package Clock 1;
use strict;
use warnings;

use POSIX;

sub new {
  my ($class, $attributes) = @_;
  my $self = {
    hour   => $attributes->{hour} || 0,
    minute => $attributes->{minute} || 0,
  };
  return bless($self, $class)->BUILD;
}

sub time {
  my ($self) = @_;
  return sprintf '%02d:%02d', $self->{hour}, $self->{minute};
}

sub add_minutes {
  my ($self, $amount) = @_;
  $self->{minute} += $amount;
  return $self->BUILD;
}

sub subtract_minutes {
  my ($self, $amount) = @_;
  return $self->add_minutes(-$amount);
}

sub BUILD {
  my ($self) = @_;
  $self->{hour} = ( $self->{hour} + floor($self->{minute} / 60) ) % 24;
  $self->{minute} %= 60;
  return $self;
}

1;