package Filters::GoogleAnalytics;
## Steven Evatt - 2007/10/29
 
use strict; 
 
 
use Apache2::Filter ();
use Apache2::Const -compile => qw(OK OR_ALL NO_ARGS);
use Apache2::Module ();
use Apache2::CmdParms;
use Apache2::RequestRec (); 
use APR::Table;
 
#use constant BUFF_LEN => 1024;
use constant BUFF_LEN => 8000;
 
# There is perldoc at the end of this file.
 
my @directives = (
		  {
		   name         => 'AddGoogleTag',
		   func         => __PACKAGE__ . '::AddGoogleTag',
		   req_override => Apache2::Const::OR_ALL,
		   args_how     => Apache2::Const::NO_ARGS,
		   errmsg       => 'AddGoogleTag',
		  },
		 );
Apache2::Module::add(__PACKAGE__, \@directives);
 
sub AddGoogleTag {
  my ($self, $parms, @args) = @_;
 
}
sub handler {
  my $f = shift;
 
  # unset Content-Length but only on the first bucket per response.
  unless ($f->ctx) {
    $f->r->headers_out->unset('Content-Length');
    $f->ctx(1);
  }
 
  # read from the incoming brigade 
  while ($f->read(my $buffer, BUFF_LEN)) { 
 
    # get the config for this module, 
    # so we can access the directive's arguments
    my $cfg = Apache2::Module::get_config(__PACKAGE__, $f->r->server);
 
    # do the switch!
    my $google_in ="</body>";
    my $google_out = <<EOF;
<script src="http://www.google-analytics.com/urchin.js" type="text/javascript">
</script>
<script type="text/javascript">
_uacct = "UA-XXXXXXX-X";
urchinTracker();
</script>
</body>
EOF
 
chomp $google_out;
 
    if ($buffer =~ m|</body>|i) {
      unless ($buffer =~ m/UA-XXXXXXX-X/) {
         $buffer =~ s/$google_in/$google_out/i;
         }
    }
 
    $f->print($buffer); # write to the outgoing brigade
 
  }
 
  return Apache2::Const::OK;
 
}
 
 
###
1;#
###
=head1 NAME
 
  Filters::GoogleAnalytics
 
=head1 SYNOPSIS
 
The following is not Perl; it goes in your Apache vhost configuration. 
(for example, /etc/apache2/sites-enabled/000-default)
 
  PerlLoadModule Filters::GoogleAnalytics
 
  <Files *.html>
          PerlOutputFilterHandler Filters::GoogleAnalytics
          AddGoogleTag
  </Files>
 
  <Files *.php>
          PerlOutputFilterHandler Filters::GoogleAnalytics
          AddGoogleTag
  </Files>
 
 
 
=head1 DESCRIPTION
 
This filter inserts your Google Analytic Javascript tag before the 
</body> tag if the page does not already contain the Google tag.
 
This is an output filter for Apache2. It will NOT work with apache 1.3.
You need to modify this .pm file to insert your google tag, and add a few
lines to your apache configuration.  See the L<synopsis> for a somewhat
complete example.
 
To use this module as shown, you will need:
 
* Apache version 2
 
* Mod_perl version 2
 
=head1 Directives
 
=over 12
 
=item C<AddGoogleTag>
 
Takes no arguments.
 
  AddGoogleTag
 
Inserts your google tag just before the </body> tag on the page.
 
=back
 
=head1 LICENSE
 
GPL.
 
=head1 AUTHOR
 
Steven Evatt
 
=head1 SEE ALSO
 
Apache2::Filter
 
mod_perl
 
The excellent tutorial at http://perl.apache.org/docs/2.0/user/handlers/filters.html
 
=cut