wikimedia/mediawiki-extensions-Wikibase

<?php

namespace Wikibase\Repo\Rdf;

use DataValues\IllegalValueException;
use DataValues\TimeValue;

/**
 * Clean datetime value to conform to RDF/XML standards
 * This class supports Julian->Gregorian conversion
 *
 * @license GPL-2.0-or-later
 * @author Stas Malyshev
 * @author Thiemo Kreuz
 */
class JulianDateTimeValueCleaner extends DateTimeValueCleaner {

    /**
     * Get standardized dateTime value, compatible with xsd:dateTime
     * If the value cannot be converted to it, returns null
     *
     * @param TimeValue $value
     *
     * @return string|null Value compatible with xsd:dateTime type, null if the input is an illegal
     *  XSD 1.0 timestamp
     */
    public function getStandardValue( TimeValue $value ) {
        try {
            // If we are less precise than a day, no point to convert
            // Julian to Gregorian since we don't have enough information to do it anyway
            if ( $value->getCalendarModel() === TimeValue::CALENDAR_JULIAN
                && $value->getPrecision() >= TimeValue::PRECISION_DAY
            ) {
                // There is a certain range of years PHP can convert; assume everything else was a
                // mistake and meant to be a Gregorian date
                return $this->julianDateValue( $value->getTime() )
                    ?: $this->cleanupGregorianValue( $value->getTime(), $value->getPrecision() );
            }
        } catch ( IllegalValueException $e ) {
            return null;
        }

        return parent::getStandardValue( $value );
    }

    /**
     * Get Julian date value and return it as Gregorian date
     *
     * @param string $dateValue
     *
     * @throws IllegalValueException if the input is an illegal XSD 1.0 timestamp
     * @return string|null Value compatible with xsd:dateTime type, null if conversion is not
     *  possible
     */
    private function julianDateValue( $dateValue ) {
        [ $minus, $y, $m, $d, $time ] = $this->parseDateValue( $dateValue );

        $y = $minus ? -$y : $y + 0;
        // There are some weird overflows happening in the PHP functions before and after this year.
        if ( !is_int( $y ) || $y < -4713 || $y > 1465072 ) {
            return null;
        }

        $jd = juliantojd( $m, $d, $y );
        if ( $jd == 0 ) {
            return null;
        }

        $gregorian = jdtogregorian( $jd );
        if ( $gregorian === '0/0/0' ) {
            return null;
        }

        [ $m, $d, $y ] = explode( '/', $gregorian );

        if ( $this->xsd11 && $y < 0 ) {
            // To make year match XSD 1.1 we need to bump up the negative years by 1
            // We know we have precision here since otherwise we wouldn't convert
            $y++;
        }

        // This is a bit weird since xsd:dateTime requires >=4 digit always,
        // and leading 0 is not allowed for 5 digits, but sprintf counts - as digit
        // See: http://www.w3.org/TR/xmlschema-2/#dateTime
        return sprintf( '%s%04d-%02d-%02dT%s', ( $y < 0 ) ? '-' : '', abs( $y ), $m, $d, $time );
    }

}