#!/usr/bin/perl -l
use lib '/PATH/TO/DesignPatterns-Perl/lib/';

package Model;
use Moose;
extends 'OODP::Observer';
has state => ( is => 'ro', isa => 'Num', default => 1 );
sub update {
    my ($self, $newval) = @_;
    $self->set_state( $newval );
}


package View;
use Moose;
extends 'OODP::Composite', 'OODP::Subject';
sub notify {
    my $self = shift;
    $self->SUPER::notify( @_ );
    $self->update_display;
}
sub update_display {
    my $self = shift;
    for my $child (values %{ $self->get_children }) {
        $child->update_display
    }
}

package View::FH;
use Moose;
use IO::File;
use IO::Handle;
extends 'View';
has '+name'    => ( default => 'view' );
has mode       => ( is => 'ro', isa => 'Str', default => '>' );
has filename   => ( is => 'ro', isa => 'Str' );
has filehandle => ( 
    is      => 'ro',
    isa     => 'IO::Handle',
    default => sub { IO::Handle->new_from_fd( fileno(STDOUT), 'w' ) }
);
sub BUILD {
    my $self = shift;
    if ($self->get_filename) {
        $self->{filehadle} = IO::File->new( $self->get_mode . $self->get_filename );
    }
}
sub DEMOLISH {
    my $self = shift;
    $self->get_filehandle->close if $self->get_filehandle;
    unlink $self->get_filename if $self->get_filename && -z $self->get_filename;
}
sub update_display {
    my $self = shift;
    my $fh = $self->get_filehandle;
    print $fh $_->get_state for @{ $self->get_observers };
    $self->SUPER::update_display( @_ );
}


package Controller;
use Moose;
extends 'OODP::Context';
has '+strategy' => ( handles => ['algorithm'], default => sub {Adder->new} );
has model => ( is => 'ro', handles => ['get_state'], default => sub {Model->new} );
has view  => ( is => 'ro', handles => ['notify'], default => sub {View::FH->new} );
sub BUILD {
    my $self = shift;
    $self->{view}->attach( $self->{model} )
}
sub context {
    my ($self,$val) = @_;
    $self->algorithm( $self->get_state, $val )
}
sub run {
    my $self = shift;
    $self->notify( $self->context( $_ ) ) for @_;
}

package Adder;
use Moose;
extends 'OODP::Strategy';
use Data::Dumper;
sub algorithm { $_[1] + $_[2] }

package Subtractor;
use Moose;
extends 'OODP::Strategy';
sub algorithm { $_[1] - $_[2] }


package main;
use Data::Dumper;
use IO::File;

Controller->new( strategy => Subtractor->new )->run( 1 .. 10 );

Controller->new(
    view => View::FH->new(
        filename => 'out.txt',
        mode => '>>'
    )
)->run( 1 .. 10 );
print `cat out.txt`;

Controller->new(
    strategy => Subtractor->new,
    view => View::FH->new(
        filename => 'out.txt',
        mode => '>>'
    )
)->run( 1 .. 10 );
print `cat out.txt`;
print `rm out.txt`;