ApiPageSet.php

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<?php
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\IResultWrapper;
use Wikimedia\Rdbms\IDatabase;
 
class ApiPageSet extends ApiBase {
    const DISABLE_GENERATORS = 1;
 
    private $mDbSource;
    private $mParams;
    private $mResolveRedirects;
    private $mConvertTitles;
    private $mAllowGenerator;
 
    private $mAllPages = []; // [ns][dbkey] => page_id or negative when missing
    private $mTitles = [];
    private $mGoodAndMissingPages = []; // [ns][dbkey] => page_id or negative when missing
    private $mGoodPages = []; // [ns][dbkey] => page_id
    private $mGoodTitles = [];
    private $mMissingPages = []; // [ns][dbkey] => fake page_id
    private $mMissingTitles = [];
    private $mInvalidTitles = [];
    private $mMissingPageIDs = [];
    private $mRedirectTitles = [];
    private $mSpecialTitles = [];
    private $mAllSpecials = []; // separate from mAllPages to avoid breaking getAllTitlesByNamespace()
    private $mNormalizedTitles = [];
    private $mInterwikiTitles = [];
    private $mPendingRedirectIDs = [];
    private $mPendingRedirectSpecialPages = []; // [dbkey] => [ Title $from, Title $to ]
    private $mResolvedRedirectTitles = [];
    private $mConvertedTitles = [];
    private $mGoodRevIDs = [];
    private $mLiveRevIDs = [];
    private $mDeletedRevIDs = [];
    private $mMissingRevIDs = [];
    private $mGeneratorData = []; // [ns][dbkey] => data array
    private $mFakePageId = -1;
    private $mCacheMode = 'public';
    private $mRequestedPageFields = [];
    private $mDefaultNamespace = NS_MAIN;
    private $mRedirectMergePolicy;
 
    private static function addValues( array &$result, $values, $flags = [], $name = null ) {
        foreach ( $values as $val ) {
            if ( $val instanceof Title ) {
                $v = [];
                ApiQueryBase::addTitleInfo( $v, $val );
            } elseif ( $name !== null ) {
                $v = [ $name => $val ];
            } else {
                $v = $val;
            }
            foreach ( $flags as $flag ) {
                $v[$flag] = true;
            }
            $result[] = $v;
        }
    }
 
    public function __construct( ApiBase $dbSource, $flags = 0, $defaultNamespace = NS_MAIN ) {
        parent::__construct( $dbSource->getMain(), $dbSource->getModuleName() );
        $this->mDbSource = $dbSource;
        $this->mAllowGenerator = ( $flags & self::DISABLE_GENERATORS ) == 0;
        $this->mDefaultNamespace = $defaultNamespace;
 
        $this->mParams = $this->extractRequestParams();
        $this->mResolveRedirects = $this->mParams['redirects'];
        $this->mConvertTitles = $this->mParams['converttitles'];
    }
 
    public function executeDryRun() {
        $this->executeInternal( true );
    }
 
    public function execute() {
        $this->executeInternal( false );
    }
 
    private function executeInternal( $isDryRun ) {
        $generatorName = $this->mAllowGenerator ? $this->mParams['generator'] : null;
        if ( isset( $generatorName ) ) {
            $dbSource = $this->mDbSource;
            if ( !$dbSource instanceof ApiQuery ) {
                // If the parent container of this pageset is not ApiQuery, we must create it to run generator
                $dbSource = $this->getMain()->getModuleManager()->getModule( 'query' );
            }
            $generator = $dbSource->getModuleManager()->getModule( $generatorName, null, true );
            if ( $generator === null ) {
                $this->dieWithError( [ 'apierror-badgenerator-unknown', $generatorName ], 'badgenerator' );
            }
            if ( !$generator instanceof ApiQueryGeneratorBase ) {
                $this->dieWithError( [ 'apierror-badgenerator-notgenerator', $generatorName ], 'badgenerator' );
            }
            // Create a temporary pageset to store generator's output,
            // add any additional fields generator may need, and execute pageset to populate titles/pageids
            $tmpPageSet = new ApiPageSet( $dbSource, self::DISABLE_GENERATORS );
            $generator->setGeneratorMode( $tmpPageSet );
            $this->mCacheMode = $generator->getCacheMode( $generator->extractRequestParams() );
 
            if ( !$isDryRun ) {
                $generator->requestExtraData( $tmpPageSet );
            }
            $tmpPageSet->executeInternal( $isDryRun );
 
            // populate this pageset with the generator output
            if ( !$isDryRun ) {
                $generator->executeGenerator( $this );
 
