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[mediawiki.git] / includes / api / ApiQueryBacklinks.php

<?php
/**
 *
 *
 * Created on Oct 16, 2006
 *
 * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
 *
 * 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
 */

/**
 * This is a three-in-one module to query:
 *   * backlinks  - links pointing to the given page,
 *   * embeddedin - what pages transclude the given page within themselves,
 *   * imageusage - what pages use the given image
 *
 * @ingroup API
 */
class ApiQueryBacklinks extends ApiQueryGeneratorBase {

        /**
         * @var Title
         */
        private $rootTitle;

        private $params, $cont, $redirect;
        private $bl_ns, $bl_from, $bl_from_ns, $bl_table, $bl_code, $bl_title, $bl_fields, $hasNS;

        /**
         * Maps ns and title to pageid
         *
         * @var array
         */
        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( ApiQuery $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_from_ns = $prefix . '_from_namespace';
                $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 );
        }

        /**
         * @param ApiPageSet $resultPageSet
         * @return void
         */
        private function runFirstQuery( $resultPageSet = null ) {
                $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( array( 'page_is_redirect', 'from_ns' => 'page_namespace' ) );

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

                if ( count( $this->cont ) >= 2 ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';
                        if ( count( $this->params['namespace'] ) > 1 ) {
                                $this->addWhere(
                                        "{$this->bl_from_ns} $op {$this->cont[0]} OR " .
                                        "({$this->bl_from_ns} = {$this->cont[0]} AND " .
                                        "{$this->bl_from} $op= {$this->cont[1]})"
                                );
                        } else {
                                $this->addWhere( "{$this->bl_from} $op= {$this->cont[1]}" );
                        }
                }

                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' : '' );
                $orderBy = array();
                if ( count( $this->params['namespace'] ) > 1 ) {
                        $orderBy[] = $this->bl_from_ns . $sort;
                }
                $orderBy[] = $this->bl_from . $sort;
                $this->addOption( 'ORDER BY', $orderBy );
                $this->addOption( 'STRAIGHT_JOIN' );

                $res = $this->select( __METHOD__ );
                $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 may be overridden at a later step
                                $this->continueStr = "{$row->from_ns}|{$row->page_id}";
                                break;
                        }

                        // Fill in continuation fields for later steps
                        if ( count( $this->cont ) < 2 ) {
                                $this->cont[] = $row->from_ns;
                                $this->cont[] = $row->page_id;
                        }

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

                        if ( is_null( $resultPageSet ) ) {
                                $a = array( 'pageid' => intval( $row->page_id ) );
                                ApiQueryBase::addTitleInfo( $a, $t );
                                if ( $row->page_is_redirect ) {
                                        $a['redirect'] = true;
                                }
                                // Put all the results in an array first
                                $this->resultArr[$a['pageid']] = $a;
                        } else {
                                $resultPageSet->processDbRow( $row );
                        }
                }
        }

        /**
         * @param ApiPageSet $resultPageSet
         * @return void
         */
        private function runSecondQuery( $resultPageSet = null ) {
                $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( array( $this->bl_title, 'from_ns' => 'page_namespace' ) );
                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();
                /** @var $t Title */
                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] = true;
                        $allRedirDBkey[$redirDBkey] = true;
                }
                $this->addWhere( $db->makeList( $titleWhere, LIST_OR ) );
                $this->addWhereFld( 'page_namespace', $this->params['namespace'] );

                if ( count( $this->cont ) >= 6 ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';

                        $where = "{$this->bl_from} $op= {$this->cont[5]}";
                        // Don't bother with namespace, title, or from_namespace if it's
                        // otherwise constant in the where clause.
                        if ( count( $this->params['namespace'] ) > 1 ) {
                                $where = "{$this->bl_from_ns} $op {$this->cont[4]} OR " .
                                        "({$this->bl_from_ns} = {$this->cont[4]} AND ($where))";
                        }
                        if ( count( $allRedirDBkey ) > 1 ) {
                                $title = $db->addQuotes( $this->cont[3] );
                                $where = "{$this->bl_title} $op $title OR " .
                                        "({$this->bl_title} = $title AND ($where))";
                        }
                        if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
                                $where = "{$this->bl_ns} $op {$this->cont[2]} OR " .
                                        "({$this->bl_ns} = {$this->cont[2]} AND ($where))";
                        }

