InfoAction.php

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<?php
class InfoAction extends FormlessAction {
    const VERSION = 1;

    public function getName() {
        return 'info';
    }

    public function requiresUnblock() {
        return false;
    }

    public function requiresWrite() {
        return false;
    }

    public static function invalidateCache( Title $title, $revid = null ) {
        if ( !$revid ) {
            $revision = Revision::newFromTitle( $title, 0, Revision::READ_LATEST );
            $revid = $revision ? $revision->getId() : null;
        }
        if ( $revid !== null ) {
            $key = self::getCacheKey( $title, $revid );
            ObjectCache::getMainWANInstance()->delete( $key );
        }
    }

    public function onView() {
        $content = '';

        // Validate revision
        $oldid = $this->page->getOldID();
        if ( $oldid ) {
            $revision = $this->page->getRevisionFetched();

            // Revision is missing
            if ( $revision === null ) {
                return $this->msg( 'missing-revision', $oldid )->parse();
            }

            // Revision is not current
            if ( !$revision->isCurrent() ) {
                return $this->msg( 'pageinfo-not-current' )->plain();
            }
        }

        // Page header
        if ( !$this->msg( 'pageinfo-header' )->isDisabled() ) {
            $content .= $this->msg( 'pageinfo-header' )->parse();
        }

        // Hide "This page is a member of # hidden categories" explanation
        $content .= Html::element( 'style', [],
            '.mw-hiddenCategoriesExplanation { display: none; }' ) . "\n";

        // Hide "Templates used on this page" explanation
        $content .= Html::element( 'style', [],
            '.mw-templatesUsedExplanation { display: none; }' ) . "\n";

        // Get page information
        $pageInfo = $this->pageInfo();

        // Allow extensions to add additional information
        Hooks::run( 'InfoAction', [ $this->getContext(), &$pageInfo ] );

        // Render page information
        foreach ( $pageInfo as $header => $infoTable ) {
            // Messages:
            // pageinfo-header-basic, pageinfo-header-edits, pageinfo-header-restrictions,
            // pageinfo-header-properties, pageinfo-category-info
            $content .= $this->makeHeader( $this->msg( "pageinfo-${header}" )->escaped() ) . "\n";
            $table = "\n";
            foreach ( $infoTable as $infoRow ) {
                $name = ( $infoRow[0] instanceof Message ) ? $infoRow[0]->escaped() : $infoRow[0];
                $value = ( $infoRow[1] instanceof Message ) ? $infoRow[1]->escaped() : $infoRow[1];
                $id = ( $infoRow[0] instanceof Message ) ? $infoRow[0]->getKey() : null;
                $table = $this->addRow( $table, $name, $value, $id ) . "\n";
            }
            $content = $this->addTable( $content, $table ) . "\n";
        }

        // Page footer
        if ( !$this->msg( 'pageinfo-footer' )->isDisabled() ) {
            $content .= $this->msg( 'pageinfo-footer' )->parse();
        }

        return $content;
    }

    protected function makeHeader( $header ) {
        $spanAttribs = [ 'class' => 'mw-headline', 'id' => Sanitizer::escapeId( $header ) ];

        return Html::rawElement( 'h2', [], Html::element( 'span', $spanAttribs, $header ) );
    }

    protected function addRow( $table, $name, $value, $id ) {
        return $table .
            Html::rawElement(
                'tr',
                $id === null ? [] : [ 'id' => 'mw-' . $id ],
                Html::rawElement( 'td', [ 'style' => 'vertical-align: top;' ], $name ) .
                    Html::rawElement( 'td', [], $value )
            );
    }

    protected function addTable( $content, $table ) {
        return $content . Html::rawElement( 'table', [ 'class' => 'wikitable mw-page-info' ],
            $table );
    }

    protected function pageInfo() {
        global $wgContLang;