                // Avoid PHP 7.1 warning of passing $this by reference
                $apiModule = $this;
                Hooks::run( 'APIQueryGeneratorAfterExecute', [ &$generator, &$apiModule ] );
            } else {
                // Prevent warnings from being reported on these parameters
                $main = $this->getMain();
                foreach ( $generator->extractRequestParams() as $paramName => $param ) {
                    $main->markParamsUsed( $generator->encodeParamName( $paramName ) );
                }
            }
 
            if ( !$isDryRun ) {
                $this->resolvePendingRedirects();
            }
        } else {
            // Only one of the titles/pageids/revids is allowed at the same time
            $dataSource = null;
            if ( isset( $this->mParams['titles'] ) ) {
                $dataSource = 'titles';
            }
            if ( isset( $this->mParams['pageids'] ) ) {
                if ( isset( $dataSource ) ) {
                    $this->dieWithError(
                        [
                            'apierror-invalidparammix-cannotusewith',
                            $this->encodeParamName( 'pageids' ),
                            $this->encodeParamName( $dataSource )
                        ],
                        'multisource'
                    );
                }
                $dataSource = 'pageids';
            }
            if ( isset( $this->mParams['revids'] ) ) {
                if ( isset( $dataSource ) ) {
                    $this->dieWithError(
                        [
                            'apierror-invalidparammix-cannotusewith',
                            $this->encodeParamName( 'revids' ),
                            $this->encodeParamName( $dataSource )
                        ],
                        'multisource'
                    );
                }
                $dataSource = 'revids';
            }
 
            if ( !$isDryRun ) {
                // Populate page information with the original user input
                switch ( $dataSource ) {
                    case 'titles':
                        $this->initFromTitles( $this->mParams['titles'] );
                        break;
                    case 'pageids':
                        $this->initFromPageIds( $this->mParams['pageids'] );
                        break;
                    case 'revids':
                        if ( $this->mResolveRedirects ) {
                            $this->addWarning( 'apiwarn-redirectsandrevids' );
                        }
                        $this->mResolveRedirects = false;
                        $this->initFromRevIDs( $this->mParams['revids'] );
                        break;
                    default:
                        // Do nothing - some queries do not need any of the data sources.
                        break;
                }
            }
        }
    }
 
    public function isResolvingRedirects() {
        return $this->mResolveRedirects;
    }
 
    public function getDataSource() {
        if ( $this->mAllowGenerator && isset( $this->mParams['generator'] ) ) {
            return 'generator';
        }
        if ( isset( $this->mParams['titles'] ) ) {
            return 'titles';
        }
        if ( isset( $this->mParams['pageids'] ) ) {
            return 'pageids';
        }
        if ( isset( $this->mParams['revids'] ) ) {
            return 'revids';
        }
 
        return null;
    }
 
    public function requestField( $fieldName ) {
        $this->mRequestedPageFields[$fieldName] = null;
    }
 
    public function getCustomField( $fieldName ) {
        return $this->mRequestedPageFields[$fieldName];
    }
 
    public function getPageTableFields() {
        // Ensure we get minimum required fields
        // DON'T change this order
        $pageFlds = [
            'page_namespace' => null,
            'page_title' => null,
            'page_id' => null,
        ];
 
        if ( $this->mResolveRedirects ) {
            $pageFlds['page_is_redirect'] = null;
        }
 
        if ( $this->getConfig()->get( 'ContentHandlerUseDB' ) ) {
            $pageFlds['page_content_model'] = null;
        }
 
        if ( $this->getConfig()->get( 'PageLanguageUseDB' ) ) {
            $pageFlds['page_lang'] = null;
        }
 
        foreach ( LinkCache::getSelectFields() as $field ) {
            $pageFlds[$field] = null;
        }
 
        $pageFlds = array_merge( $pageFlds, $this->mRequestedPageFields );
 
        return array_keys( $pageFlds );
    }
 
    public function getAllTitlesByNamespace() {
        return $this->mAllPages;
    }
 
    public function getTitles() {
        return $this->mTitles;
    }
 
    public function getTitleCount() {
        return count( $this->mTitles );
    }
 
    public function getGoodTitlesByNamespace() {
        return $this->mGoodPages;
    }
 
    public function getGoodTitles() {
        return $this->mGoodTitles;
    }
 
    public function getGoodTitleCount() {
        return count( $this->mGoodTitles );
    }
 
    public function getMissingTitlesByNamespace() {
        return $this->mMissingPages;
    }
 
    public function getMissingTitles() {
        return $this->mMissingTitles;
    }
 
    public function getGoodAndMissingTitlesByNamespace() {
        return $this->mGoodAndMissingPages;
    }
 
    public function getGoodAndMissingTitles() {
        return $this->mGoodTitles + $this->mMissingTitles;
    }
 
    public function getInvalidTitlesAndReasons() {
        return $this->mInvalidTitles;
    }
 
    public function getMissingPageIDs() {
        return $this->mMissingPageIDs;
    }
 
    public function getRedirectTitles() {
        return $this->mRedirectTitles;
    }
 
    public function getRedirectTitlesAsResult( $result = null ) {
        $values = [];
        foreach ( $this->getRedirectTitles() as $titleStrFrom => $titleTo ) {
            $r = [
                'from' => strval( $titleStrFrom ),
                'to' => $titleTo->getPrefixedText(),
            ];
            if ( $titleTo->hasFragment() ) {
                $r['tofragment'] = $titleTo->getFragment();
            }
            if ( $titleTo->isExternal() ) {
                $r['tointerwiki'] = $titleTo->getInterwiki();
            }
            if ( isset( $this->mResolvedRedirectTitles[$titleStrFrom] ) ) {
                $titleFrom = $this->mResolvedRedirectTitles[$titleStrFrom];
                $ns = $titleFrom->getNamespace();
                $dbkey = $titleFrom->getDBkey();
                if ( isset( $this->mGeneratorData[$ns][$dbkey] ) ) {
                    $r = array_merge( $this->mGeneratorData[$ns][$dbkey], $r );
                }
            }
 
