ApiQueryBacklinksprop.php

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<?php
class ApiQueryBacklinksprop extends ApiQueryGeneratorBase {

    // Data for the various modules implemented by this class
    private static $settings = [
        'redirects' => [
            'code' => 'rd',
            'prefix' => 'rd',
            'linktable' => 'redirect',
            'props' => [
                'fragment',
            ],
            'showredirects' => false,
            'show' => [
                'fragment',
                '!fragment',
            ],
        ],
        'linkshere' => [
            'code' => 'lh',
            'prefix' => 'pl',
            'linktable' => 'pagelinks',
            'indexes' => [ 'pl_namespace', 'pl_backlinks_namespace' ],
            'from_namespace' => true,
            'showredirects' => true,
        ],
        'transcludedin' => [
            'code' => 'ti',
            'prefix' => 'tl',
            'linktable' => 'templatelinks',
            'indexes' => [ 'tl_namespace', 'tl_backlinks_namespace' ],
            'from_namespace' => true,
            'showredirects' => true,
        ],
        'fileusage' => [
            'code' => 'fu',
            'prefix' => 'il',
            'linktable' => 'imagelinks',
            'indexes' => [ 'il_to', 'il_backlinks_namespace' ],
            'from_namespace' => true,
            'to_namespace' => NS_FILE,
            'exampletitle' => 'File:Example.jpg',
            'showredirects' => true,
        ],
    ];

    public function __construct( ApiQuery $query, $moduleName ) {
        parent::__construct( $query, $moduleName, self::$settings[$moduleName]['code'] );
    }

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

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

    private function run( ApiPageSet $resultPageSet = null ) {
        $settings = self::$settings[$this->getModuleName()];

        $db = $this->getDB();
        $params = $this->extractRequestParams();
        $prop = array_flip( $params['prop'] );
        $emptyString = $db->addQuotes( '' );

        $pageSet = $this->getPageSet();
        $titles = $pageSet->getGoodAndMissingTitles();
        $map = $pageSet->getGoodAndMissingTitlesByNamespace();

        // Add in special pages, they can theoretically have backlinks too.
        // (although currently they only do for prop=redirects)
        foreach ( $pageSet->getSpecialTitles() as $id => $title ) {
            $titles[] = $title;
            $map[$title->getNamespace()][$title->getDBkey()] = $id;
        }

        // Determine our fields to query on
        $p = $settings['prefix'];
        $hasNS = !isset( $settings['to_namespace'] );
        if ( $hasNS ) {
            $bl_namespace = "{$p}_namespace";
            $bl_title = "{$p}_title";
        } else {
            $bl_namespace = $settings['to_namespace'];
            $bl_title = "{$p}_to";

            $titles = array_filter( $titles, function ( $t ) use ( $bl_namespace ) {
                return $t->getNamespace() === $bl_namespace;
            } );
            $map = array_intersect_key( $map, [ $bl_namespace => true ] );
        }
        $bl_from = "{$p}_from";

        if ( !$titles ) {
            return; // nothing to do
        }
        if ( $params['namespace'] !== null && count( $params['namespace'] ) === 0 ) {
            return; // nothing to do
        }

        // Figure out what we're sorting by, and add associated WHERE clauses.
        // MySQL's query planner screws up if we include a field in ORDER BY
        // when it's constant in WHERE, so we have to test that for each field.
        $sortby = [];
        if ( $hasNS && count( $map ) > 1 ) {
            $sortby[$bl_namespace] = 'ns';
        }
        $theTitle = null;
        foreach ( $map as $nsTitles ) {
            reset( $nsTitles );
            $key = key( $nsTitles );
            if ( $theTitle === null ) {
                $theTitle = $key;
            }
            if ( count( $nsTitles ) > 1 || $key !== $theTitle ) {
                $sortby[$bl_title] = 'title';
                break;
            }
        }
        $miser_ns = null;
        if ( $params['namespace'] !== null ) {
            if ( empty( $settings['from_namespace'] ) ) {
                if ( $this->getConfig()->get( 'MiserMode' ) ) {
                    $miser_ns = $params['namespace'];
                } else {
                    $this->addWhereFld( 'page_namespace', $params['namespace'] );
                }
            } else {
                $this->addWhereFld( "{$p}_from_namespace", $params['namespace'] );
                if ( !empty( $settings['from_namespace'] )
                    && $params['namespace'] !== null && count( $params['namespace'] ) > 1
                ) {
                    $sortby["{$p}_from_namespace"] = 'int';
                }
            }
        }
        $sortby[$bl_from] = 'int';

