wikimedia/mediawiki-core

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includes/specialpage/SpecialPage.php

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<?php
/**
 * Parent class for all special pages.
 *
 * 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
 * @ingroup SpecialPage
 */

namespace MediaWiki\SpecialPage;

use ErrorPageError;
use Language;
use MediaWiki\Auth\AuthManager;
use MediaWiki\Config\Config;
use MediaWiki\Context\IContextSource;
use MediaWiki\Context\RequestContext;
use MediaWiki\HookContainer\HookContainer;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\Language\RawMessage;
use MediaWiki\Linker\LinkRenderer;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Message\Message;
use MediaWiki\Navigation\PagerNavigationBuilder;
use MediaWiki\Output\OutputPage;
use MediaWiki\Permissions\Authority;
use MediaWiki\Permissions\PermissionStatus;
use MediaWiki\Request\WebRequest;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleValue;
use MediaWiki\User\User;
use MessageLocalizer;
use MessageSpecifier;
use MWCryptRand;
use PermissionsError;
use ReadOnlyError;
use SearchEngineFactory;
use Skin;
use UserNotLoggedIn;

/**
 * Parent class for all special pages.
 *
 * Includes some static functions for handling the special page list deprecated
 * in favor of SpecialPageFactory.
 *
 * @stable to extend
 *
 * @ingroup SpecialPage
 */
class SpecialPage implements MessageLocalizer {
    /**
     * @var string The canonical name of this special page
     * Also used as the message key for the default <h1> heading,
     * @see getDescription()
     */
    protected $mName;

    /** @var string The local name of this special page */
    private $mLocalName;

    /**
     * @var string Minimum user level required to access this page, or "" for anyone.
     * Also used to categorise the pages in Special:Specialpages
     */
    protected $mRestriction;

    /** @var bool Listed in Special:Specialpages? */
    private $mListed;

    /** @var bool Whether or not this special page is being included from an article */
    protected $mIncluding;

    /** @var bool Whether the special page can be included in an article */
    protected $mIncludable;

    /**
     * Current request context
     * @var IContextSource
     */
    protected $mContext;

    /** @var Language|null */
    private $contentLanguage;

    /**
     * @var LinkRenderer|null
     */
    private $linkRenderer = null;

    /** @var HookContainer|null */
    private $hookContainer;
    /** @var HookRunner|null */
    private $hookRunner;

    /** @var AuthManager|null */
    private $authManager = null;

    /** @var SpecialPageFactory */
    private $specialPageFactory;

    /**
     * Get the users preferred search page.
     *
     * It will fall back to Special:Search if the preference points to a page
     * that doesn't exist or is not defined.
     *
     * @since 1.38
     * @param User $user Search page can be customized by user preference.
     * @return Title
     */
    public static function newSearchPage( User $user ) {
        // Try user preference first
        $userOptionsManager = MediaWikiServices::getInstance()->getUserOptionsManager();
        $title = $userOptionsManager->getOption( $user, 'search-special-page' );
        if ( $title ) {
            $page = self::getTitleFor( $title );
            $factory = MediaWikiServices::getInstance()->getSpecialPageFactory();
            if ( $factory->exists( $page->getText() ) ) {
                return $page;
            }
        }
        return self::getTitleFor( 'Search' );
    }

    /**
     * Get a localised Title object for a specified special page name
     * If you don't need a full Title object, consider using TitleValue through
     * getTitleValueFor() below.
     *
     * @since 1.9
     * @since 1.21 $fragment parameter added
     *
     * @param string $name
     * @param string|false|null $subpage Subpage string, or false/null to not use a subpage
     * @param string $fragment The link fragment (after the "#")
     * @return Title
     */
    public static function getTitleFor( $name, $subpage = false, $fragment = '' ) {
        return Title::newFromLinkTarget(
            self::getTitleValueFor( $name, $subpage, $fragment )
        );
    }

