package Apache::Precompress;

use strict;
use Compress::Zlib 1.0;
use Apache::Log;
use Apache::Constants qw(:common);
use vars qw($VERSION);

$VERSION = sprintf '%d.%d', q$Revision: 0.1 $ =~ /: (\d+).(\d+)/;

sub handler 
{
	my $r = shift;
	my $buffer;
	my $fh;
	
	# Quick file check
	unless(-e $r->filename . '.gz')
	{
		error($r->log,"Cannot open " . $r->filename . ".gz\n");
		return NOT_FOUND;
	}

	
	if ($r->dir_config->get('SSI') || $r->header_in('Accept-Encoding') !~ /gzip/)
	{
		$r->send_http_header;
		
		my $gz = gzopen($r->filename() . '.gz', "rb") 
            or return error($r->log,"Cannot open " . $r->filename . ".gz: $gzerrno\n");
				
		while($gz->gzread($buffer,4096) > 0)
		{
			$r->print($buffer);
		}
		
		if($gzerrno != Z_STREAM_END)
		{
        	return error($r->log,"Error reading from " . $r->filename . ".gz: $gzerrno\n");
		}
        $gz->gzclose();
	} 
	else
	{
		$r->content_encoding('gzip');
		$r->send_http_header;
		open(FILE, $r->filename . '.gz') || return NOT_FOUND;
		binmode(FILE);
		while( read(FILE, $buffer, 4096) > 0)
		{
			$r->print($buffer);
		}
		close(FILE);
  	}
	
  return OK;
}

sub error
{
	my $handle = shift;
	my $msg = shift;
	$handle->error($msg);
	return SERVER_ERROR;
}


1;

__END__

=head1 NAME

Apache::Preompress - Deliver already compressed files or decompress on the fly

=head1 SYNOPSIS

  PerlModule Apache::Precompress
  
  	# Handle regular files, ie index.html.gz
  	# Incoming request would be index.html
	<Directory "your-docroot/compressdfilesdir">
		SetHandler perl-script
		PerlHandler Apache::Precompress
	</Directory>

  	# Handle files by given extension .gzhtml
	<FilesMatch "\.gzhtml$">
		SetHandler perl-script
		PerlHandler Apache::Precompress
	</FilesMatch>

	# You want to use SSI but your templates are compressed
	AddHandler server-parsed .html
	<FilesMatch "\.shtml$">
		Options +Includes
		PerlSetVar  SSI  1
	</FilesMatch>

=head1 DESCRIPTION

This module lets you send pre-compressed files as though they were
not. For those clients that do not support compressed content, the
file is de-compressed on the fly.

This module overcomes the overhead of having to compress data on the
fly by keeping the data compressed on disk at all times. The driving
force behind this approach was that I couldn't afford to upgrade my
ISP account to have more disk space. The effective savings on bandwidth
are also quite handy.

This module will not allow the file to have SSI directives parsed out.
See the to do section. If you have got SSI turned on then you simply
need to use Options -Includes inside your directives.

=head1 Note

The intent of this module is to hide the fact that the content has been
precompressed from the client. At no time should the client expect to
call a file by anything other than its normal extension. Additionally,
the content should not link to other content other than in the normal
way, ie:

	<a href="/compressed/test.html">Valid</a>
	
	and not
	
	<a href="/compressed/test.html.gz">Invalid</a>

=head1 TO DO

The SSI handling requires the setting of a variable as otherwise
we end up with compressed content within the middle of an uncompressed
page. We should be to tell if we are called via ssi by some other means. 

Also, support for Apache::SSI would be useful.

=head1 AUTHOR

Simon Proctor, www.simonproctor.com

Based on the work of Apache::Compress

=head1 COPYRIGHT

Copyright (C) 2002 Simon Proctor.  All Rights Reserved.

This module is free software; you can redistribute it and/or modify it under the 
same terms as Perl itself. 

=head1 THANKS TO

belg4mit for valuable feedback

=cut