        // Now use the $sortby to figure out the continuation
        if ( !is_null( $params['continue'] ) ) {
            $cont = explode( '|', $params['continue'] );
            $this->dieContinueUsageIf( count( $cont ) != count( $sortby ) );
            $where = '';
            $i = count( $sortby ) - 1;
            foreach ( array_reverse( $sortby, true ) as $field => $type ) {
                $v = $cont[$i];
                switch ( $type ) {
                    case 'ns':
                    case 'int':
                        $v = (int)$v;
                        $this->dieContinueUsageIf( $v != $cont[$i] );
                        break;
                    default:
                        $v = $db->addQuotes( $v );
                        break;
                }

                if ( $where === '' ) {
                    $where = "$field >= $v";
                } else {
                    $where = "$field > $v OR ($field = $v AND ($where))";
                }

                $i--;
            }
            $this->addWhere( $where );
        }

        // Populate the rest of the query
        $this->addTables( [ $settings['linktable'], 'page' ] );
        $this->addWhere( "$bl_from = page_id" );

        if ( $this->getModuleName() === 'redirects' ) {
            $this->addWhere( "rd_interwiki = $emptyString OR rd_interwiki IS NULL" );
        }

        $this->addFields( array_keys( $sortby ) );
        $this->addFields( [ 'bl_namespace' => $bl_namespace, 'bl_title' => $bl_title ] );
        if ( is_null( $resultPageSet ) ) {
            $fld_pageid = isset( $prop['pageid'] );
            $fld_title = isset( $prop['title'] );
            $fld_redirect = isset( $prop['redirect'] );

            $this->addFieldsIf( 'page_id', $fld_pageid );
            $this->addFieldsIf( [ 'page_title', 'page_namespace' ], $fld_title );
            $this->addFieldsIf( 'page_is_redirect', $fld_redirect );

            // prop=redirects
            $fld_fragment = isset( $prop['fragment'] );
            $this->addFieldsIf( 'rd_fragment', $fld_fragment );
        } else {
            $this->addFields( $resultPageSet->getPageTableFields() );
        }

        $this->addFieldsIf( 'page_namespace', $miser_ns !== null );

        if ( $hasNS ) {
            // Can't use LinkBatch because it throws away Special titles.
            // And we already have the needed data structure anyway.
            $this->addWhere( $db->makeWhereFrom2d( $map, $bl_namespace, $bl_title ) );
        } else {
            $where = [];
            foreach ( $titles as $t ) {
                if ( $t->getNamespace() == $bl_namespace ) {
                    $where[] = "$bl_title = " . $db->addQuotes( $t->getDBkey() );
                }
            }
            $this->addWhere( $db->makeList( $where, LIST_OR ) );
        }

        if ( $params['show'] !== null ) {
            // prop=redirects only
            $show = array_flip( $params['show'] );
            if ( isset( $show['fragment'] ) && isset( $show['!fragment'] ) ||
                isset( $show['redirect'] ) && isset( $show['!redirect'] )
            ) {
                $this->dieWithError( 'apierror-show' );
            }
            $this->addWhereIf( "rd_fragment != $emptyString", isset( $show['fragment'] ) );
            $this->addWhereIf(
                "rd_fragment = $emptyString OR rd_fragment IS NULL",
                isset( $show['!fragment'] )
            );
            $this->addWhereIf( [ 'page_is_redirect' => 1 ], isset( $show['redirect'] ) );
            $this->addWhereIf( [ 'page_is_redirect' => 0 ], isset( $show['!redirect'] ) );
        }

        // Override any ORDER BY from above with what we calculated earlier.
        $this->addOption( 'ORDER BY', array_keys( $sortby ) );

        // MySQL's optimizer chokes if we have too many values in "$bl_title IN
        // (...)" and chooses the wrong index, so specify the correct index to
        // use for the query. See T139056 for details.
        if ( !empty( $settings['indexes'] ) ) {
            list( $idxNoFromNS, $idxWithFromNS ) = $settings['indexes'];
            if ( $params['namespace'] !== null && !empty( $settings['from_namespace'] ) ) {
                $this->addOption( 'USE INDEX', [ $settings['linktable'] => $idxWithFromNS ] );
            } else {
                $this->addOption( 'USE INDEX', [ $settings['linktable'] => $idxNoFromNS ] );
            }
        }

        // MySQL (or at least 5.5.5-10.0.23-MariaDB) chooses a really bad query
        // plan if it thinks there will be more matching rows in the linktable
        // than are in page. Use STRAIGHT_JOIN here to force it to use the
        // intended, fast plan. See T145079 for details.
        $this->addOption( 'STRAIGHT_JOIN' );

        $this->addOption( 'LIMIT', $params['limit'] + 1 );

        $res = $this->select( __METHOD__ );

        if ( is_null( $resultPageSet ) ) {
            if ( $fld_title ) {
                $this->executeGenderCacheFromResultWrapper( $res, __METHOD__ );
            }