        $user = $this->getUser();
        $lang = $this->getLanguage();
        $title = $this->getTitle();
        $id = $title->getArticleID();
        $config = $this->context->getConfig();

        $pageCounts = $this->pageCounts( $this->page );

        $pageProperties = [];
        $props = PageProps::getInstance()->getAllProperties( $title );
        if ( isset( $props[$id] ) ) {
            $pageProperties = $props[$id];
        }

        // Basic information
        $pageInfo = [];
        $pageInfo['header-basic'] = [];

        // Display title
        $displayTitle = $title->getPrefixedText();
        if ( isset( $pageProperties['displaytitle'] ) ) {
            $displayTitle = $pageProperties['displaytitle'];
        }

        $pageInfo['header-basic'][] = [
            $this->msg( 'pageinfo-display-title' ), $displayTitle
        ];

        // Is it a redirect? If so, where to?
        if ( $title->isRedirect() ) {
            $pageInfo['header-basic'][] = [
                $this->msg( 'pageinfo-redirectsto' ),
                Linker::link( $this->page->getRedirectTarget() ) .
                $this->msg( 'word-separator' )->escaped() .
                $this->msg( 'parentheses' )->rawParams( Linker::link(
                    $this->page->getRedirectTarget(),
                    $this->msg( 'pageinfo-redirectsto-info' )->escaped(),
                    [],
                    [ 'action' => 'info' ]
                ) )->escaped()
            ];
        }

        // Default sort key
        $sortKey = $title->getCategorySortkey();
        if ( isset( $pageProperties['defaultsort'] ) ) {
            $sortKey = $pageProperties['defaultsort'];
        }

        $sortKey = htmlspecialchars( $sortKey );
        $pageInfo['header-basic'][] = [ $this->msg( 'pageinfo-default-sort' ), $sortKey ];

        // Page length (in bytes)
        $pageInfo['header-basic'][] = [
            $this->msg( 'pageinfo-length' ), $lang->formatNum( $title->getLength() )
        ];

        // Page ID (number not localised, as it's a database ID)
        $pageInfo['header-basic'][] = [ $this->msg( 'pageinfo-article-id' ), $id ];

        // Language in which the page content is (supposed to be) written
        $pageLang = $title->getPageLanguage()->getCode();

        if ( $config->get( 'PageLanguageUseDB' )
            && $this->getTitle()->userCan( 'pagelang', $this->getUser() )
        ) {
            // Link to Special:PageLanguage with pre-filled page title if user has permissions
            $titleObj = SpecialPage::getTitleFor( 'PageLanguage', $title->getPrefixedText() );
            $langDisp = Linker::link(
                $titleObj,
                $this->msg( 'pageinfo-language' )->escaped()
            );
        } else {
            // Display just the message
            $langDisp = $this->msg( 'pageinfo-language' )->escaped();
        }

        $pageInfo['header-basic'][] = [ $langDisp,
            Language::fetchLanguageName( $pageLang, $lang->getCode() )
            . ' ' . $this->msg( 'parentheses', $pageLang )->escaped() ];

        // Content model of the page
        $pageInfo['header-basic'][] = [
            $this->msg( 'pageinfo-content-model' ),
            htmlspecialchars( ContentHandler::getLocalizedName( $title->getContentModel() ) )
        ];

        // Search engine status
        $pOutput = new ParserOutput();
        if ( isset( $pageProperties['noindex'] ) ) {
            $pOutput->setIndexPolicy( 'noindex' );
        }
        if ( isset( $pageProperties['index'] ) ) {
            $pOutput->setIndexPolicy( 'index' );
        }

        // Use robot policy logic
        $policy = $this->page->getRobotPolicy( 'view', $pOutput );
        $pageInfo['header-basic'][] = [
            // Messages: pageinfo-robot-index, pageinfo-robot-noindex
            $this->msg( 'pageinfo-robot-policy' ),
            $this->msg( "pageinfo-robot-${policy['index']}" )
        ];

