#!/DOCUMENT_ROOT/OCEAN_PLANET/SUPPORT_PROGRAMS/perl

# Get the document root from the path to perl.
($dr) = $^X =~ m@^(.*)/OCEAN_PLANET/@;

require "$dr/OCEAN_PLANET/SUPPORT_PROGRAMS/cgi-lib.pl";

$ENV{'RGBDEF'} = '/usr/lib/X11/rgb.txt';
$images = "$dr/OCEAN_PLANET/IMAGES";
$tmpimages = "$dr/OCEAN_PLANET/USER_LOCATIONS";
$url = '/ocean_planet_scripts/locator.pl';
$sp = "$dr/OCEAN_PLANET/SUPPORT_PROGRAMS";
$mark = "$sp/markmap";
$ppm = "$sp/giftopnm -quiet";
$quant = "$sp/ppmquant -quiet 256";
$gif = "$sp/ppmtogif -quiet";
$asin = "$sp/asin";

%map = (
'A',pack('a32S4Cf3S','locator_world.gif',24,24,512,256,0,0.0,0.0,360.0,128),
'B',pack('a32S4Cf3S','locator_africa.gif',24,24,300,300,1,20.0,0.0,80.0,150),
'C',pack('a32S4Cf3S','locator_asia.gif',24,24,300,300,1,120.0,30.0,52.0,150),
'D',pack('a32S4Cf3S','locator_australia.gif',24,24,300,300,1,140.0,-20.0,75.0,150),
'E',pack('a32S4Cf3S','locator_europe.gif',24,24,300,300,1,20.0,50.0,49.0,150),
'F',pack('a32S4Cf3S','locator_india.gif',24,24,300,300,1,75.0,25.0,53.5,150),
'G',pack('a32S4Cf3S','locator_n_america.gif',24,24,300,300,1,-100.0,50.0,53.5,150),
'H',pack('a32S4Cf3S','locator_oceania.gif',24,24,300,300,1,-180.0,-10.0,79.0,150),
'I',pack('a32S4Cf3S','locator_s_america.gif',24,24,300,300,1,-60.0,-20.0,80.0,150)
);

# Check the program input.
if(scalar(@ARGV) != 1){
  &servererr("Wrong number of arguments, client may not support ISMAP.");
}
($x,$comma,$y) = split(/(\,)/, $ARGV[0]);
if($comma ne ','){
  &servererr("Your client doesn't support image mapping properly.");
}

$PI = atan2(1,1) * 4;

# Trick ReadParse
$ENV{'QUERY_STRING'} = substr($ENV{'PATH_INFO'},1);
&ReadParse;

($f,$x0,$y0,$w,$h,$p,$clon,$clat,$s,$o) = unpack('A32S4Cf3S',$map{$in{'rgn'}});

# Get input image width and height.
($width,$height) = &gifdim("$images/$f");
$width && $height || &servererr("Could not read GIF image: $f");

# Make a temporary output filename consisting of the input name with a
# process ID and timecode added and an extension of '.gif' .
$out = $f;
$out =~ s/(.*)\.gif$/$1_$$_$^T.gif/;

# Project (x,y) to (lat,lon).
&project;

# Generate an image file that will be removed after three minutes.
# Use the csh to redirect stderr output to /dev/null .
system(<<"--");
$ppm $images/$f | $mark $x $y | $quant | $gif > $tmpimages/$out
/bin/csh -c 'echo "rm $tmpimages/$out" | at now + 3 minutes >& /dev/null'
--

# Remove older information.
$_ = $in;
s/lat\=[^&]*\&?//;
s/lon\=[^&]*\&?//;
s/pid\=[^&]*\&?//;
s/tim\=[^&]*\&?//;

print <<"--";
Location: $url?lat=$lat&lon=$lon&pid=$$&tim=$^T&$_

--

###############################################################################
###################              Subroutines              #####################
###############################################################################
# Get the dimensions of a GIF file
sub gifdim{
  local($file) = @_;
  local($bytes);
  open(FILE,$file) || return();
  read(FILE,$bytes,10);
  close(FILE);
  $bytes =~ s/^GIF8[79]a// || return();			# Check for GIF header
  $bytes =~ s/(.)(.)(.)(.)/$2$1$4$3/ || return();	# Swap bytes
  unpack("S2",$bytes);
}

#------------------------------------------------------------------------------
# Projection subroutine
sub project{
  local($xx,$yy,$rho,$r,$c,$cosc,$sinc,$cosphi,$sinphi,$tmp);

  # Restrict to map portion of image.
  $x = $x0 if($x < $x0);
  $x = $x0 + $w - 1 if($x > $x0 + $w - 1);
  $y = $y0 if($y < $y0);
  $y = $y0 + $h - 1 if($y > $y0 + $h - 1);

  $xx = $x - $x0 - $w/2;
  $yy = $h/2 - $y + $y0;
  if($p == 0){		# Plate Carree
    $r = $w/$s;
    $lon = $clon + $xx/$r;
    $lon += 360.0 if($lon < -180.0);
    $lon -= 360.0 if($lon >  180.0);
    $lat = $clat + $yy/$r;
  }
  elsif($p == 1){	# Azimuthal equidistant
    $r = $w / ($s * $PI / 180.0);
    $rho = sqrt($xx*$xx + $yy*$yy);
    $c = $rho / $r;
    $cosc = cos($c);
    $sinc = sin($c);
    $rclat = $clat * $PI / 180.0;
    $rclon = $clon * $PI / 180.0;
    $cosphi = cos($rclat);
    $sinphi = sin($rclat);
    if($clat == 90){
      $lon = ($rclon + atan2($xx,-$yy)) * 180.0 / $PI;
    }
    elsif($clat == -90){
      $lon = ($rclon + atan2($xx,$yy)) * 180.0 / $PI;
    }
    else{
      $lon = $rclon + atan2($xx*$sinc, $rho*$cosphi*$cosc - $yy*$sinphi*$sinc);
      $lon *= 180.0 / $PI;
    }
    if($rho == 0.0){
      $lat = $clat;
    }
    else{
      $tmp = $cosc * $sinphi + $yy * $sinc * $cosphi / $rho;
      $lat = `$asin $tmp`;
      $lat *= 180.0 / $PI;
    }
  }
}

#------------------------------------------------------------------------------
# Report an error to the user and exit.
sub servererr{
local($msg) = @_;
print <<"--";
Content-type: text/html

<title>Mapping Server Error</title>
<h1>Mapping Server Error</h1>
This server encountered an error:<p>
$msg
--
exit(-1);
}