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[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;

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

        /* Methods */

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

        /**
         * Set this module's name. This is called by ResourceLodaer::register()
         * when registering the module. Other code should not call this.
         *
         * @param $name String: 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 manuall
         */
        public function getOrigin() {
                return $this->origin;
        }

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

        /**
         * @param $context ResourceLoaderContext
         * @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 $context ResourceLoaderContext: Context object
         * @return String: JavaScript code
         */
        public function getScript( ResourceLoaderContext $context ) {
                // Stub, override expected
                return '';
        }

        /**
         * 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 $context ResourceLoaderContext: Context object
         * @return Array of URLs
         */
        public function getScriptURLsForDebug( ResourceLoaderContext $context ) {
                $url = ResourceLoader::makeLoaderURL(
                        array( $this->getName() ),
                        $context->getLanguage(),
                        $context->getSkin(),
                        $context->getUser(),
                        $context->getVersion(),
                        true, // debug
                        'scripts', // only
                        $context->getRequest()->getBool( 'printable' ),
                        $context->getRequest()->getBool( 'handheld' )
                );
                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 $context ResourceLoaderContext: Context object
         * @return Array: List of CSS strings keyed by media type
         */
        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 $context ResourceLoaderContext: Context object
         * @return Array: array( mediaType => array( URL1, URL2, ... ), ... )
         */
        public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
                $url = ResourceLoader::makeLoaderURL(
                        array( $this->getName() ),
                        $context->getLanguage(),
                        $context->getSkin(),
                        $context->getUser(),
                        $context->getVersion(),
                        true, // debug
                        'styles', // only
                        $context->getRequest()->getBool( 'printable' ),
                        $context->getRequest()->getBool( 'handheld' )
                );
                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. When adding a module on the server side,
         * dependency information is NOT taken into account and YOU are
         * responsible for adding dependent modules as well. If you don't do
         * this, the client side loader will send a second request back to the
         * server to fetch the missing modules, which kind of defeats the
         * purpose of the resource loader.
         *
         * 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 the files this module depends on indirectly for a given skin.
         * Currently these are only image files referenced by the module's CSS.
         *
         * @param $skin String: 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 $skin String: Skin name
         * @param $deps Array: 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 $lang String: Language code
         * @return Integer: UNIX timestamp, or 0 if the module doesn't have messages
         */
        public function getMsgBlobMtime( $lang ) {
                if ( !isset( $this->msgBlobMtime[$lang] ) ) {
                        if ( !count( $this->getMessages() ) )
                                return 0;

                        $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 $lang String: Language code
         * @param $mtime Integer: UNIX timestamp or 0 if there is no such blob
         */
        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.
         * 
         * @param $context ResourceLoaderContext: Context object
         * @return Integer: UNIX timestamp
         */
        public function getModifiedTime( ResourceLoaderContext $context ) {
                // 0 would mean now
                return 1;
        }

        /**
         * 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 $context ResourceLoaderContext: Context object
         * @return Boolean
         */
        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 ) {
                global $wgResourceLoaderValidateJS;
                if ( $wgResourceLoaderValidateJS ) {
                        // 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;
        }

}