#!/usr/bin/perl
#

#
#A very basic tic-tac-toe program (the computer chooses randomly)
#


use strict;
use CGI;
use Socket 'AF_INET';

sub do_with_board (&);

my ($rounds, $squares, $round, $player_move, $computer_move, $winner);

my $page = CGI->new();

print $page->header;
print $page->start_html();

# print table beginnings

print ("<table width=\"90\%\" border=0 cellpadding=15>\n");
print ("<tr valign=middle>\n");

# left cell is tic tac toe table

print ("<td align=center>\n");

#
# find out which round it is so we know how to define $squares
#

unless ($page->param('round')) {
   $round = 0;
}else {
   $round = $page->param('round');
}

#
# set array of tic tac toe squares
#

do_with_board { $squares->[$a][$b] = $page->param("$a$b") };

#
# set array for determing history of moves (recorded by round)
#

if ($round > 0) {
        for my $rn (1..5) {
          $rounds->{"round$rn"} = 
            { player   => $page->param("round${rn}_x"),
              computer => $page->param("round${rn}_o"),
            }
        }
}
           
#
# increment $round to give it a new hidden value
#

my $round_minus_one = $round;
$round = $round + 1;
print ("Round is: $round<br>\n");

##
## get player move using subroutine (subroutine stores it to $squares array)
##

$player_move = $page->param('choice');
if ($player_move) {
   my $round_temp = "round" . $round_minus_one;
   player_moves($player_move, $page, $squares);
   my $player_move_pretty = make_move_pretty($player_move);
   $rounds->{$round_temp}->{'player'} = $player_move_pretty;

#
# evaluate for winner after player moves
#

   $winner = evaluate_board($squares);
   if ($winner eq "x") {
      print ("<font color='blue'>Player Won!</font><p>\n");
      print_table($squares, $page, $winner, $round, $rounds, "final");
   }else {

#
# check to see if player won. if player won, don't do the rest of this


#
# get available choices for computer choices
#

      my @available_choices = get_available_choices($squares);

#
# get computer move
#
      $computer_move = $available_choices[int rand @available_choices];
      my ($x, $y) = split(//, $computer_move);  
         #get coordinates for computer move and store in $x and $y
      $squares->[$x][$y] = "o";   ## change square to "o"
      $round_temp = "round" . $round_minus_one;
      my $computer_move_pretty = make_move_pretty($computer_move);
      $rounds->{$round_temp}->{'computer'} = $computer_move_pretty;
   
   } #matches else {

} #matches if ($player_move) 


#
# now that we have the array with computer and player choices, see if there is a winner
#
$winner = evaluate_board($squares);
if ($winner eq "o") {  #we already checked for x before
   print ("<font color = 'blue'>Computer Won!</font><p>\n");
   print_table($squares, $page, $winner, $round, $rounds, "final");
}

if (($winner ne "o") and ($winner ne "x")) {
   print ("<font color='blue'>No winner yet</font><p>\n"); 


   print_table($squares, $page, $winner, $round, $rounds);


}

# end table cell

print ("</td>\n");
print ("<td align=middle>\n");

# get printable versions of moves and print choices

if ($player_move or $computer_move) {
   foreach my $x (1..$round_minus_one) {
      my $round_temp = "round" . $x;
      print ("<p><b>Round $x:</b><br>\n");
      print ("\tplayer: " . $rounds->{$round_temp}->{'player'} . "<br>\n");
      print ("\tcomputer: " . $rounds->{$round_temp}->{'computer'} . "<br>\n");
   }
}else {
   print ("No moves yet.\n");
}

# end table

print ("</td></tr></table>\n");

print $page->end_html();


sub player_moves {
  my ($move, $page, $squares) = @_;

  ## define array element for choice
  do_with_board {$squares->[$a][$b] = "x"}; 
}

sub get_available_choices {
   my $squares = $_[0];
   my @available_choices = ();

   do_with_board {
     unless (($squares->[$a][$b] eq "x") or ($squares->[$a][$b] eq "o")) {
       push @available_choices, "$a$b";
     }
   };
   return @available_choices;
}

