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[mediawiki.git] / includes / page / Article.php

<?php
/**
 * 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
 */

use MediaWiki\Block\DatabaseBlock;
use MediaWiki\Block\DatabaseBlockStore;
use MediaWiki\CommentFormatter\CommentFormatter;
use MediaWiki\Context\IContextSource;
use MediaWiki\Context\RequestContext;
use MediaWiki\EditPage\EditPage;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\HookContainer\ProtectedHookAccessorTrait;
use MediaWiki\Html\Html;
use MediaWiki\Language\Language;
use MediaWiki\Linker\Linker;
use MediaWiki\Linker\LinkRenderer;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Message\Message;
use MediaWiki\Output\OutputPage;
use MediaWiki\Page\ParserOutputAccess;
use MediaWiki\Page\ProtectionForm;
use MediaWiki\Page\WikiPageFactory;
use MediaWiki\Parser\Parser;
use MediaWiki\Parser\ParserOptions;
use MediaWiki\Parser\ParserOutput;
use MediaWiki\Permissions\Authority;
use MediaWiki\Permissions\PermissionStatus;
use MediaWiki\Permissions\RestrictionStore;
use MediaWiki\Revision\ArchivedRevisionLookup;
use MediaWiki\Revision\BadRevisionException;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Revision\RevisionStore;
use MediaWiki\Revision\SlotRecord;
use MediaWiki\Status\Status;
use MediaWiki\Title\Title;
use MediaWiki\User\Options\UserOptionsLookup;
use MediaWiki\User\UserIdentity;
use MediaWiki\User\UserNameUtils;
use MediaWiki\Xml\Xml;
use Wikimedia\IPUtils;
use Wikimedia\LightweightObjectStore\ExpirationAwareness;
use Wikimedia\NonSerializable\NonSerializableTrait;
use Wikimedia\Rdbms\IConnectionProvider;

/**
 * Legacy class representing an editable page and handling UI for some page actions.
 *
 * This has largely been superseded by WikiPage, with Action subclasses for the
 * user interface of page actions, and service classes for their backend logic.
 *
 * @todo Move and refactor remaining code
 * @todo Deprecate
 */
class Article implements Page {
        use ProtectedHookAccessorTrait;
        use NonSerializableTrait;

        /**
         * @var IContextSource|null The context this Article is executed in.
         * If null, RequestContext::getMain() is used.
         * @deprecated since 1.35, must be private, use {@link getContext}
         */
        protected $mContext;

        /** @var WikiPage The WikiPage object of this instance */
        protected $mPage;

        /**
         * @var int|null The oldid of the article that was requested to be shown,
         * 0 for the current revision.
         */
        public $mOldId;

        /** @var Title|null Title from which we were redirected here, if any. */
        public $mRedirectedFrom = null;

        /** @var string|false URL to redirect to or false if none */
        public $mRedirectUrl = false;

        /**
         * @var Status|null represents the outcome of fetchRevisionRecord().
         * $fetchResult->value is the RevisionRecord object, if the operation was successful.
         */
        private $fetchResult = null;

        /**
         * @var ParserOutput|null|false The ParserOutput generated for viewing the page,
         * initialized by view(). If no ParserOutput could be generated, this is set to false.
         * @deprecated since 1.32
         */
        public $mParserOutput = null;

        /**
         * @var bool Whether render() was called. With the way subclasses work
         * here, there doesn't seem to be any other way to stop calling
         * OutputPage::enableSectionEditLinks() and still have it work as it did before.
         */
        protected $viewIsRenderAction = false;

        protected LinkRenderer $linkRenderer;
        private RevisionStore $revisionStore;
        private UserNameUtils $userNameUtils;
        private UserOptionsLookup $userOptionsLookup;
        private CommentFormatter $commentFormatter;
        private WikiPageFactory $wikiPageFactory;
        private JobQueueGroup $jobQueueGroup;
        private ArchivedRevisionLookup $archivedRevisionLookup;
        protected IConnectionProvider $dbProvider;
        protected DatabaseBlockStore $blockStore;

        protected RestrictionStore $restrictionStore;

        /**
         * @var RevisionRecord|null Revision to be shown
         *
         * Initialized by getOldIDFromRequest() or fetchRevisionRecord(). While the output of
         * Article::view is typically based on this revision, it may be replaced by extensions.
         */
        private $mRevisionRecord = null;

        /**
         * @param Title $title
         * @param int|null $oldId Revision ID, null to fetch from request, zero for current
         */
        public function __construct( Title $title, $oldId = null ) {
                $this->mOldId = $oldId;
                $this->mPage = $this->newPage( $title );

                $services = MediaWikiServices::getInstance();
                $this->linkRenderer = $services->getLinkRenderer();
                $this->revisionStore = $services->getRevisionStore();
                $this->userNameUtils = $services->getUserNameUtils();
                $this->userOptionsLookup = $services->getUserOptionsLookup();
                $this->commentFormatter = $services->getCommentFormatter();
                $this->wikiPageFactory = $services->getWikiPageFactory();
                $this->jobQueueGroup = $services->getJobQueueGroup();
                $this->archivedRevisionLookup = $services->getArchivedRevisionLookup();
                $this->dbProvider = $services->getConnectionProvider();
                $this->blockStore = $services->getDatabaseBlockStore();
                $this->restrictionStore = $services->getRestrictionStore();
        }

        /**
         * @param Title $title
         * @return WikiPage
         */
        protected function newPage( Title $title ) {
                return new WikiPage( $title );
        }

        /**
         * Constructor from a page id
         * @param int $id Article ID to load
         * @return Article|null
         */
        public static function newFromID( $id ) {
                $t = Title::newFromID( $id );
                return $t === null ? null : new static( $t );
        }

        /**
         * Create an Article object of the appropriate class for the given page.
         *
         * @param Title $title
         * @param IContextSource $context
         * @return Article
         */
        public static function newFromTitle( $title, IContextSource $context ): self {
                if ( $title->getNamespace() === NS_MEDIA ) {
                        // XXX: This should not be here, but where should it go?
                        $title = Title::makeTitle( NS_FILE, $title->getDBkey() );
                }

                $page = null;
                ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
                        // @phan-suppress-next-line PhanTypeMismatchArgument Type mismatch on pass-by-ref args
                        ->onArticleFromTitle( $title, $page, $context );
                if ( !$page ) {
                        switch ( $title->getNamespace() ) {
                                case NS_FILE:
                                        $page = new ImagePage( $title );
                                        break;
                                case NS_CATEGORY:
                                        $page = new CategoryPage( $title );
                                        break;
                                default:
                                        $page = new Article( $title );
                        }
                }
                $page->setContext( $context );

                return $page;
        }

        /**
         * Create an Article object of the appropriate class for the given page.
         *
         * @param WikiPage $page
         * @param IContextSource $context
         * @return Article
         */
        public static function newFromWikiPage( WikiPage $page, IContextSource $context ) {
                $article = self::newFromTitle( $page->getTitle(), $context );
                $article->mPage = $page; // override to keep process cached vars
                return $article;
        }

        /**
         * Get the page this view was redirected from
         * @return Title|null
         * @since 1.28
         */
        public function getRedirectedFrom() {
                return $this->mRedirectedFrom;
        }

        /**
         * Tell the page view functions that this view was redirected
         * from another page on the wiki.
         * @param Title $from
         */
        public function setRedirectedFrom( Title $from ) {
                $this->mRedirectedFrom = $from;
        }

        /**
         * Get the title object of the article
         *
         * @return Title Title object of this page
         */
        public function getTitle() {
                return $this->mPage->getTitle();
        }

        /**
         * Get the WikiPage object of this instance
         *
         * @since 1.19
         * @return WikiPage
         */
        public function getPage() {
                return $this->mPage;
        }

        public function clear() {
                $this->mRedirectedFrom = null; # Title object if set
                $this->mRedirectUrl = false;
                $this->mRevisionRecord = null;
                $this->fetchResult = null;

                // TODO hard-deprecate direct access to public fields

                $this->mPage->clear();
        }

        /**
         * @see getOldIDFromRequest()
         * @see getRevIdFetched()
         *
         * @return int The oldid of the article that is was requested in the constructor or via the
         *         context's WebRequest.
         */
        public function getOldID() {
                if ( $this->mOldId === null ) {
                        $this->mOldId = $this->getOldIDFromRequest();
                }

                return $this->mOldId;
        }

        /**
         * Sets $this->mRedirectUrl to a correct URL if the query parameters are incorrect
         *
         * @return int The old id for the request
         */
        public function getOldIDFromRequest() {
                $this->mRedirectUrl = false;

                $request = $this->getContext()->getRequest();
                $oldid = $request->getIntOrNull( 'oldid' );

                if ( $oldid === null ) {
                        return 0;
                }

                if ( $oldid !== 0 ) {
                        # Load the given revision and check whether the page is another one.
                        # In that case, update this instance to reflect the change.
                        if ( $oldid === $this->mPage->getLatest() ) {
                                $this->mRevisionRecord = $this->mPage->getRevisionRecord();
                        } else {
                                $this->mRevisionRecord = $this->revisionStore->getRevisionById( $oldid );
                                if ( $this->mRevisionRecord !== null ) {
                                        $revPageId = $this->mRevisionRecord->getPageId();
                                        // Revision title doesn't match the page title given?
                                        if ( $this->mPage->getId() !== $revPageId ) {
                                                $this->mPage = $this->wikiPageFactory->newFromID( $revPageId );
                                        }
                                }
                        }
                }