    /**
     * Get a localised TitleValue object for a specified special page name
     *
     * @since 1.28
     * @param string $name
     * @param string|false|null $subpage Subpage string, or false/null to not use a subpage
     * @param string $fragment The link fragment (after the "#")
     * @return TitleValue
     */
    public static function getTitleValueFor( $name, $subpage = false, $fragment = '' ) {
        $name = MediaWikiServices::getInstance()->getSpecialPageFactory()->
            getLocalNameFor( $name, $subpage );

        return new TitleValue( NS_SPECIAL, $name, $fragment );
    }

    /**
     * Get a localised Title object for a page name with a possibly unvalidated subpage
     *
     * @param string $name
     * @param string|false $subpage Subpage string, or false to not use a subpage
     * @return Title|null Title object or null if the page doesn't exist
     */
    public static function getSafeTitleFor( $name, $subpage = false ) {
        $name = MediaWikiServices::getInstance()->getSpecialPageFactory()->
            getLocalNameFor( $name, $subpage );
        if ( $name ) {
            return Title::makeTitleSafe( NS_SPECIAL, $name );
        } else {
            return null;
        }
    }

    /**
     * Default constructor for special pages
     * Derivative classes should call this from their constructor
     *     Note that if the user does not have the required level, an error message will
     *     be displayed by the default execute() method, without the global function ever
     *     being called.
     *
     *     If you override execute(), you can recover the default behavior with userCanExecute()
     *     and displayRestrictionError()
     *
     * @stable to call
     *
     * @param string $name Name of the special page, as seen in links and URLs
     * @param string $restriction User right required, e.g. "block" or "delete"
     * @param bool $listed Whether the page is listed in Special:Specialpages
     * @param callable|bool $function Unused
     * @param string $file Unused
     * @param bool $includable Whether the page can be included in normal pages
     */
    public function __construct(
        $name = '', $restriction = '', $listed = true,
        $function = false, $file = '', $includable = false
    ) {
        $this->mName = $name;
        $this->mRestriction = $restriction;
        $this->mListed = $listed;
        $this->mIncludable = $includable;
    }

    /**
     * Get the canonical, unlocalized name of this special page without namespace.
     * @return string
     */
    public function getName() {
        return $this->mName;
    }

    /**
     * Get the permission that a user must have to execute this page
     * @return string
     */
    public function getRestriction() {
        return $this->mRestriction;
    }

    // @todo FIXME: Decide which syntax to use for this, and stick to it

    /**
     * Whether this special page is listed in Special:SpecialPages
     * @stable to override
     * @since 1.3 (r3583)
     * @return bool
     */
    public function isListed() {
        return $this->mListed;
    }

    /**
     * Whether it's allowed to transclude the special page via {{Special:Foo/params}}
     * @stable to override
     * @return bool
     */
    public function isIncludable() {
        return $this->mIncludable;
    }

    /**
     * How long to cache page when it is being included.
     *
     * @note If cache time is not 0, then the current user becomes an anon
     *   if you want to do any per-user customizations, than this method
     *   must be overridden to return 0.
     * @since 1.26
     * @stable to override
     * @return int Time in seconds, 0 to disable caching altogether,
     *  false to use the parent page's cache settings
     */
    public function maxIncludeCacheTime() {
        return $this->getConfig()->get( MainConfigNames::MiserMode ) ? $this->getCacheTTL() : 0;
    }

    /**
     * @stable to override
     * @return int Seconds that this page can be cached
     */
    protected function getCacheTTL() {
        return 60 * 60;
    }

    /**
     * Whether the special page is being evaluated via transclusion
     * @param bool|null $x
     * @return bool
     */
    public function including( $x = null ) {
        return wfSetVar( $this->mIncluding, $x );
    }

    /**
     * Get the localised name of the special page
     * @stable to override
     * @return string
     */
    public function getLocalName() {
        if ( !isset( $this->mLocalName ) ) {
            $this->mLocalName = $this->getSpecialPageFactory()->getLocalNameFor( $this->mName );
        }

        return $this->mLocalName;
    }

    /**
     * Is this page expensive (for some definition of expensive)?
     * Expensive pages are disabled or cached in miser mode.  Originally used
     * (and still overridden) by QueryPage and subclasses, moved here so that
     * Special:SpecialPages can safely call it for all special pages.
     *
     * @stable to override
     * @return bool
     */
    public function isExpensive() {
        return false;
    }

    /**
     * Is this page cached?
     * Expensive pages are cached or disabled in miser mode.
     * Used by QueryPage and subclasses, moved here so that
     * Special:SpecialPages can safely call it for all special pages.
     *
     * @stable to override
     * @return bool
     * @since 1.21
     */
    public function isCached() {
        return false;
    }

