# looks at all 8 in-a-rows.
# +10 for all xs
# -10 for all os
# +2 for 2 xs, no os
# -2 for 2 os, no xs
# +1 for 1 xs, no os
# -1 for 1 os, no xs

# print "in blocker file\n";

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

    # print "blocker: >$board<\n";

    local($score) = 0;

    $score += docount($board, 0,1,2);
    $score += docount($board, 3,4,5);
    $score += docount($board, 6,7,8);
    $score += docount($board, 0,3,6);
    $score += docount($board, 1,4,7);
    $score += docount($board, 2,5,8);
    $score += docount($board, 0,4,8);
    $score += docount($board, 2,4,6);

    return($score);
}

sub docount {
    local($board, $a,$b,$c) = @_;
    local(@counts);

    @counts{"x"} = 0;
    @counts{"o"} = 0;
    @counts{" "} = 0;

    @counts{substr($board,$a,1)}++;
    @counts{substr($board,$b,1)}++;
    @counts{substr($board,$c,1)}++;

    # printf "$board, $a, $b, $c\n";
    # printf "%d %d\n", @counts{"x"}, @counts{"o"};

    if (@counts{"x"} == 3) {
	return 10;
    }
    if (@counts{"o"} == 3) {
	return -10;
    }
    if ((@counts{"x"} > 0)&&(@counts{"o"}>0)) {
	return 0;
    }
    if ((@counts{"x"} == 2)) {
	return 2;
    }
    if ((@counts{"0"} == 2)) {
	return -2;
    }
    if ((@counts{"x"} == 1)) {
	return 1;
    }
    if ((@counts{"0"} == 1)) {
	return -1;
    }

    return 0;
}