            $count = 0;
            foreach ( $res as $row ) {
                if ( ++$count > $params['limit'] ) {
                    // We've reached the one extra which shows that
                    // there are additional pages to be had. Stop here...
                    $this->setContinue( $row, $sortby );
                    break;
                }

                if ( $miser_ns !== null && !in_array( $row->page_namespace, $miser_ns ) ) {
                    // Miser mode namespace check
                    continue;
                }

                // Get the ID of the current page
                $id = $map[$row->bl_namespace][$row->bl_title];

                $vals = [];
                if ( $fld_pageid ) {
                    $vals['pageid'] = (int)$row->page_id;
                }
                if ( $fld_title ) {
                    ApiQueryBase::addTitleInfo( $vals,
                        Title::makeTitle( $row->page_namespace, $row->page_title )
                    );
                }
                if ( $fld_fragment && $row->rd_fragment !== null && $row->rd_fragment !== '' ) {
                    $vals['fragment'] = $row->rd_fragment;
                }
                if ( $fld_redirect ) {
                    $vals['redirect'] = (bool)$row->page_is_redirect;
                }
                $fit = $this->addPageSubItem( $id, $vals );
                if ( !$fit ) {
                    $this->setContinue( $row, $sortby );
                    break;
                }
            }
        } else {
            $titles = [];
            $count = 0;
            foreach ( $res as $row ) {
                if ( ++$count > $params['limit'] ) {
                    // We've reached the one extra which shows that
                    // there are additional pages to be had. Stop here...
                    $this->setContinue( $row, $sortby );
                    break;
                }

                if ( $miser_ns !== null && !in_array( $row->page_namespace, $miser_ns ) ) {
                    // Miser mode namespace check
                    continue;
                }

                $titles[] = Title::makeTitle( $row->page_namespace, $row->page_title );
            }
            $resultPageSet->populateFromTitles( $titles );
        }
    }

    private function setContinue( $row, $sortby ) {
        $cont = [];
        foreach ( $sortby as $field => $v ) {
            $cont[] = $row->$field;
        }
        $this->setContinueEnumParameter( 'continue', implode( '|', $cont ) );
    }

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

    public function getAllowedParams() {
        $settings = self::$settings[$this->getModuleName()];

        $ret = [
            'prop' => [
                ApiBase::PARAM_TYPE => [
                    'pageid',
                    'title',
                ],
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_DFLT => 'pageid|title',
                ApiBase::PARAM_HELP_MSG_PER_VALUE => [],
            ],
            'namespace' => [
                ApiBase::PARAM_ISMULTI => true,
                ApiBase::PARAM_TYPE => 'namespace',
            ],
            'show' => null, // Will be filled/removed below
            'limit' => [
                ApiBase::PARAM_DFLT => 10,
                ApiBase::PARAM_TYPE => 'limit',
                ApiBase::PARAM_MIN => 1,
                ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
                ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
            ],
            'continue' => [
                ApiBase::PARAM_HELP_MSG => 'api-help-param-continue',
            ],
        ];

        if ( empty( $settings['from_namespace'] ) && $this->getConfig()->get( 'MiserMode' ) ) {
            $ret['namespace'][ApiBase::PARAM_HELP_MSG_APPEND] = [
                'api-help-param-limited-in-miser-mode',
            ];
        }

        if ( !empty( $settings['showredirects'] ) ) {
            $ret['prop'][ApiBase::PARAM_TYPE][] = 'redirect';
            $ret['prop'][ApiBase::PARAM_DFLT] .= '|redirect';
        }
        if ( isset( $settings['props'] ) ) {
            $ret['prop'][ApiBase::PARAM_TYPE] = array_merge(
                $ret['prop'][ApiBase::PARAM_TYPE], $settings['props']
            );
        }

        $show = [];
        if ( !empty( $settings['showredirects'] ) ) {
            $show[] = 'redirect';
            $show[] = '!redirect';
        }
        if ( isset( $settings['show'] ) ) {
            $show = array_merge( $show, $settings['show'] );
        }
        if ( $show ) {
            $ret['show'] = [
                ApiBase::PARAM_TYPE => $show,
                ApiBase::PARAM_ISMULTI => true,
            ];
        } else {
            unset( $ret['show'] );
        }

        return $ret;
    }

    protected function getExamplesMessages() {
        $settings = self::$settings[$this->getModuleName()];
        $name = $this->getModuleName();
        $path = $this->getModulePath();
        $title = $settings['exampletitle'] ?? 'Main Page';
        $etitle = rawurlencode( $title );

        return [
            "action=query&prop={$name}&titles={$etitle}"
                => "apihelp-$path-example-simple",
            "action=query&generator={$name}&titles={$etitle}&prop=info"
                => "apihelp-$path-example-generator",
        ];
    }

    public function getHelpUrls() {
        $name = ucfirst( $this->getModuleName() );
        return "https://www.mediawiki.org/wiki/Special:MyLanguage/API:{$name}";
    }
}