    /**
     * Can be overridden by subclasses with more complicated permissions
     * schemes.
     *
     * @stable to override
     * @return bool Should the page be displayed with the restricted-access
     *   pages?
     */
    public function isRestricted() {
        // DWIM: If anons can do something, then it is not restricted
        return $this->mRestriction != '' && !MediaWikiServices::getInstance()
            ->getGroupPermissionsLookup()
            ->groupHasPermission( '*', $this->mRestriction );
    }

    /**
     * Checks if the given user (identified by an object) can execute this
     * special page (as defined by $mRestriction).  Can be overridden by sub-
     * classes with more complicated permissions schemes.
     *
     * @stable to override
     * @param User $user The user to check
     * @return bool Does the user have permission to view the page?
     */
    public function userCanExecute( User $user ) {
        return MediaWikiServices::getInstance()
            ->getPermissionManager()
            ->userHasRight( $user, $this->mRestriction );
    }

    /**
     * Utility function for authorizing an action to be performed by the special
     * page. User blocks and rate limits are enforced implicitly.
     *
     * @see Authority::authorizeAction.
     *
     * @param ?string $action If not given, the action returned by
     *        getRestriction() will be used.
     *
     * @return PermissionStatus
     */
    protected function authorizeAction( ?string $action = null ): PermissionStatus {
        $action ??= $this->getRestriction();

        if ( !$action ) {
            return PermissionStatus::newGood();
        }

        $status = PermissionStatus::newEmpty();
        $this->getAuthority()->authorizeAction( $action, $status );
        return $status;
    }

    /**
     * Output an error message telling the user what access level they have to have
     * @stable to override
     * @throws PermissionsError
     * @return never
     */
    protected function displayRestrictionError() {
        throw new PermissionsError( $this->mRestriction );
    }

    /**
     * Checks if userCanExecute, and if not throws a PermissionsError
     *
     * @stable to override
     * @since 1.19
     * @return void
     * @throws PermissionsError
     */
    public function checkPermissions() {
        if ( !$this->userCanExecute( $this->getUser() ) ) {
            $this->displayRestrictionError();
        }
    }

    /**
     * If the wiki is currently in readonly mode, throws a ReadOnlyError
     *
     * @since 1.19
     * @return void
     * @throws ReadOnlyError
     */
    public function checkReadOnly() {
        // Can not inject the ReadOnlyMode as it would break the installer since
        // it instantiates SpecialPageFactory before the DB (via ParserFactory for message parsing)
        if ( MediaWikiServices::getInstance()->getReadOnlyMode()->isReadOnly() ) {
            throw new ReadOnlyError;
        }
    }

    /**
     * If the user is not logged in, throws UserNotLoggedIn error
     *
     * The user will be redirected to Special:Userlogin with the given message as an error on
     * the form.
     *
     * @since 1.23
     * @param string $reasonMsg [optional] Message key to be displayed on login page
     * @param string $titleMsg [optional] Passed on to UserNotLoggedIn constructor
     * @throws UserNotLoggedIn
     */
    public function requireLogin(
        $reasonMsg = 'exception-nologin-text', $titleMsg = 'exception-nologin'
    ) {
        if ( $this->getUser()->isAnon() ) {
            throw new UserNotLoggedIn( $reasonMsg, $titleMsg );
        }
    }

    /**
     * If the user is not logged in or is a temporary user, throws UserNotLoggedIn
     *
     * @since 1.39
     * @param string $reasonMsg [optional] Message key to be displayed on login page
     * @param string $titleMsg [optional] Passed on to UserNotLoggedIn constructor
     * @throws UserNotLoggedIn
     */
    public function requireNamedUser(
        $reasonMsg = 'exception-nologin-text', $titleMsg = 'exception-nologin'
    ) {
        if ( !$this->getUser()->isNamed() ) {
            throw new UserNotLoggedIn( $reasonMsg, $titleMsg );
        }
    }

    /**
     * Tells if the special page does something security-sensitive and needs extra defense against
     * a stolen account (e.g. a reauthentication). What exactly that will mean is decided by the
     * authentication framework.
     * @stable to override
     * @return string|false False or the argument for AuthManager::securitySensitiveOperationStatus().
     *   Typically a special page needing elevated security would return its name here.
     */
    protected function getLoginSecurityLevel() {
        return false;
    }

