package C4::Charset;

# $Id$

#package to work around problems in HTTP headers
# Note: This is just a utility module; it should not be instantiated.


# Copyright 2003 Katipo Communications
#
# This file is part of Koha.
#
# Koha is free software; you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# Koha is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# Koha; if not, write to the Free Software Foundation, Inc., 59 Temple Place,
# Suite 330, Boston, MA  02111-1307 USA

use strict;
require Exporter;

use vars qw($VERSION @ISA @EXPORT);

# set the version for version checking
$VERSION = 0.01;

=head1 NAME

C4::Charset - Functions for handling charsets in HTML pages

=head1 SYNOPSIS

  use C4::Charset;

  print $query->header(-type => C4::Charset::gettype($output)), $output;

=head1 DESCRIPTION

The functions in this module peek into a piece of HTML and return strings
related to the (guessed) charset.

=head1 FUNCTIONS

=over 2

=cut

@ISA = qw(Exporter);
@EXPORT = qw(
		&guesscharset
		&guesstype
	     );

=pod

  &guesscharset($output)

"Guesses" the charset from the some HTML that would be output.

C<$output> is the HTML page to be output. If it contains a META tag
with a Content-Type, the tag will be scanned for a language code.
This code is returned if it is found; undef is returned otherwise.

This function only does sloppy guessing; it will be confused by
unexpected things like SGML comments. What it basically does is to
grab something that looks like a META tag and scan it.

=cut

sub guesscharset ($) {
   my($html) = @_;
   my $charset = undef;
   local($`, $&, $', $1, $2, $3);
   # FIXME... These regular expressions will miss a lot of valid tags!
   if ($html =~ /<meta\s+http-equiv=(["']?)Content-Type\1\s+content=(["'])text\/html\s*;\s*charset=([^\2\s\r\n]+)\2\s*(?:\/?)>/is) {
      $charset = $3;
   } elsif ($html =~ /<meta\s+content=(["'])text\/html\s*;\s*charset=([^\1\s\r\n]+)\1\s+http-equiv=(["']?)Content-Type\3\s*(?:\/?)>/is) {
      $charset = $2;
   }
   return $charset;
} # guess

sub guesstype ($) {
   my($html) = @_;
   my $charset = guesscharset($html);
   return defined $charset? "text/html; charset=$charset": "text/html";
}

#---------------------------------

END { }       # module clean-up code here (global destructor)

1;
__END__

=back

=head1 AUTHOR

Koha Developement team <info@koha.org>

=cut