namespaceDupes.php

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<?php
use MediaWiki\Linker\LinkTarget;

require_once __DIR__ . '/Maintenance.php';

class NamespaceConflictChecker extends Maintenance {

    protected $db;

    private $resolvablePages = 0;
    private $totalPages = 0;

    private $resolvableLinks = 0;
    private $totalLinks = 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' );
        $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() {
        $this->db = $this->getDB( DB_MASTER );

        $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" );
        }
    }

    private function checkAll( $options ) {
        global $wgContLang, $wgNamespaceAliases, $wgCapitalLinks;

        $spaces = [];

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

        // Now pull in all canonical and alias namespaces...
        foreach ( MWNamespace::getCanonicalNamespaces() as $ns => $name ) {
            // This includes $wgExtraNamespaces
            if ( $name !== '' ) {
                $spaces[$name] = $ns;
            }
        }
        foreach ( $wgContLang->getNamespaces() as $ns => $name ) {
            if ( $name !== '' ) {
                $spaces[$name] = $ns;
            }
        }
        foreach ( $wgNamespaceAliases as $name => $ns ) {
            $spaces[$name] = $ns;
        }
        foreach ( $wgContLang->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.
        foreach ( $spaces as $name => $ns ) {
            $moreNames = [];
            $moreNames[] = $wgContLang->uc( $name );
            $moreNames[] = $wgContLang->ucfirst( $wgContLang->lc( $name ) );
            $moreNames[] = $wgContLang->ucwords( $name );
            $moreNames[] = $wgContLang->ucwords( $wgContLang->lc( $name ) );
            $moreNames[] = $wgContLang->ucwordbreaks( $name );
            $moreNames[] = $wgContLang->ucwordbreaks( $wgContLang->lc( $name ) );
            if ( !$wgCapitalLinks ) {
                foreach ( $moreNames as $altName ) {
                    $moreNames[] = $wgContLang->lcfirst( $altName );
                }
                $moreNames[] = $wgContLang->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, function ( $a, $b ) use ( $origSpaces ) {
            if ( $origSpaces[$a] < $origSpaces[$b] ) {
                return -1;
            } elseif ( $origSpaces[$a] > $origSpaces[$b] ) {
                return 1;
            } elseif ( $a < $b ) {
                return -1;
            } elseif ( $a > $b ) {
                return 1;
            } else {
                return 0;
            }
        } );

        $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' => null ] );
                $this->checkLinkTable( 'redirect', 'rd', $ns, $name, $options,
                    [ 'rd_interwiki' => '' ] );
            }
        }

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

        return $ok;
    }

    private function getInterwikiList() {
        $result = Interwiki::getAllPrefixes();
        $prefixes = [];
        foreach ( $result as $row ) {
            $prefixes[] = $row['iw_prefix'];
        }

        return $prefixes;
    }

    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, $options );
            $logStatus = false;
            if ( !$newTitle ) {
                $logStatus = 'invalid title';
                $action = 'abort';
            } elseif ( $newTitle->exists() ) {
                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 {
                    $newTitle = $this->getAlternateTitle( $newTitle, $options );
                    if ( !$newTitle ) {
                        $action = 'abort';
                        $logStatus = 'alternate title is invalid';
                    } elseif ( $newTitle->exists() ) {
                        $action = 'abort';
                        $logStatus = 'title conflict';
                    } else {
                        $action = 'move';
                        $logStatus = 'alternate';
                    }
                }
            } else {
                $action = 'move';
                $logStatus = 'no conflict';
            }

            // 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;
    }

    private function checkLinkTable( $table, $fieldPrefix, $ns, $name, $options,
        $extraConds = []
    ) {
        $batchConds = [];
        $fromField = "{$fieldPrefix}_from";
        $namespaceField = "{$fieldPrefix}_namespace";
        $titleField = "{$fieldPrefix}_title";
        $batchSize = 500;
        while ( true ) {
            $res = $this->db->select(
                $table,
                [ $fromField, $namespaceField, $titleField ],
                array_merge( $batchConds, $extraConds, [
                    $namespaceField => 0,
                    $titleField . $this->db->buildLike( "$name:", $this->db->anyString() )
                ] ),
                __METHOD__,
                [
                    'ORDER BY' => [ $titleField, $fromField ],
                    'LIMIT' => $batchSize
                ]
            );

            if ( $res->numRows() == 0 ) {
                break;
            }
            foreach ( $res as $row ) {
                $logTitle = "from={$row->$fromField} ns={$row->$namespaceField} " .
                    "dbk={$row->$titleField}";
                $destTitle = $this->getDestinationTitle( $ns, $name,
                    $row->$namespaceField, $row->$titleField, $options );
                $this->totalLinks++;
                if ( !$destTitle ) {
                    $this->output( "$table $logTitle *** INVALID\n" );
                    continue;
                }
                $this->resolvableLinks++;
                if ( !$options['fix'] ) {
                    $this->output( "$table $logTitle -> " .
                        $destTitle->getPrefixedDBkey() . " DRY RUN\n" );
                    continue;
                }