                $oldRev = $this->mRevisionRecord;
                if ( $request->getRawVal( 'direction' ) === 'next' ) {
                        $nextid = 0;
                        if ( $oldRev ) {
                                $nextRev = $this->revisionStore->getNextRevision( $oldRev );
                                if ( $nextRev ) {
                                        $nextid = $nextRev->getId();
                                }
                        }
                        if ( $nextid ) {
                                $oldid = $nextid;
                                $this->mRevisionRecord = null;
                        } else {
                                $this->mRedirectUrl = $this->getTitle()->getFullURL( 'redirect=no' );
                        }
                } elseif ( $request->getRawVal( 'direction' ) === 'prev' ) {
                        $previd = 0;
                        if ( $oldRev ) {
                                $prevRev = $this->revisionStore->getPreviousRevision( $oldRev );
                                if ( $prevRev ) {
                                        $previd = $prevRev->getId();
                                }
                        }
                        if ( $previd ) {
                                $oldid = $previd;
                                $this->mRevisionRecord = null;
                        }
                }

                return $oldid;
        }

        /**
         * Fetches the revision to work on.
         * The revision is loaded from the database. Refer to $this->fetchResult for the revision
         * or any errors encountered while loading it.
         *
         * Public since 1.35
         *
         * @return RevisionRecord|null
         */
        public function fetchRevisionRecord() {
                if ( $this->fetchResult ) {
                        return $this->mRevisionRecord;
                }

                $oldid = $this->getOldID();

                // $this->mRevisionRecord might already be fetched by getOldIDFromRequest()
                if ( !$this->mRevisionRecord ) {
                        if ( !$oldid ) {
                                $this->mRevisionRecord = $this->mPage->getRevisionRecord();

                                if ( !$this->mRevisionRecord ) {
                                        wfDebug( __METHOD__ . " failed to find page data for title " .
                                                $this->getTitle()->getPrefixedText() );

                                        // Output for this case is done by showMissingArticle().
                                        $this->fetchResult = Status::newFatal( 'noarticletext' );
                                        return null;
                                }
                        } else {
                                $this->mRevisionRecord = $this->revisionStore->getRevisionById( $oldid );

                                if ( !$this->mRevisionRecord ) {
                                        wfDebug( __METHOD__ . " failed to load revision, rev_id $oldid" );

                                        $this->fetchResult = Status::newFatal( $this->getMissingRevisionMsg( $oldid ) );
                                        return null;
                                }
                        }
                }

                if ( !$this->mRevisionRecord->userCan( RevisionRecord::DELETED_TEXT, $this->getContext()->getAuthority() ) ) {
                        wfDebug( __METHOD__ . " failed to retrieve content of revision " . $this->mRevisionRecord->getId() );

                        // Output for this case is done by showDeletedRevisionHeader().
                        // title used in wikilinks, should not contain whitespaces
                        $this->fetchResult = new Status;
                        $title = $this->getTitle()->getPrefixedDBkey();

                        if ( $this->mRevisionRecord->isDeleted( RevisionRecord::DELETED_RESTRICTED ) ) {
                                $this->fetchResult->fatal( 'rev-suppressed-text' );
                        } else {
                                $this->fetchResult->fatal( 'rev-deleted-text-permission', $title );
                        }

                        return null;
                }

                $this->fetchResult = Status::newGood( $this->mRevisionRecord );
                return $this->mRevisionRecord;
        }

        /**
         * Returns true if the currently-referenced revision is the current edit
         * to this page (and it exists).
         * @return bool
         */
        public function isCurrent() {
                # If no oldid, this is the current version.
                if ( $this->getOldID() == 0 ) {
                        return true;
                }

                return $this->mPage->exists() &&
                        $this->mRevisionRecord &&
                        $this->mRevisionRecord->isCurrent();
        }

        /**
         * Use this to fetch the rev ID used on page views
         *
         * Before fetchRevisionRecord was called, this returns the page's latest revision,
         * regardless of what getOldID() returns.
         *
         * @return int Revision ID of last article revision
         */
        public function getRevIdFetched() {
                if ( $this->fetchResult && $this->fetchResult->isOK() ) {
                        /** @var RevisionRecord $rev */
                        $rev = $this->fetchResult->getValue();
                        return $rev->getId();
                } else {
                        return $this->mPage->getLatest();
                }
        }

        /**
         * This is the default action of the index.php entry point: just view the
         * page of the given title.
         */
        public function view() {
                $context = $this->getContext();
                $useFileCache = $context->getConfig()->get( MainConfigNames::UseFileCache );

                # Get variables from query string
                # As side effect this will load the revision and update the title
                # in a revision ID is passed in the request, so this should remain
                # the first call of this method even if $oldid is used way below.
                $oldid = $this->getOldID();

                $authority = $context->getAuthority();
                # Another check in case getOldID() is altering the title
                $permissionStatus = PermissionStatus::newEmpty();
                if ( !$authority
                        ->authorizeRead( 'read', $this->getTitle(), $permissionStatus )
                ) {
                        wfDebug( __METHOD__ . ": denied on secondary read check" );
                        throw new PermissionsError( 'read', $permissionStatus );
                }

                $outputPage = $context->getOutput();
                # getOldID() may as well want us to redirect somewhere else
                if ( $this->mRedirectUrl ) {
                        $outputPage->redirect( $this->mRedirectUrl );
                        wfDebug( __METHOD__ . ": redirecting due to oldid" );

                        return;
                }

                # If we got diff in the query, we want to see a diff page instead of the article.
                if ( $context->getRequest()->getCheck( 'diff' ) ) {
                        wfDebug( __METHOD__ . ": showing diff page" );
                        $this->showDiffPage();

                        return;
                }

                $this->showProtectionIndicator();

                # Set page title (may be overridden from ParserOutput if title conversion is enabled or DISPLAYTITLE is used)
                $outputPage->setPageTitle( Parser::formatPageTitle(
                        str_replace( '_', ' ', $this->getTitle()->getNsText() ),
                        ':',
                        $this->getTitle()->getText()
                ) );

                $outputPage->setArticleFlag( true );
                # Allow frames by default
                $outputPage->getMetadata()->setPreventClickjacking( false );

                $parserOptions = $this->getParserOptions();

                $poOptions = [];
                # Allow extensions to vary parser options used for article rendering
                ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )
                        ->onArticleParserOptions( $this, $parserOptions );
                # Render printable version, use printable version cache
                if ( $outputPage->isPrintable() ) {
                        $parserOptions->setIsPrintable( true );
                        $poOptions['enableSectionEditLinks'] = false;
                        $this->addMessageBoxStyles( $outputPage );
                        $outputPage->prependHTML(
                                Html::warningBox(
                                        $outputPage->msg( 'printableversion-deprecated-warning' )->escaped()
                                )
                        );
                } elseif ( $this->viewIsRenderAction || !$this->isCurrent() ||
                        !$authority->probablyCan( 'edit', $this->getTitle() )
                ) {
                        $poOptions['enableSectionEditLinks'] = false;
                }

                # Try client and file cache
                if ( $oldid === 0 && $this->mPage->checkTouched() ) {
                        # Try to stream the output from file cache
                        if ( $useFileCache && $this->tryFileCache() ) {
                                wfDebug( __METHOD__ . ": done file cache" );
                                # tell wgOut that output is taken care of
                                $outputPage->disable();
                                $this->mPage->doViewUpdates( $authority, $oldid );

                                return;
                        }
                }

                $this->showRedirectedFromHeader();
                $this->showNamespaceHeader();

                if ( $this->viewIsRenderAction ) {
                        $poOptions += [ 'absoluteURLs' => true ];
                }
                $poOptions += [ 'includeDebugInfo' => true ];

                try {
                        $continue =
                                $this->generateContentOutput( $authority, $parserOptions, $oldid, $outputPage, $poOptions );
                } catch ( BadRevisionException $e ) {
                        $continue = false;
                        $this->showViewError( wfMessage( 'badrevision' )->text() );
                }

                if ( !$continue ) {
                        return;
                }

                # For the main page, overwrite the <title> element with the con-
                # tents of 'pagetitle-view-mainpage' instead of the default (if
                # that's not empty).
                # This message always exists because it is in the i18n files
                if ( $this->getTitle()->isMainPage() ) {
                        $msg = $context->msg( 'pagetitle-view-mainpage' )->inContentLanguage();
                        if ( !$msg->isDisabled() ) {
                                $outputPage->setHTMLTitle( $msg->text() );
                        }
                }

                # Use adaptive TTLs for CDN so delayed/failed purges are noticed less often.
                # This could use getTouched(), but that could be scary for major template edits.
                $outputPage->adaptCdnTTL( $this->mPage->getTimestamp(), ExpirationAwareness::TTL_DAY );

                $this->showViewFooter();
                $this->mPage->doViewUpdates( $authority, $oldid, $this->fetchRevisionRecord() );

