wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Repo\Rdf;

use Wikibase\DataModel\Entity\EntityDocument;
use Wikibase\DataModel\Term\AliasesProvider;
use Wikibase\DataModel\Term\AliasGroup;
use Wikibase\DataModel\Term\AliasGroupList;
use Wikibase\DataModel\Term\DescriptionsProvider;
use Wikibase\DataModel\Term\LabelsProvider;
use Wikibase\DataModel\Term\TermList;
use Wikimedia\Purtle\RdfWriter;

/**
 * RDF mapping for entity terms.
 *
 * @license GPL-2.0-or-later
 */
class TermsRdfBuilder implements EntityRdfBuilder {

    /**
     * @var RdfVocabulary
     */
    private $vocabulary;

    /**
     * @var RdfWriter
     */
    private $writer;

    /**
     * @var string[]|null a list of desired languages, or null for all languages.
     */
    private $languages;

    /**
     * @var string[][][] Map of type to array of [ ns, local ] for each label predicate
     */
    private $labelPredicates;

    /**
     * @param RdfVocabulary $vocabulary
     * @param RdfWriter $writer
     * @param string[][][] $labelPredicates Map of type to array of [ ns, local ] for each label predicate
     * @param string[]|null $languages
     */
    public function __construct(
        RdfVocabulary $vocabulary,
        RdfWriter $writer,
        array $labelPredicates = [],
        array $languages = null
    ) {
        $this->vocabulary = $vocabulary;
        $this->writer = $writer;
        $this->languages = $languages === null ? null : array_flip( $languages );
        $this->labelPredicates = $labelPredicates;
    }

    /**
     * Get predicates that will be used for labels.
     * @param EntityDocument $entity
     * @return string[][] array of [ ns, local ] for each label predicate
     */
    private function getLabelPredicates( EntityDocument $entity ) {
        return $this->labelPredicates[$entity->getType()] ?? [
                [ 'rdfs', 'label' ],
                [ RdfVocabulary::NS_SKOS, 'prefLabel' ],
                [ RdfVocabulary::NS_SCHEMA_ORG, 'name' ],
            ];
    }

    /**
     * Adds the labels of the given entity to the RDF graph
     *
     * @param string $entityNamespace
     * @param string $entityLName
     * @param TermList $labels
     * @param string[][] $labelPredicates array of [ ns, local ] for each label predicate
     */
    private function addLabels( $entityNamespace, $entityLName, TermList $labels, array $labelPredicates ) {
        if ( !$labelPredicates ) {
            // If we want no predicates, no need to bother with the rest.
            return;
        }
        foreach ( $labels->toTextArray() as $languageCode => $labelText ) {
            if ( $this->languages !== null && !isset( $this->languages[$languageCode] ) ) {
                continue;
            }

            $this->writer->about( $entityNamespace, $entityLName );
            foreach ( $labelPredicates as $predicate ) {
                $this->writer->say( $predicate[0], $predicate[1] )->text( $labelText, $languageCode );
            }
        }
    }

    /**
     * Adds the descriptions of the given entity to the RDF graph.
     *
     * @param string $entityNamespace
     * @param string $entityLName
     * @param TermList $descriptions
     */
    private function addDescriptions( $entityNamespace, $entityLName, TermList $descriptions ) {
        foreach ( $descriptions->toTextArray() as $languageCode => $description ) {
            if ( $this->languages !== null && !isset( $this->languages[$languageCode] ) ) {
                continue;
            }

            $this->writer->about( $entityNamespace, $entityLName )
                ->say( RdfVocabulary::NS_SCHEMA_ORG, 'description' )->text( $description, $languageCode );
        }
    }

    /**
     * Adds the aliases of the given entity to the RDF graph.
     *
     * @param string $entityNamespace
     * @param string $entityLName
     * @param AliasGroupList $aliases
     */
    private function addAliases( $entityNamespace, $entityLName, AliasGroupList $aliases ) {
        /** @var AliasGroup $aliasGroup */
        foreach ( $aliases as $aliasGroup ) {
            $languageCode = $aliasGroup->getLanguageCode();
            if ( $this->languages !== null && !isset( $this->languages[$languageCode] ) ) {
                continue;
            }

            foreach ( $aliasGroup->getAliases() as $alias ) {
                $this->writer->about(
                    $entityNamespace,
                    $entityLName
                )->say( RdfVocabulary::NS_SKOS, 'altLabel' )->text( $alias, $languageCode );
            }
        }
    }

    /**
     * Add the entity's labels, descriptions, and aliases to the RDF graph.
     *
     * @see EntityRdfBuilder::addEntity
     *
     * @param EntityDocument $entity the entity to output.
     */
    public function addEntity( EntityDocument $entity ) {
        $entityId = $entity->getId();
        $entityLName = $this->vocabulary->getEntityLName( $entityId );
        $entityRepoName = $this->vocabulary->getEntityRepositoryName( $entityId );
        $entityNamespace = $this->vocabulary->entityNamespaceNames[$entityRepoName];

        if ( $entity instanceof LabelsProvider ) {
            $this->addLabels( $entityNamespace, $entityLName, $entity->getLabels(),
                $this->getLabelPredicates( $entity ) );
        }

        if ( $entity instanceof DescriptionsProvider ) {
            $this->addDescriptions( $entityNamespace, $entityLName, $entity->getDescriptions() );
        }

        if ( $entity instanceof AliasesProvider ) {
            $this->addAliases( $entityNamespace, $entityLName, $entity->getAliasGroups() );
        }
    }

}