wikimedia/mediawiki-extensions-CirrusSearch

<?php

namespace CirrusSearch\Query;

use CirrusSearch\CrossSearchStrategy;
use CirrusSearch\Parser\AST\KeywordFeatureNode;
use CirrusSearch\Query\Builder\QueryBuildingContext;
use CirrusSearch\Search\Rescore\BoostFunctionBuilder;
use CirrusSearch\Search\Rescore\PreferRecentFunctionScoreBuilder;
use CirrusSearch\Search\SearchContext;
use CirrusSearch\SearchConfig;
use CirrusSearch\WarningCollector;
use MediaWiki\Config\Config;

/**
 * Matches "prefer-recent:" and then an optional floating point number <= 1 but
 * >= 0 (decay portion) and then an optional comma followed by another floating
 * point number >0 0 (half life).
 *
 * Examples:
 *  prefer-recent:
 *  prefer-recent:.6
 *  prefer-recent:0.5,.0001
 */
class PreferRecentFeature extends SimpleKeywordFeature implements BoostFunctionFeature {
    /**
     * @var float Default number of days for the portion of the score effected
     *  by this feature to be cut in half. Used when `prefer-recent:` is present
     *  in the query without any arguments.
     */
    private $halfLife;

    /**
     * @var float Value between 0 and 1 indicating the default portion of the
     *  score affected by this feature when not specified in the search term.
     */
    private $unspecifiedDecay;

    /**
     * @param Config $config
     */
    public function __construct( Config $config ) {
        $this->halfLife = $config->get( 'CirrusSearchPreferRecentDefaultHalfLife' );
        $this->unspecifiedDecay = $config->get( 'CirrusSearchPreferRecentUnspecifiedDecayPortion' );
    }

    /**
     * @return string[] The list of keywords this feature is supposed to match
     */
    protected function getKeywords() {
        return [ "prefer-recent" ];
    }

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

    /**
     * @param string $key
     * @param string $value
     * @param string $quotedValue
     * @param string $valueDelimiter
     * @param string $suffix
     * @param WarningCollector $warningCollector
     * @return array|null|false
     */
    public function parseValue( $key, $value, $quotedValue, $valueDelimiter, $suffix, WarningCollector $warningCollector ) {
        $matches = [];
        $retValue = [];
        // FIXME: we should probably no longer accept the empty string and simply return false
        // instead of null
        if ( preg_match( '/^(1|0?(?:\.\d+)?)?(?:,(\d*\.?\d+))?$/', $value, $matches ) === 1 ) {
            if ( isset( $matches[1] ) && strlen( $matches[1] ) > 0 ) {
                $retValue['decay'] = floatval( $matches[1] );
            }

            if ( isset( $matches[2] ) ) {
                $retValue['halfLife'] = floatval( $matches[2] );
            }
            return $retValue !== [] ? $retValue : null;
        }
        return false;
    }

    /**
     * @param KeywordFeatureNode $node
     * @return CrossSearchStrategy
     */
    public function getCrossSearchStrategy( KeywordFeatureNode $node ) {
        return CrossSearchStrategy::allWikisStrategy();
    }

    /**
     * Applies the detected keyword from the search term. May apply changes
     * either to $context directly, or return a filter to be added.
     *
     * @param SearchContext $context
     * @param string $key The keyword
     * @param string $value The value attached to the keyword with quotes stripped and escaped
     *  quotes un-escaped.
     * @param string $quotedValue The original value in the search string, including quotes if used
     * @param bool $negated Is the search negated? Not used to generate the returned AbstractQuery,
     *  that will be negated as necessary. Used for any other building/context necessary.
     * @return array Two element array, first an AbstractQuery or null to apply to the
     *  query. Second a boolean indicating if the quotedValue should be kept in the search
     *  string.
     */
    protected function doApply( SearchContext $context, $key, $value, $quotedValue, $negated ) {
        $parsedValue = $this->parseValue( $key, $value, $quotedValue, '', '', $context );
        $context->addCustomRescoreComponent( $this->buildBoost( $parsedValue, $context->getConfig() ) );
        return [ null, $parsedValue === false ];
    }

    /**
     * @param KeywordFeatureNode $node
     * @param QueryBuildingContext $context
     * @return BoostFunctionBuilder|null
     */
    public function getBoostFunctionBuilder( KeywordFeatureNode $node, QueryBuildingContext $context ) {
        return $this->buildBoost( $node->getParsedValue(), $context->getSearchConfig() );
    }

    /**
     * @param array|null|false $parsedValue
     * @param SearchConfig $config
     * @return PreferRecentFunctionScoreBuilder
     */
    private function buildBoost( $parsedValue, SearchConfig $config ) {
        $halfLife = $this->halfLife;
        $decay = $this->unspecifiedDecay;
        if ( is_array( $parsedValue ) ) {
            if ( isset( $parsedValue['halfLife'] ) ) {
                $halfLife = $parsedValue['halfLife'];
            }
            if ( isset( $parsedValue['decay'] ) ) {
                $decay = $parsedValue['decay'];
            }
        }
        return new PreferRecentFunctionScoreBuilder( $config, 1, $halfLife, $decay );
    }
}