##---------------------------------------------------------------------------##
##  File:
##      $Id: CharEnt.pm,v 1.3 2002/04/13 00:58:09 ehood Exp $
##  Author:
##      Earl Hood       earl@earlhood.com
##  Description:
##      Module to deal with 8-bit character data conversion to
##      (SGML) entity references.
##---------------------------------------------------------------------------##
##    Copyright (C) 1997-2002   Earl Hood, earl@earlhood.com
##
##    This program 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.
##
##    This program 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 this program; if not, write to the Free Software
##    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
##    02111-1307, USA
##---------------------------------------------------------------------------##
package MHonArc::CharEnt;
use strict;
##---------------------------------------------------------------------------
##      US-ASCII/Common characters
##---------------------------------------------------------------------------
my %ASCIIMap = (
  #--------------------------------------------------------------------------
  # Hex Code    Entity Ref      # ISO external entity and description
  #--------------------------------------------------------------------------
    0x22 =>  "quot",         # ISOnum : Quotation mark
    0x26 =>  "amp",          # ISOnum : Ampersand
    0x3C =>  "lt",           # ISOnum : Less-than sign
    0x3E =>  "gt",           # ISOnum : Greater-than sign
    0xA0 =>  "nbsp",         # ISOnum : NO-BREAK SPACE
);
my %ASCIIMapReverse = reverse %ASCIIMap;
##---------------------------------------------------------------------------
##      Loaded Maps
##---------------------------------------------------------------------------
# character => entity
my %char2ent_maps = (
    'us-ascii'  => \%ASCIIMap,
);
# entity => character
my %ent2char_maps = (
    'us-ascii'  => \%ASCIIMapReverse,
);
##---------------------------------------------------------------------------
##      Charset specification to mapping
##---------------------------------------------------------------------------
my %CharsetMaps = (
    'iso-8859-1'  => 'MHonArc/CharEnt/ISO8859_1.pm',
    'iso-8859-2'  => 'MHonArc/CharEnt/ISO8859_2.pm',
    'iso-8859-3'  => 'MHonArc/CharEnt/ISO8859_3.pm',
    'iso-8859-4'  => 'MHonArc/CharEnt/ISO8859_4.pm',
    'iso-8859-5'  => 'MHonArc/CharEnt/ISO8859_5.pm',
    'iso-8859-6'  => 'MHonArc/CharEnt/ISO8859_6.pm',
    'iso-8859-7'  => 'MHonArc/CharEnt/ISO8859_7.pm',
    'iso-8859-8'  => 'MHonArc/CharEnt/ISO8859_8.pm',
    'iso-8859-9'  => 'MHonArc/CharEnt/ISO8859_9.pm',
    'iso-8859-10' => 'MHonArc/CharEnt/ISO8859_10.pm',
    'iso-8859-15' => 'MHonArc/CharEnt/ISO8859_15.pm',
    'latin1'      => 'MHonArc/CharEnt/ISO8859_1.pm',
    'latin2'      => 'MHonArc/CharEnt/ISO8859_2.pm',
    'latin3'      => 'MHonArc/CharEnt/ISO8859_3.pm',
    'latin4'      => 'MHonArc/CharEnt/ISO8859_4.pm',
    'latin5'      => 'MHonArc/CharEnt/ISO8859_9.pm',
    'latin6'      => 'MHonArc/CharEnt/ISO8859_10.pm',
    'latin9'      => 'MHonArc/CharEnt/ISO8859_15.pm',
    'windows-1250'=> 'MHonArc/CharEnt/CP1250.pm',
    'windows-1252'=> 'MHonArc/CharEnt/CP1252.pm',
);
my %ReverseCharsetMaps = (
    'iso-8859-1'  => 'MHonArc/CharEnt/ISO8859_1R.pm',
    'iso-8859-3'  => 'MHonArc/CharEnt/ISO8859_3R.pm',
    'iso-8859-7'  => 'MHonArc/CharEnt/ISO8859_7R.pm',
    'iso-8859-8'  => 'MHonArc/CharEnt/ISO8859_8R.pm',
    'iso-8859-9'  => 'MHonArc/CharEnt/ISO8859_9R.pm',
    'iso-8859-15' => 'MHonArc/CharEnt/ISO8859_15R.pm',
    'latin1'      => 'MHonArc/CharEnt/ISO8859_1R.pm',
    'latin3'      => 'MHonArc/CharEnt/ISO8859_3R.pm',
    'latin5'      => 'MHonArc/CharEnt/ISO8859_9R.pm',
    'latin9'      => 'MHonArc/CharEnt/ISO8859_15R.pm',
);
