package Isanchez;
use strict;
use Carp;
our $VERSION = '0.01';

sub new {
    my ($class, $file) = @_;
    my $self = bless {}, $class;
    $self->_build($file);
    return $self;
}

sub _build {
    my ($self, $file) = @_;
    croak "Unable to retrieve data" unless open(INPUT,$file);
    while (my $line = <INPUT>) {
        chomp $line;
        my($id, $parent_id, $title) = split /\s+/ , $line, 3;
        unless ($title && $id =~ /^\d+$/ && $parent_id =~ /^\d+/ && $parent_id < $id) {
            carp "Unable to parse\n$line";
            next;
        }
        $self->{$title}{decendent} = $id;
        push @{$self->{decendents}{$parent_id}}, $title;
    }    
}

sub get_decendents {
    my ($self, $origin) = @_;
    croak "You must enter an origin in the tree" unless $origin;
    croak "$origin can not be found" unless exists $self->{$origin};
    my $index = $self->{$origin}{decendent};
    my @list = @{$self->{decendents}{$index}} if exists $self->{decendents}{$index};
    return $origin unless @list;
    my @decendents = ($origin);
    while (@list) {
        my $decendent = shift @list;
        push @decendents, $decendent;
        my $index = $self->{$decendent}{decendent};
        push @list, @{$self->{decendents}{$index}} if exists $self->{decendents}{$index};
    }
    return @decendents;
}