            $values[] = $r;
        }
        if ( !empty( $values ) && $result ) {
            ApiResult::setIndexedTagName( $values, 'r' );
        }
 
        return $values;
    }
 
    public function getNormalizedTitles() {
        return $this->mNormalizedTitles;
    }
 
    public function getNormalizedTitlesAsResult( $result = null ) {
        $values = [];
        $contLang = MediaWikiServices::getInstance()->getContentLanguage();
        foreach ( $this->getNormalizedTitles() as $rawTitleStr => $titleStr ) {
            $encode = $contLang->normalize( $rawTitleStr ) !== $rawTitleStr;
            $values[] = [
                'fromencoded' => $encode,
                'from' => $encode ? rawurlencode( $rawTitleStr ) : $rawTitleStr,
                'to' => $titleStr
            ];
        }
        if ( !empty( $values ) && $result ) {
            ApiResult::setIndexedTagName( $values, 'n' );
        }
 
        return $values;
    }
 
    public function getConvertedTitles() {
        return $this->mConvertedTitles;
    }
 
    public function getConvertedTitlesAsResult( $result = null ) {
        $values = [];
        foreach ( $this->getConvertedTitles() as $rawTitleStr => $titleStr ) {
            $values[] = [
                'from' => $rawTitleStr,
                'to' => $titleStr
            ];
        }
        if ( !empty( $values ) && $result ) {
            ApiResult::setIndexedTagName( $values, 'c' );
        }
 
        return $values;
    }
 
    public function getInterwikiTitles() {
        return $this->mInterwikiTitles;
    }
 
    public function getInterwikiTitlesAsResult( $result = null, $iwUrl = false ) {
        $values = [];
        foreach ( $this->getInterwikiTitles() as $rawTitleStr => $interwikiStr ) {
            $item = [
                'title' => $rawTitleStr,
                'iw' => $interwikiStr,
            ];
            if ( $iwUrl ) {
                $title = Title::newFromText( $rawTitleStr );
                $item['url'] = $title->getFullURL( '', false, PROTO_CURRENT );
            }
            $values[] = $item;
        }
        if ( !empty( $values ) && $result ) {
            ApiResult::setIndexedTagName( $values, 'i' );
        }
 
        return $values;
    }
 
    public function getInvalidTitlesAndRevisions( $invalidChecks = [ 'invalidTitles',
        'special', 'missingIds', 'missingRevIds', 'missingTitles', 'interwikiTitles' ]
    ) {
        $result = [];
        if ( in_array( 'invalidTitles', $invalidChecks ) ) {
            self::addValues( $result, $this->getInvalidTitlesAndReasons(), [ 'invalid' ] );
        }
        if ( in_array( 'special', $invalidChecks ) ) {
            $known = [];
            $unknown = [];
            foreach ( $this->getSpecialTitles() as $title ) {
                if ( $title->isKnown() ) {
                    $known[] = $title;
                } else {
                    $unknown[] = $title;
                }
            }
            self::addValues( $result, $unknown, [ 'special', 'missing' ] );
            self::addValues( $result, $known, [ 'special' ] );
        }
        if ( in_array( 'missingIds', $invalidChecks ) ) {
            self::addValues( $result, $this->getMissingPageIDs(), [ 'missing' ], 'pageid' );
        }
        if ( in_array( 'missingRevIds', $invalidChecks ) ) {
            self::addValues( $result, $this->getMissingRevisionIDs(), [ 'missing' ], 'revid' );
        }
        if ( in_array( 'missingTitles', $invalidChecks ) ) {
            $known = [];
            $unknown = [];
            foreach ( $this->getMissingTitles() as $title ) {
                if ( $title->isKnown() ) {
                    $known[] = $title;
                } else {
                    $unknown[] = $title;
                }
            }
            self::addValues( $result, $unknown, [ 'missing' ] );
            self::addValues( $result, $known, [ 'missing', 'known' ] );
        }
        if ( in_array( 'interwikiTitles', $invalidChecks ) ) {
            self::addValues( $result, $this->getInterwikiTitlesAsResult() );
        }
 
        return $result;
    }
 
    public function getRevisionIDs() {
        return $this->mGoodRevIDs;
    }
 
    public function getLiveRevisionIDs() {
        return $this->mLiveRevIDs;
    }
 
    public function getDeletedRevisionIDs() {
        return $this->mDeletedRevIDs;
    }
 
