<?php
namespace Misuzu;

final class DateCheck {
    public static function isLeapYear(int $year): bool {
        return (($year % 4) === 0 && ($year % 100) !== 0)
            || ($year % 400) === 0;
    }

    // i realise this implementation is probably horribly naive,
    //  but for what i need it will Do the Job
    public static function isValidDate(int $year, int $month, int $day): bool {
        if($month < 1 || $month > 12)
            return false;
        if($day < 1 || $day > 31)
            return false;

        if($month === 2)
            $days = $year === 0 || self::isLeapYear($year) ? 29 : 28;
        elseif($month === 4 || $month === 6 || $month === 9 || $month === 11)
            $days = 30;
        else
            $days = 31;

        return $day <= $days;
    }
}