                # Load the postEdit module if the user just saved this revision
                # See also EditPage::setPostEditCookie
                $request = $context->getRequest();
                $cookieKey = EditPage::POST_EDIT_COOKIE_KEY_PREFIX . $this->getRevIdFetched();
                $postEdit = $request->getCookie( $cookieKey );
                if ( $postEdit ) {
                        # Clear the cookie. This also prevents caching of the response.
                        $request->response()->clearCookie( $cookieKey );
                        $outputPage->addJsConfigVars( 'wgPostEdit', $postEdit );
                        $outputPage->addModules( 'mediawiki.action.view.postEdit' ); // FIXME: test this
                        if ( $this->getContext()->getConfig()->get( MainConfigNames::EnableEditRecovery )
                                && $this->userOptionsLookup->getOption( $this->getContext()->getUser(), 'editrecovery' )
                        ) {
                                $outputPage->addModules( 'mediawiki.editRecovery.postEdit' );
                        }
                }
        }

        /**
         * Show a lock icon above the article body if the page is protected.
         */
        public function showProtectionIndicator(): void {
                $title = $this->getTitle();
                $context = $this->getContext();
                $outputPage = $context->getOutput();

                $protectionIndicatorsAreEnabled = $context->getConfig()
                        ->get( MainConfigNames::EnableProtectionIndicators );

                if ( !$protectionIndicatorsAreEnabled || $title->isMainPage() ) {
                        return;
                }

                $protection = $this->restrictionStore->getRestrictions( $title, 'edit' );

                $cascadeProtection = $this->restrictionStore->getCascadeProtectionSources( $title )[1];

                $isCascadeProtected = array_key_exists( 'edit', $cascadeProtection );

                if ( !$protection && !$isCascadeProtected ) {
                        return;
                }

                if ( $isCascadeProtected ) {
                        // Cascade-protected pages are protected at the sysop level. So it
                        // should not matter if we take the protection level of the first
                        // or last page that is being cascaded to the current page.
                        $protectionLevel = $cascadeProtection['edit'][0];
                } else {
                        $protectionLevel = $protection[0];
                }

                // Protection levels are stored in the database as plain text, but
                // they are expected to be valid protection levels. So we should be able to
                // safely use them. However phan thinks this could be a XSS problem so we
                // are being paranoid and escaping them once more.
                $protectionLevel = htmlspecialchars( $protectionLevel );

                $protectionExpiry = $this->restrictionStore->getRestrictionExpiry( $title, 'edit' );
                $formattedProtectionExpiry = $context->getLanguage()
                        ->formatExpiry( $protectionExpiry ?? '' );

                $protectionMsg = 'protection-indicator-title';
                if ( $protectionExpiry === 'infinity' || !$protectionExpiry ) {
                        $protectionMsg .= '-infinity';
                }

                // Potential values: 'protection-sysop', 'protection-autoconfirmed',
                // 'protection-sysop-cascade' etc.
                // If the wiki has more protection levels, the additional ids that get
                // added take the form 'protection-<protectionLevel>' and
                // 'protection-<protectionLevel>-cascade'.
                $protectionIndicatorId = 'protection-' . $protectionLevel;
                $protectionIndicatorId .= ( $isCascadeProtected ? '-cascade' : '' );

                // Messages 'protection-indicator-title', 'protection-indicator-title-infinity'
                $protectionMsg = $outputPage->msg( $protectionMsg, $protectionLevel, $formattedProtectionExpiry )->text();

                // Use a trick similar to the one used in Action::addHelpLink() to allow wikis
                // to customize where the help link points to.
                $protectionHelpLink = $outputPage->msg( $protectionIndicatorId . '-helppage' );
                if ( $protectionHelpLink->isDisabled() ) {
                        $protectionHelpLink = 'https://mediawiki.org/wiki/Special:MyLanguage/Help:Protection';
                } else {
                        $protectionHelpLink = $protectionHelpLink->text();
                }

                $outputPage->setIndicators( [
                        $protectionIndicatorId => Html::rawElement( 'a', [
                                'class' => 'mw-protection-indicator-icon--lock',
                                'title' => $protectionMsg,
                                'href' => $protectionHelpLink
                        ],
                        // Screen reader-only text describing the same thing as
                        // was mentioned in the title attribute.
                        Html::element( 'span', [], $protectionMsg ) )
                ] );

                $outputPage->addModuleStyles( 'mediawiki.protectionIndicators.styles' );
        }

        /**
         * Determines the desired ParserOutput and passes it to $outputPage.
         *
         * @param Authority $performer
         * @param ParserOptions $parserOptions
         * @param int $oldid
         * @param OutputPage $outputPage
         * @param array $textOptions
         *
         * @return bool True if further processing like footer generation should be applied,
         *              false to skip further processing.
         */
        private function generateContentOutput(
                Authority $performer,
                ParserOptions $parserOptions,
                int $oldid,
                OutputPage $outputPage,
                array $textOptions
        ): bool {
                # Should the parser cache be used?
                $useParserCache = true;
                $pOutput = null;
                $parserOutputAccess = MediaWikiServices::getInstance()->getParserOutputAccess();

                // NOTE: $outputDone and $useParserCache may be changed by the hook
                $this->getHookRunner()->onArticleViewHeader( $this, $outputDone, $useParserCache );
                if ( $outputDone ) {
                        if ( $outputDone instanceof ParserOutput ) {
                                $pOutput = $outputDone;
                        }

                        if ( $pOutput ) {
                                $this->doOutputMetaData( $pOutput, $outputPage );
                        }
                        return true;
                }

                // Early abort if the page doesn't exist
                if ( !$this->mPage->exists() ) {
                        wfDebug( __METHOD__ . ": showing missing article" );
                        $this->showMissingArticle();
                        $this->mPage->doViewUpdates( $performer );
                        return false; // skip all further output to OutputPage
                }

                // Try the latest parser cache
                // NOTE: try latest-revision cache first to avoid loading revision.
                if ( $useParserCache && !$oldid ) {
                        $pOutput = $parserOutputAccess->getCachedParserOutput(
                                $this->getPage(),
                                $parserOptions,
                                null,
                                ParserOutputAccess::OPT_NO_AUDIENCE_CHECK // we already checked
                        );

                        if ( $pOutput ) {
                                $this->doOutputFromParserCache( $pOutput, $outputPage, $textOptions );
                                $this->doOutputMetaData( $pOutput, $outputPage );
                                return true;
                        }
                }

                $rev = $this->fetchRevisionRecord();
                if ( !$this->fetchResult->isOK() ) {
                        $this->showViewError( $this->fetchResult->getWikiText(
                                false, false, $this->getContext()->getLanguage()
                        ) );
                        return true;
                }

                # Are we looking at an old revision
                if ( $oldid ) {
                        $this->setOldSubtitle( $oldid );

                        if ( !$this->showDeletedRevisionHeader() ) {
                                wfDebug( __METHOD__ . ": cannot view deleted revision" );
                                return false; // skip all further output to OutputPage
                        }

                        // Try the old revision parser cache
                        // NOTE: Repeating cache check for old revision to avoid fetching $rev
                        // before it's absolutely necessary.
                        if ( $useParserCache ) {
                                $pOutput = $parserOutputAccess->getCachedParserOutput(
                                        $this->getPage(),
                                        $parserOptions,
                                        $rev,
                                        ParserOutputAccess::OPT_NO_AUDIENCE_CHECK // we already checked in fetchRevisionRecord
                                );

                                if ( $pOutput ) {
                                        $this->doOutputFromParserCache( $pOutput, $outputPage, $textOptions );
                                        $this->doOutputMetaData( $pOutput, $outputPage );
                                        return true;
                                }
                        }
                }

                # Ensure that UI elements requiring revision ID have
                # the correct version information. (This may be overwritten after creation of ParserOutput)
                $outputPage->setRevisionId( $this->getRevIdFetched() );
                $outputPage->setRevisionIsCurrent( $rev->isCurrent() );
                # Preload timestamp to avoid a DB hit
                $outputPage->setRevisionTimestamp( $rev->getTimestamp() );

                # Pages containing custom CSS or JavaScript get special treatment
                if ( $this->getTitle()->isSiteConfigPage() || $this->getTitle()->isUserConfigPage() ) {
                        $dir = $this->getContext()->getLanguage()->getDir();
                        $lang = $this->getContext()->getLanguage()->getHtmlCode();

                        $outputPage->wrapWikiMsg(
                                "<div id='mw-clearyourcache' lang='$lang' dir='$dir' class='mw-content-$dir'>\n$1\n</div>",
                                'clearyourcache'
                        );
                        $outputPage->addModuleStyles( 'mediawiki.action.styles' );
                } elseif ( !$this->getHookRunner()->onArticleRevisionViewCustom(
                        $rev,
                        $this->getTitle(),
                        $oldid,
                        $outputPage )
                ) {
                        // NOTE: sync with hooks called in DifferenceEngine::renderNewRevision()
                        // Allow extensions do their own custom view for certain pages
                        $this->doOutputMetaData( $pOutput, $outputPage );
                        return true;
                }

                # Run the parse, protected by a pool counter
                wfDebug( __METHOD__ . ": doing uncached parse" );

                $opt = 0;

