Easter date calculation error

[rChassat]

Hello I have done some testing on the easter date calcultation function from the ChristianHolidays.php, and I saw some incorrect date returned like for the 2025 year.
So I compared to the C solution from php-src calendar/easter.c and found out what caused the problem, so here is the function fixed :

    protected function calculateEaster(int $year, string $timezone): \DateTimeInterface
    {
        if (\extension_loaded('calendar')) {
            $easterDays = easter_days($year);
        } else {
            $golden = ($year % 19) + 1; // The Golden Number

            // The Julian calendar applies to the original method from 326AD. The Gregorian calendar was first
            // introduced in October 1582 in Italy. Easter algorithms using the Gregorian calendar apply to years
            // 1583 AD to 4099 (A day adjustment is required in or shortly after 4100 AD).
            // After 1752, most western churches have adopted the current algorithm.
            if ($year <= 1752) {
                $dom = ($year + (int) ($year / 4) + 5) % 7; // The 'Dominical number' - finding a Sunday
                if ($dom < 0) {
                    $dom += 7;
                }

                $pfm = (3 - (11 * $golden) - 7) % 30; // Uncorrected date of the Paschal full moon
            } else {
                $dom = ($year + (int) ($year / 4) - (int) ($year / 100) + (int) ($year / 400)) % 7; // The 'Dominical number' - finding a Sunday
                if ($dom < 0) {
                    $dom += 7;
                }

                $solar = (int) (($year - 1600) / 100) - (int) (($year - 1600) / 400); // The solar correction
                $lunar = (int) ((int) (($year - 1400) / 100) * 8 / 25); // The lunar correction

                $pfm = (3 - (11 * $golden) + $solar - $lunar) % 30; // Uncorrected date of the Paschal full moon
            }

            if ($pfm < 0) {
                $pfm += 30;
            }

            // Corrected date of the Paschal full moon, - days after 21st March
            if ((29 === $pfm) || (28 === $pfm && $golden > 11)) {
                --$pfm;
            }

            $tmp = (4 - $pfm - $dom) % 7;
            if ($tmp < 0) {
                $tmp += 7;
            }

            $easterDays = $pfm + $tmp + 1; // Easter as the number of days after 21st March
        }

        if ($easterDays < 11) {
            $easter = new \DateTime("{$year}-3-21");
            $easter->add(new \DateInterval('P' . $easterDays . 'D'));
        } else {
            $easterDays = $easterDays - 10;
            $easter = new \DateTime("{$year}-4-{$easterDays}");
        }

        return $easter;
    }

Basically I fixed the lunar calculation rounding and changed the ending calculation of the date based on the php-src code.

[stelgenhof]

@rChasaat Thank you very much for reporting this. Could you create a PR including unit tests that resolve this error?

Cheers! Sacha

[rChassat]

Yes here you go : #326

[stelgenhof]

Resolved in #326