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

use TicTacToe::Display;

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

$VERSION='1.0';

sub new() {
    return bless [' ',' ',' ', ' ',' ',' ', ' ',' ',' '];
}

sub clone($) {
    my $self = shift;
    return bless [@$self];
}

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

sub display {
    my $self = shift;
    return &display_position($self);
}

sub won($$) {
    my $self = shift;
    my $player = shift;
    return &game_won($player, $self);
}

sub child() {
    my $self = shift;
    my $square = shift;
    my $player = shift;

    my($newpos)=$self->clone();
    $newpos->square($square, $player);
    return bless $newpos;
}

sub test_slice {
    my($player,$pos,$offset,$step)=@_;
    for(my($i) = 0; $i < 3; $i ++) {
	return 0 unless $pos->[$offset] eq $player;
	$offset+=$step;
    }
    return 1;
}

sub game_won {
    my($player,$pos)=@_;
    return
	# Diagonals
	&test_slice($player, $pos, 0, 4) ||
	&test_slice($player, $pos, 2, 2) ||
	# Rows
	&test_slice($player, $pos, 0, 1) ||
	&test_slice($player, $pos, 3, 1) ||
	&test_slice($player, $pos, 6, 1) ||
	# Columns
	&test_slice($player, $pos, 0, 3) ||
	&test_slice($player, $pos, 1, 3) ||
	&test_slice($player, $pos, 2, 3);
}

sub unoccupied_squares {
    my($position)=@_;
    my @squares;
    # Squares in the order of importance
    foreach (4,0,2,6,8,1,3,5,7) {
	if($position->[$_] eq ' ') {
	    push @squares, $_;
	}
    }
    return @squares;
}



1;