    /**
     * Record preserved POST data after a reauthentication.
     *
     * This is called from checkLoginSecurityLevel() when returning from the
     * redirect for reauthentication, if the redirect had been served in
     * response to a POST request.
     *
     * The base SpecialPage implementation does nothing. If your subclass uses
     * getLoginSecurityLevel() or checkLoginSecurityLevel(), it should probably
     * implement this to do something with the data.
     *
     * @note Call self::setAuthManager from special page constructor when overriding
     *
     * @stable to override
     * @since 1.32
     * @param array $data
     */
    protected function setReauthPostData( array $data ) {
    }

    /**
     * Verifies that the user meets the security level, possibly reauthenticating them in the process.
     *
     * This should be used when the page does something security-sensitive and needs extra defense
     * against a stolen account (e.g. a reauthentication). The authentication framework will make
     * an extra effort to make sure the user account is not compromised. What that exactly means
     * will depend on the system and user settings; e.g. the user might be required to log in again
     * unless their last login happened recently, or they might be given a second-factor challenge.
     *
     * Calling this method will result in one if these actions:
     * - return true: all good.
     * - return false and set a redirect: caller should abort; the redirect will take the user
     *   to the login page for reauthentication, and back.
     * - throw an exception if there is no way for the user to meet the requirements without using
     *   a different access method (e.g. this functionality is only available from a specific IP).
     *
     * Note that this does not in any way check that the user is authorized to use this special page
     * (use checkPermissions() for that).
     *
     * @param string|null $level A security level. Can be an arbitrary string, defaults to the page
     *   name.
     * @return bool False means a redirect to the reauthentication page has been set and processing
     *   of the special page should be aborted.
     * @throws ErrorPageError If the security level cannot be met, even with reauthentication.
     */
    protected function checkLoginSecurityLevel( $level = null ) {
        $level = $level ?: $this->getName();
        $key = 'SpecialPage:reauth:' . $this->getName();
        $request = $this->getRequest();

        $securityStatus = $this->getAuthManager()->securitySensitiveOperationStatus( $level );
        if ( $securityStatus === AuthManager::SEC_OK ) {
            $uniqueId = $request->getVal( 'postUniqueId' );
            if ( $uniqueId ) {
                $key .= ':' . $uniqueId;
                $session = $request->getSession();
                $data = $session->getSecret( $key );
                if ( $data ) {
                    $session->remove( $key );
                    $this->setReauthPostData( $data );
                }
            }
            return true;
        } elseif ( $securityStatus === AuthManager::SEC_REAUTH ) {
            $title = self::getTitleFor( 'Userlogin' );
            $queryParams = $request->getQueryValues();

            if ( $request->wasPosted() ) {
                $data = array_diff_assoc( $request->getValues(), $request->getQueryValues() );
                if ( $data ) {
                    // unique ID in case the same special page is open in multiple browser tabs
                    $uniqueId = MWCryptRand::generateHex( 6 );
                    $key .= ':' . $uniqueId;
                    $queryParams['postUniqueId'] = $uniqueId;
                    $session = $request->getSession();
                    $session->persist(); // Just in case
                    $session->setSecret( $key, $data );
                }
            }

            $query = [
                'returnto' => $this->getFullTitle()->getPrefixedDBkey(),
                'returntoquery' => wfArrayToCgi( array_diff_key( $queryParams, [ 'title' => true ] ) ),
                'force' => $level,
            ];
            $url = $title->getFullURL( $query, false, PROTO_HTTPS );

            $this->getOutput()->redirect( $url );
            return false;
        }

        $titleMessage = wfMessage( 'specialpage-securitylevel-not-allowed-title' );
        $errorMessage = wfMessage( 'specialpage-securitylevel-not-allowed' );
        throw new ErrorPageError( $titleMessage, $errorMessage );
    }

    /**
     * Set the injected AuthManager from the special page constructor
     *
     * @since 1.36
     * @param AuthManager $authManager
     */
    final protected function setAuthManager( AuthManager $authManager ) {
        $this->authManager = $authManager;
    }

    /**
     * @note Call self::setAuthManager from special page constructor when using
     *
     * @since 1.36
     * @return AuthManager
     */
    final protected function getAuthManager(): AuthManager {
        if ( $this->authManager === null ) {
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            $this->authManager = MediaWikiServices::getInstance()->getAuthManager();
        }
        return $this->authManager;
    }

