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[mediawiki.git] / maintenance / namespaceDupes.php

<?php
/**
 * Check for articles to fix after adding/deleting namespaces
 *
 * Copyright © 2005-2007 Brooke Vibber <bvibber@wikimedia.org>
 * https://www.mediawiki.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Maintenance
 */

// @codeCoverageIgnoreStart
require_once __DIR__ . '/Maintenance.php';
// @codeCoverageIgnoreEnd

use MediaWiki\Deferred\DeferredUpdates;
use MediaWiki\Deferred\LinksUpdate\LinksDeletionUpdate;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MainConfigNames;
use MediaWiki\Maintenance\Maintenance;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleValue;
use Wikimedia\Rdbms\IDBAccessObject;
use Wikimedia\Rdbms\IExpression;
use Wikimedia\Rdbms\IResultWrapper;
use Wikimedia\Rdbms\LikeValue;

/**
 * Maintenance script that checks for articles to fix after
 * adding/deleting namespaces.
 *
 * @ingroup Maintenance
 */
class NamespaceDupes extends Maintenance {

        /**
         * Total number of pages that need fixing that are automatically resolveable
         * @var int
         */
        private $resolvablePages = 0;

        /**
         * Total number of pages that need fixing
         * @var int
         */
        private $totalPages = 0;

        /**
         * Total number of links that need fixing that are automatically resolveable
         * @var int
         */
        private $resolvableLinks = 0;

        /**
         * Total number of erroneous links
         * @var int
         */
        private $totalLinks = 0;

        /**
         * Total number of links deleted because they weren't automatically resolveable due to the
         * target already existing
         * @var int
         */
        private $deletedLinks = 0;

        public function __construct() {
                parent::__construct();
                $this->addDescription( 'Find and fix pages affected by namespace addition/removal' );
                $this->addOption( 'fix', 'Attempt to automatically fix errors and delete broken links' );
                $this->addOption( 'merge', "Instead of renaming conflicts, do a history merge with " .
                        "the correct title" );
                $this->addOption( 'add-suffix', "Dupes will be renamed with correct namespace with " .
                        "<text> appended after the article name", false, true );
                $this->addOption( 'add-prefix', "Dupes will be renamed with correct namespace with " .
                        "<text> prepended before the article name", false, true );
                $this->addOption( 'source-pseudo-namespace', "Move all pages with the given source " .
                        "prefix (with an implied colon following it). If --dest-namespace is not specified, " .
                        "the colon will be replaced with a hyphen.",
                        false, true );
                $this->addOption( 'dest-namespace', "In combination with --source-pseudo-namespace, " .
                        "specify the namespace ID of the destination.", false, true );
                $this->addOption( 'move-talk', "If this is specified, pages in the Talk namespace that " .
                        "begin with a conflicting prefix will be renamed, for example " .
                        "Talk:File:Foo -> File_Talk:Foo" );
        }

        public function execute() {
                $options = [
                        'fix' => $this->hasOption( 'fix' ),
                        'merge' => $this->hasOption( 'merge' ),
                        'add-suffix' => $this->getOption( 'add-suffix', '' ),
                        'add-prefix' => $this->getOption( 'add-prefix', '' ),
                        'move-talk' => $this->hasOption( 'move-talk' ),
                        'source-pseudo-namespace' => $this->getOption( 'source-pseudo-namespace', '' ),
                        'dest-namespace' => intval( $this->getOption( 'dest-namespace', 0 ) )
                ];

                if ( $options['source-pseudo-namespace'] !== '' ) {
                        $retval = $this->checkPrefix( $options );
                } else {
                        $retval = $this->checkAll( $options );
                }

                if ( $retval ) {
                        $this->output( "\nLooks good!\n" );
                } else {
                        $this->output( "\nOh noeees\n" );
                }
        }

        /**
         * Check all namespaces
         *
         * @param array $options Associative array of validated command-line options
         *
         * @return bool
         */
        private function checkAll( $options ) {
                $contLang = $this->getServiceContainer()->getContentLanguage();
                $spaces = [];

                // List interwikis first, so they'll be overridden
                // by any conflicting local namespaces.
                foreach ( $this->getInterwikiList() as $prefix ) {
                        $name = $contLang->ucfirst( $prefix );
                        $spaces[$name] = 0;
                }