                $this->db->update( $table,
                    // SET
                    [
                        $namespaceField => $destTitle->getNamespace(),
                        $titleField => $destTitle->getDBkey()
                    ],
                    // WHERE
                    [
                        $namespaceField => 0,
                        $titleField => $row->$titleField,
                        $fromField => $row->$fromField
                    ],
                    __METHOD__,
                    [ 'IGNORE' ]
                );
                $this->output( "$table $logTitle -> " .
                    $destTitle->getPrefixedDBkey() . "\n" );
            }
            $encLastTitle = $this->db->addQuotes( $row->$titleField );
            $encLastFrom = $this->db->addQuotes( $row->$fromField );

            $batchConds = [
                "$titleField > $encLastTitle " .
                "OR ($titleField = $encLastTitle AND $fromField > $encLastFrom)" ];

            wfWaitForSlaves();
        }
    }

    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 );
    }

    private function getTargetList( $ns, $name, $options ) {
        if ( $options['move-talk'] && MWNamespace::isSubject( $ns ) ) {
            $checkNamespaces = [ NS_MAIN, NS_TALK ];
        } else {
            $checkNamespaces = NS_MAIN;
        }

        return $this->db->select( 'page',
            [
                'page_id',
                'page_title',
                'page_namespace',
            ],
            [
                'page_namespace' => $checkNamespaces,
                'page_title' . $this->db->buildLike( "$name:", $this->db->anyString() ),
            ],
            __METHOD__
        );
    }

    private function getDestinationTitle( $ns, $name, $sourceNs, $sourceDbk, $options ) {
        $dbk = substr( $sourceDbk, strlen( "$name:" ) );
        if ( $ns == 0 ) {
            // An interwiki; try an alternate encoding with '-' for ':'
            $dbk = "$name-" . $dbk;
        }
        $destNS = $ns;
        if ( $sourceNs == NS_TALK && MWNamespace::isSubject( $ns ) ) {
            // This is an associated talk page moved with the --move-talk feature.
            $destNS = MWNamespace::getTalk( $destNS );
        }
        $newTitle = Title::makeTitleSafe( $destNS, $dbk );
        if ( !$newTitle || !$newTitle->canExist() ) {
            return false;
        }
        return $newTitle;
    }

    private function getAlternateTitle( LinkTarget $linkTarget, $options ) {
        $prefix = $options['add-prefix'];
        $suffix = $options['add-suffix'];
        if ( $prefix == '' && $suffix == '' ) {
            return false;
        }
        while ( true ) {
            $dbk = $prefix . $linkTarget->getDBkey() . $suffix;
            $title = Title::makeTitleSafe( $linkTarget->getNamespace(), $dbk );
            if ( !$title ) {
                return false;
            }
            if ( !$title->exists() ) {
                return $title;
            }
        }
    }

    private function movePage( $id, LinkTarget $newLinkTarget ) {
        $this->db->update( 'page',
            [
                "page_namespace" => $newLinkTarget->getNamespace(),
                "page_title" => $newLinkTarget->getDBkey(),
            ],
            [
                "page_id" => $id,
            ],
            __METHOD__ );

        // Update *_from_namespace in links tables
        $fromNamespaceTables = [
            [ 'pagelinks', 'pl' ],
            [ 'templatelinks', 'tl' ],
            [ 'imagelinks', 'il' ] ];
        foreach ( $fromNamespaceTables as $tableInfo ) {
            list( $table, $fieldPrefix ) = $tableInfo;
            $this->db->update( $table,
                // SET
                [ "{$fieldPrefix}_from_namespace" => $newLinkTarget->getNamespace() ],
                // WHERE
                [ "{$fieldPrefix}_from" => $id ],
                __METHOD__ );
        }

        return true;
    }

    private function canMerge( $id, LinkTarget $linkTarget, &$logStatus ) {
        $latestDest = Revision::newFromTitle( $linkTarget, 0, Revision::READ_LATEST );
        $latestSource = Revision::newFromPageId( $id, 0, Revision::READ_LATEST );
        if ( $latestSource->getTimestamp() > $latestDest->getTimestamp() ) {
            $logStatus = 'cannot merge since source is later';
            return false;
        } else {
            return true;
        }
    }

    private function mergePage( $row, Title $newTitle ) {
        $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 = new WikiPage( $sourceTitle );
        $wikiPage->loadPageData( 'fromdbmaster' );

        $destId = $newTitle->getArticleID();
        $this->beginTransaction( $this->db, __METHOD__ );
        $this->db->update( 'revision',
            // SET
            [ 'rev_page' => $destId ],
            // WHERE
            [ 'rev_page' => $id ],
            __METHOD__ );

        $this->db->delete( 'page', [ 'page_id' => $id ], __METHOD__ );

        $this->commitTransaction( $this->db, __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;
    }
}

$maintClass = "NamespaceConflictChecker";
require_once RUN_MAINTENANCE_IF_MAIN;