    public function getMissingRevisionIDs() {
        return $this->mMissingRevIDs;
    }
 
    public function getMissingRevisionIDsAsResult( $result = null ) {
        $values = [];
        foreach ( $this->getMissingRevisionIDs() as $revid ) {
            $values[$revid] = [
                'revid' => $revid
            ];
        }
        if ( !empty( $values ) && $result ) {
            ApiResult::setIndexedTagName( $values, 'rev' );
        }
 
        return $values;
    }
 
    public function getSpecialTitles() {
        return $this->mSpecialTitles;
    }
 
    public function getRevisionCount() {
        return count( $this->getRevisionIDs() );
    }
 
    public function populateFromTitles( $titles ) {
        $this->initFromTitles( $titles );
    }
 
    public function populateFromPageIDs( $pageIDs ) {
        $this->initFromPageIds( $pageIDs );
    }
 
    public function populateFromQueryResult( $db, $queryResult ) {
        $this->initFromQueryResult( $queryResult );
    }
 
    public function populateFromRevisionIDs( $revIDs ) {
        $this->initFromRevIDs( $revIDs );
    }
 
    public function processDbRow( $row ) {
        // Store Title object in various data structures
        $title = Title::newFromRow( $row );
 
        $linkCache = MediaWikiServices::getInstance()->getLinkCache();
        $linkCache->addGoodLinkObjFromRow( $title, $row );
 
        $pageId = (int)$row->page_id;
        $this->mAllPages[$row->page_namespace][$row->page_title] = $pageId;
        $this->mTitles[] = $title;
 
        if ( $this->mResolveRedirects && $row->page_is_redirect == '1' ) {
            $this->mPendingRedirectIDs[$pageId] = $title;
        } else {
            $this->mGoodPages[$row->page_namespace][$row->page_title] = $pageId;
            $this->mGoodAndMissingPages[$row->page_namespace][$row->page_title] = $pageId;
            $this->mGoodTitles[$pageId] = $title;
        }
 
        foreach ( $this->mRequestedPageFields as $fieldName => &$fieldValues ) {
            $fieldValues[$pageId] = $row->$fieldName;
        }
    }
 
    private function initFromTitles( $titles ) {
        // Get validated and normalized title objects
        $linkBatch = $this->processTitlesArray( $titles );
        if ( $linkBatch->isEmpty() ) {
            // There might be special-page redirects
            $this->resolvePendingRedirects();
            return;
        }
 
        $db = $this->getDB();
        $set = $linkBatch->constructSet( 'page', $db );
 
        // Get pageIDs data from the `page` table
        $res = $db->select( 'page', $this->getPageTableFields(), $set,
            __METHOD__ );
 
        // Hack: get the ns:titles stored in [ ns => [ titles ] ] format
        $this->initFromQueryResult( $res, $linkBatch->data, true ); // process Titles
 
        // Resolve any found redirects
        $this->resolvePendingRedirects();
    }
 
    private function initFromPageIds( $pageids, $filterIds = true ) {
        if ( !$pageids ) {
            return;
        }
 
        $pageids = array_map( 'intval', $pageids ); // paranoia
        $remaining = array_flip( $pageids );
 
        if ( $filterIds ) {
            $pageids = $this->filterIDs( [ [ 'page', 'page_id' ] ], $pageids );
        }
 
        $res = null;
        if ( !empty( $pageids ) ) {
            $set = [
                'page_id' => $pageids
            ];
            $db = $this->getDB();
 
            // Get pageIDs data from the `page` table
            $res = $db->select( 'page', $this->getPageTableFields(), $set,
                __METHOD__ );
        }
 
        $this->initFromQueryResult( $res, $remaining, false ); // process PageIDs
 
        // Resolve any found redirects
        $this->resolvePendingRedirects();
    }
 
    private function initFromQueryResult( $res, &$remaining = null, $processTitles = null ) {
        if ( !is_null( $remaining ) && is_null( $processTitles ) ) {
            ApiBase::dieDebug( __METHOD__, 'Missing $processTitles parameter when $remaining is provided' );
        }
 
        $nsInfo = MediaWikiServices::getInstance()->getNamespaceInfo();
 
        $usernames = [];
        if ( $res ) {
            foreach ( $res as $row ) {
                $pageId = (int)$row->page_id;
 
                // Remove found page from the list of remaining items
                if ( isset( $remaining ) ) {
                    if ( $processTitles ) {
                        unset( $remaining[$row->page_namespace][$row->page_title] );
                    } else {
                        unset( $remaining[$pageId] );
                    }
                }
 
                // Store any extra fields requested by modules
                $this->processDbRow( $row );
 
