ApiQueryBacklinks.php

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<?php
class ApiQueryBacklinks extends ApiQueryGeneratorBase {

        private $rootTitle;

        private $params, $contID, $redirID, $redirect;
        private $bl_ns, $bl_from, $bl_table, $bl_code, $bl_title, $bl_fields, $hasNS;

        private $pageMap = array();
        private $resultArr;

        private $redirTitles = array();
        private $continueStr = null;

        // output element name, database column field prefix, database table
        private $backlinksSettings = array(
                'backlinks' => array(
                        'code' => 'bl',
                        'prefix' => 'pl',
                        'linktbl' => 'pagelinks',
                        'helpurl' => 'https://www.mediawiki.org/wiki/API:Backlinks',
                ),
                'embeddedin' => array(
                        'code' => 'ei',
                        'prefix' => 'tl',
                        'linktbl' => 'templatelinks',
                        'helpurl' => 'https://www.mediawiki.org/wiki/API:Embeddedin',
                ),
                'imageusage' => array(
                        'code' => 'iu',
                        'prefix' => 'il',
                        'linktbl' => 'imagelinks',
                        'helpurl' => 'https://www.mediawiki.org/wiki/API:Imageusage',
                )
        );

        public function __construct( $query, $moduleName ) {
                $settings = $this->backlinksSettings[$moduleName];
                $prefix = $settings['prefix'];
                $code = $settings['code'];
                $this->resultArr = array();

                parent::__construct( $query, $moduleName, $code );
                $this->bl_ns = $prefix . '_namespace';
                $this->bl_from = $prefix . '_from';
                $this->bl_table = $settings['linktbl'];
                $this->bl_code = $code;
                $this->helpUrl = $settings['helpurl'];

                $this->hasNS = $moduleName !== 'imageusage';
                if ( $this->hasNS ) {
                        $this->bl_title = $prefix . '_title';
                        $this->bl_fields = array(
                                $this->bl_ns,
                                $this->bl_title
                        );
                } else {
                        $this->bl_title = $prefix . '_to';
                        $this->bl_fields = array(
                                $this->bl_title
                        );
                }
        }

        public function execute() {
                $this->run();
        }

        public function getCacheMode( $params ) {
                return 'public';
        }

        public function executeGenerator( $resultPageSet ) {
                $this->run( $resultPageSet );
        }

        private function prepareFirstQuery( $resultPageSet = null ) {
                /* SELECT page_id, page_title, page_namespace, page_is_redirect
                 * FROM pagelinks, page WHERE pl_from=page_id
                 * AND pl_title='Foo' AND pl_namespace=0
                 * LIMIT 11 ORDER BY pl_from
                 */
                $this->addTables( array( $this->bl_table, 'page' ) );
                $this->addWhere( "{$this->bl_from}=page_id" );
                if ( is_null( $resultPageSet ) ) {
                        $this->addFields( array( 'page_id', 'page_title', 'page_namespace' ) );
                } else {
                        $this->addFields( $resultPageSet->getPageTableFields() );
                }

                $this->addFields( 'page_is_redirect' );
                $this->addWhereFld( $this->bl_title, $this->rootTitle->getDBkey() );

                if ( $this->hasNS ) {
                        $this->addWhereFld( $this->bl_ns, $this->rootTitle->getNamespace() );
                }
                $this->addWhereFld( 'page_namespace', $this->params['namespace'] );

                if ( !is_null( $this->contID ) ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';
                        $this->addWhere( "{$this->bl_from}$op={$this->contID}" );
                }

                if ( $this->params['filterredir'] == 'redirects' ) {
                        $this->addWhereFld( 'page_is_redirect', 1 );
                } elseif ( $this->params['filterredir'] == 'nonredirects' && !$this->redirect ) {
                        // bug 22245 - Check for !redirect, as filtering nonredirects, when getting what links to them is contradictory
                        $this->addWhereFld( 'page_is_redirect', 0 );
                }

