#!/usr/bin/perl

use Image::Magick;

$sleeptime = 20;
$imgfile = '/tmp/sgfwallpaper.png';
$lines = 19;
$width = 1024;
$height = 600;
$yoffset = $height / 12;
$gridsize = ($height - $yoffset * 2) / ($lines - 1);
$xoffset = ($width - (($lines - 1) * $gridsize)) / 2;
$bg = '#ba6'; # background color
$lc = '#333'; # lines and hoshi
$bc = '#111'; # black stones
$wc = '#eff'; # white stones
$lw = $height / 500; # stroke width (lines & hoshi)

$gb = Image::Magick->new(size=>$width.'x'.$height);
$gb->ReadImage("canvas:$bg");

@goban = ();
@checked = ();
for ($i = 0; $i < $lines; $i++) {
    for ($j = 0; $j < $lines; $j++) {
   $goban[$i][$j] = 0;
   $checked[$i][$j] = 0;
    }
}

# draw_hoshi(x, y)
sub draw_hoshi{
    my $x = $_[0] - 1;
    my $y = $_[1] - 1;
    $x = $xoffset + $x * $gridsize;
    $y = $yoffset + $y * $gridsize;
    $r = $y + $lw * 2;
    $gb->Draw(primitive=>'circle',points=>"$x,$y $x,$r",fill=>$lc);
}

# draw_stone(color, x, y, x-off, y-off)
sub draw_stone{
    my $f = $_[0];
    my $x = $_[1];
    my $y = $_[2];
    my $xoff = $_[3];
    my $yoff = $_[4];
    $x = $xoffset + $x * $gridsize + $xoff;
    $y = $yoffset + $y * $gridsize + $yoff;
    $r = $y + ($gridsize / 2.1);
    $gb->Draw(primitive=>'circle',points=>"$x,$y $x,$r",fill=>$f);
}

# liberties(x, y, color)
sub liberties{
    my $x = $_[0];
    my $y = $_[1];
    my $f = $_[2];
    my $lib = 0;

    if ($checked[$x][$y]) {
   return 0;
    }

    $checked[$x][$y] = 1;
    if ($x > 0 and !$goban[$x - 1][$y]) {
   $lib++;
    }
    if ($x < $lines - 1 and !$goban[$x + 1][$y]) {
   $lib++;
    }
    if ($y > 0 and !$goban[$x][$y - 1]) {
   $lib++;
    }
    if ($y < $lines - 1 and !$goban[$x][$y + 1]) {
   $lib++;
    }
    if ($lib < 4) {
   if ($y < $lines - 1 and $goban[$x][$y + 1] =~ /^$f/) {
       $lib += liberties($x, $y + 1, $f);
   }
   if ($y > 0 and $goban[$x][$y - 1] =~ /^$f/) {
       $lib += liberties($x, $y - 1, $f);
   }
   if ($x < $lines - 1 and $goban[$x + 1][$y] =~ /^$f/) {
       $lib += liberties($x + 1, $y, $f);
   }
   if ($x > 0 and $goban[$x - 1][$y] =~ /^$f/) {
       $lib += liberties($x - 1, $y, $f);
   }
    }
    $checked[$x][$y] = 0;
    return $lib;
}

# remove_stone(x, y, color)
sub remove_stone{
    my $x = $_[0];
    my $y = $_[1];
    my $f = $_[2];

    $goban[$x][$y] = 0;
    if ($y < $lines - 1 and $goban[$x][$y + 1] =~ /^$f/) {
   remove_stone($x, $y + 1, $f);
    }
    if ($y > 0 and $goban[$x][$y - 1] =~ /^$f/) {
   remove_stone($x, $y - 1, $f);
    }
    if ($x < $lines - 1 and $goban[$x + 1][$y] =~ /^$f/) {
   remove_stone($x + 1, $y, $f);
    }
    if ($x > 0 and $goban[$x - 1][$y] =~ /^$f/) {
   remove_stone($x - 1, $y, $f);
    }
}

# check_stone(x, y, color)
sub check_stone{
    my $x = $_[0];
    my $y = $_[1];
    my $f = $_[2];
    if (!liberties($x, $y, $f)) {
   remove_stone($x, $y, $f);
    }
}

# check_life(last_move_color, last_move_x, last_move_y)
sub check_life{
    my $f = $_[0];
    my $fm;
    my $x = $_[1];
    my $y = $_[2];
    if ($f eq $bc) {
   $fm = $wc;
    } elsif ($f eq $wc) {
   $fm = $bc;
    }
    if ($y < $lines - 1 and $goban[$x][$y + 1] =~ /^$fm/) {
   check_stone($x, $y + 1, $fm);
    }
    if ($y > 0 and $goban[$x][$y - 1] =~ /^$fm/) {
   check_stone($x, $y - 1, $fm);
    }
    if ($x < $lines - 1 and $goban[$x + 1][$y] =~ /^$fm/) {
   check_stone($x + 1, $y, $fm);
    }
    if ($x > 0 and $goban[$x - 1][$y] =~ /^$fm/) {
   check_stone($x - 1, $y, $fm);
    }
    check_stone($x, $y, $f);
}

# redraw()
sub redraw{
    my $s;

    $gb->Draw(primitive=>'rectangle', points=>"0,0 $width,$height", fill=>$bg);
    for ($i = 0; $i < $lines; $i++) {
   $ax = $xoffset + $i * $gridsize;
   $ay = $yoffset;
   $bx = $ax;
   $by = $yoffset + ($lines - 1) * $gridsize;
   $gb->Draw(primitive=>'line', points=>"$ax,$ay $bx,$by", stroke=>$lc, strokewidth=>$lw);
    }
    for ($i = 0; $i < $lines; $i++) {
   $ax = $xoffset;
   $ay = $yoffset + $i * $gridsize;
   $bx = $width - $xoffset;
   $by = $ay;
   $gb->Draw(primitive=>'line', points=>"$ax,$ay $bx,$by", stroke=>$lc, strokewidth=>$lw);
    }
    draw_hoshi(4, 4);
    draw_hoshi(4, 10);
    draw_hoshi(4, 16);
    draw_hoshi(10, 4);
    draw_hoshi(10, 10);
    draw_hoshi(10, 16);
    draw_hoshi(16, 4);
    draw_hoshi(16, 10);
    draw_hoshi(16, 16);
   
    for ($i = 0; $i < $lines; $i++) {
   for ($j = 0; $j < $lines; $j++) {
       if ($goban[$i][$j]) {
      @s = split(':', $goban[$i][$j]);
      draw_stone($s[0], $i, $j, $s[1], $s[2]);
       }
   }
    }
}


$f = $bc;

while (<>) {
    @sgf = split(';');
    foreach (@sgf) {
   if ($f) {
       redraw();
       $gb->Write($imgfile);
       system("feh --bg-center $imgfile");
       sleep($sleeptime);      
   }
   $f = 0;
   if (/\[[a-w]{2}\]/) {
       if (/^B\[/ or /^AB\[/) {
      $f = $bc;
       } elsif (/^W\[/ or /^AW\[/) {
      $f = $wc;
       }
       if ($f) {
      $xoff = rand($lw * 2) - $lw;
      $yoff = rand($lw * 2) - $lw;
      s/[^\[]*\[//;
      s/\].*//;
      @k = split('');
      $x = ord($k[0]) - ord('a');
      $y = ord($k[1]) - ord('a');
      $goban[$x][$y] = "$f:$xoff:$yoff";
      check_life($f, $x, $y);
       }
   }
    }
}