wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Repo;

use InvalidArgumentException;
use Wikibase\DataModel\Services\Statement\Grouper\NullStatementGrouper;
use Wikibase\DataModel\Services\Statement\Grouper\StatementGrouper;
use Wikibase\DataModel\Services\Statement\StatementGuidParser;
use Wikibase\DataModel\Services\Statement\StatementGuidParsingException;
use Wikibase\DataModel\Statement\Statement;
use Wikibase\DataModel\Statement\StatementList;

/**
 * @license GPL-2.0-or-later
 * @author Thiemo Kreuz
 */
class DispatchingEntityTypeStatementGrouper implements StatementGrouper {

    /**
     * @var StatementGrouper[]
     */
    private $statementGroupers = [];

    /**
     * @var StatementGuidParser
     */
    private $guidParser;

    /**
     * @param StatementGuidParser $statementGuidParser
     * @param StatementGrouper[] $statementGroupers An associative array, mapping entity types
     *  (typically "item" and "property") to StatementGrouper objects.
     *
     * @throws InvalidArgumentException
     */
    public function __construct(
        StatementGuidParser $statementGuidParser,
        array $statementGroupers
    ) {
        foreach ( $statementGroupers as $key => $grouper ) {
            if ( !is_string( $key ) || !( $grouper instanceof StatementGrouper ) ) {
                throw new InvalidArgumentException(
                    '$statementGroupers must map strings to StatementGroupers'
                );
            }
            $this->statementGroupers[$key] = $grouper;
        }

        $this->guidParser = $statementGuidParser;
    }

    /**
     * @param StatementList $statements
     *
     * @return StatementList[]
     */
    public function groupStatements( StatementList $statements ) {
        return $this->guessStatementGrouper( $statements )->groupStatements( $statements );
    }

    /**
     * @param StatementList $statements
     *
     * @return StatementGrouper
     */
    private function guessStatementGrouper( StatementList $statements ) {
        foreach ( $statements->toArray() as $statement ) {
            $entityType = $this->getEntityType( $statement );

            if ( array_key_exists( $entityType, $this->statementGroupers ) ) {
                return $this->statementGroupers[$entityType];
            }

            // FIXME: Check all statements and fail if they don't share the same entity type?
        }

        return new NullStatementGrouper();
    }

    /**
     * @param Statement $statement
     *
     * @return string|null
     */
    private function getEntityType( Statement $statement ) {
        $statementGuid = $statement->getGuid();
        if ( $statementGuid === null ) {
            return null;
        }
        try {
            $guid = $this->guidParser->parse( $statementGuid );
        } catch ( StatementGuidParsingException $ex ) {
            // FIXME: Fail when there is a statement with no GUID?
            return null;
        }

        return $guid->getEntityId()->getEntityType();
    }

}