                // Now pull in all canonical and alias namespaces...
                foreach (
                        $this->getServiceContainer()->getNamespaceInfo()->getCanonicalNamespaces()
                        as $ns => $name
                ) {
                        // This includes $wgExtraNamespaces
                        if ( $name !== '' ) {
                                $spaces[$name] = $ns;
                        }
                }
                foreach ( $contLang->getNamespaces() as $ns => $name ) {
                        if ( $name !== '' ) {
                                $spaces[$name] = $ns;
                        }
                }
                foreach ( $contLang->getNamespaceAliases() as $name => $ns ) {
                        $spaces[$name] = $ns;
                }

                // We'll need to check for lowercase keys as well,
                // since we're doing case-sensitive searches in the db.
                $capitalLinks = $this->getConfig()->get( MainConfigNames::CapitalLinks );
                foreach ( $spaces as $name => $ns ) {
                        $moreNames = [];
                        $moreNames[] = $contLang->uc( $name );
                        $moreNames[] = $contLang->ucfirst( $contLang->lc( $name ) );
                        $moreNames[] = $contLang->ucwords( $name );
                        $moreNames[] = $contLang->ucwords( $contLang->lc( $name ) );
                        $moreNames[] = $contLang->ucwordbreaks( $name );
                        $moreNames[] = $contLang->ucwordbreaks( $contLang->lc( $name ) );
                        if ( !$capitalLinks ) {
                                foreach ( $moreNames as $altName ) {
                                        $moreNames[] = $contLang->lcfirst( $altName );
                                }
                                $moreNames[] = $contLang->lcfirst( $name );
                        }
                        foreach ( array_unique( $moreNames ) as $altName ) {
                                if ( $altName !== $name ) {
                                        $spaces[$altName] = $ns;
                                }
                        }
                }

                // Sort by namespace index, and if there are two with the same index,
                // break the tie by sorting by name
                $origSpaces = $spaces;
                uksort( $spaces, static function ( $a, $b ) use ( $origSpaces ) {
                        return $origSpaces[$a] <=> $origSpaces[$b]
                                ?: $a <=> $b;
                } );

                $ok = true;
                foreach ( $spaces as $name => $ns ) {
                        $ok = $this->checkNamespace( $ns, $name, $options ) && $ok;
                }

                $this->output(
                        "{$this->totalPages} pages to fix, " .
                        "{$this->resolvablePages} were resolvable.\n\n"
                );

                foreach ( $spaces as $name => $ns ) {
                        if ( $ns != 0 ) {
                                /* Fix up link destinations for non-interwiki links only.
                                 *
                                 * For example if a page has [[Foo:Bar]] and then a Foo namespace
                                 * is introduced, pagelinks needs to be updated to have
                                 * page_namespace = NS_FOO.
                                 *
                                 * If instead an interwiki prefix was introduced called "Foo",
                                 * the link should instead be moved to the iwlinks table. If a new
                                 * language is introduced called "Foo", or if there is a pagelink
                                 * [[fr:Bar]] when interlanguage magic links are turned on, the
                                 * link would have to be moved to the langlinks table. Let's put
                                 * those cases in the too-hard basket for now. The consequences are
                                 * not especially severe.
                                 * @fixme Handle interwiki links, and pagelinks to Category:, File:
                                 * which probably need reparsing.
                                 */

                                $this->checkLinkTable( 'pagelinks', 'pl', $ns, $name, $options );
                                $this->checkLinkTable( 'templatelinks', 'tl', $ns, $name, $options );

                                // The redirect table has interwiki links randomly mixed in, we
                                // need to filter those out. For example [[w:Foo:Bar]] would
                                // have rd_interwiki=w and rd_namespace=0, which would match the
                                // query for a conflicting namespace "Foo" if filtering wasn't done.
                                $this->checkLinkTable( 'redirect', 'rd', $ns, $name, $options,
                                        [ 'rd_interwiki' => '' ] );
                        }
                }

                $this->output(
                        "{$this->totalLinks} links to fix, " .
                        "{$this->resolvableLinks} were resolvable, " .
                        "{$this->deletedLinks} were deleted.\n"
                );

                return $ok;
        }

        /**
         * @return string[]
         */
        private function getInterwikiList() {
                $result = $this->getServiceContainer()->getInterwikiLookup()->getAllPrefixes();
                return array_column( $result, 'iw_prefix' );
        }