                // we already checked the cache in case 2, don't check again.
                $opt |= ParserOutputAccess::OPT_NO_CHECK_CACHE;

                // we already checked in fetchRevisionRecord()
                $opt |= ParserOutputAccess::OPT_NO_AUDIENCE_CHECK;

                // enable stampede protection and allow stale content
                $opt |= ParserOutputAccess::OPT_FOR_ARTICLE_VIEW;

                // Attempt to trigger WikiPage::triggerOpportunisticLinksUpdate
                // Ideally this should not be the responsibility of the ParserCache to control this.
                // See https://phabricator.wikimedia.org/T329842#8816557 for more context.
                $opt |= ParserOutputAccess::OPT_LINKS_UPDATE;

                if ( !$rev->getId() || !$useParserCache ) {
                        // fake revision or uncacheable options
                        $opt |= ParserOutputAccess::OPT_NO_CACHE;
                }

                $renderStatus = $parserOutputAccess->getParserOutput(
                        $this->getPage(),
                        $parserOptions,
                        $rev,
                        $opt
                );

                // T327164: If parsoid cache warming is enabled, we want to ensure that the page
                // the user is currently looking at has a cached parsoid rendering, in case they
                // open visual editor. The cache entry would typically be missing if it has expired
                // from the cache or it was invalidated by RefreshLinksJob. When "traditional"
                // parser output has been invalidated by RefreshLinksJob, we will render it on
                // the fly when a user requests the page, and thereby populate the cache again,
                // per the code above.
                // The code below is intended to do the same for parsoid output, but asynchronously
                // in a job, so the user does not have to wait.
                // Note that we get here if the traditional parser output was missing from the cache.
                // We do not check if the parsoid output is present in the cache, because that check
                // takes time. The assumption is that if we have traditional parser output
                // cached, we probably also have parsoid output cached.
                // So we leave it to ParsoidCachePrewarmJob to determine whether or not parsing is
                // needed.
                if ( $oldid === 0 || $oldid === $this->getPage()->getLatest() ) {
                        $parsoidCacheWarmingEnabled = $this->getContext()->getConfig()
                                ->get( MainConfigNames::ParsoidCacheConfig )['WarmParsoidParserCache'];

                        if ( $parsoidCacheWarmingEnabled ) {
                                $parsoidJobSpec = ParsoidCachePrewarmJob::newSpec(
                                        $rev->getId(),
                                        $this->getPage()->toPageRecord(),
                                        [ 'causeAction' => 'view' ]
                                );
                                $this->jobQueueGroup->lazyPush( $parsoidJobSpec );
                        }
                }

                $this->doOutputFromRenderStatus(
                        $rev,
                        $renderStatus,
                        $outputPage,
                        $textOptions
                );

                if ( !$renderStatus->isOK() ) {
                        return true;
                }

                $pOutput = $renderStatus->getValue();
                $this->doOutputMetaData( $pOutput, $outputPage );
                return true;
        }

        /**
         * @param ?ParserOutput $pOutput
         * @param OutputPage $outputPage
         */
        private function doOutputMetaData( ?ParserOutput $pOutput, OutputPage $outputPage ) {
                # Adjust title for main page & pages with displaytitle
                if ( $pOutput ) {
                        $this->adjustDisplayTitle( $pOutput );

                        // It would be nice to automatically set this during the first call
                        // to OutputPage::addParserOutputMetadata, but we can't because doing
                        // so would break non-pageview actions where OutputPage::getContLangForJS
                        // has different requirements.
                        $pageLang = $pOutput->getLanguage();
                        if ( $pageLang ) {
                                $outputPage->setContentLangForJS( $pageLang );
                        }
                }

                # Check for any __NOINDEX__ tags on the page using $pOutput
                $policy = $this->getRobotPolicy( 'view', $pOutput ?: null );
                $outputPage->getMetadata()->setIndexPolicy( $policy['index'] );
                $outputPage->setFollowPolicy( $policy['follow'] ); // FIXME: test this

                $this->mParserOutput = $pOutput;
        }

        /**
         * @param ParserOutput $pOutput
         * @param OutputPage $outputPage
         * @param array $textOptions
         */
        private function doOutputFromParserCache(
                ParserOutput $pOutput,
                OutputPage $outputPage,
                array $textOptions
        ) {
                # Ensure that UI elements requiring revision ID have
                # the correct version information.
                $oldid = $pOutput->getCacheRevisionId() ?? $this->getRevIdFetched();
                $outputPage->setRevisionId( $oldid );
                $outputPage->setRevisionIsCurrent( $oldid === $this->mPage->getLatest() );
                $outputPage->addParserOutput( $pOutput, $textOptions );
                # Preload timestamp to avoid a DB hit
                $cachedTimestamp = $pOutput->getRevisionTimestamp();
                if ( $cachedTimestamp !== null ) {
                        $outputPage->setRevisionTimestamp( $cachedTimestamp );
                        $this->mPage->setTimestamp( $cachedTimestamp );
                }
        }

        /**
         * @param RevisionRecord $rev
         * @param Status $renderStatus
         * @param OutputPage $outputPage
         * @param array $textOptions
         */
        private function doOutputFromRenderStatus(
                RevisionRecord $rev,
                Status $renderStatus,
                OutputPage $outputPage,
                array $textOptions
        ) {
                $context = $this->getContext();
                if ( !$renderStatus->isOK() ) {
                        $this->showViewError( $renderStatus->getWikiText(
                                false, 'view-pool-error', $context->getLanguage()
                        ) );
                        return;
                }

                $pOutput = $renderStatus->getValue();

                // Cache stale ParserOutput object with a short expiry
                if ( $renderStatus->hasMessage( 'view-pool-dirty-output' ) ) {
                        $outputPage->lowerCdnMaxage( $context->getConfig()->get( MainConfigNames::CdnMaxageStale ) );
                        $outputPage->setLastModified( $pOutput->getCacheTime() );
                        $staleReason = $renderStatus->hasMessage( 'view-pool-contention' )
                                ? $context->msg( 'view-pool-contention' )->escaped()
                                : $context->msg( 'view-pool-timeout' )->escaped();
                        $outputPage->addHTML( "<!-- parser cache is expired, " .
                                "sending anyway due to $staleReason-->\n" );

                        // Ensure OutputPage knowns the id from the dirty cache, but keep the current flag (T341013)
                        $cachedId = $pOutput->getCacheRevisionId();
                        if ( $cachedId !== null ) {
                                $outputPage->setRevisionId( $cachedId );
                                $outputPage->setRevisionTimestamp( $pOutput->getTimestamp() );
                        }
                }

                $outputPage->addParserOutput( $pOutput, $textOptions );

                if ( $this->getRevisionRedirectTarget( $rev ) ) {
                        $outputPage->addSubtitle( "<span id=\"redirectsub\">" .
                                $context->msg( 'redirectpagesub' )->parse() . "</span>" );
                }
        }

        /**
         * @param RevisionRecord $revision
         * @return null|Title
         */
        private function getRevisionRedirectTarget( RevisionRecord $revision ) {
                // TODO: find a *good* place for the code that determines the redirect target for
                // a given revision!
                // NOTE: Use main slot content. Compare code in DerivedPageDataUpdater::revisionIsRedirect.
                $content = $revision->getContent( SlotRecord::MAIN );
                return $content ? $content->getRedirectTarget() : null;
        }

        /**
         * Adjust title for pages with displaytitle, -{T|}- or language conversion
         * @param ParserOutput $pOutput
         */
        public function adjustDisplayTitle( ParserOutput $pOutput ) {
                $out = $this->getContext()->getOutput();

                # Adjust the title if it was set by displaytitle, -{T|}- or language conversion
                $titleText = $pOutput->getTitleText();
                if ( strval( $titleText ) !== '' ) {
                        $out->setPageTitle( $titleText );
                        $out->setDisplayTitle( $titleText );
                }
        }

        /**
         * Show a diff page according to current request variables. For use within
         * Article::view() only, other callers should use the DifferenceEngine class.
         */
        protected function showDiffPage() {
                $context = $this->getContext();
                $outputPage = $context->getOutput();
                $outputPage->addBodyClasses( 'mw-article-diff' );
                $request = $context->getRequest();
                $diff = $request->getVal( 'diff' );
                $rcid = $request->getInt( 'rcid' );
                $purge = $request->getRawVal( 'action' ) === 'purge';
                $unhide = $request->getInt( 'unhide' ) === 1;
                $oldid = $this->getOldID();

                $rev = $this->fetchRevisionRecord();

                if ( !$rev ) {
                        // T213621: $rev maybe null due to either lack of permission to view the
                        // revision or actually not existing. So let's try loading it from the id
                        $rev = $this->revisionStore->getRevisionById( $oldid );
                        if ( $rev ) {
                                // Revision exists but $user lacks permission to diff it.
                                // Do nothing here.
                                // The $rev will later be used to create standard diff elements however.
                        } else {
                                $outputPage->setPageTitleMsg( $context->msg( 'errorpagetitle' ) );
                                $msg = $context->msg( 'difference-missing-revision' )
                                        ->params( $oldid )
                                        ->numParams( 1 )
                                        ->parseAsBlock();
                                $outputPage->addHTML( $msg );
                                return;
                        }
                }

                $services = MediaWikiServices::getInstance();