    /**
     * Return an array of subpages beginning with $search that this special page will accept.
     *
     * For example, if a page supports subpages "foo", "bar" and "baz" (as in Special:PageName/foo,
     * etc.):
     *
     *   - `prefixSearchSubpages( "ba" )` should return `[ "bar", "baz" ]`
     *   - `prefixSearchSubpages( "f" )` should return `[ "foo" ]`
     *   - `prefixSearchSubpages( "z" )` should return `[]`
     *   - `prefixSearchSubpages( "" )` should return `[ foo", "bar", "baz" ]`
     *
     * @stable to override
     * @param string $search Prefix to search for
     * @param int $limit Maximum number of results to return (usually 10)
     * @param int $offset Number of results to skip (usually 0)
     * @return string[] Matching subpages
     */
    public function prefixSearchSubpages( $search, $limit, $offset ) {
        $subpages = $this->getSubpagesForPrefixSearch();
        if ( !$subpages ) {
            return [];
        }

        return self::prefixSearchArray( $search, $limit, $subpages, $offset );
    }

    /**
     * Return an array of subpages that this special page will accept for prefix
     * searches. If this method requires a query you might instead want to implement
     * prefixSearchSubpages() directly so you can support $limit and $offset. This
     * method is better for static-ish lists of things.
     *
     * @stable to override
     * @return string[] subpages to search from
     */
    protected function getSubpagesForPrefixSearch() {
        return [];
    }

    /**
     * Return an array of strings representing page titles that are discoverable to end users via UI.
     *
     * @since 1.39
     * @stable to call or override
     * @return string[] strings representing page titles that can be rendered by skins if required.
     */
    public function getAssociatedNavigationLinks() {
        return [];
    }

    /**
     * Perform a regular substring search for prefixSearchSubpages
     * @since 1.36 Added $searchEngineFactory parameter
     * @param string $search Prefix to search for
     * @param int $limit Maximum number of results to return (usually 10)
     * @param int $offset Number of results to skip (usually 0)
     * @param SearchEngineFactory|null $searchEngineFactory Provide the service
     * @return string[] Matching subpages
     */
    protected function prefixSearchString( $search, $limit, $offset, SearchEngineFactory $searchEngineFactory = null ) {
        $title = Title::newFromText( $search );
        if ( !$title || !$title->canExist() ) {
            // No prefix suggestion in special and media namespace
            return [];
        }

        $searchEngine = $searchEngineFactory
            ? $searchEngineFactory->create()
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            : MediaWikiServices::getInstance()->newSearchEngine();
        $searchEngine->setLimitOffset( $limit, $offset );
        $searchEngine->setNamespaces( [] );
        $result = $searchEngine->defaultPrefixSearch( $search );
        return array_map( static function ( Title $t ) {
            return $t->getPrefixedText();
        }, $result );
    }

    /**
     * Helper function for implementations of prefixSearchSubpages() that
     * filter the values in memory (as opposed to making a query).
     *
     * @since 1.24
     * @param string $search
     * @param int $limit
     * @param array $subpages
     * @param int $offset
     * @return string[]
     */
    protected static function prefixSearchArray( $search, $limit, array $subpages, $offset ) {
        $escaped = preg_quote( $search, '/' );
        return array_slice( preg_grep( "/^$escaped/i",
            array_slice( $subpages, $offset ) ), 0, $limit );
    }

    /**
     * Sets headers - this should be called from the execute() method of all derived classes!
     * @stable to override
     */
    protected function setHeaders() {
        $out = $this->getOutput();
        $out->setArticleRelated( false );
        $out->setRobotPolicy( $this->getRobotPolicy() );
        $title = $this->getDescription();
        // T343849
        if ( is_string( $title ) ) {
            wfDeprecated( "string return from {$this->getName()}::getDescription()", '1.41' );
            $title = ( new RawMessage( '$1' ) )->rawParams( $title );
        }
        $out->setPageTitleMsg( $title );
    }

    /**
     * Entry point.
     *
     * @since 1.20
     *
     * @param string|null $subPage
     */
    final public function run( $subPage ) {
        if ( !$this->getHookRunner()->onSpecialPageBeforeExecute( $this, $subPage ) ) {
            return;
        }

        if ( $this->beforeExecute( $subPage ) === false ) {
            return;
        }
        $this->execute( $subPage );
        $this->afterExecute( $subPage );