        /**
         * Check a given prefix and try to move it into the given destination namespace
         *
         * @param int $ns Destination namespace id
         * @param string $name
         * @param array $options Associative array of validated command-line options
         * @return bool
         */
        private function checkNamespace( $ns, $name, $options ) {
                $targets = $this->getTargetList( $ns, $name, $options );
                $count = $targets->numRows();
                $this->totalPages += $count;
                if ( $count == 0 ) {
                        return true;
                }

                $dryRunNote = $options['fix'] ? '' : ' DRY RUN ONLY';

                $ok = true;
                foreach ( $targets as $row ) {
                        // Find the new title and determine the action to take

                        $newTitle = $this->getDestinationTitle(
                                $ns, $name, $row->page_namespace, $row->page_title );
                        $logStatus = false;
                        if ( !$newTitle ) {
                                if ( $options['add-prefix'] == '' && $options['add-suffix'] == '' ) {
                                        $logStatus = 'invalid title and --add-prefix not specified';
                                        $action = 'abort';
                                } else {
                                        $action = 'alternate';
                                }
                        } elseif ( $newTitle->exists( IDBAccessObject::READ_LATEST ) ) {
                                if ( $options['merge'] ) {
                                        if ( $this->canMerge( $row->page_id, $newTitle, $logStatus ) ) {
                                                $action = 'merge';
                                        } else {
                                                $action = 'abort';
                                        }
                                } elseif ( $options['add-prefix'] == '' && $options['add-suffix'] == '' ) {
                                        $action = 'abort';
                                        $logStatus = 'dest title exists and --add-prefix not specified';
                                } else {
                                        $action = 'alternate';
                                }
                        } else {
                                $action = 'move';
                                $logStatus = 'no conflict';
                        }
                        if ( $action === 'alternate' ) {
                                [ $ns, $dbk ] = $this->getDestination( $ns, $name, $row->page_namespace,
                                        $row->page_title );
                                $newTitle = $this->getAlternateTitle( $ns, $dbk, $options );
                                if ( !$newTitle ) {
                                        $action = 'abort';
                                        $logStatus = 'alternate title is invalid';
                                } elseif ( $newTitle->exists() ) {
                                        $action = 'abort';
                                        $logStatus = 'alternate title conflicts';
                                } else {
                                        $action = 'move';
                                        $logStatus = 'alternate';
                                }
                        }

                        // Take the action or log a dry run message

                        $logTitle = "id={$row->page_id} ns={$row->page_namespace} dbk={$row->page_title}";
                        $pageOK = true;

                        switch ( $action ) {
                                case 'abort':
                                        $this->output( "$logTitle *** $logStatus\n" );
                                        $pageOK = false;
                                        break;
                                case 'move':
                                        $this->output( "$logTitle -> " .
                                                $newTitle->getPrefixedDBkey() . " ($logStatus)$dryRunNote\n" );

                                        if ( $options['fix'] ) {
                                                $pageOK = $this->movePage( $row->page_id, $newTitle );
                                        }
                                        break;
                                case 'merge':
                                        $this->output( "$logTitle => " .
                                                $newTitle->getPrefixedDBkey() . " (merge)$dryRunNote\n" );

                                        if ( $options['fix'] ) {
                                                $pageOK = $this->mergePage( $row, $newTitle );
                                        }
                                        break;
                        }

                        if ( $pageOK ) {
                                $this->resolvablePages++;
                        } else {
                                $ok = false;
                        }
                }

                return $ok;
        }

        /**
         * Check and repair the destination fields in a link table
         * @param string $table The link table name
         * @param string $fieldPrefix The field prefix in the link table
         * @param int $ns Destination namespace id
         * @param string $name
         * @param array $options Associative array of validated command-line options
         * @param array $extraConds Extra conditions for the SQL query
         */
        private function checkLinkTable( $table, $fieldPrefix, $ns, $name, $options,
                $extraConds = []
        ) {
                $dbw = $this->getPrimaryDB();

