# $Id: Board.pm,v 1.1.1.1 2008/10/12 04:05:34 alamos Exp $
# The state is in an array
package TicTacToe::Board;
use strict;
use TicTacToe::Position;
use TicTacToe::Move;


use base qw(Exporter);
use vars qw($VERSION);

$VERSION='1.0';

# Mapping to the opponent
my($opponent) = { x =>'o', o => 'x'};

# Constructor
sub new () {
    return bless {
	position   =>  TicTacToe::Position->new(),
	player     => 'o',
	ply        =>  0
	};
}

## Accessors
sub position($) {
    my $self = shift;
    return $self->{position};
}

sub player($) {
    my $self = shift;
    return $self->{player};
}

sub ply($) {
    my $self = shift;
    return $self->{ply};
}

sub result {
    my $self = shift;
    if(@_) { $self->{result} = shift }
    return $self->{result};
}

## Subs

sub apply_move($$) {
    my $self = shift;
    my $move = shift;
    my($value);
    my($result) = undef;
    my($new_game) = bless {
	position => $self->position()->child($move->square(), $self->player()),
	player   => $opponent->{$self->player()},
	ply      => $self->{ply} + 1
	};
    if($new_game->position()->won($self->player())) {
	$move->value(100 - $new_game->ply()) ;
	$new_game->result('won');
    } else {
	# Number of occupied squares is the value
	my(@blanks) = grep /^ $/, @{$new_game->position()};
	if($new_game->ply() == 9) {
	    $new_game->result('stalemate');
	} 
	$move->value($new_game->ply());
    }
    return bless $new_game;
}

sub generate_moves($) {
    my($game)=@_;
    my(@squares) = $game->position()->unoccupied_squares();
    $game->result('stalemate')  unless(@squares);
    map { TicTacToe::Move->new($_) } @squares;
}

sub display($$) {
    my $self = shift;
    $self->position()->display();
    print "Ply:",  $self->ply(), "\n";
    print $self->player(), " to move\n";
}

1;