        $this->getHookRunner()->onSpecialPageAfterExecute( $this, $subPage );
    }

    /**
     * Gets called before @see SpecialPage::execute.
     * Return false to prevent calling execute() (since 1.27+).
     *
     * @stable to override
     * @since 1.20
     *
     * @param string|null $subPage
     * @return bool|void
     */
    protected function beforeExecute( $subPage ) {
        // No-op
    }

    /**
     * Gets called after @see SpecialPage::execute.
     *
     * @stable to override
     * @since 1.20
     *
     * @param string|null $subPage
     */
    protected function afterExecute( $subPage ) {
        // No-op
    }

    /**
     * Default execute method
     * Checks user permissions
     *
     * This must be overridden by subclasses; it will be made abstract in a future version
     *
     * @stable to override
     *
     * @param string|null $subPage
     */
    public function execute( $subPage ) {
        $this->setHeaders();
        $this->checkPermissions();
        $securityLevel = $this->getLoginSecurityLevel();
        if ( $securityLevel !== false && !$this->checkLoginSecurityLevel( $securityLevel ) ) {
            return;
        }
        $this->outputHeader();
    }

    /**
     * Outputs a summary message on top of special pages
     * By default the message key is the canonical name of the special page
     * May be overridden, i.e. by extensions to stick with the naming conventions
     * for message keys: 'extensionname-xxx'
     *
     * @stable to override
     *
     * @param string $summaryMessageKey Message key of the summary
     */
    protected function outputHeader( $summaryMessageKey = '' ) {
        if ( $summaryMessageKey == '' ) {
            $msg = strtolower( $this->getName() ) . '-summary';
        } else {
            $msg = $summaryMessageKey;
        }
        if ( !$this->msg( $msg )->isDisabled() && !$this->including() ) {
            $this->getOutput()->wrapWikiMsg(
                "<div class='mw-specialpage-summary'>\n$1\n</div>", $msg );
        }
    }

    /**
     * Returns the name that goes in the \<h1\> in the special page itself, and
     * also the name that will be listed in Special:Specialpages
     *
     * Derived classes can override this, but usually it is easier to keep the
     * default behavior.
     *
     * Returning a string from this method has been deprecated since 1.41.
     *
     * @stable to override
     *
     * @return string|Message
     */
    public function getDescription() {
        return $this->msg( strtolower( $this->mName ) );
    }

    /**
     * Similar to getDescription but takes into account sub pages and designed for display
     * in tabs.
     *
     * @since 1.39
     * @stable to override if special page has complex parameter handling. Use default message keys
     * where possible.
     *
     * @param string $path (optional)
     * @return string
     */
    public function getShortDescription( string $path = '' ): string {
        $lowerPath = strtolower( str_replace( '/', '-', $path ) );
        $shortKey = 'special-tab-' . $lowerPath;
        $shortKey .= '-short';
        $msgShort = $this->msg( $shortKey );
        return $msgShort->text();
    }

    /**
     * Get a self-referential title object
     *
     * @param string|false|null $subpage
     * @return Title
     * @since 1.23
     */
    public function getPageTitle( $subpage = false ) {
        return self::getTitleFor( $this->mName, $subpage );
    }

    /**
     * Sets the context this SpecialPage is executed in
     *
     * @param IContextSource $context
     * @since 1.18
     */
    public function setContext( $context ) {
        $this->mContext = $context;
    }

    /**
     * Gets the context this SpecialPage is executed in
     *
     * @return IContextSource|RequestContext
     * @since 1.18
     */
    public function getContext() {
        if ( !( $this->mContext instanceof IContextSource ) ) {
            wfDebug( __METHOD__ . " called and \$mContext is null. " .
                "Using RequestContext::getMain()" );

            $this->mContext = RequestContext::getMain();
        }
        return $this->mContext;
    }

    /**
     * Get the WebRequest being used for this instance
     *
     * @return WebRequest
     * @since 1.18
     */
    public function getRequest() {
        return $this->getContext()->getRequest();
    }

    /**
     * Get the OutputPage being used for this instance
     *
     * @return OutputPage
     * @since 1.18
     */
    public function getOutput() {
        return $this->getContext()->getOutput();
    }

    /**
     * Shortcut to get the User executing this instance
     *
     * @return User
     * @since 1.18
     */
    public function getUser() {
        return $this->getContext()->getUser();
    }