                        $this->addWhere( $where );
                }
                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/from_namespace if it's constant in the WHERE clause
                if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
                        $orderBy[] = $this->bl_ns . $sort;
                }
                if ( count( $allRedirDBkey ) > 1 ) {
                        $orderBy[] = $this->bl_title . $sort;
                }
                if ( count( $this->params['namespace'] ) > 1 ) {
                        $orderBy[] = $this->bl_from_ns . $sort;
                }
                $orderBy[] = $this->bl_from . $sort;
                $this->addOption( 'ORDER BY', $orderBy );
                $this->addOption( 'USE INDEX', array( 'page' => 'PRIMARY' ) );

                $res = $this->select( __METHOD__ );
                $count = 0;
                foreach ( $res as $row ) {
                        $ns = $this->hasNS ? $row->{$this->bl_ns} : NS_FILE;

                        if ( ++$count > $this->params['limit'] ) {
                                // We've reached the one extra which shows that there are
                                // additional pages to be had. Stop here...
                                // Note we must keep the parameters for the first query constant
                                // This may be overridden at a later step
                                $title = $row->{$this->bl_title};
                                $this->continueStr = join( '|', array_slice( $this->cont, 0, 2 ) ) .
                                        "|$ns|$title|{$row->from_ns}|{$row->page_id}";
                                break;
                        }

                        // Fill in continuation fields for later steps
                        if ( count( $this->cont ) < 6 ) {
                                $this->cont[] = $ns;
                                $this->cont[] = $row->{$this->bl_title};
                                $this->cont[] = $row->from_ns;
                                $this->cont[] = $row->page_id;
                        }

                        if ( is_null( $resultPageSet ) ) {
                                $a['pageid'] = intval( $row->page_id );
                                ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
                                if ( $row->page_is_redirect ) {
                                        $a['redirect'] = true;
                                }
                                $parentID = $this->pageMap[$ns][$row->{$this->bl_title}];
                                // Put all the results in an array first
                                $this->resultArr[$parentID]['redirlinks'][$row->page_id] = $a;
                        } else {
                                $resultPageSet->processDbRow( $row );
                        }
                }
        }

        /**
         * @param ApiPageSet $resultPageSet
         * @return void
         */
        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->addParsedLimit( $this->getModuleName(), $this->params['limit'] );
                } else {
                        $this->params['limit'] = intval( $this->params['limit'] );
                        $this->validateLimit( 'limit', $this->params['limit'], 1, $userMax, $botMax );
                }

                $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 a file",
                                'bad_image_title'
                        );
                }

                // Parse and validate continuation parameter
                $this->cont = array();
                if ( $this->params['continue'] !== null ) {
                        $cont = explode( '|', $this->params['continue'] );

                        switch ( count( $cont ) ) {
                                case 8:
                                        // redirect page ID for result adding
                                        $this->cont[7] = (int)$cont[7];
                                        $this->dieContinueUsageIf( $cont[7] !== (string)$this->cont[7] );

                                        /* Fall through */

                                case 7:
                                        // top-level page ID for result adding
                                        $this->cont[6] = (int)$cont[6];
                                        $this->dieContinueUsageIf( $cont[6] !== (string)$this->cont[6] );

                                        /* Fall through */

                                case 6:
                                        // ns for 2nd query (even for imageusage)
                                        $this->cont[2] = (int)$cont[2];
                                        $this->dieContinueUsageIf( $cont[2] !== (string)$this->cont[2] );

                                        // title for 2nd query
                                        $this->cont[3] = $cont[3];

                                        // from_ns for 2nd query
                                        $this->cont[4] = (int)$cont[4];
                                        $this->dieContinueUsageIf( $cont[4] !== (string)$this->cont[4] );

                                        // from_id for 1st query
                                        $this->cont[5] = (int)$cont[5];
                                        $this->dieContinueUsageIf( $cont[5] !== (string)$this->cont[5] );

                                        /* Fall through */

                                case 2:
                                        // from_ns for 1st query
                                        $this->cont[0] = (int)$cont[0];
                                        $this->dieContinueUsageIf( $cont[0] !== (string)$this->cont[0] );

                                        // from_id for 1st query
                                        $this->cont[1] = (int)$cont[1];
                                        $this->dieContinueUsageIf( $cont[1] !== (string)$this->cont[1] );

                                        break;

                                default:
                                        $this->dieContinueUsageIf( true );
                        }

                        ksort( $this->cont );
                }

                $this->runFirstQuery( $resultPageSet );
                if ( $this->redirect && count( $this->redirTitles ) ) {
                        $this->resetQueryParams();
                        $this->runSecondQuery( $resultPageSet );
                }

