {
                        return $contents;
                }
        }

        /**
         * @return JSParser
         */
        protected static function javaScriptParser() {
                if ( !self::$jsParser ) {
                        self::$jsParser = new JSParser();
                }
                return self::$jsParser;
        }

        /**
         * Safe version of filemtime(), which doesn't throw a PHP warning if the file doesn't exist
         * but returns 1 instead.
         * @param string $filename File name
         * @return int UNIX timestamp
         */
        protected static function safeFilemtime( $filename ) {
                if ( !file_exists( $filename ) ) {
                        return 1;
                }
                return filemtime( $filename );
        }
}