        $unwatchedPageThreshold = $config->get( 'UnwatchedPageThreshold' );
        if (
            $user->isAllowed( 'unwatchedpages' ) ||
            ( $unwatchedPageThreshold !== false &&
                $pageCounts['watchers'] >= $unwatchedPageThreshold )
        ) {
            // Number of page watchers
            $pageInfo['header-basic'][] = [
                $this->msg( 'pageinfo-watchers' ),
                $lang->formatNum( $pageCounts['watchers'] )
            ];
            if (
                $config->get( 'ShowUpdatedMarker' ) &&
                isset( $pageCounts['visitingWatchers'] )
            ) {
                $minToDisclose = $config->get( 'UnwatchedPageSecret' );
                if ( $pageCounts['visitingWatchers'] > $minToDisclose ||
                    $user->isAllowed( 'unwatchedpages' ) ) {
                    $pageInfo['header-basic'][] = [
                        $this->msg( 'pageinfo-visiting-watchers' ),
                        $lang->formatNum( $pageCounts['visitingWatchers'] )
                    ];
                } else {
                    $pageInfo['header-basic'][] = [
                        $this->msg( 'pageinfo-visiting-watchers' ),
                        $this->msg( 'pageinfo-few-visiting-watchers' )
                    ];
                }
            }
        } elseif ( $unwatchedPageThreshold !== false ) {
            $pageInfo['header-basic'][] = [
                $this->msg( 'pageinfo-watchers' ),
                $this->msg( 'pageinfo-few-watchers' )->numParams( $unwatchedPageThreshold )
            ];
        }

        // Redirects to this page
        $whatLinksHere = SpecialPage::getTitleFor( 'Whatlinkshere', $title->getPrefixedText() );
        $pageInfo['header-basic'][] = [
            Linker::link(
                $whatLinksHere,
                $this->msg( 'pageinfo-redirects-name' )->escaped(),
                [],
                [
                    'hidelinks' => 1,
                    'hidetrans' => 1,
                    'hideimages' => $title->getNamespace() == NS_FILE
                ]
            ),
            $this->msg( 'pageinfo-redirects-value' )
                ->numParams( count( $title->getRedirectsHere() ) )
        ];

        // Is it counted as a content page?
        if ( $this->page->isCountable() ) {
            $pageInfo['header-basic'][] = [
                $this->msg( 'pageinfo-contentpage' ),
                $this->msg( 'pageinfo-contentpage-yes' )
            ];
        }

        // Subpages of this page, if subpages are enabled for the current NS
        if ( MWNamespace::hasSubpages( $title->getNamespace() ) ) {
            $prefixIndex = SpecialPage::getTitleFor(
                'Prefixindex', $title->getPrefixedText() . '/' );
            $pageInfo['header-basic'][] = [
                Linker::link( $prefixIndex, $this->msg( 'pageinfo-subpages-name' )->escaped() ),
                $this->msg( 'pageinfo-subpages-value' )
                    ->numParams(
                        $pageCounts['subpages']['total'],
                        $pageCounts['subpages']['redirects'],
                        $pageCounts['subpages']['nonredirects'] )
            ];
        }

        if ( $title->inNamespace( NS_CATEGORY ) ) {
            $category = Category::newFromTitle( $title );

            // $allCount is the total number of cat members,
            // not the count of how many members are normal pages.
            $allCount = (int)$category->getPageCount();
            $subcatCount = (int)$category->getSubcatCount();
            $fileCount = (int)$category->getFileCount();
            $pagesCount = $allCount - $subcatCount - $fileCount;

            $pageInfo['category-info'] = [
                [
                    $this->msg( 'pageinfo-category-total' ),
                    $lang->formatNum( $allCount )
                ],
                [
                    $this->msg( 'pageinfo-category-pages' ),
                    $lang->formatNum( $pagesCount )
                ],
                [
                    $this->msg( 'pageinfo-category-subcats' ),
                    $lang->formatNum( $subcatCount )
                ],
                [
                    $this->msg( 'pageinfo-category-files' ),
                    $lang->formatNum( $fileCount )
                ]
            ];
        }

