# Plugin for TWiki Collaboration Platform, http://TWiki.org/
#
# Copyright (C) 2000-2003 Andrea Sterbini, a.sterbini@flashnet.it
# Copyright (C) 2001-2003 Peter Thoeny, peter@thoeny.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, published at 
# http://www.gnu.org/copyleft/gpl.html
# =========================
package TWiki::Plugins::AliasPlugin;    # change the package name and $pluginName!!!
# =========================
use vars qw(
        $web $topic $user $installWeb $VERSION
        $aliasPattern $debug $acceptNonTWikiWord
    );

$VERSION = '1.010';

# =========================
sub writeDebug {
  TWiki::Func::writeDebug("AliasPlugin - " . $_[0]) if $debug;
}

# =========================
sub initPlugin
{
  ( $topic, $web, $user, $installWeb ) = @_;

  # check for Plugins.pm versions
  if ($TWiki::Plugins::VERSION < 1) {
    TWiki::Func::writeWarning( "Version mismatch between AliasPlugin and Plugins.pm" );
    return 0;
  }

  # 0: off, 1: debug, 2: heavy debug
  $debug = 0;

  # get plugin flag for non-twiki aliases
  $acceptNonTWikiWord = 
    TWiki::Func::getPreferencesFlag( "ALIASPLUGIN_ACCEPT_NON_TWIKI_WORD_ALIASES" );
  
  #writeDebug($acceptNonTWikiWord?"DOES":"Does NOT" . " accept non-TWiki-word aliases");
  
  # decide on how to match alias words
  #    $wordMatch = '[a-zA-Z0-9]+';
  my $wordMatch;
  my $wikiWordRegex = &TWiki::Func::getRegularExpression('wikiWordRegex');
  if ($acceptNonTWikiWord) {
    $wordMatch = '.+';
  } else {
    $wordMatch = $wikiWordRegex;
  }

  # parse the plugin preferences lines
  my $prefText = TWiki::Func::readTopicText(($web), 'AliasPlugin');
  foreach my $line (split /\n/, $prefText) {
    if ($line =~ /^(?:\t| {3})+\* (?:\<nop\>)?($wordMatch): +(.*)$/) {
      my $key = $1;
      my $value = $2;
      $value =~ s/\s+$//go;

      # convenience for alias-links
      if ($value =~ /([^.]+)\.$wikiWordRegex/) {
	$value = "\[\[$value\]\[$key\]\]";
      }

      $aliasHash{$key} = $value;
      writeDebug("config match: key='$key', value='$value'") if $debug > 1;
    }
  }

  # create alias pattern
  $aliasPattern = join('|', keys(%aliasHash));
  writeDebug("generated aliasPattern: $aliasPattern") if $aliasPattern;

  # Plugin correctly initialized
  writeDebug("initPlugin( $web.$topic ) is OK" );

  return 1;
}


# =========================
sub startRenderingHandler
{

### my ( $text ) = @_;   # do not uncomment, use $_[0] instead
  writeDebug("startRenderingHandler(...,$_[1]) was called");
  return if !$aliasPattern;


  $_[0] =~ s/<nop>/NOPTOKEN/g;
  $_[0] =~ s/([^<]+)(<[^>*]+>)?/&_substitute($1,$2)/ge;
  $_[0] =~ s/NOPTOKEN/<nop>/g;
}

# =========================
sub _substitute {

  my ($text, $skip) = @_;

  $skip = '' if !$skip;

  if ($debug) {
    writeDebug("_substitute() called");
    writeDebug("text='$text'");
    writeDebug("skip='$skip'");
  }

  if ($debug > 1) { # heavy debug
    $text =~ s/\b($aliasPattern)\b/&_debugAliasReplacement($1)/ge
  } else {
    $text =~ s/($aliasPattern)/$aliasHash{$1}/g;
  }

  return "$text$skip";
}

# =========================
sub _debugAliasReplacement
{
  my ($key) = @_;
  my $value = $aliasHash{$key};
  writeDebug("substs '$key' -> '$value'");
  return $value; 
}

1;