                // Fill in any missing fields in case it's needed below
                $this->cont += array( 0, 0, 0, '', 0, 0, 0 );

                if ( is_null( $resultPageSet ) ) {
                        // Try to add the result data in one go and pray that it fits
                        $code = $this->bl_code;
                        $data = array_map( function ( $arr ) use ( $result, $code ) {
                                if ( isset( $arr['redirlinks'] ) ) {
                                        $arr['redirlinks'] = array_values( $arr['redirlinks'] );
                                        ApiResult::setIndexedTagName( $arr['redirlinks'], $code );
                                }
                                return $arr;
                        }, array_values( $this->resultArr ) );
                        $fit = $result->addValue( 'query', $this->getModuleName(), $data );
                        if ( !$fit ) {
                                // It didn't fit. Add elements one by one until the
                                // result is full.
                                ksort( $this->resultArr );
                                if ( count( $this->cont ) >= 7 ) {
                                        $startAt = $this->cont[6];
                                } else {
                                        reset( $this->resultArr );
                                        $startAt = key( $this->resultArr );
                                }
                                $idx = 0;
                                foreach ( $this->resultArr as $pageID => $arr ) {
                                        if ( $pageID < $startAt ) {
                                                continue;
                                        }

                                        // Add the basic entry without redirlinks first
                                        $fit = $result->addValue(
                                                array( 'query', $this->getModuleName() ),
                                                $idx, array_diff_key( $arr, array( 'redirlinks' => '' ) ) );
                                        if ( !$fit ) {
                                                $this->continueStr = join( '|', array_slice( $this->cont, 0, 6 ) ) .
                                                        "|$pageID";
                                                break;
                                        }

                                        $hasRedirs = false;
                                        $redirLinks = isset( $arr['redirlinks'] ) ? (array)$arr['redirlinks'] : array();
                                        ksort( $redirLinks );
                                        if ( count( $this->cont ) >= 8 && $pageID == $startAt ) {
                                                $redirStartAt = $this->cont[7];
                                        } else {
                                                reset( $redirLinks );
                                                $redirStartAt = key( $redirLinks );
                                        }
                                        foreach ( $redirLinks as $key => $redir ) {
                                                if ( $key < $redirStartAt ) {
                                                        continue;
                                                }

                                                $fit = $result->addValue(
                                                        array( 'query', $this->getModuleName(), $idx, 'redirlinks' ),
                                                        null, $redir );
                                                if ( !$fit ) {
                                                        $this->continueStr = join( '|', array_slice( $this->cont, 0, 6 ) ) .
                                                                "|$pageID|$key";
                                                        break;
                                                }
                                                $hasRedirs = true;
                                        }
                                        if ( $hasRedirs ) {
                                                $result->addIndexedTagName(
                                                        array( 'query', $this->getModuleName(), $idx, 'redirlinks' ),
                                                        $this->bl_code );
                                        }
                                        if ( !$fit ) {
                                                break;
                                        }

                                        $idx++;
                                }
                        }

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

        public function getAllowedParams() {
                $retval = array(
                        'title' => array(
                                ApiBase::PARAM_TYPE => 'string',
                        ),
                        'pageid' => array(
                                ApiBase::PARAM_TYPE => 'integer',
                        ),
                        'continue' => array(
                                ApiBase::PARAM_HELP_MSG => 'api-help-param-continue',
                        ),
                        '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;
        }

        protected function getExamplesMessages() {
                static $examples = array(
                        'backlinks' => array(
                                'action=query&list=backlinks&bltitle=Main%20Page'
                                        => 'apihelp-query+backlinks-example-simple',
                                'action=query&generator=backlinks&gbltitle=Main%20Page&prop=info'
                                        => 'apihelp-query+backlinks-example-generator',
                        ),
                        'embeddedin' => array(
                                'action=query&list=embeddedin&eititle=Template:Stub'
                                        => 'apihelp-query+embeddedin-example-simple',
                                'action=query&generator=embeddedin&geititle=Template:Stub&prop=info'
                                        => 'apihelp-query+embeddedin-example-generator',
                        ),
                        'imageusage' => array(
                                'action=query&list=imageusage&iutitle=File:Albert%20Einstein%20Head.jpg'
                                        => 'apihelp-query+imageusage-example-simple',
                                'action=query&generator=imageusage&giutitle=File:Albert%20Einstein%20Head.jpg&prop=info'
                                        => 'apihelp-query+imageusage-example-generator',
                        )
                );

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

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