    /**
     * Shortcut to get the Authority executing this instance
     *
     * @return Authority
     * @since 1.36
     */
    public function getAuthority(): Authority {
        return $this->getContext()->getAuthority();
    }

    /**
     * Shortcut to get the skin being used for this instance
     *
     * @return Skin
     * @since 1.18
     */
    public function getSkin() {
        return $this->getContext()->getSkin();
    }

    /**
     * Shortcut to get user's language
     *
     * @return Language
     * @since 1.19
     */
    public function getLanguage() {
        return $this->getContext()->getLanguage();
    }

    /**
     * Shortcut to get content language
     *
     * @return Language
     * @since 1.36
     */
    final public function getContentLanguage(): Language {
        if ( $this->contentLanguage === null ) {
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            $this->contentLanguage = MediaWikiServices::getInstance()->getContentLanguage();
        }
        return $this->contentLanguage;
    }

    /**
     * Set content language
     *
     * @internal For factory only
     * @param Language $contentLanguage
     * @since 1.36
     */
    final public function setContentLanguage( Language $contentLanguage ) {
        $this->contentLanguage = $contentLanguage;
    }

    /**
     * Shortcut to get main config object
     * @return Config
     * @since 1.24
     */
    public function getConfig() {
        return $this->getContext()->getConfig();
    }

    /**
     * Return the full title, including $par
     *
     * @return Title
     * @since 1.18
     */
    public function getFullTitle() {
        return $this->getContext()->getTitle();
    }

    /**
     * Return the robot policy. Derived classes that override this can change
     * the robot policy set by setHeaders() from the default 'noindex,nofollow'.
     *
     * @return string
     * @since 1.23
     */
    protected function getRobotPolicy() {
        return 'noindex,nofollow';
    }

    /**
     * Wrapper around wfMessage that sets the current context.
     *
     * @since 1.16
     * @param string|string[]|MessageSpecifier $key
     * @param mixed ...$params
     * @return Message
     * @see wfMessage
     */
    public function msg( $key, ...$params ) {
        $message = $this->getContext()->msg( $key, ...$params );
        // RequestContext passes context to wfMessage, and the language is set from
        // the context, but setting the language for Message class removes the
        // interface message status, which breaks for example usernameless gender
        // invocations. Restore the flag when not including special page in content.
        if ( $this->including() ) {
            $message->setInterfaceMessageFlag( false );
        }

        return $message;
    }

    /**
     * Adds RSS/atom links
     *
     * @param array $params
     */
    protected function addFeedLinks( $params ) {
        $feedTemplate = wfScript( 'api' );

        foreach ( $this->getConfig()->get( MainConfigNames::FeedClasses ) as $format => $class ) {
            $theseParams = $params + [ 'feedformat' => $format ];
            $url = wfAppendQuery( $feedTemplate, $theseParams );
            $this->getOutput()->addFeedLink( $format, $url );
        }
    }

    /**
     * Adds help link with an icon via page indicators.
     * Link target can be overridden by a local message containing a wikilink:
     * the message key is: lowercase special page name + '-helppage'.
     * @param string $to Target MediaWiki.org page title or encoded URL.
     * @param bool $overrideBaseUrl Whether $url is a full URL, to avoid MW.o.
     * @since 1.25
     */
    public function addHelpLink( $to, $overrideBaseUrl = false ) {
        if ( $this->including() ) {
            return;
        }

        $msg = $this->msg( strtolower( $this->getName() ) . '-helppage' );

        if ( !$msg->isDisabled() ) {
            $title = Title::newFromText( $msg->plain() );
            if ( $title instanceof Title ) {
                $this->getOutput()->addHelpLink( $title->getLocalURL(), true );
            }
        } else {
            $this->getOutput()->addHelpLink( $to, $overrideBaseUrl );
        }
    }

    /**
     * Get the group that the special page belongs in on Special:SpecialPage
     * Use this method, instead of getGroupName to allow customization
     * of the group name from the wiki side
     *
     * @return string Group of this special page
     * @since 1.21
     */
    public function getFinalGroupName() {
        $name = $this->getName();

        // Allow overriding the group from the wiki side
        $msg = $this->msg( 'specialpages-specialpagegroup-' . strtolower( $name ) )->inContentLanguage();
        if ( !$msg->isBlank() ) {
            $group = $msg->text();
        } else {
            // Than use the group from this object
            $group = $this->getGroupName();
        }

        return $group;
    }

    /**
     * Indicates whether this special page may perform database writes
     *
     * @stable to override
     *
     * @return bool
     * @since 1.27
     */
    public function doesWrites() {
        return false;
    }