                $contentHandler = $services
                        ->getContentHandlerFactory()
                        ->getContentHandler(
                                $rev->getMainContentModel()
                        );
                $de = $contentHandler->createDifferenceEngine(
                        $context,
                        $oldid,
                        $diff,
                        $rcid,
                        $purge,
                        $unhide
                );

                $diffType = $request->getVal( 'diff-type' );

                if ( $diffType === null ) {
                        $diffType = $this->userOptionsLookup
                                ->getOption( $context->getUser(), 'diff-type' );
                } else {
                        $de->setExtraQueryParams( [ 'diff-type' => $diffType ] );
                }

                $de->setSlotDiffOptions( [
                        'diff-type' => $diffType,
                        'expand-url' => $this->viewIsRenderAction,
                        'inline-toggle' => true,
                ] );
                $de->showDiffPage( $this->isDiffOnlyView() );

                // Run view updates for the newer revision being diffed (and shown
                // below the diff if not diffOnly).
                [ , $new ] = $de->mapDiffPrevNext( $oldid, $diff );
                // New can be false, convert it to 0 - this conveniently means the latest revision
                $this->mPage->doViewUpdates( $context->getAuthority(), (int)$new );

                // Add link to help page; see T321569
                $context->getOutput()->addHelpLink( 'Help:Diff' );
        }

        protected function isDiffOnlyView() {
                return $this->getContext()->getRequest()->getBool(
                        'diffonly',
                        $this->userOptionsLookup->getBoolOption( $this->getContext()->getUser(), 'diffonly' )
                );
        }

        /**
         * Get the robot policy to be used for the current view
         * @param string $action The action= GET parameter
         * @param ParserOutput|null $pOutput
         * @return string[] The policy that should be set
         * @todo actions other than 'view'
         */
        public function getRobotPolicy( $action, ?ParserOutput $pOutput = null ) {
                $context = $this->getContext();
                $mainConfig = $context->getConfig();
                $articleRobotPolicies = $mainConfig->get( MainConfigNames::ArticleRobotPolicies );
                $namespaceRobotPolicies = $mainConfig->get( MainConfigNames::NamespaceRobotPolicies );
                $defaultRobotPolicy = $mainConfig->get( MainConfigNames::DefaultRobotPolicy );
                $title = $this->getTitle();
                $ns = $title->getNamespace();

                # Don't index user and user talk pages for blocked users (T13443)
                if ( $ns === NS_USER || $ns === NS_USER_TALK ) {
                        $specificTarget = null;
                        $vagueTarget = null;
                        $titleText = $title->getText();
                        if ( IPUtils::isValid( $titleText ) ) {
                                $vagueTarget = $titleText;
                        } else {
                                $specificTarget = $title->getRootText();
                        }
                        if ( $this->blockStore->newFromTarget( $specificTarget, $vagueTarget ) instanceof DatabaseBlock ) {
                                return [
                                        'index' => 'noindex',
                                        'follow' => 'nofollow'
                                ];
                        }
                }

                if ( $this->mPage->getId() === 0 || $this->getOldID() ) {
                        # Non-articles (special pages etc), and old revisions
                        return [
                                'index' => 'noindex',
                                'follow' => 'nofollow'
                        ];
                } elseif ( $context->getOutput()->isPrintable() ) {
                        # Discourage indexing of printable versions, but encourage following
                        return [
                                'index' => 'noindex',
                                'follow' => 'follow'
                        ];
                } elseif ( $context->getRequest()->getInt( 'curid' ) ) {
                        # For ?curid=x urls, disallow indexing
                        return [
                                'index' => 'noindex',
                                'follow' => 'follow'
                        ];
                }

                # Otherwise, construct the policy based on the various config variables.
                $policy = self::formatRobotPolicy( $defaultRobotPolicy );

                if ( isset( $namespaceRobotPolicies[$ns] ) ) {
                        # Honour customised robot policies for this namespace
                        $policy = array_merge(
                                $policy,
                                self::formatRobotPolicy( $namespaceRobotPolicies[$ns] )
                        );
                }
                if ( $title->canUseNoindex() && $pOutput && $pOutput->getIndexPolicy() ) {
                        # __INDEX__ and __NOINDEX__ magic words, if allowed. Incorporates
                        # a final check that we have really got the parser output.
                        $policy = array_merge(
                                $policy,
                                [ 'index' => $pOutput->getIndexPolicy() ]
                        );
                }

                if ( isset( $articleRobotPolicies[$title->getPrefixedText()] ) ) {
                        # (T16900) site config can override user-defined __INDEX__ or __NOINDEX__
                        $policy = array_merge(
                                $policy,
                                self::formatRobotPolicy( $articleRobotPolicies[$title->getPrefixedText()] )
                        );
                }

                return $policy;
        }

        /**
         * Converts a String robot policy into an associative array, to allow
         * merging of several policies using array_merge().
         * @param array|string $policy Returns empty array on null/false/'', transparent
         *   to already-converted arrays, converts string.
         * @return array 'index' => \<indexpolicy\>, 'follow' => \<followpolicy\>
         */
        public static function formatRobotPolicy( $policy ) {
                if ( is_array( $policy ) ) {
                        return $policy;
                } elseif ( !$policy ) {
                        return [];
                }

                $arr = [];
                foreach ( explode( ',', $policy ) as $var ) {
                        $var = trim( $var );
                        if ( $var === 'index' || $var === 'noindex' ) {
                                $arr['index'] = $var;
                        } elseif ( $var === 'follow' || $var === 'nofollow' ) {
                                $arr['follow'] = $var;
                        }
                }

                return $arr;
        }

        /**
         * If this request is a redirect view, send "redirected from" subtitle to
         * the output. Returns true if the header was needed, false if this is not
         * a redirect view. Handles both local and remote redirects.
         *
         * @return bool
         */
        public function showRedirectedFromHeader() {
                $context = $this->getContext();
                $redirectSources = $context->getConfig()->get( MainConfigNames::RedirectSources );
                $outputPage = $context->getOutput();
                $request = $context->getRequest();
                $rdfrom = $request->getVal( 'rdfrom' );

                // Construct a URL for the current page view, but with the target title
                $query = $request->getQueryValues();
                unset( $query['rdfrom'] );
                unset( $query['title'] );
                if ( $this->getTitle()->isRedirect() ) {
                        // Prevent double redirects
                        $query['redirect'] = 'no';
                }
                $redirectTargetUrl = $this->getTitle()->getLinkURL( $query );

                if ( $this->mRedirectedFrom ) {
                        // This is an internally redirected page view.
                        // We'll need a backlink to the source page for navigation.
                        if ( $this->getHookRunner()->onArticleViewRedirect( $this ) ) {
                                $redir = $this->linkRenderer->makeKnownLink(
                                        $this->mRedirectedFrom,
                                        null,
                                        [],
                                        [ 'redirect' => 'no' ]
                                );

                                $outputPage->addSubtitle( "<span class=\"mw-redirectedfrom\">" .
                                        $context->msg( 'redirectedfrom' )->rawParams( $redir )->parse()
                                . "</span>" );

                                // Add the script to update the displayed URL and
                                // set the fragment if one was specified in the redirect
                                $outputPage->addJsConfigVars( [
                                        'wgInternalRedirectTargetUrl' => $redirectTargetUrl,
                                ] );
                                $outputPage->addModules( 'mediawiki.action.view.redirect' );

                                // Add a <link rel="canonical"> tag
                                $outputPage->setCanonicalUrl( $this->getTitle()->getCanonicalURL() );

                                // Tell the output object that the user arrived at this article through a redirect
                                $outputPage->setRedirectedFrom( $this->mRedirectedFrom );

                                return true;
                        }
                } elseif ( $rdfrom ) {
                        // This is an externally redirected view, from some other wiki.
                        // If it was reported from a trusted site, supply a backlink.
                        if ( $redirectSources && preg_match( $redirectSources, $rdfrom ) ) {
                                $redir = $this->linkRenderer->makeExternalLink( $rdfrom, $rdfrom, $this->getTitle() );
                                $outputPage->addSubtitle( "<span class=\"mw-redirectedfrom\">" .
                                        $context->msg( 'redirectedfrom' )->rawParams( $redir )->parse()
                                . "</span>" );

                                // Add the script to update the displayed URL
                                $outputPage->addJsConfigVars( [
                                        'wgInternalRedirectTargetUrl' => $redirectTargetUrl,
                                ] );
                                $outputPage->addModules( 'mediawiki.action.view.redirect' );

                                return true;
                        }
                }

                return false;
        }

        /**
         * Show a header specific to the namespace currently being viewed, like
         * [[MediaWiki:Talkpagetext]]. For Article::view().
         */
        public function showNamespaceHeader() {
                if ( $this->getTitle()->isTalkPage() && !$this->getContext()->msg( 'talkpageheader' )->isDisabled() ) {
                        $this->getContext()->getOutput()->wrapWikiMsg(
                                "<div class=\"mw-talkpageheader\">\n$1\n</div>",
                                [ 'talkpageheader' ]
                        );
                }
        }