                $batchConds = [];
                $fromField = "{$fieldPrefix}_from";
                $batchSize = 100;
                $sqb = $dbw->newSelectQueryBuilder()
                        ->select( $fromField )
                        ->where( $extraConds )
                        ->limit( $batchSize );

                $linksMigration = $this->getServiceContainer()->getLinksMigration();
                if ( isset( $linksMigration::$mapping[$table] ) ) {
                        $sqb->queryInfo( $linksMigration->getQueryInfo( $table ) );
                        [ $namespaceField, $titleField ] = $linksMigration->getTitleFields( $table );
                        $schemaMigrationStage = $linksMigration::$mapping[$table]['config'] === -1
                                ? MIGRATION_NEW
                                : $this->getConfig()->get( $linksMigration::$mapping[$table]['config'] );
                        $linkTargetLookup = $this->getServiceContainer()->getLinkTargetLookup();
                        $targetIdField = $linksMigration::$mapping[$table]['target_id'];
                } else {
                        $sqb->table( $table );
                        $namespaceField = "{$fieldPrefix}_namespace";
                        $titleField = "{$fieldPrefix}_title";
                        $sqb->fields( [ $namespaceField, $titleField ] );
                        // Variables only used for links migration, init only
                        $schemaMigrationStage = -1;
                        $linkTargetLookup = null;
                        $targetIdField = '';
                }
                $sqb->andWhere( [
                                $namespaceField => 0,
                                $dbw->expr( $titleField, IExpression::LIKE, new LikeValue( "$name:", $dbw->anyString() ) ),
                        ] )
                        ->orderBy( [ $titleField, $fromField ] )
                        ->caller( __METHOD__ );

                $updateRowsPerQuery = $this->getConfig()->get( MainConfigNames::UpdateRowsPerQuery );
                while ( true ) {
                        $res = ( clone $sqb )
                                ->andWhere( $batchConds )
                                ->fetchResultSet();
                        if ( $res->numRows() == 0 ) {
                                break;
                        }

                        $rowsToDeleteIfStillExists = [];

                        foreach ( $res as $row ) {
                                $logTitle = "from={$row->$fromField} ns={$row->$namespaceField} " .
                                        "dbk={$row->$titleField}";
                                $destTitle = $this->getDestinationTitle(
                                        $ns, $name, $row->$namespaceField, $row->$titleField );
                                $this->totalLinks++;
                                if ( !$destTitle ) {
                                        $this->output( "$table $logTitle *** INVALID\n" );
                                        continue;
                                }
                                $this->resolvableLinks++;
                                if ( !$options['fix'] ) {
                                        $this->output( "$table $logTitle -> " .
                                                $destTitle->getPrefixedDBkey() . " DRY RUN\n" );
                                        continue;
                                }

                                if ( isset( $linksMigration::$mapping[$table] ) ) {
                                        $setValue = [];
                                        if ( $schemaMigrationStage & SCHEMA_COMPAT_WRITE_NEW ) {
                                                $setValue[$targetIdField] = $linkTargetLookup->acquireLinkTargetId( $destTitle, $dbw );
                                        }
                                        if ( $schemaMigrationStage & SCHEMA_COMPAT_WRITE_OLD ) {
                                                $setValue["{$fieldPrefix}_namespace"] = $destTitle->getNamespace();
                                                $setValue["{$fieldPrefix}_title"] = $destTitle->getDBkey();
                                        }
                                        $whereCondition = $linksMigration->getLinksConditions(
                                                $table,
                                                new TitleValue( 0, $row->$titleField )
                                        );
                                        $deleteCondition = $linksMigration->getLinksConditions(
                                                $table,
                                                new TitleValue( (int)$row->$namespaceField, $row->$titleField )
                                        );
                                } else {
                                        $setValue = [
                                                $namespaceField => $destTitle->getNamespace(),
                                                $titleField => $destTitle->getDBkey()
                                        ];
                                        $whereCondition = [
                                                $namespaceField => 0,
                                                $titleField => $row->$titleField
                                        ];
                                        $deleteCondition = [
                                                $namespaceField => $row->$namespaceField,
                                                $titleField => $row->$titleField,
                                        ];
                                }

                                $dbw->newUpdateQueryBuilder()
                                        ->update( $table )
                                        ->ignore()
                                        ->set( $setValue )
                                        ->where( [ $fromField => $row->$fromField ] )
                                        ->andWhere( $whereCondition )
                                        ->caller( __METHOD__ )
                                        ->execute();

