#!/usr/bin/perl -T

use strict;
use warnings;

use CGI;
use JavaScript;
use LWP::Simple;
use HTML::TokeParser::Simple;

if (CGI::param('go')) {
   print CGI::header('text/plain');
   my $javascript = fetch_js(CGI::param('url'));
   parse_js($javascript);
} else {
   print_form();
}

sub parse_js {
   my $javascript = shift;
   my $runtime    = JavaScript::Runtime->new();
   my $context    = $runtime->create_context();

   $context->bind_function(name => 'write', func => sub{ print @_});
   return $context->eval($javascript);
}

sub fetch_js {
   my $html   = LWP::Simple::get(shift);
   my $parser = HTML::TokeParser::Simple->new(\$html);

   my ($token,$js);
   while ($token = $parser->get_token) {
      if ($token->is_start_tag('script')) {
         $js = $parser->get_token->as_is;
         last;
      }
   }
   $js =~ s/document\.write/write/g;
   return $js;
}

sub print_form {
   my $q = CGI->new;
   print $q->header(),
      $q->start_html('See the source of cleverSource encrypted page'),
      $q->start_form,
      $q->textfield('url','http://cleverscripts.com/index.php?a=cleversource'),
      $q->submit('go'),
      $q->end_form,
      $q->end_html,
   ;
}