                $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
                $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
                $this->addOption( 'ORDER BY', $this->bl_from . $sort );
                $this->addOption( 'STRAIGHT_JOIN' );
        }

        private function prepareSecondQuery( $resultPageSet = null ) {
                /* SELECT page_id, page_title, page_namespace, page_is_redirect, pl_title, pl_namespace
                   FROM pagelinks, page WHERE pl_from=page_id
                   AND (pl_title='Foo' AND pl_namespace=0) OR (pl_title='Bar' AND pl_namespace=1)
                   ORDER BY pl_namespace, pl_title, pl_from LIMIT 11
                 */
                $db = $this->getDB();
                $this->addTables( array( 'page', $this->bl_table ) );
                $this->addWhere( "{$this->bl_from}=page_id" );

                if ( is_null( $resultPageSet ) ) {
                        $this->addFields( array( 'page_id', 'page_title', 'page_namespace', 'page_is_redirect' ) );
                } else {
                        $this->addFields( $resultPageSet->getPageTableFields() );
                }

                $this->addFields( $this->bl_title );
                if ( $this->hasNS ) {
                        $this->addFields( $this->bl_ns );
                }

                // We can't use LinkBatch here because $this->hasNS may be false
                $titleWhere = array();
                $allRedirNs = array();
                $allRedirDBkey = array();
                foreach ( $this->redirTitles as $t ) {
                        $redirNs = $t->getNamespace();
                        $redirDBkey = $t->getDBkey();
                        $titleWhere[] = "{$this->bl_title} = " . $db->addQuotes( $redirDBkey ) .
                                        ( $this->hasNS ? " AND {$this->bl_ns} = {$redirNs}" : '' );
                        $allRedirNs[] = $redirNs;
                        $allRedirDBkey[] = $redirDBkey;
                }
                $this->addWhere( $db->makeList( $titleWhere, LIST_OR ) );
                $this->addWhereFld( 'page_namespace', $this->params['namespace'] );

                if ( !is_null( $this->redirID ) ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';
                        $first = $this->redirTitles[0];
                        $title = $db->addQuotes( $first->getDBkey() );
                        $ns = $first->getNamespace();
                        $from = $this->redirID;
                        if ( $this->hasNS ) {
                                $this->addWhere( "{$this->bl_ns} $op $ns OR " .
                                                "({$this->bl_ns} = $ns AND " .
                                                "({$this->bl_title} $op $title OR " .
                                                "({$this->bl_title} = $title AND " .
                                                "{$this->bl_from} $op= $from)))" );
                        } else {
                                $this->addWhere( "{$this->bl_title} $op $title OR " .
                                                "({$this->bl_title} = $title AND " .
                                                "{$this->bl_from} $op= $from)" );
                        }
                }
                if ( $this->params['filterredir'] == 'redirects' ) {
                        $this->addWhereFld( 'page_is_redirect', 1 );
                } elseif ( $this->params['filterredir'] == 'nonredirects' ) {
                        $this->addWhereFld( 'page_is_redirect', 0 );
                }

                $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
                $orderBy = array();
                $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
                // Don't order by namespace/title if it's constant in the WHERE clause
                if( $this->hasNS && count( array_unique( $allRedirNs ) ) != 1 ) {
                        $orderBy[] = $this->bl_ns . $sort;
                }
                if( count( array_unique( $allRedirDBkey ) ) != 1 ) {
                        $orderBy[] = $this->bl_title . $sort;
                }
                $orderBy[] = $this->bl_from . $sort;
                $this->addOption( 'ORDER BY', $orderBy );
                $this->addOption( 'USE INDEX', array( 'page' => 'PRIMARY' ) );
        }

        private function run( $resultPageSet = null ) {
                $this->params = $this->extractRequestParams( false );
                $this->redirect = isset( $this->params['redirect'] ) && $this->params['redirect'];
                $userMax = ( $this->redirect ? ApiBase::LIMIT_BIG1 / 2 : ApiBase::LIMIT_BIG1 );
                $botMax  = ( $this->redirect ? ApiBase::LIMIT_BIG2 / 2 : ApiBase::LIMIT_BIG2 );