                // Need gender information
                if ( $nsInfo->hasGenderDistinction( $row->page_namespace ) ) {
                    $usernames[] = $row->page_title;
                }
            }
        }
 
        if ( isset( $remaining ) ) {
            // Any items left in the $remaining list are added as missing
            if ( $processTitles ) {
                // The remaining titles in $remaining are non-existent pages
                $linkCache = MediaWikiServices::getInstance()->getLinkCache();
                foreach ( $remaining as $ns => $dbkeys ) {
                    foreach ( array_keys( $dbkeys ) as $dbkey ) {
                        $title = Title::makeTitle( $ns, $dbkey );
                        $linkCache->addBadLinkObj( $title );
                        $this->mAllPages[$ns][$dbkey] = $this->mFakePageId;
                        $this->mMissingPages[$ns][$dbkey] = $this->mFakePageId;
                        $this->mGoodAndMissingPages[$ns][$dbkey] = $this->mFakePageId;
                        $this->mMissingTitles[$this->mFakePageId] = $title;
                        $this->mFakePageId--;
                        $this->mTitles[] = $title;
 
                        // need gender information
                        if ( $nsInfo->hasGenderDistinction( $ns ) ) {
                            $usernames[] = $dbkey;
                        }
                    }
                }
            } else {
                // The remaining pageids do not exist
                if ( !$this->mMissingPageIDs ) {
                    $this->mMissingPageIDs = array_keys( $remaining );
                } else {
                    $this->mMissingPageIDs = array_merge( $this->mMissingPageIDs, array_keys( $remaining ) );
                }
            }
        }
 
        // Get gender information
        $genderCache = MediaWikiServices::getInstance()->getGenderCache();
        $genderCache->doQuery( $usernames, __METHOD__ );
    }
 
    private function initFromRevIDs( $revids ) {
        if ( !$revids ) {
            return;
        }
 
        $revids = array_map( 'intval', $revids ); // paranoia
        $db = $this->getDB();
        $pageids = [];
        $remaining = array_flip( $revids );
 
        $revids = $this->filterIDs( [ [ 'revision', 'rev_id' ], [ 'archive', 'ar_rev_id' ] ], $revids );
        $goodRemaining = array_flip( $revids );
 
        if ( $revids ) {
            $tables = [ 'revision', 'page' ];
            $fields = [ 'rev_id', 'rev_page' ];
            $where = [ 'rev_id' => $revids, 'rev_page = page_id' ];
 
            // Get pageIDs data from the `page` table
            $res = $db->select( $tables, $fields, $where, __METHOD__ );
            foreach ( $res as $row ) {
                $revid = (int)$row->rev_id;
                $pageid = (int)$row->rev_page;
                $this->mGoodRevIDs[$revid] = $pageid;
                $this->mLiveRevIDs[$revid] = $pageid;
                $pageids[$pageid] = '';
                unset( $remaining[$revid] );
                unset( $goodRemaining[$revid] );
            }
        }
 
        // Populate all the page information
        $this->initFromPageIds( array_keys( $pageids ), false );
 
        // If the user can see deleted revisions, pull out the corresponding
        // titles from the archive table and include them too. We ignore
        // ar_page_id because deleted revisions are tied by title, not page_id.
        if ( $goodRemaining &&
             $this->getPermissionManager()->userHasRight( $this->getUser(), 'deletedhistory' ) ) {
            $tables = [ 'archive' ];
            $fields = [ 'ar_rev_id', 'ar_namespace', 'ar_title' ];
            $where = [ 'ar_rev_id' => array_keys( $goodRemaining ) ];
 
            $res = $db->select( $tables, $fields, $where, __METHOD__ );
            $titles = [];
            foreach ( $res as $row ) {
                $revid = (int)$row->ar_rev_id;
                $titles[$revid] = Title::makeTitle( $row->ar_namespace, $row->ar_title );
                unset( $remaining[$revid] );
            }
 
            $this->initFromTitles( $titles );
 
            foreach ( $titles as $revid => $title ) {
                $ns = $title->getNamespace();
                $dbkey = $title->getDBkey();
 
                // Handle converted titles
                if ( !isset( $this->mAllPages[$ns][$dbkey] ) &&
                    isset( $this->mConvertedTitles[$title->getPrefixedText()] )
                ) {
                    $title = Title::newFromText( $this->mConvertedTitles[$title->getPrefixedText()] );
                    $ns = $title->getNamespace();
                    $dbkey = $title->getDBkey();
                }
 
                if ( isset( $this->mAllPages[$ns][$dbkey] ) ) {
                    $this->mGoodRevIDs[$revid] = $this->mAllPages[$ns][$dbkey];
                    $this->mDeletedRevIDs[$revid] = $this->mAllPages[$ns][$dbkey];
                } else {
                    $remaining[$revid] = true;
                }
            }
        }
 
        $this->mMissingRevIDs = array_keys( $remaining );
    }
 
    private function resolvePendingRedirects() {
        if ( $this->mResolveRedirects ) {
            $db = $this->getDB();
            $pageFlds = $this->getPageTableFields();
 
            // Repeat until all redirects have been resolved
            // The infinite loop is prevented by keeping all known pages in $this->mAllPages
            while ( $this->mPendingRedirectIDs || $this->mPendingRedirectSpecialPages ) {
                // Resolve redirects by querying the pagelinks table, and repeat the process
                // Create a new linkBatch object for the next pass
                $linkBatch = $this->getRedirectTargets();
 
                if ( $linkBatch->isEmpty() ) {
                    break;
                }
 
                $set = $linkBatch->constructSet( 'page', $db );
                if ( $set === false ) {
                    break;
                }
 