        /**
         * Show the footer section of an ordinary page view
         */
        public function showViewFooter() {
                # check if we're displaying a [[User talk:x.x.x.x]] anonymous talk page
                if ( $this->getTitle()->getNamespace() === NS_USER_TALK
                        && IPUtils::isValid( $this->getTitle()->getText() )
                ) {
                        $this->getContext()->getOutput()->addWikiMsg( 'anontalkpagetext' );
                }

                // Show a footer allowing the user to patrol the shown revision or page if possible
                $patrolFooterShown = $this->showPatrolFooter();

                $this->getHookRunner()->onArticleViewFooter( $this, $patrolFooterShown );
        }

        /**
         * If patrol is possible, output a patrol UI box. This is called from the
         * footer section of ordinary page views. If patrol is not possible or not
         * desired, does nothing.
         *
         * Side effect: When the patrol link is build, this method will call
         * OutputPage::setPreventClickjacking(true) and load a JS module.
         *
         * @return bool
         */
        public function showPatrolFooter() {
                $context = $this->getContext();
                $mainConfig = $context->getConfig();
                $useNPPatrol = $mainConfig->get( MainConfigNames::UseNPPatrol );
                $useRCPatrol = $mainConfig->get( MainConfigNames::UseRCPatrol );
                $useFilePatrol = $mainConfig->get( MainConfigNames::UseFilePatrol );
                // Allow hooks to decide whether to not output this at all
                if ( !$this->getHookRunner()->onArticleShowPatrolFooter( $this ) ) {
                        return false;
                }

                $outputPage = $context->getOutput();
                $user = $context->getUser();
                $title = $this->getTitle();
                $rc = false;

                if ( !$context->getAuthority()->probablyCan( 'patrol', $title )
                        || !( $useRCPatrol || $useNPPatrol
                                || ( $useFilePatrol && $title->inNamespace( NS_FILE ) ) )
                ) {
                        // Patrolling is disabled or the user isn't allowed to
                        return false;
                }

                if ( $this->mRevisionRecord
                        && !RecentChange::isInRCLifespan( $this->mRevisionRecord->getTimestamp(), 21600 )
                ) {
                        // The current revision is already older than what could be in the RC table
                        // 6h tolerance because the RC might not be cleaned out regularly
                        return false;
                }

                // Check for cached results
                $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
                $key = $cache->makeKey( 'unpatrollable-page', $title->getArticleID() );
                if ( $cache->get( $key ) ) {
                        return false;
                }

                $dbr = $this->dbProvider->getReplicaDatabase();
                $oldestRevisionRow = $dbr->newSelectQueryBuilder()
                        ->select( [ 'rev_id', 'rev_timestamp' ] )
                        ->from( 'revision' )
                        ->where( [ 'rev_page' => $title->getArticleID() ] )
                        ->orderBy( [ 'rev_timestamp', 'rev_id' ] )
                        ->caller( __METHOD__ )->fetchRow();
                $oldestRevisionTimestamp = $oldestRevisionRow ? $oldestRevisionRow->rev_timestamp : false;

                // New page patrol: Get the timestamp of the oldest revision which
                // the revision table holds for the given page. Then we look
                // whether it's within the RC lifespan and if it is, we try
                // to get the recentchanges row belonging to that entry.
                $recentPageCreation = false;
                if ( $oldestRevisionTimestamp
                        && RecentChange::isInRCLifespan( $oldestRevisionTimestamp, 21600 )
                ) {
                        // 6h tolerance because the RC might not be cleaned out regularly
                        $recentPageCreation = true;
                        $rc = RecentChange::newFromConds(
                                [
                                        'rc_this_oldid' => intval( $oldestRevisionRow->rev_id ),
                                        // Avoid selecting a categorization entry
                                        'rc_type' => RC_NEW,
                                ],
                                __METHOD__
                        );
                        if ( $rc ) {
                                // Use generic patrol message for new pages
                                $markPatrolledMsg = $context->msg( 'markaspatrolledtext' );
                        }
                }

                // File patrol: Get the timestamp of the latest upload for this page,
                // check whether it is within the RC lifespan and if it is, we try
                // to get the recentchanges row belonging to that entry
                // (with rc_type = RC_LOG, rc_log_type = upload).
                $recentFileUpload = false;
                if ( ( !$rc || $rc->getAttribute( 'rc_patrolled' ) ) && $useFilePatrol
                        && $title->getNamespace() === NS_FILE ) {
                        // Retrieve timestamp from the current file (lastest upload)
                        $newestUploadTimestamp = $dbr->newSelectQueryBuilder()
                                ->select( 'img_timestamp' )
                                ->from( 'image' )
                                ->where( [ 'img_name' => $title->getDBkey() ] )
                                ->caller( __METHOD__ )->fetchField();
                        if ( $newestUploadTimestamp
                                && RecentChange::isInRCLifespan( $newestUploadTimestamp, 21600 )
                        ) {
                                // 6h tolerance because the RC might not be cleaned out regularly
                                $recentFileUpload = true;
                                $rc = RecentChange::newFromConds(
                                        [
                                                'rc_type' => RC_LOG,
                                                'rc_log_type' => 'upload',
                                                'rc_timestamp' => $newestUploadTimestamp,
                                                'rc_namespace' => NS_FILE,
                                                'rc_cur_id' => $title->getArticleID()
                                        ],
                                        __METHOD__
                                );
                                if ( $rc ) {
                                        // Use patrol message specific to files
                                        $markPatrolledMsg = $context->msg( 'markaspatrolledtext-file' );
                                }
                        }
                }

                if ( !$recentPageCreation && !$recentFileUpload ) {
                        // Page creation and latest upload (for files) is too old to be in RC

                        // We definitely can't patrol so cache the information
                        // When a new file version is uploaded, the cache is cleared
                        $cache->set( $key, '1' );

                        return false;
                }

                if ( !$rc ) {
                        // Don't cache: This can be hit if the page gets accessed very fast after
                        // its creation / latest upload or in case we have high replica DB lag. In case
                        // the revision is too old, we will already return above.
                        return false;
                }

                if ( $rc->getAttribute( 'rc_patrolled' ) ) {
                        // Patrolled RC entry around

                        // Cache the information we gathered above in case we can't patrol
                        // Don't cache in case we can patrol as this could change
                        $cache->set( $key, '1' );

                        return false;
                }

                if ( $rc->getPerformerIdentity()->equals( $user ) ) {
                        // Don't show a patrol link for own creations/uploads. If the user could
                        // patrol them, they already would be patrolled
                        return false;
                }

                $outputPage->getMetadata()->setPreventClickjacking( true );
                $outputPage->addModules( 'mediawiki.misc-authed-curate' );

                $link = $this->linkRenderer->makeKnownLink(
                        $title,
                        new HtmlArmor( '<button class="cdx-button cdx-button--action-progressive">'
                                // @phan-suppress-next-line PhanPossiblyUndeclaredVariable $markPatrolledMsg is always set
                                . $markPatrolledMsg->escaped() . '</button>' ),
                        [],
                        [
                                'action' => 'markpatrolled',
                                'rcid' => $rc->getAttribute( 'rc_id' ),
                        ]
                );

                $outputPage->addModuleStyles( 'mediawiki.action.styles' );
                $outputPage->addHTML( "<div class='patrollink' data-mw='interface'>$link</div>" );

                return true;
        }

        /**
         * Purge the cache used to check if it is worth showing the patrol footer
         * For example, it is done during re-uploads when file patrol is used.
         * @param int $articleID ID of the article to purge
         * @since 1.27
         */
        public static function purgePatrolFooterCache( $articleID ) {
                $cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
                $cache->delete( $cache->makeKey( 'unpatrollable-page', $articleID ) );
        }

        /**
         * Show the error text for a missing article. For articles in the MediaWiki
         * namespace, show the default message text. To be called from Article::view().
         */
        public function showMissingArticle() {
                $context = $this->getContext();
                $send404Code = $context->getConfig()->get( MainConfigNames::Send404Code );

                $outputPage = $context->getOutput();
                // Whether the page is a root user page of an existing user (but not a subpage)
                $validUserPage = false;

                $title = $this->getTitle();

                $services = MediaWikiServices::getInstance();

                $contextUser = $context->getUser();

                # Show info in user (talk) namespace. Does the user exist? Is he blocked?
                if ( $title->getNamespace() === NS_USER
                        || $title->getNamespace() === NS_USER_TALK
                ) {
                        $rootPart = $title->getRootText();
                        $userFactory = $services->getUserFactory();
                        $user = $userFactory->newFromNameOrIp( $rootPart );

                        $block = $this->blockStore->newFromTarget( $user, $user );

                        if ( $user && $user->isRegistered() && $user->isHidden() &&
                                !$context->getAuthority()->isAllowed( 'hideuser' )
                        ) {
                                // T120883 if the user is hidden and the viewer cannot see hidden
                                // users, pretend like it does not exist at all.
                                $user = false;
                        }

                        if ( !( $user && $user->isRegistered() ) && !$this->userNameUtils->isIP( $rootPart ) ) {
                                $this->addMessageBoxStyles( $outputPage );
                                // User does not exist
                                $outputPage->addHTML( Html::warningBox(
                                        $context->msg( 'userpage-userdoesnotexist-view', wfEscapeWikiText( $rootPart ) )->parse(),
                                        'mw-userpage-userdoesnotexist'
                                ) );