                                // In case there is a key conflict on UPDATE IGNORE the row needs deletion
                                $rowsToDeleteIfStillExists[] = array_merge( [ $fromField => $row->$fromField ], $deleteCondition );

                                $this->output( "$table $logTitle -> " .
                                        $destTitle->getPrefixedDBkey() . "\n"
                                );
                        }

                        if ( $options['fix'] && count( $rowsToDeleteIfStillExists ) > 0 ) {
                                $affectedRows = 0;
                                $deleteBatches = array_chunk( $rowsToDeleteIfStillExists, $updateRowsPerQuery );
                                foreach ( $deleteBatches as $deleteBatch ) {
                                        $dbw->newDeleteQueryBuilder()
                                                ->deleteFrom( $table )
                                                ->where( $dbw->factorConds( $deleteBatch ) )
                                                ->caller( __METHOD__ )
                                                ->execute();
                                        $affectedRows += $dbw->affectedRows();
                                        if ( count( $deleteBatches ) > 1 ) {
                                                $this->waitForReplication();
                                        }
                                }

                                $this->deletedLinks += $affectedRows;
                                $this->resolvableLinks -= $affectedRows;
                        }

                        $batchConds = [
                                $dbw->buildComparison( '>', [
                                        // @phan-suppress-next-line PhanPossiblyUndeclaredVariable rows contains at least one item
                                        $titleField => $row->$titleField,
                                        // @phan-suppress-next-line PhanPossiblyUndeclaredVariable rows contains at least one item
                                        $fromField => $row->$fromField,
                                ] )
                        ];

                        $this->waitForReplication();
                }
        }

        /**
         * Move the given pseudo-namespace, either replacing the colon with a hyphen
         * (useful for pseudo-namespaces that conflict with interwiki links) or move
         * them to another namespace if specified.
         * @param array $options Associative array of validated command-line options
         * @return bool
         */
        private function checkPrefix( $options ) {
                $prefix = $options['source-pseudo-namespace'];
                $ns = $options['dest-namespace'];
                $this->output( "Checking prefix \"$prefix\" vs namespace $ns\n" );

                return $this->checkNamespace( $ns, $prefix, $options );
        }

        /**
         * Find pages in main and talk namespaces that have a prefix of the new
         * namespace so we know titles that will need migrating
         *
         * @param int $ns Destination namespace id
         * @param string $name Prefix that is being made a namespace
         * @param array $options Associative array of validated command-line options
         *
         * @return IResultWrapper
         */
        private function getTargetList( $ns, $name, $options ) {
                $dbw = $this->getPrimaryDB();

                if (
                        $options['move-talk'] &&
                        $this->getServiceContainer()->getNamespaceInfo()->isSubject( $ns )
                ) {
                        $checkNamespaces = [ NS_MAIN, NS_TALK ];
                } else {
                        $checkNamespaces = NS_MAIN;
                }

                return $dbw->newSelectQueryBuilder()
                        ->select( [ 'page_id', 'page_title', 'page_namespace' ] )
                        ->from( 'page' )
                        ->where( [
                                'page_namespace' => $checkNamespaces,
                                $dbw->expr( 'page_title', IExpression::LIKE, new LikeValue( "$name:", $dbw->anyString() ) ),
                        ] )
                        ->caller( __METHOD__ )->fetchResultSet();
        }

        /**
         * Get the preferred destination for a given target page.
         * @param int $ns The destination namespace ID
         * @param string $name The conflicting prefix
         * @param int $sourceNs The source namespace
         * @param string $sourceDbk The source DB key (i.e. page_title)
         * @return array [ ns, dbkey ], not necessarily valid
         */
        private function getDestination( $ns, $name, $sourceNs, $sourceDbk ) {
                $dbk = substr( $sourceDbk, strlen( "$name:" ) );
                if ( $ns <= 0 ) {
                        // An interwiki or an illegal namespace like "Special" or "Media"
                        // try an alternate encoding with '-' for ':'
                        $dbk = "$name-" . $dbk;
                        $ns = 0;
                }
                $destNS = $ns;
                $nsInfo = $this->getServiceContainer()->getNamespaceInfo();
                if ( $sourceNs == NS_TALK && $nsInfo->isSubject( $ns ) ) {
                        // This is an associated talk page moved with the --move-talk feature.
                        $destNS = $nsInfo->getTalk( $destNS );
                }
                return [ $destNS, $dbk ];
        }

