PIN Validation

<?php
date_default_timezone_set('Europe/Sofia');

$name = trim($_GET['name']);
$gender = trim($_GET['gender']);
$pin = trim($_GET['pin']);
if (!preg_match('/^[A-Z][a-z]+\s[A-Z][a-z]+$/', $name) || ($gender != 'male' && $gender != 'female') ||
    !preg_match('/^\d{10}$/', $pin)
) {
    die('<h2>Incorrect data</h2>');
}

$sexDigit = (int)$pin[8];
if (($gender == 'male' && ($sexDigit % 2) !== 0) ||
    ($gender == 'female' && ($sexDigit % 2) === 0)
) {
    die('<h2>Incorrect data</h2>');
}

$year = substr($pin, 0, 2);
$month = substr($pin, 2, 2);
$dayOfMonth = substr($pin, 4, 2);
if ((int)$month > 40) {
    $year = '20' . $year;
    $month = (int)$month - 40;
} elseif ((int)$month > 20) {
    $year = '18' . $year;
    $month = (int)$month - 20;
} else {
    $year = '19' . $year;
}

$dateStr = $month . '/' . $dayOfMonth . '/' . $year;
$date = new DateTime($dateStr);
if (!$date || ($date->format('n') != $month)) {
    die('<h2>Incorrect data</h2>');
}

$multipliers = [2, 4, 8, 5, 10, 9, 7, 3, 6];
$totalSum = 0;
foreach ($multipliers as $key => $multiplier) {
    $digit = (int)$pin[$key];
    $totalSum += ($digit * $multiplier);
}

$totalSum = ($totalSum % 11) % 10;
$checksum = (int)$pin[9];
if ($checksum !== $totalSum) {
    die('<h2>Incorrect data</h2>');
}

$data = array('name' => $name, 'gender' => $gender, 'pin' => $pin);
echo json_encode($data);