    /**
     * Under which header this special page is listed in Special:SpecialPages
     * See messages 'specialpages-group-*' for valid names
     * This method defaults to group 'other'
     *
     * @stable to override
     *
     * @return string
     * @since 1.21
     */
    protected function getGroupName() {
        return 'other';
    }

    /**
     * Call wfTransactionalTimeLimit() if this request was POSTed
     * @since 1.26
     */
    protected function useTransactionalTimeLimit() {
        if ( $this->getRequest()->wasPosted() ) {
            wfTransactionalTimeLimit();
        }
    }

    /**
     * @since 1.28
     * @return LinkRenderer
     */
    public function getLinkRenderer(): LinkRenderer {
        if ( $this->linkRenderer === null ) {
            // TODO Inject the service
            $this->linkRenderer = MediaWikiServices::getInstance()->getLinkRendererFactory()
                ->create();
        }
        return $this->linkRenderer;
    }

    /**
     * @since 1.28
     * @param LinkRenderer $linkRenderer
     */
    public function setLinkRenderer( LinkRenderer $linkRenderer ) {
        $this->linkRenderer = $linkRenderer;
    }

    /**
     * Generate (prev x| next x) (20|50|100...) type links for paging
     *
     * @param int $offset
     * @param int $limit
     * @param array $query Optional URL query parameter string
     * @param bool $atend Optional param for specified if this is the last page
     * @param string|false $subpage Optional param for specifying subpage
     * @return string
     */
    protected function buildPrevNextNavigation(
        $offset,
        $limit,
        array $query = [],
        $atend = false,
        $subpage = false
    ) {
        $navBuilder = new PagerNavigationBuilder( $this );
        $navBuilder
            ->setPage( $this->getPageTitle( $subpage ) )
            ->setLinkQuery( [ 'limit' => $limit, 'offset' => $offset ] + $query )
            ->setLimitLinkQueryParam( 'limit' )
            ->setCurrentLimit( $limit )
            ->setPrevTooltipMsg( 'prevn-title' )
            ->setNextTooltipMsg( 'nextn-title' )
            ->setLimitTooltipMsg( 'shown-title' );

        if ( $offset > 0 ) {
            $navBuilder->setPrevLinkQuery( [ 'offset' => (string)max( $offset - $limit, 0 ) ] );
        }
        if ( !$atend ) {
            $navBuilder->setNextLinkQuery( [ 'offset' => (string)( $offset + $limit ) ] );
        }

        return $navBuilder->getHtml();
    }

    /**
     * @since 1.35
     * @internal
     * @param HookContainer $hookContainer
     */
    public function setHookContainer( HookContainer $hookContainer ) {
        $this->hookContainer = $hookContainer;
        $this->hookRunner = new HookRunner( $hookContainer );
    }

    /**
     * @since 1.35
     * @return HookContainer
     */
    protected function getHookContainer() {
        if ( !$this->hookContainer ) {
            $this->hookContainer = MediaWikiServices::getInstance()->getHookContainer();
        }
        return $this->hookContainer;
    }

    /**
     * @internal This is for use by core only. Hook interfaces may be removed
     *   without notice.
     * @since 1.35
     * @return HookRunner
     */
    protected function getHookRunner() {
        if ( !$this->hookRunner ) {
            $this->hookRunner = new HookRunner( $this->getHookContainer() );
        }
        return $this->hookRunner;
    }

    /**
     * @internal For factory only
     * @since 1.36
     * @param SpecialPageFactory $specialPageFactory
     */
    final public function setSpecialPageFactory( SpecialPageFactory $specialPageFactory ) {
        $this->specialPageFactory = $specialPageFactory;
    }

    /**
     * @since 1.36
     * @return SpecialPageFactory
     */
    final protected function getSpecialPageFactory(): SpecialPageFactory {
        if ( !$this->specialPageFactory ) {
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            $this->specialPageFactory = MediaWikiServices::getInstance()->getSpecialPageFactory();
        }
        return $this->specialPageFactory;
    }
}

/** @deprecated class alias since 1.41 */
class_alias( SpecialPage::class, 'SpecialPage' );