Dutch off-of-work-holiday-days

dutch-holidays.php

<?php
/**
 * @class Returns a list of DUTCH holidays on which we brave people stop and do nothing for a day... just 'cause :)
 */
class Holidays {
  /**
   * Returns all dates on which we Dutch people get a day off of work.
   * @param  int $year The year for which to get the list of holidays
   * @return Array The list of holidays, associative array [holiday name] => [date in d-m-Y format]
   */
  public static function getHolidays($year=null)
  {
    $year = intval( $year ?: date('Y') );

    $pasen = easter_date($year);

    $holidayList = array(
        '1e Paasdag' => date("d-m-Y", $pasen),
        '2e Paasdag' => date("d-m-Y", $pasen + 86400),
        'Hemelvaart' => date("d-m-Y", $pasen + (86400 * 39)),
        '1e Pinksterdag' => date("d-m-Y", $pasen + (86400 * 49)),
        '2e Pinksterdag' => date("d-m-Y", $pasen + (86400 * 50)),

        'Nieuwsjaarsdag' => "01-01-" . $year,
        'Koningsdag' => "27-04-" . $year,
        '1e Kerstdag' => "25-12-" . $year,
        '2e Kerstdag' => "26-12-" . $year
    );
    if (0 === $year % 5) {
      $holidayList['Bevrijdingsdag'] = "05-05" . $year;
    }

    return $holidayList;
  }

  /**
   * List the upcoming holidays on which Dutch people get a day off of work
   * @return Array The list of holidays, sorted by date, associative array [holiday name] => [date in d-m-Y format]
   */
  public static function getUpcomingHolidays()
  {
    $year = intval( date('Y') );

    $this_year = self::getHolidays($year);
    $next_year = self::getHolidays($year+1);

    $this_year = array_filter($this_year, array('self', '_filter_callback'));

    $upcoming = array_merge($next_year, $this_year);
    uasort($upcoming, array('self', '_compare_callback'));

    return $upcoming;
  }

  /**
   * transform date d-m-Y into a sortable string Ymd
   * @param  String $in The date in d-m-Y format
   * @return String The date in Ymd format
   */
  private static function d_m_y_to_ymd( $in ) {
    return implode('', array_reverse(explode('-', $in)));
  }

  /**
   * Internal: use as callback for array_filter; returns true for future (or TODAY) holidays
   * @param  String $date The date in d-m-Y format
   * @return boolean true for keep, false for drop
   */
  private static function _filter_callback( $date ) {
    $today = date('d-m-Y');
    return self::d_m_y_to_ymd($date) >= self::d_m_y_to_ymd($today);
  }

  /**
   * Internal: use as callback for uasort
   * @param  String $date_A The date in d-m-Y format
   * @param  String $date_B The date in d-m-Y format
   * @return mixed The sort-value
   * @see http://php.net/strcmp
   */
  private static function _compare_callback( $date_A, $date_B ) {
    return strcmp(self::d_m_y_to_ymd($date_A),self::d_m_y_to_ymd($date_B));
  }
}

/** example use */
$offdays = Holidays::getUpcomingHolidays();
var_dump($offdays);