wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Lib\Formatters;

use InvalidArgumentException;
use ValueFormatters\ValueFormatter;
use Wikibase\DataModel\Entity\EntityIdParser;
use Wikibase\DataModel\Entity\EntityIdParsingException;
use Wikibase\DataModel\Services\Lookup\LabelDescriptionLookup;
use Wikibase\DataModel\Services\Lookup\LabelDescriptionLookupException;

/**
 * A dedicated formatter for concept URIs referring to entities on a vocabulary repository.
 *
 * @license GPL-2.0-or-later
 * @author Thiemo Kreuz
 */
class VocabularyUriFormatter implements ValueFormatter {

    /**
     * @var EntityIdParser
     */
    private $vocabUriParser;

    /**
     * @var LabelDescriptionLookup
     */
    private $labelLookup;

    /**
     * @var array A set of unitless IDs, represented as string keys.
     */
    private $unitlessUnitIds;

    /**
     * @param EntityIdParser $vocabUriParser
     * @param LabelDescriptionLookup $labelLookup
     * @param string[] $unitlessUnitIds A list of IDs that represent the "unitless" unit (one),
     *        e.g. "http://www.wikidata.org/entity/Q199". The strings "" and "1" are always
     *        treated as "non-units".
     */
    public function __construct(
        EntityIdParser $vocabUriParser,
        LabelDescriptionLookup $labelLookup,
        array $unitlessUnitIds = []
    ) {
        $this->vocabUriParser = $vocabUriParser;
        $this->labelLookup = $labelLookup;

        $this->unitlessUnitIds = array_flip( $unitlessUnitIds );
        $this->unitlessUnitIds[''] = true;
        $this->unitlessUnitIds['1'] = true;
    }

    /**
     * @see ValueFormatter::format
     *
     * @param string $conceptUri
     *
     * @throws InvalidArgumentException
     * @return string|null Null if the concept URI refers to a unitless unit. Otherwise a label or
     * an entity ID or the original concept URI.
     */
    public function format( $conceptUri ) {
        if ( !is_string( $conceptUri ) ) {
            throw new InvalidArgumentException( '$conceptUri must be a string' );
        }

        if ( array_key_exists( $conceptUri, $this->unitlessUnitIds ) ) {
            return null;
        }

        try {
            $entityId = $this->vocabUriParser->parse( $conceptUri );

            try {
                // TODO: Ideally we would show unit *symbols*, taking from a config file,
                // a system message, or a statement on the unit's item.
                $term = $this->labelLookup->getLabel( $entityId );
            } catch ( LabelDescriptionLookupException $ex ) {
                $term = null;
            }

            if ( $term !== null ) {
                return $term->getText();
            } else {
                // Fall back to the entity ID.
                return $entityId->getSerialization();
            }
        } catch ( EntityIdParsingException $ex ) {
            // Fall back to the raw concept URI.
            return $conceptUri;
        }
    }

}