wikimedia/mediawiki-extensions-Wikibase

<?php

declare( strict_types = 1 );

namespace Wikibase\Repo\Diff;

use Diff\Differ\Differ;
use Diff\DiffOp\Diff\Diff;
use Diff\DiffOp\DiffOpChange;
use Wikibase\DataModel\Statement\Statement;

/**
 * Class for generating a ClaimDifference given two statements.
 *
 * @license GPL-2.0-or-later
 * @author Tobias Gritschacher < tobias.gritschacher@wikimedia.de >
 * @author Addshore
 * @author Thiemo Kreuz
 */
class ClaimDiffer {

    /** @var Differ */
    private $listDiffer;

    public function __construct( Differ $listDiffer ) {
        $this->listDiffer = $listDiffer;
    }

    /**
     * Calculates diff of two Statements and stores the difference in a ClaimDifference
     *
     * @param Statement|null $oldStatement
     * @param Statement|null $newStatement
     *
     * @return ClaimDifference
     */
    public function diffClaims(
        ?Statement $oldStatement,
        ?Statement $newStatement
    ): ClaimDifference {
        if ( $oldStatement === $newStatement ) {
            return new ClaimDifference();
        }

        return new ClaimDifference(
            $this->diffMainSnaks( $oldStatement, $newStatement ),
            $this->diffQualifiers( $oldStatement, $newStatement ),
            $this->diffReferences( $oldStatement, $newStatement ),
            $this->diffRanks( $oldStatement, $newStatement )
        );
    }

    private function diffMainSnaks(
        ?Statement $oldStatement,
        ?Statement $newStatement
    ): ?DiffOpChange {
        $oldSnak = $oldStatement === null ? null : $oldStatement->getMainSnak();
        $newSnak = $newStatement === null ? null : $newStatement->getMainSnak();

        if ( $oldSnak !== null && $oldSnak->equals( $newSnak ) ) {
            return null;
        }

        return new DiffOpChange( $oldSnak, $newSnak );
    }

    private function diffQualifiers(
        ?Statement $oldStatement,
        ?Statement $newStatement
    ): ?Diff {
        if ( $oldStatement !== null
            && $newStatement !== null
            && $oldStatement->getQualifiers()->equals( $newStatement->getQualifiers() )
        ) {
            return null;
        }

        $oldQualifiers = $oldStatement === null
            ? []
            : iterator_to_array( $oldStatement->getQualifiers() );
        $newQualifiers = $newStatement === null
            ? []
            : iterator_to_array( $newStatement->getQualifiers() );

        if ( $oldQualifiers === $newQualifiers ) {
            return null;
        }

        return new Diff( $this->listDiffer->doDiff( $oldQualifiers, $newQualifiers ), false );
    }

    private function diffRanks(
        ?Statement $oldStatement,
        ?Statement $newStatement
    ): ?DiffOpChange {
        $oldRank = $oldStatement === null ? null : $oldStatement->getRank();
        $newRank = $newStatement === null ? null : $newStatement->getRank();

        if ( $oldRank === $newRank ) {
            return null;
        }

        return new DiffOpChange( $oldRank, $newRank );
    }

    private function diffReferences(
        ?Statement $oldStatement,
        ?Statement $newStatement
    ): ?Diff {
        if ( $oldStatement !== null
            && $newStatement !== null
            && $oldStatement->getReferences()->equals( $newStatement->getReferences() )
        ) {
            return null;
        }

        $oldReferences = $oldStatement === null
            ? []
            : iterator_to_array( $oldStatement->getReferences() );
        $newReferences = $newStatement === null
            ? []
            : iterator_to_array( $newStatement->getReferences() );

        if ( $oldReferences === $newReferences ) {
            return null;
        }

        return new Diff( $this->listDiffer->doDiff( $oldReferences, $newReferences ), false );
    }

}