        // Page protection
        $pageInfo['header-restrictions'] = [];

        // Is this page affected by the cascading protection of something which includes it?
        if ( $title->isCascadeProtected() ) {
            $cascadingFrom = '';
            $sources = $title->getCascadeProtectionSources()[0];

            foreach ( $sources as $sourceTitle ) {
                $cascadingFrom .= Html::rawElement(
                    'li', [], Linker::linkKnown( $sourceTitle ) );
            }

            $cascadingFrom = Html::rawElement( 'ul', [], $cascadingFrom );
            $pageInfo['header-restrictions'][] = [
                $this->msg( 'pageinfo-protect-cascading-from' ),
                $cascadingFrom
            ];
        }

        // Is out protection set to cascade to other pages?
        if ( $title->areRestrictionsCascading() ) {
            $pageInfo['header-restrictions'][] = [
                $this->msg( 'pageinfo-protect-cascading' ),
                $this->msg( 'pageinfo-protect-cascading-yes' )
            ];
        }

        // Page protection
        foreach ( $title->getRestrictionTypes() as $restrictionType ) {
            $protectionLevel = implode( ', ', $title->getRestrictions( $restrictionType ) );

            if ( $protectionLevel == '' ) {
                // Allow all users
                $message = $this->msg( 'protect-default' )->escaped();
            } else {
                // Administrators only
                // Messages: protect-level-autoconfirmed, protect-level-sysop
                $message = $this->msg( "protect-level-$protectionLevel" );
                if ( $message->isDisabled() ) {
                    // Require "$1" permission
                    $message = $this->msg( "protect-fallback", $protectionLevel )->parse();
                } else {
                    $message = $message->escaped();
                }
            }
            $expiry = $title->getRestrictionExpiry( $restrictionType );
            $formattedexpiry = $this->msg( 'parentheses',
                $this->getLanguage()->formatExpiry( $expiry ) )->escaped();
            $message .= $this->msg( 'word-separator' )->escaped() . $formattedexpiry;

            // Messages: restriction-edit, restriction-move, restriction-create,
            // restriction-upload
            $pageInfo['header-restrictions'][] = [
                $this->msg( "restriction-$restrictionType" ), $message
            ];
        }

        if ( !$this->page->exists() ) {
            return $pageInfo;
        }

        // Edit history
        $pageInfo['header-edits'] = [];

        $firstRev = $this->page->getOldestRevision();
        $lastRev = $this->page->getRevision();
        $batch = new LinkBatch;

        if ( $firstRev ) {
            $firstRevUser = $firstRev->getUserText( Revision::FOR_THIS_USER );
            if ( $firstRevUser !== '' ) {
                $batch->add( NS_USER, $firstRevUser );
                $batch->add( NS_USER_TALK, $firstRevUser );
            }
        }

        if ( $lastRev ) {
            $lastRevUser = $lastRev->getUserText( Revision::FOR_THIS_USER );
            if ( $lastRevUser !== '' ) {
                $batch->add( NS_USER, $lastRevUser );
                $batch->add( NS_USER_TALK, $lastRevUser );
            }
        }

        $batch->execute();

        if ( $firstRev ) {
            // Page creator
            $pageInfo['header-edits'][] = [
                $this->msg( 'pageinfo-firstuser' ),
                Linker::revUserTools( $firstRev )
            ];

