#!/usr/local/bin/perl -w
##################
use DateTime::TimeZone;
use Data::Dumper;

my $tz = shift || 'America/New_York';

my $utc_start = DateTime::TimeZone::UTC_START();
my $utc_end = DateTime::TimeZone::UTC_END();
my $short_name = DateTime::TimeZone::SHORT_NAME();

my $tzobj = DateTime::TimeZone->new( name => $tz );
foreach my $span ( @{ $tzobj->{ 'spans' } } ) {
    my $start = RD->new(
		$span->[ $utc_start ],
		$tzobj,
	)->as_datetime;
    my $end = RD->new(
		$span->[ $utc_end ],
		$tzobj,
	)->as_datetime;
    print "$span->[ $short_name ]: $start - $end\n";
}

package RD;

use constant SECONDS_PER_DAY  => 86400;

sub new {
    my $class = shift;
    my $seconds = shift;
    my $timezone = shift;

    my $self = bless(
		[ $seconds, $timezone ],
		$class,
	);

    return $self;
}

sub time_zone { shift->[1] }

sub utc_rd_values {
    my ( $self ) = @_;

    my $days = int( $self->[0] / SECONDS_PER_DAY );
    my $seconds = int( $self->[0] % SECONDS_PER_DAY );

    return ( $days, $seconds, 0 );
}

sub as_datetime {
    my ( $self ) = @_;

    if ( $self->[0] eq '-inf' ) {
		return DateTime::Infinite::Past->new;
	}
    if ( $self->[0] eq 'inf' ) {
		return DateTime::Infinite::Future->new;
	}
    return DateTime->from_object( object => $self );
}