                $result = $this->getResult();

                if ( $this->params['limit'] == 'max' ) {
                        $this->params['limit'] = $this->getMain()->canApiHighLimits() ? $botMax : $userMax;
                        $result->setParsedLimit( $this->getModuleName(), $this->params['limit'] );
                }

                $this->processContinue();
                $this->prepareFirstQuery( $resultPageSet );

                $res = $this->select( __METHOD__ . '::firstQuery' );

                $count = 0;

                foreach ( $res as $row ) {
                        if ( ++ $count > $this->params['limit'] ) {
                                // We've reached the one extra which shows that there are additional pages to be had. Stop here...
                                // Continue string preserved in case the redirect query doesn't pass the limit
                                $this->continueStr = $this->getContinueStr( $row->page_id );
                                break;
                        }

                        if ( is_null( $resultPageSet ) ) {
                                $this->extractRowInfo( $row );
                        } else {
                                $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
                                if ( $row->page_is_redirect ) {
                                        $this->redirTitles[] = Title::makeTitle( $row->page_namespace, $row->page_title );
                                }

                                $resultPageSet->processDbRow( $row );
                        }
                }

                if ( $this->redirect && count( $this->redirTitles ) ) {
                        $this->resetQueryParams();
                        $this->prepareSecondQuery( $resultPageSet );
                        $res = $this->select( __METHOD__ . '::secondQuery' );
                        $count = 0;
                        foreach ( $res as $row ) {
                                if ( ++$count > $this->params['limit'] ) {
                                        // We've reached the one extra which shows that there are additional pages to be had. Stop here...
                                        // We need to keep the parent page of this redir in
                                        if ( $this->hasNS ) {
                                                $parentID = $this->pageMap[$row-> { $this->bl_ns } ][$row-> { $this->bl_title } ];
                                        } else {
                                                $parentID = $this->pageMap[NS_FILE][$row-> { $this->bl_title } ];
                                        }
                                        $this->continueStr = $this->getContinueRedirStr( $parentID, $row->page_id );
                                        break;
                                }

                                if ( is_null( $resultPageSet ) ) {
                                        $this->extractRedirRowInfo( $row );
                                } else {
                                        $resultPageSet->processDbRow( $row );
                                }
                        }
                }
                if ( is_null( $resultPageSet ) ) {
                        // Try to add the result data in one go and pray that it fits
                        $fit = $result->addValue( 'query', $this->getModuleName(), array_values( $this->resultArr ) );
                        if ( !$fit ) {
                                // It didn't fit. Add elements one by one until the
                                // result is full.
                                foreach ( $this->resultArr as $pageID => $arr ) {
                                        // Add the basic entry without redirlinks first
                                        $fit = $result->addValue(
                                                array( 'query', $this->getModuleName() ),
                                                null, array_diff_key( $arr, array( 'redirlinks' => '' ) ) );
                                        if ( !$fit ) {
                                                $this->continueStr = $this->getContinueStr( $pageID );
                                                break;
                                        }

                                        $hasRedirs = false;
                                        $redirLinks = isset( $arr['redirlinks'] ) ? $arr['redirlinks'] : array();
                                        foreach ( (array)$redirLinks as $key => $redir ) {
                                                $fit = $result->addValue(
                                                        array( 'query', $this->getModuleName(), $pageID, 'redirlinks' ),
                                                        $key, $redir );
                                                if ( !$fit ) {
                                                        $this->continueStr = $this->getContinueRedirStr( $pageID, $redir['pageid'] );
                                                        break;
                                                }
                                                $hasRedirs = true;
                                        }
                                        if ( $hasRedirs ) {
                                                $result->setIndexedTagName_internal(
                                                        array( 'query', $this->getModuleName(), $pageID, 'redirlinks' ),
                                                        $this->bl_code );
                                        }
                                        if ( !$fit ) {
                                                break;
                                        }
                                }
                        }