        /**
         * Get the preferred destination title for a given target page.
         * @param int $ns The destination namespace ID
         * @param string $name The conflicting prefix
         * @param int $sourceNs The source namespace
         * @param string $sourceDbk The source DB key (i.e. page_title)
         * @return Title|false
         */
        private function getDestinationTitle( $ns, $name, $sourceNs, $sourceDbk ) {
                [ $destNS, $dbk ] = $this->getDestination( $ns, $name, $sourceNs, $sourceDbk );
                $newTitle = Title::makeTitleSafe( $destNS, $dbk );
                if ( !$newTitle || !$newTitle->canExist() ) {
                        return false;
                }
                return $newTitle;
        }

        /**
         * Get an alternative title to move a page to. This is used if the
         * preferred destination title already exists.
         *
         * @param int $ns The destination namespace ID
         * @param string $dbk The source DB key (i.e. page_title)
         * @param array $options Associative array of validated command-line options
         * @return Title|false
         */
        private function getAlternateTitle( $ns, $dbk, $options ) {
                $prefix = $options['add-prefix'];
                $suffix = $options['add-suffix'];
                if ( $prefix == '' && $suffix == '' ) {
                        return false;
                }
                $newDbk = $prefix . $dbk . $suffix;
                return Title::makeTitleSafe( $ns, $newDbk );
        }

        /**
         * Move a page
         *
         * @param int $id The page_id
         * @param LinkTarget $newLinkTarget The new title link target
         * @return bool
         */
        private function movePage( $id, LinkTarget $newLinkTarget ) {
                $dbw = $this->getPrimaryDB();

                $dbw->newUpdateQueryBuilder()
                        ->update( 'page' )
                        ->set( [
                                "page_namespace" => $newLinkTarget->getNamespace(),
                                "page_title" => $newLinkTarget->getDBkey(),
                        ] )
                        ->where( [
                                "page_id" => $id,
                        ] )
                        ->caller( __METHOD__ )
                        ->execute();

                // Update *_from_namespace in links tables
                $fromNamespaceTables = [
                        [ 'templatelinks', 'tl', [ 'tl_target_id' ] ],
                        [ 'imagelinks', 'il', [ 'il_to' ] ]
                ];
                if ( $this->getConfig()->get( MainConfigNames::PageLinksSchemaMigrationStage ) & SCHEMA_COMPAT_WRITE_OLD ) {
                        $fromNamespaceTables[] = [ 'pagelinks', 'pl', [ 'pl_namespace', 'pl_title' ] ];
                } else {
                        $fromNamespaceTables[] = [ 'pagelinks', 'pl', [ 'pl_target_id' ] ];
                }
                $updateRowsPerQuery = $this->getConfig()->get( MainConfigNames::UpdateRowsPerQuery );
                foreach ( $fromNamespaceTables as [ $table, $fieldPrefix, $additionalPrimaryKeyFields ] ) {
                        $fromField = "{$fieldPrefix}_from";
                        $fromNamespaceField = "{$fieldPrefix}_from_namespace";

                        $res = $dbw->newSelectQueryBuilder()
                                ->select( $additionalPrimaryKeyFields )
                                ->from( $table )
                                ->where( [ $fromField => $id ] )
                                ->andWhere( $dbw->expr( $fromNamespaceField, '!=', $newLinkTarget->getNamespace() ) )
                                ->caller( __METHOD__ )
                                ->fetchResultSet();
                        if ( !$res ) {
                                continue;
                        }

