PHP function to check if a date is a holiday in Lithuania

Here is a simple function for PHP to check if a date, given in standard ISO format (Y-m-d) is a public holiday in Lithuania. I needed one for a project, so here it is for everyone:

/**
 * Checks if a passed date is a public holiday
 * (or weekend) in Lithuania
 *
 * @param bool $weekends – true if you want the function to include weekends
 *    default – false
 * @param string $date – 'Y-m-d' format date (or full ISO 8601 datetime string)
 *    defaults to current date
 * @return bool true (if holiday) or false (not a holiday)
*/

function is_lt_holiday(bool $weekends = false, string $date = null): int
{
    //date is today if it was not passed to the function
    if (!isset($date)) $date = date('Y-m-d');

    //check if the date is valid
    if (
         strlen($date) < 10
      || !checkdate(substr($date,5,2), substr($date,8,2), substr($date,0,4))
    )
    {
        trigger_error('You should pass a valid date in \'Y-m-d\' format');
        return false;
    }

    $year = substr($date,0,4);
    $mday = substr($date,5,5);
    $easter = date('Y-m-d',easter_date($year));
    $easter2 = date('Y-m-d', strtotime($easter . ' +1 day'));
    $public_holidays = [
        '01-01', //new year
        '02-16', //independence day
        '03-11', //restoration of independence day
        substr($easter,5,5), //easter day1
        substr($easter2,5,5), //easter day2
        '05-01', //int worker's day
        '06-24', //summer solstice
        '07-06', //state day
        '08-15', //mary's assumption
        '11-01', //all saints day
        '11-02', //day of the dead
        '12-24', //christmas eve
        '12-25', // christmas day1
        '12-26'  //christmas day2
       ];

    if (in_array($mday,$public_holidays)) {
        return true;
    }
    elseif (
       $weekends == true
       && (date('D',strtotime($date)) == 'Sat'
       || date('D',strtotime($date)) == 'Sun')
    )
    {
        return true;
    }
    return false;
}

And now let’s test it:

echo is_lt_holiday(true);
//today; it depends 🙂
echo is_lt_holiday(false,'2022-01-01');
//returns true
echo is_lt_holiday(false,'2022-01-02');
//returns false
echo is_lt_holiday(false,'2022-01-32');
//returns false and error notice – an impossible date