wikimedia/mediawiki-extensions-CirrusSearch

<?php

namespace CirrusSearch\Query;

use CirrusSearch\CrossSearchStrategy;
use CirrusSearch\Parser\AST\KeywordFeatureNode;
use CirrusSearch\Search\SearchContext;
use CirrusSearch\SearchConfig;
use CirrusSearch\WarningCollector;
use MediaWiki\Title\Title;

/**
 * Finds pages similar to another one.
 * Greedy keyword kept for BC purposes, MoreLikeThisFeature should be preferred.
 */
class MoreLikeFeature extends SimpleKeywordFeature implements LegacyKeywordFeature {
    use MoreLikeTrait;

    private const MORE_LIKE_THIS = 'morelike';

    /**
     * @var SearchConfig
     */
    private $config;

    /**
     * @param SearchConfig $config
     */
    public function __construct( SearchConfig $config ) {
        $this->config = $config;
    }

    /**
     * @return bool
     */
    public function greedy() {
        return true;
    }

    /**
     * morelike is only allowed at the beginning of the query
     * @return bool
     */
    public function queryHeader() {
        return true;
    }

    /** @inheritDoc */
    protected function getKeywords() {
        return [ self::MORE_LIKE_THIS ];
    }

    /**
     * @param string $key
     * @param string $valueDelimiter
     * @return string
     */
    public function getFeatureName( $key, $valueDelimiter ) {
        return "more_like";
    }

    /**
     * @param KeywordFeatureNode $node
     * @return CrossSearchStrategy
     */
    public function getCrossSearchStrategy( KeywordFeatureNode $node ) {
        // We depend on the db to fetch the title
        return CrossSearchStrategy::hostWikiOnlyStrategy();
    }

    /**
     * @param SearchContext $context
     * @param string $key
     * @param string $value
     * @param string $quotedValue
     * @param bool $negated
     * @return array
     */
    protected function doApply( SearchContext $context, $key, $value, $quotedValue, $negated ) {
        $context->setCacheTtl( $this->config->get( 'CirrusSearchMoreLikeThisTTL' ) );
        $titles = $this->doExpand( $key, $value, $context );
        if ( $titles === [] ) {
            $context->setResultsPossible( false );
            return [ null, false ];
        }
        $query = $this->buildMoreLikeQuery( $titles );

        // this erases the main query making it impossible to combine with
        // other keywords/search query. MoreLikeThisFeature addresses this problem.
        $context->setMainQuery( $query );

        // highlight snippets are not great so it's worth running a match all query
        // to save cpu cycles
        $context->setHighlightQuery( new \Elastica\Query\MatchAll() );

        return [ null, false ];
    }

    /**
     * @param KeywordFeatureNode $node
     * @param SearchConfig $config
     * @param WarningCollector $warningCollector
     * @return array|Title[]
     */
    public function expand( KeywordFeatureNode $node, SearchConfig $config, WarningCollector $warningCollector ) {
        return $this->doExpand( $node->getKey(), $node->getValue(), $warningCollector );
    }

    /**
     * @return SearchConfig
     */
    public function getConfig(): SearchConfig {
        return $this->config;
    }
}