                        $result->setIndexedTagName_internal(
                                array( 'query', $this->getModuleName() ),
                                $this->bl_code
                        );
                }
                if ( !is_null( $this->continueStr ) ) {
                        $this->setContinueEnumParameter( 'continue', $this->continueStr );
                }
        }

        private function extractRowInfo( $row ) {
                $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
                $t = Title::makeTitle( $row->page_namespace, $row->page_title );
                $a = array( 'pageid' => intval( $row->page_id ) );
                ApiQueryBase::addTitleInfo( $a, $t );
                if ( $row->page_is_redirect ) {
                        $a['redirect'] = '';
                        $this->redirTitles[] = $t;
                }
                // Put all the results in an array first
                $this->resultArr[$a['pageid']] = $a;
        }

        private function extractRedirRowInfo( $row ) {
                $a['pageid'] = intval( $row->page_id );
                ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
                if ( $row->page_is_redirect ) {
                        $a['redirect'] = '';
                }
                $ns = $this->hasNS ? $row-> { $this->bl_ns } : NS_FILE;
                $parentID = $this->pageMap[$ns][$row-> { $this->bl_title } ];
                // Put all the results in an array first
                $this->resultArr[$parentID]['redirlinks'][] = $a;
                $this->getResult()->setIndexedTagName( $this->resultArr[$parentID]['redirlinks'], $this->bl_code );
        }

        protected function processContinue() {
                if ( !is_null( $this->params['continue'] ) ) {
                        $this->parseContinueParam();
                } else {
                        $this->rootTitle = $this->getTitleOrPageId( $this->params )->getTitle();
                }

                // only image titles are allowed for the root in imageinfo mode
                if ( !$this->hasNS && $this->rootTitle->getNamespace() !== NS_FILE ) {
                        $this->dieUsage( "The title for {$this->getModuleName()} query must be an image", 'bad_image_title' );
                }
        }

        protected function parseContinueParam() {
                $continueList = explode( '|', $this->params['continue'] );
                // expected format:
                // ns | key | id1 [| id2]
                // ns+key: root title
                // id1: first-level page ID to continue from
                // id2: second-level page ID to continue from

                // null stuff out now so we know what's set and what isn't
                $this->rootTitle = $this->contID = $this->redirID = null;
                $rootNs = intval( $continueList[0] );
                if ( $rootNs === 0 && $continueList[0] !== '0' ) {
                        // Illegal continue parameter
                        $this->dieUsage( 'Invalid continue param. You should pass the original value returned by the previous query', '_badcontinue' );
                }
                $this->rootTitle = Title::makeTitleSafe( $rootNs, $continueList[1] );

                if ( !$this->rootTitle ) {
                        $this->dieUsage( 'Invalid continue param. You should pass the original value returned by the previous query', '_badcontinue' );
                }
                $contID = intval( $continueList[2] );

                if ( $contID === 0 && $continueList[2] !== '0' ) {
                        $this->dieUsage( 'Invalid continue param. You should pass the original value returned by the previous query', '_badcontinue' );
                }
                $this->contID = $contID;
                $id2 = isset( $continueList[3] ) ? $continueList[3] : null;
                $redirID = intval( $id2 );

                if ( $redirID === 0 && $id2 !== '0' ) {
                        // This one isn't required
                        return;
                }
                $this->redirID = $redirID;

        }

        protected function getContinueStr( $lastPageID ) {
                return $this->rootTitle->getNamespace() .
                '|' . $this->rootTitle->getDBkey() .
                '|' . $lastPageID;
        }

        protected function getContinueRedirStr( $lastPageID, $lastRedirID ) {
                return $this->getContinueStr( $lastPageID ) . '|' . $lastRedirID;
        }

