#!/usr/bin/env perl
# Core Modules
use strict;
use warnings;
use utf8;
use open ':encoding(UTF-8)';
use open ':std';

use DateTime;
use DateTime::Format::Strptime;

# Wochenstart im America/Chicago
my $parser = DateTime::Format::Strptime->new(
    pattern   => '%d.%m.%Y',
    locale    => 'en_US',
    time_zone => 'America/Chicago',
);

my $dt = $parser->parse_datetime('19.12.2009');
my $offset = $dt->local_day_of_week;
$dt->subtract( days => $offset-1 );
print "In America/Chicago ist der Wochenstart der ", $dt->dmy('.'), "\n";


# Wochenstart in Europe/Berlin
my $parser2 = DateTime::Format::Strptime->new(
    pattern   => '%d.%m.%Y',
    locale    => 'de_DE',
    time_zone => 'Europe/Berlin',
);

my $dt2 = $parser2->parse_datetime('19.12.2009');
my $offset2 = $dt2->local_day_of_week;
$dt2->subtract( days => $offset2-1 );
print "In Europe/Berlin ist der Wochenstart der ", $dt2->dmy('.'), "\n";