wikimedia/mediawiki-extensions-CirrusSearch

<?php

namespace CirrusSearch\Search\Rescore;

use CirrusSearch\SearchConfig;
use Elastica\Query\FunctionScore;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MediaWikiServices;
use MediaWiki\Title\NamespaceInfo;

/**
 * Builds a set of functions with namespaces.
 * Uses a weight function with a filter for each namespace.
 * Activated only if more than one namespace is requested.
 */
class NamespacesFunctionScoreBuilder extends FunctionScoreBuilder {
    /**
     * @var null|float[] initialized version of $wgCirrusSearchNamespaceWeights with all string keys
     * translated into integer namespace codes using $this->language.
     */
    private $normalizedNamespaceWeights;

    /**
     * @var int[] List of namespace id's
     */
    private $namespacesToBoost;

    /**
     * @var NamespaceInfo
     */
    private $namespaceInfo;

    /**
     * @param SearchConfig $config
     * @param int[]|null $namespaces
     * @param float $weight
     * @param NamespaceInfo|null $namespaceInfo
     */
    public function __construct( SearchConfig $config, $namespaces, $weight, NamespaceInfo $namespaceInfo = null ) {
        parent::__construct( $config, $weight );

        $this->namespaceInfo = $namespaceInfo ?: MediaWikiServices::getInstance()->getNamespaceInfo();
        $this->namespacesToBoost =
            $namespaces ?: $this->namespaceInfo->getValidNamespaces();
        if ( !$this->namespacesToBoost || count( $this->namespacesToBoost ) == 1 ) {
            // nothing to boost, no need to initialize anything else.
            return;
        }
        $this->normalizedNamespaceWeights = [];
        foreach ( $config->get( 'CirrusSearchNamespaceWeights' ) as $ns =>
                  $weight
        ) {
            if ( !is_int( $ns ) && !ctype_digit( $ns ) ) {
                LoggerFactory::getInstance( 'CirrusSearch' )->warning(
                    'Namespace names are no longer accepted as namespaces in '
                    . "CirrusSearchNamespaceWeights. Ignoring {invalid_ns}",
                    [ 'invalid_ns' => $ns ]
                );

                continue;
            }
            // Now $ns should always be an integer.
            $this->normalizedNamespaceWeights[(int)$ns] = $weight;
        }
    }

    /**
     * Get the weight of a namespace.
     *
     * @param int $namespace
     * @return float the weight of the namespace
     */
    private function getBoostForNamespace( $namespace ) {
        if ( isset( $this->normalizedNamespaceWeights[$namespace] ) ) {
            return $this->normalizedNamespaceWeights[$namespace];
        }
        if ( $this->namespaceInfo->isSubject( $namespace ) ) {
            if ( $namespace === NS_MAIN ) {
                return 1;
            }

            return $this->config->get( 'CirrusSearchDefaultNamespaceWeight' );
        }
        $subjectNs = $this->namespaceInfo->getSubject( $namespace );
        if ( isset( $this->normalizedNamespaceWeights[$subjectNs] ) ) {
            return $this->config->get( 'CirrusSearchTalkNamespaceWeight' ) *
                   $this->normalizedNamespaceWeights[$subjectNs];
        }
        if ( $namespace === NS_TALK ) {
            return $this->config->get( 'CirrusSearchTalkNamespaceWeight' );
        }

        return $this->config->get( 'CirrusSearchDefaultNamespaceWeight' ) *
               $this->config->get( 'CirrusSearchTalkNamespaceWeight' );
    }

    public function append( FunctionScore $functionScore ) {
        if ( !$this->namespacesToBoost || count( $this->namespacesToBoost ) == 1 ) {
            // nothing to boost, no need to initialize anything else.
            return;
        }

        // first build the opposite map, this will allow us to add a
        // single factor function per weight by using a terms filter.
        $weightToNs = [];
        foreach ( $this->namespacesToBoost as $ns ) {
            $weight = $this->getBoostForNamespace( $ns ) * $this->weight;
            $key = (string)$weight;
            if ( $key == '1' ) {
                // such weights would have no effect
                // we can ignore them.
                continue;
            }
            if ( !isset( $weightToNs[$key] ) ) {
                $weightToNs[$key] = [
                    'weight' => $weight,
                    'ns' => [ $ns ]
                ];
            } else {
                $weightToNs[$key]['ns'][] = $ns;
            }
        }
        foreach ( $weightToNs as $weight => $namespacesAndWeight ) {
            $filter = new \Elastica\Query\Terms( 'namespace', $namespacesAndWeight['ns'] );
            $functionScore->addWeightFunction( $namespacesAndWeight['weight'], $filter );
        }
    }
}