SpecialDoubleRedirects.php

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<?php
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IResultWrapper;
 
class SpecialDoubleRedirects extends QueryPage {
    public function __construct( $name = 'DoubleRedirects' ) {
        parent::__construct( $name );
    }
 
    public function isExpensive() {
        return true;
    }
 
    public function isSyndicated() {
        return false;
    }
 
    protected function sortDescending() {
        return false;
    }
 
    protected function getPageHeader() {
        return $this->msg( 'doubleredirectstext' )->parseAsBlock();
    }
 
    private function reallyGetQueryInfo( $namespace = null, $title = null ) {
        $limitToTitle = !( $namespace === null && $title === null );
        $dbr = wfGetDB( DB_REPLICA );
        $retval = [
            'tables' => [
                'ra' => 'redirect',
                'rb' => 'redirect',
                'pa' => 'page',
                'pb' => 'page'
            ],
            'fields' => [
                'namespace' => 'pa.page_namespace',
                'title' => 'pa.page_title',
 
                'b_namespace' => 'pb.page_namespace',
                'b_title' => 'pb.page_title',
 
                // Select fields from redirect instead of page. Because there may
                // not actually be a page table row for this target (e.g. for interwiki redirects)
                'c_namespace' => 'rb.rd_namespace',
                'c_title' => 'rb.rd_title',
                'c_fragment' => 'rb.rd_fragment',
                'c_interwiki' => 'rb.rd_interwiki',
            ],
            'conds' => [
                'ra.rd_from = pa.page_id',
 
                // Filter out redirects where the target goes interwiki (T42353).
                // This isn't an optimization, it is required for correct results,
                // otherwise a non-double redirect like Bar -> w:Foo will show up
                // like "Bar -> Foo -> w:Foo".
 
                // Need to check both NULL and "" for some reason,
                // apparently either can be stored for non-iw entries.
                'ra.rd_interwiki IS NULL OR ra.rd_interwiki = ' . $dbr->addQuotes( '' ),
 
                'pb.page_namespace = ra.rd_namespace',
                'pb.page_title = ra.rd_title',
 
                'rb.rd_from = pb.page_id',
            ]
        ];
 
        if ( $limitToTitle ) {
            $retval['conds']['pa.page_namespace'] = $namespace;
            $retval['conds']['pa.page_title'] = $title;
        }
 
        return $retval;
    }
 
    public function getQueryInfo() {
        return $this->reallyGetQueryInfo();
    }
 
    protected function getOrderFields() {
        return [ 'ra.rd_namespace', 'ra.rd_title' ];
    }
 
    public function formatResult( $skin, $result ) {
        // If no Title B or C is in the query, it means this came from
        // querycache (which only saves the 3 columns for title A).
        // That does save the bulk of the query cost, but now we need to
        // get a little more detail about each individual entry quickly
        // using the filter of reallyGetQueryInfo.
        $deep = false;
        if ( $result ) {
            if ( isset( $result->b_namespace ) ) {
                $deep = $result;
            } else {
                $dbr = wfGetDB( DB_REPLICA );
                $qi = $this->reallyGetQueryInfo(
                    $result->namespace,
                    $result->title
                );
                $res = $dbr->select(
                    $qi['tables'],
                    $qi['fields'],
                    $qi['conds'],
                    __METHOD__
                );
 
                if ( $res ) {
                    $deep = $dbr->fetchObject( $res ) ?: false;
                }
            }
        }
 
        $titleA = Title::makeTitle( $result->namespace, $result->title );
 
        $linkRenderer = $this->getLinkRenderer();
        if ( !$deep ) {
            return '<del>' . $linkRenderer->makeLink( $titleA, null, [], [ 'redirect' => 'no' ] ) . '</del>';
        }
 
        // if the page is editable, add an edit link
        if (
            // check user permissions
            MediaWikiServices::getInstance()
                ->getPermissionManager()
                ->userHasRight( $this->getUser(), 'edit' ) &&
            // check, if the content model is editable through action=edit
            MediaWikiServices::getInstance()
                ->getContentHandlerFactory()
                ->getContentHandler( $titleA->getContentModel() )
                ->supportsDirectEditing()
        ) {
            $edit = $linkRenderer->makeKnownLink(
                $titleA,
                $this->msg( 'parentheses', $this->msg( 'editlink' )->text() )->text(),
                [],
                [ 'action' => 'edit' ]
            );
        } else {
            $edit = '';
        }
 
        $linkA = $linkRenderer->makeKnownLink(
            $titleA,
            null,
            [],
            [ 'redirect' => 'no' ]
        );
 
        $titleB = Title::makeTitle( $deep->b_namespace, $deep->b_title );
        $linkB = $linkRenderer->makeKnownLink(
            $titleB,
            null,
            [],
            [ 'redirect' => 'no' ]
        );
 
        $titleC = Title::makeTitle(
            $deep->c_namespace,
            $deep->c_title,
            $deep->c_fragment,
            $deep->c_interwiki
        );
        $linkC = $linkRenderer->makeKnownLink( $titleC, $titleC->getFullText() );
 
        $lang = $this->getLanguage();
        $arr = $lang->getArrow() . $lang->getDirMark();
 
        return ( "{$linkA} {$edit} {$arr} {$linkB} {$arr} {$linkC}" );
    }
 
    public function execute( $par ) {
        $this->addHelpLink( 'Help:Redirects' );
        parent::execute( $par );
    }
 
    public function preprocessResults( $db, $res ) {
        if ( !$res->numRows() ) {
            return;
        }
 
        $batch = new LinkBatch;
        foreach ( $res as $row ) {
            $batch->add( $row->namespace, $row->title );
            if ( isset( $row->b_namespace ) ) {
                // lazy loaded when using cached results
                $batch->add( $row->b_namespace, $row->b_title );
            }
            if ( isset( $row->c_interwiki ) && !$row->c_interwiki ) {
                // lazy loaded when using cached result, not added when interwiki link
                $batch->add( $row->c_namespace, $row->c_title );
            }
        }
        $batch->execute();
 
        // Back to start for display
        $res->seek( 0 );
    }
 
    protected function getGroupName() {
        return 'maintenance';
    }
}