                // Get pageIDs data from the `page` table
                $res = $db->select( 'page', $pageFlds, $set, __METHOD__ );
 
                // Hack: get the ns:titles stored in [ns => array(titles)] format
                $this->initFromQueryResult( $res, $linkBatch->data, true );
            }
        }
    }
 
    private function getRedirectTargets() {
        $titlesToResolve = [];
        $db = $this->getDB();
 
        if ( $this->mPendingRedirectIDs ) {
            $res = $db->select(
                'redirect',
                [
                    'rd_from',
                    'rd_namespace',
                    'rd_fragment',
                    'rd_interwiki',
                    'rd_title'
                ], [ 'rd_from' => array_keys( $this->mPendingRedirectIDs ) ],
                    __METHOD__
                );
            foreach ( $res as $row ) {
                $rdfrom = (int)$row->rd_from;
                $from = $this->mPendingRedirectIDs[$rdfrom]->getPrefixedText();
                $to = Title::makeTitle(
                    $row->rd_namespace,
                    $row->rd_title,
                    $row->rd_fragment,
                    $row->rd_interwiki
                );
                $this->mResolvedRedirectTitles[$from] = $this->mPendingRedirectIDs[$rdfrom];
                unset( $this->mPendingRedirectIDs[$rdfrom] );
                if ( $to->isExternal() ) {
                    $this->mInterwikiTitles[$to->getPrefixedText()] = $to->getInterwiki();
                } elseif ( !isset( $this->mAllPages[$to->getNamespace()][$to->getDBkey()] ) ) {
                    $titlesToResolve[] = $to;
                }
                $this->mRedirectTitles[$from] = $to;
            }
 
            if ( $this->mPendingRedirectIDs ) {
                // We found pages that aren't in the redirect table
                // Add them
                foreach ( $this->mPendingRedirectIDs as $id => $title ) {
                    $page = WikiPage::factory( $title );
                    $rt = $page->insertRedirect();
                    if ( !$rt ) {
                        // What the hell. Let's just ignore this
                        continue;
                    }
                    if ( $rt->isExternal() ) {
                        $this->mInterwikiTitles[$rt->getPrefixedText()] = $rt->getInterwiki();
                    } elseif ( !isset( $this->mAllPages[$rt->getNamespace()][$rt->getDBkey()] ) ) {
                        $titlesToResolve[] = $rt;
                    }
                    $from = $title->getPrefixedText();
                    $this->mResolvedRedirectTitles[$from] = $title;
                    $this->mRedirectTitles[$from] = $rt;
                    unset( $this->mPendingRedirectIDs[$id] );
                }
            }
        }
 
        if ( $this->mPendingRedirectSpecialPages ) {
            foreach ( $this->mPendingRedirectSpecialPages as $key => list( $from, $to ) ) {
                $fromKey = $from->getPrefixedText();
                $this->mResolvedRedirectTitles[$fromKey] = $from;
                $this->mRedirectTitles[$fromKey] = $to;
                if ( $to->isExternal() ) {
                    $this->mInterwikiTitles[$to->getPrefixedText()] = $to->getInterwiki();
                } elseif ( !isset( $this->mAllPages[$to->getNamespace()][$to->getDBkey()] ) ) {
                    $titlesToResolve[] = $to;
                }
            }
            $this->mPendingRedirectSpecialPages = [];
 
            // Set private caching since we don't know what criteria the
            // special pages used to decide on these redirects.
            $this->mCacheMode = 'private';
        }
 
        return $this->processTitlesArray( $titlesToResolve );
    }
 
    public function getCacheMode( $params = null ) {
        return $this->mCacheMode;
    }
 
    private function processTitlesArray( $titles ) {
        $usernames = [];
        $linkBatch = new LinkBatch();
        $services = MediaWikiServices::getInstance();
        $contLang = $services->getContentLanguage();
 
        $titleObjects = [];
        foreach ( $titles as $index => $title ) {
            if ( is_string( $title ) ) {
                try {
                    $titleObj = Title::newFromTextThrow( $title, $this->mDefaultNamespace );
                } catch ( MalformedTitleException $ex ) {
                    // Handle invalid titles gracefully
                    if ( !isset( $this->mAllPages[0][$title] ) ) {
                        $this->mAllPages[0][$title] = $this->mFakePageId;
                        $this->mInvalidTitles[$this->mFakePageId] = [
                            'title' => $title,
                            'invalidreason' => $this->getErrorFormatter()->formatException( $ex, [ 'bc' => true ] ),
                        ];
                        $this->mFakePageId--;
                    }
                    continue; // There's nothing else we can do
                }
            } else {
                $titleObj = $title;
            }
 
