wikimedia/mediawiki-extensions-Wikibase

<?php

declare( strict_types = 1 );

namespace Wikibase\Lib\Store;

use MediaWiki\Language\Language;
use Wikibase\DataModel\Entity\EntityId;
use Wikibase\DataModel\Services\Lookup\TermLookup;
use Wikibase\DataModel\Services\Term\TermBuffer;
use Wikibase\DataModel\Term\TermTypes;
use Wikibase\Lib\LanguageFallbackChainFactory;
use Wikibase\Lib\TermFallbackCache\TermFallbackCacheFacade;

/**
 * Factory to create a {@link FallbackLabelDescriptionLookup} that also resolves redirects.
 *
 * @license GPL-2.0-or-later
 */
class FallbackLabelDescriptionLookupFactory {

    /** @var LanguageFallbackChainFactory */
    private $languageFallbackChainFactory;
    /** @var RedirectResolvingLatestRevisionLookup */
    private $redirectResolvingRevisionLookup;
    /** @var TermFallbackCacheFacade */
    private $termFallbackCache;
    /** @var TermLookup */
    private $termLookup;
    /** @var TermBuffer|null */
    private $termBuffer;

    /**
     * $termBuffer will be used to prefetch terms if it is provided;
     * in that case, $termLookup should be based on it
     * (they may even be the same object, a {@link PrefetchingTermLookup}).
     */
    public function __construct(
        LanguageFallbackChainFactory $languageFallbackChainFactory,
        RedirectResolvingLatestRevisionLookup $redirectResolvingLatestRevisionLookup,
        TermFallbackCacheFacade $termFallbackCache,
        TermLookup $termLookup,
        TermBuffer $termBuffer = null
    ) {
        $this->languageFallbackChainFactory = $languageFallbackChainFactory;
        $this->redirectResolvingRevisionLookup = $redirectResolvingLatestRevisionLookup;
        $this->termFallbackCache = $termFallbackCache;
        $this->termLookup = $termLookup;
        $this->termBuffer = $termBuffer;
    }

    /**
     * Create a new LabelDescriptionLookup in the given language
     * that applies language fallbacks, resolves redirects,
     * and has the given entity ID term types (if any) prefetched.
     *
     * @param Language $language
     * @param EntityId[] $entityIds Entity IDs to prefetch terms for, if any.
     * Only relevant if the factory was constructed with a TermBuffer.
     * @param string[] $termTypes Term types to prefetch (default: only labels).
     * One or more TermTypes constants.
     * @return FallbackLabelDescriptionLookup
     */
    public function newLabelDescriptionLookup(
        Language $language,
        array $entityIds = [],
        array $termTypes = [ TermTypes::TYPE_LABEL ]
    ): FallbackLabelDescriptionLookup {
        $languageFallbackChain = $this->languageFallbackChainFactory->newFromLanguage( $language );

        // this implementation actually gets terms and does language fallback
        $languageImplementation = new LanguageFallbackLabelDescriptionLookup(
            $this->termLookup,
            $languageFallbackChain
        );

        // this implementation adds caching and resolves redirects
        $cachingImplementation = new CachingFallbackLabelDescriptionLookup(
            $this->termFallbackCache,
            $this->redirectResolvingRevisionLookup,
            $languageImplementation,
            $languageFallbackChain
        );

        // this implementation ensures $cachingImplementation is not used for federated properties,
        // where it does not work as of July 2022; the missing caching is unfortunate but okay,
        // the missing redirect resolving is not relevant for properties
        $dispatchingImplementation = new DispatchingFallbackLabelDescriptionLookup(
            $cachingImplementation, // use this for most entity IDs
            $languageImplementation // use this for federated properties
        );

        // Optionally prefetch the terms of the entities passed in here
        // ($termLookup is assumed to be based on $termBuffer then)
        if ( $this->termBuffer !== null && $entityIds !== [] ) {
            $languages = $languageFallbackChain->getFetchLanguageCodes();
            $this->termBuffer->prefetchTerms( $entityIds, $termTypes, $languages );
        }

        return $dispatchingImplementation;
    }

}