                                // Show renameuser log extract
                                LogEventsList::showLogExtract(
                                        $outputPage,
                                        'renameuser',
                                        Title::makeTitleSafe( NS_USER, $rootPart ),
                                        '',
                                        [
                                                'lim' => 10,
                                                'showIfEmpty' => false,
                                                'msgKey' => [ 'renameuser-renamed-notice', $title->getBaseText() ]
                                        ]
                                );
                        } elseif (
                                $user && $block !== null &&
                                $block->getType() != DatabaseBlock::TYPE_AUTO &&
                                (
                                        $block->isSitewide() ||
                                        $services->getPermissionManager()->isBlockedFrom( $user, $title, true )
                                )
                        ) {
                                // Show log extract if the user is sitewide blocked or is partially
                                // blocked and not allowed to edit their user page or user talk page
                                LogEventsList::showLogExtract(
                                        $outputPage,
                                        'block',
                                        $services->getNamespaceInfo()->getCanonicalName( NS_USER ) . ':' .
                                                $block->getTargetName(),
                                        '',
                                        [
                                                'lim' => 1,
                                                'showIfEmpty' => false,
                                                'msgKey' => [
                                                        'blocked-notice-logextract',
                                                        $user->getName() # Support GENDER in notice
                                                ]
                                        ]
                                );
                                $validUserPage = !$title->isSubpage();
                        } else {
                                $validUserPage = !$title->isSubpage();
                        }
                }

                $this->getHookRunner()->onShowMissingArticle( $this );

                # Show delete and move logs if there were any such events.
                # The logging query can DOS the site when bots/crawlers cause 404 floods,
                # so be careful showing this. 404 pages must be cheap as they are hard to cache.
                $dbCache = MediaWikiServices::getInstance()->getMainObjectStash();
                $key = $dbCache->makeKey( 'page-recent-delete', md5( $title->getPrefixedText() ) );
                $isRegistered = $contextUser->isRegistered();
                $sessionExists = $context->getRequest()->getSession()->isPersistent();

                if ( $isRegistered || $dbCache->get( $key ) || $sessionExists ) {
                        $logTypes = [ 'delete', 'move', 'protect', 'merge' ];

                        $dbr = $this->dbProvider->getReplicaDatabase();

                        $conds = [ $dbr->expr( 'log_action', '!=', 'revision' ) ];
                        // Give extensions a chance to hide their (unrelated) log entries
                        $this->getHookRunner()->onArticle__MissingArticleConditions( $conds, $logTypes );
                        LogEventsList::showLogExtract(
                                $outputPage,
                                $logTypes,
                                $title,
                                '',
                                [
                                        'lim' => 10,
                                        'conds' => $conds,
                                        'showIfEmpty' => false,
                                        'msgKey' => [ $isRegistered || $sessionExists
                                                ? 'moveddeleted-notice'
                                                : 'moveddeleted-notice-recent'
                                        ]
                                ]
                        );
                }

                if ( !$this->mPage->hasViewableContent() && $send404Code && !$validUserPage ) {
                        // If there's no backing content, send a 404 Not Found
                        // for better machine handling of broken links.
                        $context->getRequest()->response()->statusHeader( 404 );
                }

                // Also apply the robot policy for nonexisting pages (even if a 404 was used)
                $policy = $this->getRobotPolicy( 'view' );
                $outputPage->getMetadata()->setIndexPolicy( $policy['index'] );
                $outputPage->setFollowPolicy( $policy['follow'] );

                $hookResult = $this->getHookRunner()->onBeforeDisplayNoArticleText( $this );

                if ( !$hookResult ) {
                        return;
                }

                # Show error message
                $oldid = $this->getOldID();
                if ( !$oldid && $title->getNamespace() === NS_MEDIAWIKI && $title->hasSourceText() ) {
                        $text = $this->getTitle()->getDefaultMessageText() ?? '';
                        $outputPage->addWikiTextAsContent( $text );
                } else {
                        if ( $oldid ) {
                                $text = $this->getMissingRevisionMsg( $oldid )->plain();
                        } elseif ( $context->getAuthority()->probablyCan( 'edit', $title ) ) {
                                $message = $isRegistered ? 'noarticletext' : 'noarticletextanon';
                                $text = $context->msg( $message )->plain();
                        } else {
                                $text = $context->msg( 'noarticletext-nopermission' )->plain();
                        }

                        $dir = $context->getLanguage()->getDir();
                        $lang = $context->getLanguage()->getHtmlCode();
                        $outputPage->addWikiTextAsInterface( Xml::openElement( 'div', [
                                'class' => "noarticletext mw-content-$dir",
                                'dir' => $dir,
                                'lang' => $lang,
                        ] ) . "\n$text\n</div>" );
                }
        }

        /**
         * Show error text for errors generated in Article::view().
         * @param string $errortext localized wikitext error message
         */
        private function showViewError( string $errortext ) {
                $outputPage = $this->getContext()->getOutput();
                $outputPage->setPageTitleMsg( $this->getContext()->msg( 'errorpagetitle' ) );
                $outputPage->disableClientCache();
                $outputPage->setRobotPolicy( 'noindex,nofollow' );
                $outputPage->clearHTML();
                $this->addMessageBoxStyles( $outputPage );
                $outputPage->addHTML( Html::errorBox( $outputPage->parseAsContent( $errortext ) ) );
        }

        /**
         * If the revision requested for view is deleted, check permissions.
         * Send either an error message or a warning header to the output.
         *
         * @return bool True if the view is allowed, false if not.
         */
        public function showDeletedRevisionHeader() {
                if ( !$this->mRevisionRecord->isDeleted( RevisionRecord::DELETED_TEXT ) ) {
                        // Not deleted
                        return true;
                }
                $outputPage = $this->getContext()->getOutput();
                // Used in wikilinks, should not contain whitespaces
                $titleText = $this->getTitle()->getPrefixedDBkey();
                $this->addMessageBoxStyles( $outputPage );
                // If the user is not allowed to see it...
                if ( !$this->mRevisionRecord->userCan(
                        RevisionRecord::DELETED_TEXT,
                        $this->getContext()->getAuthority()
                ) ) {
                        $outputPage->addHTML(
                                Html::warningBox(
                                        $outputPage->msg( 'rev-deleted-text-permission', $titleText )->parse(),
                                        'plainlinks'
                                )
                        );

                        return false;
                // If the user needs to confirm that they want to see it...
                } elseif ( $this->getContext()->getRequest()->getInt( 'unhide' ) !== 1 ) {
                        # Give explanation and add a link to view the revision...
                        $oldid = intval( $this->getOldID() );
                        $link = $this->getTitle()->getFullURL( "oldid={$oldid}&unhide=1" );
                        $msg = $this->mRevisionRecord->isDeleted( RevisionRecord::DELETED_RESTRICTED ) ?
                                'rev-suppressed-text-unhide' : 'rev-deleted-text-unhide';
                        $outputPage->addHTML(
                                Html::warningBox(
                                        $outputPage->msg( $msg, $link )->parse(),
                                        'plainlinks'
                                )
                        );

                        return false;
                // We are allowed to see...
                } else {
                        $msg = $this->mRevisionRecord->isDeleted( RevisionRecord::DELETED_RESTRICTED )
                                ? [ 'rev-suppressed-text-view', $titleText ]
                                : [ 'rev-deleted-text-view', $titleText ];
                        $outputPage->addHTML(
                                Html::warningBox(
                                        $outputPage->msg( $msg[0], $msg[1] )->parse(),
                                        'plainlinks'
                                )
                        );

                        return true;
                }
        }

        /**
         * @param OutputPage $outputPage
         */
        private function addMessageBoxStyles( OutputPage $outputPage ) {
                $outputPage->addModuleStyles( [
                        'mediawiki.codex.messagebox.styles',
                ] );
        }

        /**
         * Generate the navigation links when browsing through an article revisions
         * It shows the information as:
         *   Revision as of \<date\>; view current revision
         *   \<- Previous version | Next Version -\>
         *
         * @param int $oldid Revision ID of this article revision
         */
        public function setOldSubtitle( $oldid = 0 ) {
                if ( !$this->getHookRunner()->onDisplayOldSubtitle( $this, $oldid ) ) {
                        return;
                }

                $context = $this->getContext();
                $unhide = $context->getRequest()->getInt( 'unhide' ) === 1;

                # Cascade unhide param in links for easy deletion browsing
                $extraParams = [];
                if ( $unhide ) {
                        $extraParams['unhide'] = 1;
                }

                if ( $this->mRevisionRecord && $this->mRevisionRecord->getId() === $oldid ) {
                        $revisionRecord = $this->mRevisionRecord;
                } else {
                        $revisionRecord = $this->revisionStore->getRevisionById( $oldid );
                }
                if ( !$revisionRecord ) {
                        throw new LogicException( 'There should be a revision record at this point.' );
                }

                $timestamp = $revisionRecord->getTimestamp();

                $current = ( $oldid == $this->mPage->getLatest() );
                $language = $context->getLanguage();
                $user = $context->getUser();

                $td = $language->userTimeAndDate( $timestamp, $user );
                $tddate = $language->userDate( $timestamp, $user );
                $tdtime = $language->userTime( $timestamp, $user );