            $titleObjects[$index] = $titleObj;
        }
 
        // Get gender information
        $genderCache = $services->getGenderCache();
        $genderCache->doTitlesArray( $titleObjects, __METHOD__ );
 
        foreach ( $titleObjects as $index => $titleObj ) {
            $title = is_string( $titles[$index] ) ? $titles[$index] : false;
            $unconvertedTitle = $titleObj->getPrefixedText();
            $titleWasConverted = false;
            if ( $titleObj->isExternal() ) {
                // This title is an interwiki link.
                $this->mInterwikiTitles[$unconvertedTitle] = $titleObj->getInterwiki();
            } else {
                // Variants checking
                if (
                    $this->mConvertTitles && $contLang->hasVariants() && !$titleObj->exists()
                ) {
                    // Language::findVariantLink will modify titleText and titleObj into
                    // the canonical variant if possible
                    $titleText = $title !== false ? $title : $titleObj->getPrefixedText();
                    $contLang->findVariantLink( $titleText, $titleObj );
                    $titleWasConverted = $unconvertedTitle !== $titleObj->getPrefixedText();
                }
 
                if ( $titleObj->getNamespace() < 0 ) {
                    // Handle Special and Media pages
                    $titleObj = $titleObj->fixSpecialName();
                    $ns = $titleObj->getNamespace();
                    $dbkey = $titleObj->getDBkey();
                    if ( !isset( $this->mAllSpecials[$ns][$dbkey] ) ) {
                        $this->mAllSpecials[$ns][$dbkey] = $this->mFakePageId;
                        $target = null;
                        if ( $ns === NS_SPECIAL && $this->mResolveRedirects ) {
                            $spFactory = $services->getSpecialPageFactory();
                            $special = $spFactory->getPage( $dbkey );
                            if ( $special instanceof RedirectSpecialArticle ) {
                                // Only RedirectSpecialArticle is intended to redirect to an article, other kinds of
                                // RedirectSpecialPage are probably applying weird URL parameters we don't want to handle.
                                $context = new DerivativeContext( $this );
                                $context->setTitle( $titleObj );
                                $context->setRequest( new FauxRequest );
                                $special->setContext( $context );
                                list( /* $alias */, $subpage ) = $spFactory->resolveAlias( $dbkey );
                                $target = $special->getRedirect( $subpage );
                            }
                        }
                        if ( $target ) {
                            $this->mPendingRedirectSpecialPages[$dbkey] = [ $titleObj, $target ];
                        } else {
                            $this->mSpecialTitles[$this->mFakePageId] = $titleObj;
                            $this->mFakePageId--;
                        }
                    }
                } else {
                    // Regular page
                    $linkBatch->addObj( $titleObj );
                }
            }
 
            // Make sure we remember the original title that was
            // given to us. This way the caller can correlate new
            // titles with the originally requested when e.g. the
            // namespace is localized or the capitalization is
            // different
            if ( $titleWasConverted ) {
                $this->mConvertedTitles[$unconvertedTitle] = $titleObj->getPrefixedText();
                // In this case the page can't be Special.
                if ( $title !== false && $title !== $unconvertedTitle ) {
                    $this->mNormalizedTitles[$title] = $unconvertedTitle;
                }
            } elseif ( $title !== false && $title !== $titleObj->getPrefixedText() ) {
                $this->mNormalizedTitles[$title] = $titleObj->getPrefixedText();
            }
        }
 
        return $linkBatch;
    }
 
    public function setGeneratorData( Title $title, array $data ) {
        $ns = $title->getNamespace();
        $dbkey = $title->getDBkey();
        $this->mGeneratorData[$ns][$dbkey] = $data;
    }
 
    public function setRedirectMergePolicy( $callable ) {
        $this->mRedirectMergePolicy = $callable;
    }
 
    public function populateGeneratorData( &$result, array $path = [] ) {
        if ( $result instanceof ApiResult ) {
            $data = $result->getResultData( $path );
            if ( $data === null ) {
                return true;
            }
        } else {
            $data = &$result;
            foreach ( $path as $key ) {
                if ( !isset( $data[$key] ) ) {
                    // Path isn't in $result, so nothing to add, so everything
                    // "fits"
                    return true;
                }
                $data = &$data[$key];
            }
        }
        foreach ( $this->mGeneratorData as $ns => $dbkeys ) {
            if ( $ns === NS_SPECIAL ) {
                $pages = [];
                foreach ( $this->mSpecialTitles as $id => $title ) {
                    $pages[$title->getDBkey()] = $id;
                }
            } else {
                if ( !isset( $this->mAllPages[$ns] ) ) {
                    // No known titles in the whole namespace. Skip it.
                    continue;
                }
                $pages = $this->mAllPages[$ns];
            }
            foreach ( $dbkeys as $dbkey => $genData ) {
                if ( !isset( $pages[$dbkey] ) ) {
                    // Unknown title. Forget it.
                    continue;
                }
                $pageId = $pages[$dbkey];
                if ( !isset( $data[$pageId] ) ) {
                    // $pageId didn't make it into the result. Ignore it.
                    continue;
                }
 
                if ( $result instanceof ApiResult ) {
                    $path2 = array_merge( $path, [ $pageId ] );
                    foreach ( $genData as $key => $value ) {
                        if ( !$result->addValue( $path2, $key, $value ) ) {
                            return false;
                        }
                    }
                } else {
                    $data[$pageId] = array_merge( $data[$pageId], $genData );
                }
            }
        }
 