            // Date of page creation
            $pageInfo['header-edits'][] = [
                $this->msg( 'pageinfo-firsttime' ),
                Linker::linkKnown(
                    $title,
                    htmlspecialchars( $lang->userTimeAndDate( $firstRev->getTimestamp(), $user ) ),
                    [],
                    [ 'oldid' => $firstRev->getId() ]
                )
            ];
        }

        if ( $lastRev ) {
            // Latest editor
            $pageInfo['header-edits'][] = [
                $this->msg( 'pageinfo-lastuser' ),
                Linker::revUserTools( $lastRev )
            ];

            // Date of latest edit
            $pageInfo['header-edits'][] = [
                $this->msg( 'pageinfo-lasttime' ),
                Linker::linkKnown(
                    $title,
                    htmlspecialchars(
                        $lang->userTimeAndDate( $this->page->getTimestamp(), $user )
                    ),
                    [],
                    [ 'oldid' => $this->page->getLatest() ]
                )
            ];
        }

        // Total number of edits
        $pageInfo['header-edits'][] = [
            $this->msg( 'pageinfo-edits' ), $lang->formatNum( $pageCounts['edits'] )
        ];

        // Total number of distinct authors
        if ( $pageCounts['authors'] > 0 ) {
            $pageInfo['header-edits'][] = [
                $this->msg( 'pageinfo-authors' ), $lang->formatNum( $pageCounts['authors'] )
            ];
        }

        // Recent number of edits (within past 30 days)
        $pageInfo['header-edits'][] = [
            $this->msg( 'pageinfo-recent-edits',
                $lang->formatDuration( $config->get( 'RCMaxAge' ) ) ),
            $lang->formatNum( $pageCounts['recent_edits'] )
        ];

        // Recent number of distinct authors
        $pageInfo['header-edits'][] = [
            $this->msg( 'pageinfo-recent-authors' ),
            $lang->formatNum( $pageCounts['recent_authors'] )
        ];

        // Array of MagicWord objects
        $magicWords = MagicWord::getDoubleUnderscoreArray();

        // Array of magic word IDs
        $wordIDs = $magicWords->names;

        // Array of IDs => localized magic words
        $localizedWords = $wgContLang->getMagicWords();

        $listItems = [];
        foreach ( $pageProperties as $property => $value ) {
            if ( in_array( $property, $wordIDs ) ) {
                $listItems[] = Html::element( 'li', [], $localizedWords[$property][1] );
            }
        }

        $localizedList = Html::rawElement( 'ul', [], implode( '', $listItems ) );
        $hiddenCategories = $this->page->getHiddenCategories();

        if (
            count( $listItems ) > 0 ||
            count( $hiddenCategories ) > 0 ||
            $pageCounts['transclusion']['from'] > 0 ||
            $pageCounts['transclusion']['to'] > 0
        ) {
            $options = [ 'LIMIT' => $config->get( 'PageInfoTransclusionLimit' ) ];
            $transcludedTemplates = $title->getTemplateLinksFrom( $options );
            if ( $config->get( 'MiserMode' ) ) {
                $transcludedTargets = [];
            } else {
                $transcludedTargets = $title->getTemplateLinksTo( $options );
            }

            // Page properties
            $pageInfo['header-properties'] = [];

            // Magic words
            if ( count( $listItems ) > 0 ) {
                $pageInfo['header-properties'][] = [
                    $this->msg( 'pageinfo-magic-words' )->numParams( count( $listItems ) ),
                    $localizedList
                ];
            }

            // Hidden categories
            if ( count( $hiddenCategories ) > 0 ) {
                $pageInfo['header-properties'][] = [
                    $this->msg( 'pageinfo-hidden-categories' )
                        ->numParams( count( $hiddenCategories ) ),
                    Linker::formatHiddenCategories( $hiddenCategories )
                ];
            }

            // Transcluded templates
            if ( $pageCounts['transclusion']['from'] > 0 ) {
                if ( $pageCounts['transclusion']['from'] > count( $transcludedTemplates ) ) {
                    $more = $this->msg( 'morenotlisted' )->escaped();
                } else {
                    $more = null;
                }

