package DateTime::TimeZone::OlsonDB::Rule;

use strict;
use warnings;

use DateTime;
use DateTime::Duration;
use DateTime::TimeZone::OlsonDB;

use Params::Validate qw( validate SCALAR );

sub new
{
    my $class = shift;
    my %p = validate( @_, { name => { type => SCALAR },
                            from => { type => SCALAR },
                            to   => { type => SCALAR },
                            type => { type => SCALAR, default => undef },
                            in   => { type => SCALAR },
                            on   => { type => SCALAR },
                            at   => { type => SCALAR },
                            save => { type => SCALAR },
                            letter => { type => SCALAR, default => '' },
                          },
                    );

    my $save = $p{save};

    if ($save)
    {
        $p{offset_from_std} = DateTime::TimeZone::offset_as_seconds($save);
    }
    else
    {
        $p{offset_from_std} = 0;
    }

    return bless \%p, $class;
}

sub name { $_[0]->{name} }
sub offset_from_std { $_[0]->{offset_from_std} }
sub letter { $_[0]->{letter} }
sub min_year { $_[0]->{from} }

sub max_year { $_[0]->{to} eq 'only' ? $_[0]->min_year :
               $_[0]->{to} eq 'max' ? undef : $_[0]->{to} }

sub is_infinite { $_[0]->{to} eq 'max' ? 1 : 0 }

sub month { $DateTime::TimeZone::OlsonDB::MONTHS{ $_[0]->{in} } }
sub on { $_[0]->{on} }
sub at { $_[0]->{at} }

sub utc_start_datetime_for_year
{
    my $self   = shift;
    my $year   = shift;
    my $offset_from_utc = shift;
    # should be the offset of the _previous_ rule
    my $offset_from_std = shift;

    my $day =
        DateTime::TimeZone::OlsonDB::parse_day_spec( $self->on, $self->month, $year );

    my $utc =
        DateTime::TimeZone::OlsonDB::utc_datetime_for_time_spec
                ( spec  => $self->at,
                  year  => $year,
                  month => $self->month,
                  day   => $day,
                  offset_from_utc => $offset_from_utc,
                  offset_from_std => $offset_from_std,
                );

    return $utc;
}

1;