   

sub print_hidden_values {
  my ($page, $squares, $rounds) = @_;
   
   #print hidden values for cells
   do_with_board { 
     print "<input type='hidden' name='$a$b' value='" . $squares->[$a][$b] . "'>\n"; 
   };
   
   #print hidden values for rounds (history)
   foreach my $x (1..5) {
     my $round = "round$x";
     print ("<input type='hidden' name='$round" . "_x' value ='" . $rounds->{$round}->{'player'} . "'>\n");
     print ("<input type='hidden' name='$round" . "_o' value='" . $rounds->{$round}->{'computer'} . "'>\n");
   }
}


sub evaluate_board {
    my ($board) = $_[0];

    my @table = (
       [ 0,0 , 0,1 , 0,2 ],
       [ 1,0 , 1,1 , 1,2 ],
       [ 2,0 , 2,1 , 2,2 ],
       [ 0,0 , 1,0 , 2,0 ],
       [ 0,1 , 1,1 , 2,1 ],
       [ 0,2 , 1,2 , 2,2 ],
       [ 0,0 , 1,1 , 2,2 ],
       [ 0,2 , 1,1 , 2,0 ],
    );

    for my $win (@table) {
      my ($x1, $y1, $x2, $y2, $x3, $y3) = @$win;
      if ($board->[$x1][$y1] eq $board->[$x2][$y2] 
          &&  $board->[$x1][$y1] eq $board->[$x3][$y3]) {
        return $board->[$x1][$y1];
      }
    }        
    return;
}

sub print_table {
   my ($squares, $page, $winner, $round, $rounds, $final) = @_;
   my ($visitor, $visitor_name, $time);

   ## print ending table

   print $page->startform(-method=>'POST');

   print_hidden_values($page,$squares,$rounds);

   print ("<input type='hidden' name='round', value='$round'>\n");

   print ("<table border=1 cellpadding=10>\n");
   print ("<tr valign=middle>\n");
   for my $row (0..2) {
     for my $col (0..2) {
       my $cell = $squares->[$row][$col];
       if ($cell eq "") {
         $cell = $final ? "?" 
           : "<td><input type='checkbox' name='choice' value='$row$col'></td>\n";
       }
       print ("<td align=center>" . $cell . "</td>\n");
     }
     print ("</tr><tr valign=middle>\n") unless $row == 2;
   }
   print ("</tr></table><p>\n");

   if ($final) {
     print ("<a href=\"http://www.example.com/cgi-bin/tic_tac.cgi\">Play Again!</a>") ;
   } else {
     print $page->submit();
     
     print ("<p><font color='red'>Note: if you pick more than one square, your choice will be the upper and leftmost square that you choose!!</font><p>\n");
   }
   
   print $page->endform();


   print $page->end_html();

   if ($final) {
     #print log of play

     $visitor = $page->remote_host();
     if ($visitor =~ /\d*\.\d*\.\d*\.\d*/) {
       $visitor_name = gethostbyaddr(inet_aton($visitor), AF_INET);
     }

     $time = localtime(time());

     #   open (MAIL, "| /usr/sbin/sendmail -t");
     #   print MAIL "To: author\@example.com\n";
     #   print MAIL "Subject: tic tac toe results\n";
     #   print MAIL "\n$visitor, $visitor_name: $time: $winner on round $round";
     #   close MAIL;
   }

}

sub make_move_pretty {
   my %squares_names = ("00" => "top left",
                        "01" => "top center",
                        "02" => "top right",
                        "10" => "center left",
                        "11" => "center",
                        "12" => "center right",
                        "20" => "lower left",
                        "21" => "lower center",
                        "22" => "lower right"
                       );

   return $squares_names{$_[0]};
}

sub do_with_board (&) {
  my $code = shift;
  for $a (0..2) {
    for $b (0..2) {
      $code->();
    }
  }
}