        // Merge data generated about redirect titles into the redirect destination
        if ( $this->mRedirectMergePolicy ) {
            foreach ( $this->mResolvedRedirectTitles as $titleFrom ) {
                $dest = $titleFrom;
                while ( isset( $this->mRedirectTitles[$dest->getPrefixedText()] ) ) {
                    $dest = $this->mRedirectTitles[$dest->getPrefixedText()];
                }
                $fromNs = $titleFrom->getNamespace();
                $fromDBkey = $titleFrom->getDBkey();
                $toPageId = $dest->getArticleID();
                if ( isset( $data[$toPageId] ) &&
                    isset( $this->mGeneratorData[$fromNs][$fromDBkey] )
                ) {
                    // It is necessary to set both $data and add to $result, if an ApiResult,
                    // to ensure multiple redirects to the same destination are all merged.
                    $data[$toPageId] = call_user_func(
                        $this->mRedirectMergePolicy,
                        $data[$toPageId],
                        $this->mGeneratorData[$fromNs][$fromDBkey]
                    );
                    if ( $result instanceof ApiResult &&
                        !$result->addValue( $path, $toPageId, $data[$toPageId], ApiResult::OVERRIDE )
                    ) {
                        return false;
                    }
                }
            }
        }
 
        return true;
    }
 
    protected function getDB() {
        return $this->mDbSource->getDB();
    }
 
    public function getAllowedParams( $flags = 0 ) {
        $result = [
            'titles' => [
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_HELP_MSG => 'api-pageset-param-titles',
            ],
            'pageids' => [
                ApiBase::PARAM_TYPE => 'integer',
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_HELP_MSG => 'api-pageset-param-pageids',
            ],
            'revids' => [
                ApiBase::PARAM_TYPE => 'integer',
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_HELP_MSG => 'api-pageset-param-revids',
            ],
            'generator' => [
                ApiBase::PARAM_TYPE => null,
                ApiBase::PARAM_HELP_MSG => 'api-pageset-param-generator',
                ApiBase::PARAM_SUBMODULE_PARAM_PREFIX => 'g',
            ],
            'redirects' => [
                ApiBase::PARAM_DFLT => false,
                ApiBase::PARAM_HELP_MSG => $this->mAllowGenerator
                    ? 'api-pageset-param-redirects-generator'
                    : 'api-pageset-param-redirects-nogenerator',
            ],
            'converttitles' => [
                ApiBase::PARAM_DFLT => false,
                ApiBase::PARAM_HELP_MSG => [
                    'api-pageset-param-converttitles',
                    [ Message::listParam( LanguageConverter::$languagesWithVariants, 'text' ) ],
                ],
            ],
        ];
 
        if ( !$this->mAllowGenerator ) {
            unset( $result['generator'] );
        } elseif ( $flags & ApiBase::GET_VALUES_FOR_HELP ) {
            $result['generator'][ApiBase::PARAM_TYPE] = 'submodule';
            $result['generator'][ApiBase::PARAM_SUBMODULE_MAP] = $this->getGenerators();
        }
 
        return $result;
    }
 
    protected function handleParamNormalization( $paramName, $value, $rawValue ) {
        parent::handleParamNormalization( $paramName, $value, $rawValue );
 
        if ( $paramName === 'titles' ) {
            // For the 'titles' parameter, we want to split it like ApiBase would
            // and add any changed titles to $this->mNormalizedTitles
            $value = $this->explodeMultiValue( $value, self::LIMIT_SML2 + 1 );
            $l = count( $value );
            $rawValue = $this->explodeMultiValue( $rawValue, $l );
            for ( $i = 0; $i < $l; $i++ ) {
                if ( $value[$i] !== $rawValue[$i] ) {
                    $this->mNormalizedTitles[$rawValue[$i]] = $value[$i];
                }
            }
        }
    }
 
    private static $generators = null;
 
    private function getGenerators() {
        if ( self::$generators === null ) {
            $query = $this->mDbSource;
            if ( !( $query instanceof ApiQuery ) ) {
                // If the parent container of this pageset is not ApiQuery,
                // we must create it to get module manager
                $query = $this->getMain()->getModuleManager()->getModule( 'query' );
            }
            $gens = [];
            $prefix = $query->getModulePath() . '+';
            $mgr = $query->getModuleManager();
            foreach ( $mgr->getNamesWithClasses() as $name => $class ) {
                if ( is_subclass_of( $class, ApiQueryGeneratorBase::class ) ) {
                    $gens[$name] = $prefix . $name;
                }
            }
            ksort( $gens );
            self::$generators = $gens;
        }
 
        return self::$generators;
    }
}