# rddb.pm
#
#  rhrdlibs
#
#  Copyright (C) 2015 Christian Pointner <equinox@helsinki.at>
#
#  This file is part of rhrdlibs.
#
#  rhrdlibs is free software: you can redistribute it and/or modify
#  it under the terms of the GNU Affero General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  any later version.
#
#  rhrdlibs is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU Affero General Public License for more details.
#
#  You should have received a copy of the GNU Affero General Public License
#  along with rhrdlibs. If not, see <http://www.gnu.org/licenses/>.
#

package RHRD::utils;

use strict;
use DateTime;
use DateTime::TimeZone;

sub get_rd_week
{
  #
  # This computes the current Rivendell Week based on the number
  # of weeks since epoch.
  #
  # Explanation:
  #  epoch was at 01.01.1970 which was a Thursday.
  #  Monday in that week is (s-from-epoch + 3*24*60*60) seconds ago.
  #  This needs to be adjusted by the timezone offset for Europe/Vienna
  #  which is of course not constant (damn you daylight savings time)
  #  Divide this by (7*24*60*60) and you get the number of
  #  weeks since the Monday in the week of epoch adjusted for timezone offsets.
  #  This week had week number 3 so add an offset of 2 and
  #  get the modulo of 4. This rounded down gives you the current week
  #  with 0 meaning Week 1. So add 1 to that number and you will get
  #  the current RD week.
  #
  my $now = DateTime->now();
  my $tz = DateTime::TimeZone->new(name => 'Europe/Vienna');
  my $tz_offset = $tz->offset_for_datetime($now);
  my $sEpoch = $now->epoch() + $tz_offset;
  my $week = floor(((($sEpoch + 259200)/604800) + 2) % 4) + 1;

  return $week;
}

return 1;