        public function getAllowedParams() {
                $retval = array(
                        'title' => array(
                                ApiBase::PARAM_TYPE => 'string',
                        ),
                        'pageid' => array(
                                ApiBase::PARAM_TYPE => 'integer',
                        ),
                        'continue' => null,
                        'namespace' => array(
                                ApiBase::PARAM_ISMULTI => true,
                                ApiBase::PARAM_TYPE => 'namespace'
                        ),
                        'dir' => array(
                                ApiBase::PARAM_DFLT => 'ascending',
                                ApiBase::PARAM_TYPE => array(
                                        'ascending',
                                        'descending'
                                )
                        ),
                        'filterredir' => array(
                                ApiBase::PARAM_DFLT => 'all',
                                ApiBase::PARAM_TYPE => array(
                                        'all',
                                        'redirects',
                                        'nonredirects'
                                )
                        ),
                        'limit' => array(
                                ApiBase::PARAM_DFLT => 10,
                                ApiBase::PARAM_TYPE => 'limit',
                                ApiBase::PARAM_MIN => 1,
                                ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
                                ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
                        )
                );
                if ( $this->getModuleName() == 'embeddedin' ) {
                        return $retval;
                }
                $retval['redirect'] = false;
                return $retval;
        }

        public function getParamDescription() {
                $retval = array(
                        'title' => "Title to search. Cannot be used together with {$this->bl_code}pageid",
                        'pageid' => "Pageid to search. Cannot be used together with {$this->bl_code}title",
                        'continue' => 'When more results are available, use this to continue',
                        'namespace' => 'The namespace to enumerate',
                        'dir' => 'The direction in which to list',
                );
                if ( $this->getModuleName() != 'embeddedin' ) {
                        return array_merge( $retval, array(
                                'redirect' => 'If linking page is a redirect, find all pages that link to that redirect as well. Maximum limit is halved.',
                                'filterredir' => "How to filter for redirects. If set to nonredirects when {$this->bl_code}redirect is enabled, this is only applied to the second level",
                                'limit' => "How many total pages to return. If {$this->bl_code}redirect is enabled, limit applies to each level separately (which means you may get up to 2 * limit results)."
                        ) );
                }
                return array_merge( $retval, array(
                        'filterredir' => 'How to filter for redirects',
                        'limit' => 'How many total pages to return'
                ) );
        }

        public function getResultProperties() {
                return array(
                        '' => array(
                                'pageid' => 'integer',
                                'ns' => 'namespace',
                                'title' => 'string',
                                'redirect' => 'boolean'
                        )
                );
        }

        public function getDescription() {
                switch ( $this->getModuleName() ) {
                        case 'backlinks':
                                return 'Find all pages that link to the given page';
                        case 'embeddedin':
                                return 'Find all pages that embed (transclude) the given title';
                        case 'imageusage':
                                return 'Find all pages that use the given image title.';
                        default:
                                ApiBase::dieDebug( __METHOD__, 'Unknown module name' );
                }
        }

        public function getPossibleErrors() {
                return array_merge( parent::getPossibleErrors(),
                        $this->getTitleOrPageIdErrorMessage(),
                        array(
                                array( 'code' => 'bad_image_title', 'info' => "The title for {$this->getModuleName()} query must be an image" ),
                                array( 'code' => '_badcontinue', 'info' => 'Invalid continue param. You should pass the original value returned by the previous query' ),
                        )
                );
        }

        public function getExamples() {
                static $examples = array(
                        'backlinks' => array(
                                'api.php?action=query&list=backlinks&bltitle=Main%20Page',
                                'api.php?action=query&generator=backlinks&gbltitle=Main%20Page&prop=info'
                        ),
                        'embeddedin' => array(
                                'api.php?action=query&list=embeddedin&eititle=Template:Stub',
                                'api.php?action=query&generator=embeddedin&geititle=Template:Stub&prop=info'
                        ),
                        'imageusage' => array(
                                'api.php?action=query&list=imageusage&iutitle=File:Albert%20Einstein%20Head.jpg',
                                'api.php?action=query&generator=imageusage&giutitle=File:Albert%20Einstein%20Head.jpg&prop=info'
                        )
                );

                return $examples[$this->getModuleName()];
        }

        public function getHelpUrls() {
                return $this->helpUrl;
        }

        public function getVersion() {
                return __CLASS__ . ': $Id$';
        }
}