                        $updateConds = [];
                        foreach ( $res as $row ) {
                                $updateConds[] = array_merge( [ $fromField => $id ], (array)$row );
                        }
                        $updateBatches = array_chunk( $updateConds, $updateRowsPerQuery );
                        foreach ( $updateBatches as $updateBatch ) {
                                $this->beginTransactionRound( __METHOD__ );
                                $dbw->newUpdateQueryBuilder()
                                        ->update( $table )
                                        ->set( [ $fromNamespaceField => $newLinkTarget->getNamespace() ] )
                                        ->where( $dbw->factorConds( $updateBatch ) )
                                        ->caller( __METHOD__ )
                                        ->execute();
                                $this->commitTransactionRound( __METHOD__ );
                        }
                }

                return true;
        }

        /**
         * Determine if we can merge a page.
         * We check if an inaccessible revision would become the latest and
         * deny the merge if so -- it's theoretically possible to update the
         * latest revision, but opens a can of worms -- search engine updates,
         * recentchanges review, etc.
         *
         * @param int $id The page_id
         * @param LinkTarget $linkTarget The new link target
         * @param string &$logStatus This is set to the log status message on failure @phan-output-reference
         * @return bool
         */
        private function canMerge( $id, LinkTarget $linkTarget, &$logStatus ) {
                $revisionLookup = $this->getServiceContainer()->getRevisionLookup();
                $latestDest = $revisionLookup->getRevisionByTitle( $linkTarget, 0,
                        IDBAccessObject::READ_LATEST );
                $latestSource = $revisionLookup->getRevisionByPageId( $id, 0,
                        IDBAccessObject::READ_LATEST );
                if ( $latestSource->getTimestamp() > $latestDest->getTimestamp() ) {
                        $logStatus = 'cannot merge since source is later';
                        return false;
                } else {
                        return true;
                }
        }

        /**
         * Merge page histories
         *
         * @param stdClass $row Page row
         * @param Title $newTitle
         * @return bool
         */
        private function mergePage( $row, Title $newTitle ) {
                $updateRowsPerQuery = $this->getConfig()->get( MainConfigNames::UpdateRowsPerQuery );

                $id = $row->page_id;

                // Construct the WikiPage object we will need later, while the
                // page_id still exists. Note that this cannot use makeTitleSafe(),
                // we are deliberately constructing an invalid title.
                $sourceTitle = Title::makeTitle( $row->page_namespace, $row->page_title );
                $sourceTitle->resetArticleID( $id );
                $wikiPage = $this->getServiceContainer()->getWikiPageFactory()->newFromTitle( $sourceTitle );
                $wikiPage->loadPageData( IDBAccessObject::READ_LATEST );
                $destId = $newTitle->getArticleID();

                $dbw = $this->getPrimaryDB();
                $this->beginTransactionRound( __METHOD__ );
                $revIds = $dbw->newSelectQueryBuilder()
                        ->select( 'rev_id' )
                        ->from( 'revision' )
                        ->where( [ 'rev_page' => $id ] )
                        ->caller( __METHOD__ )
                        ->fetchFieldValues();
                $updateBatches = array_chunk( array_map( 'intval', $revIds ), $updateRowsPerQuery );
                foreach ( $updateBatches as $updateBatch ) {
                        $dbw->newUpdateQueryBuilder()
                                ->update( 'revision' )
                                ->set( [ 'rev_page' => $destId ] )
                                ->where( [ 'rev_id' => $updateBatch ] )
                                ->caller( __METHOD__ )
                                ->execute();
                        if ( count( $updateBatches ) > 1 ) {
                                $this->commitTransactionRound( __METHOD__ );
                                $this->beginTransactionRound( __METHOD__ );
                        }
                }
                $dbw->newDeleteQueryBuilder()
                        ->deleteFrom( 'page' )
                        ->where( [ 'page_id' => $id ] )
                        ->caller( __METHOD__ )
                        ->execute();
                $this->commitTransactionRound( __METHOD__ );

                /* Call LinksDeletionUpdate to delete outgoing links from the old title,
                 * and update category counts.
                 *
                 * Calling external code with a fake broken Title is a fairly dubious
                 * idea. It's necessary because it's quite a lot of code to duplicate,
                 * but that also makes it fragile since it would be easy for someone to
                 * accidentally introduce an assumption of title validity to the code we
                 * are calling.
                 */
                DeferredUpdates::addUpdate( new LinksDeletionUpdate( $wikiPage ) );
                DeferredUpdates::doUpdates();

                return true;
        }
}

// @codeCoverageIgnoreStart
$maintClass = NamespaceDupes::class;
require_once RUN_MAINTENANCE_IF_MAIN;
// @codeCoverageIgnoreEnd