# fen2diag.pl - FEN chess position to 8x8 chess diagram
#
# DrDave chessnut at blueyonder.co.uk
#
# V2 10x10 grid suitable for Alpine fonts Linares/Hastings/Zurich
# 

sub Reset { @ranks = "";
#       $fenfile = "";
#       $fenstring = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
        $fenstring = "";      
        $fenchar = "";
#       $targetfile = "";
        $ranks[0]="cuuuuuuuuC\n";
        $ranks[1]="(wdwdwdwd}\n";
        $ranks[2]="7dwdwdwdw}\n";
        $ranks[3]="6wdwdwdwd}\n";
        $ranks[4]="5dwdwdwdw}\n";
        $ranks[5]="&wdwdwdwd}\n";
        $ranks[6]="3dwdwdwdw}\n";
        $ranks[7]="2wdwdwdwd}\n";
        $ranks[8]="%dwdwdwdw}\n";
        $ranks[9]="v,./9EFJMV\n"; 
        $colour = "";
        $coloured = "";
        $fileno = 1;
        $rankno = 1;
        $line = "";
#        print "Target FEN string=$fenstring\n";
        $messages = 0;
        $char = "";
#        print "1st: " . substr($ranks[$rankno], $fileno, 1) ;
        }

sub Message {
    if ($messages == 1) {
    my (@message) = @_ ;
    print "I say: @message\n";
    }
}

sub LetMeOutOfHere 
{
  my @lastgasp = @_ ;
  print "Quitting programme: @lastgasp \n";
  die ;
}

sub FlipSquareColour {
         Message ("sub: FlipSquareColour");
         Message("Square before = $colour");
         $coloured = $colour ;
         if ($coloured =~ "w") { $colour = "d"; }
         if ($coloured =~ "d") { $colour = "w"; }
         Message("Square after = $colour");
         } 

sub FlipPieceColour {
         Message("sub: FlipPieceColour");
         Message ("Piece before: $piece") ;
         if ($piece =~ "w") { $piece = "d" ; }
         if ($piece =~ "p") { $piece = "0" ; }
         if ($piece =~ "r") { $piece = "4" ; }
         if ($piece =~ "n") { $piece = "h" ; }
         if ($piece =~ "b") { $piece = "g" ; }
         if ($piece =~ "q") { $piece = "1" ; }
         if ($piece =~ "k") { $piece = "i" ; }
         if ($piece =~ "P") { $piece = ")" ; }
         if ($piece =~ "R") { $piece = "\$" ; }
         if ($piece =~ "N") { $piece = "H" ; }
         if ($piece =~ "B") { $piece = "G" ; }
         if ($piece =~ "Q") { $piece = "\!" ; }
         if ($piece =~ "K") { $piece = "I" ; }
         Message ("Piece after: $piece") ;
 }
 

sub PrintDiagram {
   Message("sub:PrintDiagram");
   print "Diagram:\n";
   print (@ranks) ;
#   for ($ranknos=0 ; $ranknos < 9 ; $ranknos++  ) {
#       print "$ranks[$rankno]\n";
#      }
   return;  
   }



#sub ReadFile;
#   Message("sub:ReadFile");
# read $fenfile;
# split ($line, \",99);
# @Field = split(' ', $line, 99);
# $key = substr($Field[4], 6, 4);
# $fenstring = $line[1];
# open (FD1, $datafile);
# open (FD2, "> pcg$target.dat");

sub Piece {
   Message("rankno=$rankno, fileno=$fileno, FENchar2=$fenchar");
   $colour = "w";
   $piece=$colour;
   if ( $fenchar > 0 ) { $fileno = $fileno+$fenchar-1 ; }
                            else { $piece="$fenchar" ;
                                 }
   if (($rankno + $fileno) % 2 == 0) { $colour = "w" ; } else { $colour="d"; }
   if ( $colour =~ "d" ) { FlipPieceColour ;  }
#   print "$rankno\t$fileno\tBefore: " . substr($ranks[$rankno], $fileno, 1) . "\t";
   substr($ranks[$rankno], $fileno, 1) = "$piece" ;
#   print "After: " . substr($ranks[$rankno], $fileno, 1)  . "\n";
   }   

sub MakeGrid {
  Message("sub:MakeGrid");
  for ($char = 0 ; $char < length($fenstring) ; $char++ ) {
     $fenchar = substr($fenstring, $char, 1);
     Message("FENchar=$fenchar");
     if ( $fenchar =~ "/" ) {
        $rankno++ ;
        $fileno = 0 ;
     }  else {
     Piece;
     }
     $fileno++; 
     if ($fenchar =~ " ") { 
        Message ("Hit a space! Adding side-to-move");
        substr($ranks[8], 9, 1) = "}";
        $char++;
        $fenchar = substr($fenstring, $char, 1);
        if ($fenchar =~ "w") {
         substr($ranks[8], 9, 3) = "}a\n";
         return;
         } 
        if ($fenchar =~ "b") {
         substr($ranks[1], 9, 3) = "}e\n";
         return;
         }
      }
   } 
}


sub Work {
Message("Making Grid...");
MakeGrid;
Message("Printing Diagram...");
PrintDiagram;
}
 
sub GetFEN {
print "FEN string? =";
chop ($fenstring = <STDIN>);
Message("Checking for quit");
Message("FEN string = $fenstring");
if  ($fenstring eq 'N' || $fenstring eq 'n')
  {
   LetMeOutOfHere ("Ended at user's request.");
  }
Message("Very good, carry on");
} 


print "\n";
print "FEN2DIAG chess position converter\n";
print "=================================\n";
print "N.B. To proceed, type or paste in FEN; to quit, press N or n\n";
print "\n";

for ($i = 0; $i < 1000 ; $i++ ) {
 Reset;
 GetFEN;
 Work;
}