class calendar
{
    protected $holidays = array();
    protected $year = 0;

    /**
     * calendar constructor.
     * @param int|string $year
     */
    public function __construct( $year = 0 )
    {
        $this->year = ( $year == 0 ) ? date( 'Y' ) : $year;

        // feste Feiertage definieren
        $this->holidays[] = '01.01.'; // Neujahr
        $this->holidays[] = '01.05.'; // Tag der Arbeit
        $this->holidays[] = '03.10.'; // Tag der Deutschen Einheit
        $this->holidays[] = '25.12.'; // 1. Weihnachtsfeiertag
        $this->holidays[] = '26.12.'; // 2. Weihnachtsfeiertag

        // alle beweglichen Feiertage von Karfreitag bis Pfinstmontag
        $easterSunday = date( 'd.M.Y', easter_date( $this->year ) );

        foreach( array( -2, 1, 39, 49, 50 ) as $day )
        {
            $time = array( $easterSunday, $day, 'day');
            $ts = strtotime( implode( ' ', $time ) );
            $this->holidays[] = date( 'd.m.', $ts );
        }
    }

    /**
     * @param int $timestamp
     * @return bool
     */
    public function isHoliday( $timestamp )
    {
        $date = date( 'd.m.', $timestamp );
        return in_array( $date, $this->holidays );
    }
}