                $pageInfo['header-properties'][] = [
                    $this->msg( 'pageinfo-templates' )
                        ->numParams( $pageCounts['transclusion']['from'] ),
                    Linker::formatTemplates(
                        $transcludedTemplates,
                        false,
                        false,
                        $more )
                ];
            }

            if ( !$config->get( 'MiserMode' ) && $pageCounts['transclusion']['to'] > 0 ) {
                if ( $pageCounts['transclusion']['to'] > count( $transcludedTargets ) ) {
                    $more = Linker::link(
                        $whatLinksHere,
                        $this->msg( 'moredotdotdot' )->escaped(),
                        [],
                        [ 'hidelinks' => 1, 'hideredirs' => 1 ]
                    );
                } else {
                    $more = null;
                }

                $pageInfo['header-properties'][] = [
                    $this->msg( 'pageinfo-transclusions' )
                        ->numParams( $pageCounts['transclusion']['to'] ),
                    Linker::formatTemplates(
                        $transcludedTargets,
                        false,
                        false,
                        $more )
                ];
            }
        }

        return $pageInfo;
    }

    protected function pageCounts( Page $page ) {
        $fname = __METHOD__;
        $config = $this->context->getConfig();

        return ObjectCache::getMainWANInstance()->getWithSetCallback(
            self::getCacheKey( $page->getTitle(), $page->getLatest() ),
            86400 * 7,
            function ( $oldValue, &$ttl, &$setOpts ) use ( $page, $config, $fname ) {
                $title = $page->getTitle();
                $id = $title->getArticleID();

                $dbr = wfGetDB( DB_SLAVE );
                $dbrWatchlist = wfGetDB( DB_SLAVE, 'watchlist' );

                $setOpts += Database::getCacheSetOptions( $dbr, $dbrWatchlist );

                $watchedItemStore = WatchedItemStore::getDefaultInstance();

                $result = [];
                $result['watchers'] = $watchedItemStore->countWatchers( $title );

                if ( $config->get( 'ShowUpdatedMarker' ) ) {
                    $updated = wfTimestamp( TS_UNIX, $page->getTimestamp() );
                    $result['visitingWatchers'] = $watchedItemStore->countVisitingWatchers(
                        $title,
                        $updated - $config->get( 'WatchersMaxAge' )
                    );
                }

                // Total number of edits
                $edits = (int)$dbr->selectField(
                    'revision',
                    'COUNT(*)',
                    [ 'rev_page' => $id ],
                    $fname
                );
                $result['edits'] = $edits;

                // Total number of distinct authors
                if ( $config->get( 'MiserMode' ) ) {
                    $result['authors'] = 0;
                } else {
                    $result['authors'] = (int)$dbr->selectField(
                        'revision',
                        'COUNT(DISTINCT rev_user_text)',
                        [ 'rev_page' => $id ],
                        $fname
                    );
                }

                // "Recent" threshold defined by RCMaxAge setting
                $threshold = $dbr->timestamp( time() - $config->get( 'RCMaxAge' ) );

                // Recent number of edits
                $edits = (int)$dbr->selectField(
                    'revision',
                    'COUNT(rev_page)',
                    [
                        'rev_page' => $id,
                        "rev_timestamp >= " . $dbr->addQuotes( $threshold )
                    ],
                    $fname
                );
                $result['recent_edits'] = $edits;

                // Recent number of distinct authors
                $result['recent_authors'] = (int)$dbr->selectField(
                    'revision',
                    'COUNT(DISTINCT rev_user_text)',
                    [
                        'rev_page' => $id,
                        "rev_timestamp >= " . $dbr->addQuotes( $threshold )
                    ],
                    $fname
                );

                // Subpages (if enabled)
                if ( MWNamespace::hasSubpages( $title->getNamespace() ) ) {
                    $conds = [ 'page_namespace' => $title->getNamespace() ];
                    $conds[] = 'page_title ' .
                        $dbr->buildLike( $title->getDBkey() . '/', $dbr->anyString() );

