#!/usr/bin/perl -w
use strict;

# This script was written by Rick Dean.
# It will make a lame attempt to create a _half.html
# file  with bigger (half size) thumbnails

if ($#ARGV == -1) {  # if no command line arguments
  printf("usage: $0 filename.html [..]\n");
  exit(1);
};

sub halfhtml {
  my ($filename) = @_;
  open(INFILE,"<$filename") || die "couldn't open $filename"; 
  print("process $filename\n");
  my $sourcedoc;
  read(INFILE,$sourcedoc,1000000) || die "couldn't read $filename";
  close(INFILE);
  my $outfilename = $filename;
  $outfilename =~ s/.html$/_half.html/i || die "$filename doesn't end in .html";

  my $changed=0;
  my @html = split('<',$sourcedoc);
  for(my $i=0;$i < $#html;$i++) {  # for every tag 
    if ($html[$i] =~ /(^[^>]*)/) {  # grab tag contents (everything until > )
      my $tag=$1;
      next unless $tag =~ /^img\s/i; # must begin with img
      next unless $tag =~ /src=(\S*)/; # must have src=
      my $src=$1;
      $src =~ s/^"(.*)"$/$1/;  # strip bounding double quotes
      next unless $src =~ /.jpg$/i;  # must be a link to a picture
      next if $src =~ /_half.jpg$/i;  # but not a half picture
      my $newsrc = $src;
      $newsrc =~ s/_small.jpg$/_half.jpg/i;  # change the image name
      if(!  -s $newsrc) { # if file doesn't exist (or has zero length)
        print("couldn't find $newsrc\n");
        next;  # skip because half image doesn't exist 
      };
      next unless -s $newsrc; # half must exist and be non-zero in length
      $html[$i] =~ s/width=([^>\s]*)//i;  # delete width attributes
      $html[$i] =~ s/height=([^>\s]*)//i;  # delete height attributes
      my($width,$height) = pixelSizeOfFile($newsrc);
      $html[$i] =~ s/src=([^>\s]*)/src="$newsrc" WIDTH=$width HEIGHT=$height/i or print("damn\n");
      $changed=1;
    };
  };

  if($changed) {
    open(OUTFILE,">$outfilename") || die "couldn't open $filename"; 
    print OUTFILE join('<',@html);
    close(OUTFILE);
    my $mode = (stat($filename))[2];
    chmod($mode,$outfilename);
  };
}


for my $filename (@ARGV) {
  next if $filename =~ /_half.html$/i;  # if end in _half.html case insensitive
  next if ! $filename =~ /.html$/i; # if doesn't end in .html
  halfhtml($filename);
};


# jpegsize : gets the width and height (in pixels) of a jpeg file
# Andrew Tong, werdna@ugcs.caltech.edu           February 14, 1995
# modified slightly by alex@ed.ac.uk
sub jpegsize {
  my($JPEG) = @_;
  my($done)=0;
  my($c1,$c2,$ch,$s,$length, $dummy)=(0,0,0,0,0,0);
  my($a,$b,$c,$d);

  if(defined($JPEG)             &&
     read($JPEG, $c1, 1)        &&
     read($JPEG, $c2, 1)        &&
     ord($c1) == 0xFF           &&
     ord($c2) == 0xD8           ){
    while (ord($ch) != 0xDA && !$done) {
      # Find next marker (JPEG markers begin with 0xFF)
      # This can hang the program!!
      while (ord($ch) != 0xFF) { return(0,0) unless read($JPEG, $ch, 1); }
      # JPEG markers can be padded with unlimited 0xFF's
      while (ord($ch) == 0xFF) { return(0,0) unless read($JPEG, $ch, 1); }
      # Now, $ch contains the value of the marker.
      if ((ord($ch) >= 0xC0) && (ord($ch) <= 0xC3)) {
        return(0,0) unless read ($JPEG, $dummy, 3);
        return(0,0) unless read($JPEG, $s, 4);
        ($a,$b,$c,$d)=unpack("C"x4,$s);
        return ($c<<8|$d, $a<<8|$b );
      } else {
        # We **MUST** skip variables, since FF's within variable names are
        # NOT valid JPEG markers
        return(0,0) unless read ($JPEG, $s, 2);
        ($c1, $c2) = unpack("C"x2,$s);
        $length = $c1<<8|$c2;
        last if (!defined($length) || $length < 2);
        read($JPEG, $dummy, $length-2);
      }
    }
  }
  return (0,0);
}

sub pixelSizeOfFile {
  my($filename) = @_;
  my($imageData);
  my($width,$height);

  open(IMAGEFILE,$filename);
  ($width,$height) = jpegsize(\*IMAGEFILE);
  close(IMAGEFILE);
  return ($width,$height);
}