                # Show user links if allowed to see them. If hidden, then show them only if requested...
                $userlinks = Linker::revUserTools( $revisionRecord, !$unhide );

                $infomsg = $current && !$context->msg( 'revision-info-current' )->isDisabled()
                        ? 'revision-info-current'
                        : 'revision-info';

                $outputPage = $context->getOutput();
                $outputPage->addModuleStyles( [
                        'mediawiki.action.styles',
                        'mediawiki.interface.helpers.styles'
                ] );

                $revisionUser = $revisionRecord->getUser();
                $revisionInfo = "<div id=\"mw-{$infomsg}\">" .
                        $context->msg( $infomsg, $td )
                                ->rawParams( $userlinks )
                                ->params(
                                        $revisionRecord->getId(),
                                        $tddate,
                                        $tdtime,
                                        $revisionUser ? $revisionUser->getName() : ''
                                )
                                ->rawParams( $this->commentFormatter->formatRevision(
                                        $revisionRecord,
                                        $user,
                                        true,
                                        !$unhide
                                ) )
                                ->parse() .
                        "</div>";

                $lnk = $current
                        ? $context->msg( 'currentrevisionlink' )->escaped()
                        : $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'currentrevisionlink' )->text(),
                                [],
                                $extraParams
                        );
                $curdiff = $current
                        ? $context->msg( 'diff' )->escaped()
                        : $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'diff' )->text(),
                                [],
                                [
                                        'diff' => 'cur',
                                        'oldid' => $oldid
                                ] + $extraParams
                        );
                $prevExist = (bool)$this->revisionStore->getPreviousRevision( $revisionRecord );
                $prevlink = $prevExist
                        ? $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'previousrevision' )->text(),
                                [],
                                [
                                        'direction' => 'prev',
                                        'oldid' => $oldid
                                ] + $extraParams
                        )
                        : $context->msg( 'previousrevision' )->escaped();
                $prevdiff = $prevExist
                        ? $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'diff' )->text(),
                                [],
                                [
                                        'diff' => 'prev',
                                        'oldid' => $oldid
                                ] + $extraParams
                        )
                        : $context->msg( 'diff' )->escaped();
                $nextlink = $current
                        ? $context->msg( 'nextrevision' )->escaped()
                        : $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'nextrevision' )->text(),
                                [],
                                [
                                        'direction' => 'next',
                                        'oldid' => $oldid
                                ] + $extraParams
                        );
                $nextdiff = $current
                        ? $context->msg( 'diff' )->escaped()
                        : $this->linkRenderer->makeKnownLink(
                                $this->getTitle(),
                                $context->msg( 'diff' )->text(),
                                [],
                                [
                                        'diff' => 'next',
                                        'oldid' => $oldid
                                ] + $extraParams
                        );

                $cdel = Linker::getRevDeleteLink(
                        $context->getAuthority(),
                        $revisionRecord,
                        $this->getTitle()
                );
                if ( $cdel !== '' ) {
                        $cdel .= ' ';
                }

                // the outer div is need for styling the revision info and nav in MobileFrontend
                $this->addMessageBoxStyles( $outputPage );
                $outputPage->addSubtitle(
                        Html::warningBox(
                                $revisionInfo .
                                "<div id=\"mw-revision-nav\">" . $cdel .
                                $context->msg( 'revision-nav' )->rawParams(
                                        $prevdiff, $prevlink, $lnk, $curdiff, $nextlink, $nextdiff
                                )->escaped() . "</div>",
                                'mw-revision'
                        )
                );
        }

        /**
         * Return the HTML for the top of a redirect page
         *
         * Chances are you should just be using the ParserOutput from
         * WikitextContent::getParserOutput instead of calling this for redirects.
         *
         * @since 1.23
         * @param Language $lang
         * @param Title $target Destination to redirect
         * @param bool $forceKnown Should the image be shown as a bluelink regardless of existence?
         * @return string Containing HTML with redirect link
         * @deprecated since 1.41, use LinkRenderer::makeRedirectHeader() instead
         */
        public static function getRedirectHeaderHtml( Language $lang, Title $target, $forceKnown = false ) {
                wfDeprecated( __METHOD__, '1.41' );
                $linkRenderer = MediaWikiServices::getInstance()->getLinkRenderer();
                return $linkRenderer->makeRedirectHeader( $lang, $target, $forceKnown );
        }

        /**
         * 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: 'namespace-' + namespace number + '-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 ) {
                $out = $this->getContext()->getOutput();
                $msg = $out->msg( 'namespace-' . $this->getTitle()->getNamespace() . '-helppage' );

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

        /**
         * Handle action=render
         */
        public function render() {
                $this->getContext()->getRequest()->response()->header( 'X-Robots-Tag: noindex' );
                $this->getContext()->getOutput()->setArticleBodyOnly( true );
                // We later set 'enableSectionEditLinks=false' based on this; also used by ImagePage
                $this->viewIsRenderAction = true;
                $this->view();
        }

        /**
         * action=protect handler
         */
        public function protect() {
                $form = new ProtectionForm( $this );
                $form->execute();
        }

        /**
         * action=unprotect handler (alias)
         */
        public function unprotect() {
                $this->protect();
        }

        /* Caching functions */

        /**
         * checkLastModified returns true if it has taken care of all
         * output to the client that is necessary for this request.
         * (that is, it has sent a cached version of the page)
         *
         * @return bool True if cached version send, false otherwise
         */
        protected function tryFileCache() {
                static $called = false;

                if ( $called ) {
                        wfDebug( "Article::tryFileCache(): called twice!?" );
                        return false;
                }

                $called = true;
                if ( $this->isFileCacheable() ) {
                        $cache = new HTMLFileCache( $this->getTitle(), 'view' );
                        if ( $cache->isCacheGood( $this->mPage->getTouched() ) ) {
                                wfDebug( "Article::tryFileCache(): about to load file" );
                                $cache->loadFromFileCache( $this->getContext() );
                                return true;
                        } else {
                                wfDebug( "Article::tryFileCache(): starting buffer" );
                                ob_start( [ &$cache, 'saveToFileCache' ] );
                        }
                } else {
                        wfDebug( "Article::tryFileCache(): not cacheable" );
                }

                return false;
        }

        /**
         * Check if the page can be cached
         * @param int $mode One of the HTMLFileCache::MODE_* constants (since 1.28)
         * @return bool
         */
        public function isFileCacheable( $mode = HTMLFileCache::MODE_NORMAL ) {
                $cacheable = false;

                if ( HTMLFileCache::useFileCache( $this->getContext(), $mode ) ) {
                        $cacheable = $this->mPage->getId()
                                && !$this->mRedirectedFrom && !$this->getTitle()->isRedirect();
                        // Extension may have reason to disable file caching on some pages.
                        if ( $cacheable ) {
                                $cacheable = $this->getHookRunner()->onIsFileCacheable( $this ) ?? false;
                        }
                }

                return $cacheable;
        }

        /**
         * Lightweight method to get the parser output for a page, checking the parser cache
         * and so on. Doesn't consider most of the stuff that Article::view() is forced to
         * consider, so it's not appropriate to use there.
         *
         * @since 1.16 (r52326) for LiquidThreads
         *
         * @param int|null $oldid Revision ID or null
         * @param UserIdentity|null $user The relevant user
         * @return ParserOutput|false ParserOutput or false if the given revision ID is not found
         */
        public function getParserOutput( $oldid = null, ?UserIdentity $user = null ) {
                if ( $user === null ) {
                        $parserOptions = $this->getParserOptions();
                } else {
                        $parserOptions = $this->mPage->makeParserOptions( $user );
                        $parserOptions->setRenderReason( 'page-view' );
                }

                return $this->mPage->getParserOutput( $parserOptions, $oldid );
        }

        /**
         * Get parser options suitable for rendering the primary article wikitext
         * @return ParserOptions
         */
        public function getParserOptions() {
                $parserOptions = $this->mPage->makeParserOptions( $this->getContext() );
                $parserOptions->setRenderReason( 'page-view' );
                return $parserOptions;
        }

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

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

        /**
         * Call to WikiPage function for backwards compatibility.
         * @see ContentHandler::getActionOverrides
         * @return array
         */
        public function getActionOverrides() {
                return $this->mPage->getActionOverrides();
        }

        private function getMissingRevisionMsg( int $oldid ): Message {
                // T251066: Try loading the revision from the archive table.
                // Show link to view it if it exists and the user has permission to view it.
                // (Ignore the given title, if any; look it up from the revision instead.)
                $context = $this->getContext();
                $revRecord = $this->archivedRevisionLookup->getArchivedRevisionRecord( null, $oldid );
                if (
                        $revRecord &&
                        $revRecord->userCan(
                                RevisionRecord::DELETED_TEXT,
                                $context->getAuthority()
                        ) &&
                        $context->getAuthority()->isAllowedAny( 'deletedtext', 'undelete' )
                ) {
                        return $context->msg(
                                'missing-revision-permission',
                                $oldid,
                                $revRecord->getTimestamp(),
                                Title::newFromPageIdentity( $revRecord->getPage() )->getPrefixedDBkey()
                        );
                }
                return $context->msg( 'missing-revision', $oldid );
        }
}