#!/usr/local/bin/perl

# Runs tic tac toe players in ARGV[0] and ARGV[1]
$player1 = $ARGV[0];
$player2 = $ARGV[1];

$globalboard = initgame();
$moves = 0;
while (!($winner = gameover($globalboard))) {
    $globalboard = makemove($player1, $globalboard);
    $moves++;
    if (!($winner = gameover($globalboard))) {
	$globalboard = swapsides($globalboard);
	$globalboard = makemove($player2, $globalboard);
	$moves++;
	$globalboard = swapsides($globalboard);
    }
}
printboard($globalboard);
print "First move: 1, Winner: $winner, Moves; $moves\n";

$globalboard = initgame();
$moves = 0;
while (!($winner = gameover($globalboard))) {
    $globalboard = makemove($player2, $globalboard);
    $moves++;
    if (!($winner = gameover($globalboard))) {
	$globalboard = swapsides($globalboard);
	$globalboard = makemove($player1, $globalboard);
	$moves++;
	$globalboard = swapsides($globalboard);
    }
}

# Since gameover is calculated assuming player 1 plays x (goes first)
if ($winner == 1) {
    $winner = 2;
} elsif ($winner == 2) {
    $winner = 1;
}
$globalboard = swapsides($globalboard);

printboard($globalboard);
print "First move: 2, Winner: $winner, Moves: $moves\n";

exit();

sub initgame {
    return("         ");
}

# 1 = x wins, 2 = o wins, 3 = tie, 0 = game not over
sub gameover {
    local($var) = @_;
    $_ = $var;

    # print ">($_)<\n";

    if (/xxx....../) {
	return 1;
    }
    if (/...xxx.../) {
	return 1;
    }
    if (/......xxx/) {
	return 1;
    }
    if (/x..x..x../) {
	return 1;
    }
    if (/.x..x..x./) {
	return 1;
    }
    if (/..x..x..x/) {
	return 1;
    }
    if (/x...x...x/) {
	return 1;
    }
    if (/..x.x.x../) {
	return 1;
    }
    if (/ooo....../) {
	return 2;
    }
    if (/...ooo.../) {
	return 2;
    }
    if (/......ooo/) {
	return 2;
    }
    if (/o..o..o../) {
	return 2;
    }
    if (/.o..o..o./) {
	return 2;
    }
    if (/..o..o..o/) {
	return 2;
    }
    if (/o...o...o/) {
	return 2;
    }
    if (/..o.o.o../) {
	return 2;
    }
    if (/ /) {
	return 0;
    }
    return 3;
}

sub swapsides {
    local($temp) = @_;
    $temp =~ s/x/t/g;
    $temp =~ s/o/x/g;
    $temp =~ s/t/o/g;
    return($temp);
}

# always assumes it is x's turn
# also assumes -100 is near the bottom of the eval range
# loads file $player to define eval
sub makemove {
    local($player, $board) = @_;
    local($i, $temp, $best, $bestscore, $score);

    do $player;
    # print "loading $player\n";

    $bestscore = -100;
    $best = $board;
    for ($i = 0; $i < 9; $i++) {
	$temp = $board;
	# blank space
	if (substr($temp, $i, 1) eq " ") {
	    substr($temp, $i, 1) = "x";
	    $score = &eval($temp);
	    if ($score > $bestscore) {
		$bestscore = $score;
		$best = $temp;
	    }
	}
    }
 
    return($best);
}

sub printboard {
    local($board) = @_;

    # print ">$board<\n";

    printf "%s|%s|%s\n",substr($board,0,1),substr($board,1,1),substr($board,2,1);
    printf "-+-+-\n";
    printf "%s|%s|%s\n",substr($board,3,1),substr($board,4,1),substr($board,5,1);
    printf "-+-+-\n";
    printf "%s|%s|%s\n",substr($board,6,1),substr($board,7,1),substr($board,8,1);
}