###############################################################################
##      Routines
###############################################################################
##---------------------------------------------------------------------------##
##      str2sgml converts a string encoded by $charset to an sgml
##      string where special characters are converted to entity
##      references.
##
##      $return_data = MHonArc::CharEnt::str2sgml($data, $charset, $only8bit);
##
##      If $only8bit is non-zero, than only 8-bit characters are
##      translated.
##
sub str2sgml {
    my $data     =    shift;
    my $charset  = lc shift;
    my $only8bit =    shift;
    my($ret, $offset, $len) = ('', 0, 0);
    my($map, $char);
    $charset =~ tr/_/-/;
    # Get mapping
    $map = $char2ent_maps{$charset};
    $map = _load_charmap($charset)  unless defined $map;
    # Convert string
    $len = length($data);
    while ($offset < $len) {
        $char = unpack("C", substr($data, $offset++, 1));
        if ($only8bit && $char < 0xA0) {
            $ret .= pack("C", $char);
        } elsif ($map->{$char}) {
            $ret .= join('', '&', $map->{$char}, ';');
        } elsif ($ASCIIMap{$char}) {
            $ret .= join('', '&', $ASCIIMap{$char}, ';');
        } else {
            $ret .= pack("C", $char);
        }
    }
    $ret;
}
##---------------------------------------------------------------------------##
##      sgml2str converts a string with sdata character entity references
##      to the raw character values denoted by a character set.
##
##      $return_data = MHonArc::CharEnt::sgml2str($data, $charset);
##
sub sgml2str {
    my $data     =    shift;
    my $charset  = lc shift;
    my($map);
    $charset =~ tr/_/-/;
    # Get mapping
    $map = $ent2char_maps{$charset};
    $map = _reverse_load_charmap($charset)  unless defined $map;
    # Convert character entites to raw values
    $data =~ s/\&([\w\.\-]+);
              /defined($map->{$1}) ? sprintf("%c", $map->{$1}) :
                   defined($ASCIIMapReverse{$1}) ?
                       sprintf("%c", $ASCIIMapReverse{$1}) : "&$1;"
              /gex;
    $data;
}
##---------------------------------------------------------------------------##
sub _load_charmap {
  my $charset   = shift;
  my $map       = undef;
  my $file = $CharsetMaps{$charset};
  if (!defined($file)) {
      warn 'Warning: MHonArc::CharEnt: Unknown charset: ', $charset, "\n";
      $map = $char2ent_maps{$charset} = { };
  } else {
      delete $INC{$file};
      eval {
          $map = $char2ent_maps{$charset} = require $file;
      };
      if ($@) {
          warn 'Warning: MHonArc::CharEnt: ', $@, "\n";
          $map = $char2ent_maps{$charset} = { };
      }
  }
  $map;
}
sub _reverse_load_charmap {
  my $charset   = shift;
  my $map       = undef;
  my $file = $ReverseCharsetMaps{$charset};
  if (!defined($file)) {
      if (!defined($map = $char2ent_maps{$charset})) {
          $map = _load_charmap($charset);
      }
      $map = $ent2char_maps{$charset} = { reverse %$map };
  } else {
      delete $INC{$file};
      eval {
          $map = $ent2char_maps{$charset} = require $file;
      };
      if ($@) {
          warn 'Warning: MHonArc::CharEnt: ', $@, "\n";
          $map = $ent2char_maps{$charset} = { };
      }
  }
  $map;
}
##---------------------------------------------------------------------------##
1;