                    // Subpages of this page (redirects)
                    $conds['page_is_redirect'] = 1;
                    $result['subpages']['redirects'] = (int)$dbr->selectField(
                        'page',
                        'COUNT(page_id)',
                        $conds,
                        $fname
                    );

                    // Subpages of this page (non-redirects)
                    $conds['page_is_redirect'] = 0;
                    $result['subpages']['nonredirects'] = (int)$dbr->selectField(
                        'page',
                        'COUNT(page_id)',
                        $conds,
                        $fname
                    );

                    // Subpages of this page (total)
                    $result['subpages']['total'] = $result['subpages']['redirects']
                        + $result['subpages']['nonredirects'];
                }

                // Counts for the number of transclusion links (to/from)
                if ( $config->get( 'MiserMode' ) ) {
                    $result['transclusion']['to'] = 0;
                } else {
                    $result['transclusion']['to'] = (int)$dbr->selectField(
                        'templatelinks',
                        'COUNT(tl_from)',
                        [
                            'tl_namespace' => $title->getNamespace(),
                            'tl_title' => $title->getDBkey()
                        ],
                        $fname
                    );
                }

                $result['transclusion']['from'] = (int)$dbr->selectField(
                    'templatelinks',
                    'COUNT(*)',
                    [ 'tl_from' => $title->getArticleID() ],
                    $fname
                );

                return $result;
            }
        );
    }

    protected function getPageTitle() {
        return $this->msg( 'pageinfo-title', $this->getTitle()->getPrefixedText() )->text();
    }

    protected function getContributors() {
        $contributors = $this->page->getContributors();
        $real_names = [];
        $user_names = [];
        $anon_ips = [];

        # Sift for real versus user names

        foreach ( $contributors as $user ) {
            $page = $user->isAnon()
                ? SpecialPage::getTitleFor( 'Contributions', $user->getName() )
                : $user->getUserPage();

            $hiddenPrefs = $this->context->getConfig()->get( 'HiddenPrefs' );
            if ( $user->getId() == 0 ) {
                $anon_ips[] = Linker::link( $page, htmlspecialchars( $user->getName() ) );
            } elseif ( !in_array( 'realname', $hiddenPrefs ) && $user->getRealName() ) {
                $real_names[] = Linker::link( $page, htmlspecialchars( $user->getRealName() ) );
            } else {
                $user_names[] = Linker::link( $page, htmlspecialchars( $user->getName() ) );
            }
        }

        $lang = $this->getLanguage();

        $real = $lang->listToText( $real_names );

        # "ThisSite user(s) A, B and C"
        if ( count( $user_names ) ) {
            $user = $this->msg( 'siteusers' )
                ->rawParams( $lang->listToText( $user_names ) )
                ->params( count( $user_names ) )->escaped();
        } else {
            $user = false;
        }

        if ( count( $anon_ips ) ) {
            $anon = $this->msg( 'anonusers' )
                ->rawParams( $lang->listToText( $anon_ips ) )
                ->params( count( $anon_ips ) )->escaped();
        } else {
            $anon = false;
        }

        # This is the big list, all mooshed together. We sift for blank strings
        $fulllist = [];
        foreach ( [ $real, $user, $anon ] as $s ) {
            if ( $s !== '' ) {
                array_push( $fulllist, $s );
            }
        }

        $count = count( $fulllist );

        # "Based on work by ..."
        return $count
            ? $this->msg( 'othercontribs' )->rawParams(
                $lang->listToText( $fulllist ) )->params( $count )->escaped()
            : '';
    }

    protected function getDescription() {
        return '';
    }

    protected static function getCacheKey( Title $title, $revId ) {
        return wfMemcKey( 'infoaction', md5( $title->getPrefixedText() ), $revId, self::VERSION );
    }
}