wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Lib\Store;

use Wikibase\DataModel\Entity\EntityId;
use Wikibase\DataModel\Services\Lookup\LabelDescriptionLookupException;
use Wikibase\DataModel\Services\Lookup\TermLookup;
use Wikibase\DataModel\Services\Lookup\TermLookupException;
use Wikibase\DataModel\Term\TermFallback;
use Wikibase\Lib\TermLanguageFallbackChain;

/**
 * A lookup for labels and descriptions in a given language.
 * Applies language fallbacks; does not resolve redirects.
 * Use {@link FallbackLabelDescriptionLookupFactory} instead of using this class directly.
 *
 * @license GPL-2.0-or-later
 * @author Katie Filbert < aude.wiki@gmail.com >
 * @author Marius Hoch < hoo@online.de >
 */
class LanguageFallbackLabelDescriptionLookup implements FallbackLabelDescriptionLookup {

    /**
     * @var TermLookup
     */
    private $termLookup;

    /**
     * @var TermLanguageFallbackChain
     */
    private $termLanguageFallbackChain;

    /**
     * @param TermLookup $termLookup
     * @param TermLanguageFallbackChain $termLanguageFallbackChain
     */
    public function __construct(
        TermLookup $termLookup,
        TermLanguageFallbackChain $termLanguageFallbackChain
    ) {
        $this->termLookup = $termLookup;
        $this->termLanguageFallbackChain = $termLanguageFallbackChain;
    }

    /**
     * @param EntityId $entityId
     *
     * @throws LabelDescriptionLookupException
     * @return TermFallback|null
     */
    public function getLabel( EntityId $entityId ) {
        $fetchLanguages = $this->termLanguageFallbackChain->getFetchLanguageCodes();

        try {
            $labels = $this->termLookup->getLabels( $entityId, $fetchLanguages );
        } catch ( TermLookupException $ex ) {
            throw new LabelDescriptionLookupException( $entityId, $ex->getMessage(), $ex );
        }

        return $this->getTermFallback( $labels, $fetchLanguages );
    }

    /**
     * @param EntityId $entityId
     *
     * @throws LabelDescriptionLookupException
     * @return TermFallback|null
     */
    public function getDescription( EntityId $entityId ) {
        $fetchLanguages = $this->termLanguageFallbackChain->getFetchLanguageCodes();

        try {
            $descriptions = $this->termLookup->getDescriptions( $entityId, $fetchLanguages );
        } catch ( TermLookupException $ex ) {
            throw new LabelDescriptionLookupException( $entityId, $ex->getMessage(), $ex );
        }

        return $this->getTermFallback( $descriptions, $fetchLanguages );
    }

    /**
     * @param string[] $terms
     * @param string[] $fetchLanguages
     *
     * @return TermFallback|null
     */
    private function getTermFallback( array $terms, array $fetchLanguages ) {
        $extractedData = $this->termLanguageFallbackChain->extractPreferredValue( $terms );

        if ( $extractedData === null ) {
            return null;
        }

        // $fetchLanguages are in order of preference
        $requestLanguage = reset( $fetchLanguages );

        // see extractPreferredValue for array keys
        return new TermFallback(
            $requestLanguage,
            $extractedData['value'],
            $extractedData['language'],
            $extractedData['source']
        );
    }

}