Indexing HTML parts

While HTML integration is improving in Manitou-Mail, the current version (0.9.12) does not index the contents of HTML parts. This is generally not a problem because messages tend to carry a text version inside a multipart/alternative MIME construct, and that version gets indexed so that the message can still be retrieved by the words it contains. But still, some people send HTML-only messages, in which case we want to automatically extract the text from the HTML and pass it to the indexer.

It’s relatively easy to write a manitou-mdx Perl plugin that does just that, by using a CPAN module to do the HTML to text conversion: HTML::FormatText

Apart from the usual init and process functions that are described in the mdx plugins reference, we need to provide two functions: one that recursively descends the MIME tree to find the html parts, and another that extracts them to text and pass them to the indexer.

sub index_contents {
  my ($fh, $ctxt)=@_;
  my $html;
  my $text;
  {
    local $/;
    $html = $fh->getline();
  }
 
  if (defined $html) {
    my $tree = HTML::TreeBuilder->new;
    $tree->parse_content($html);
    my $formatter = HTML::FormatText->new(leftmargin=>0, rightmargin=>78);
    $text = $formatter->format($tree);
  }
  if (defined $text) {
    Manitou::Words::index_words($ctxt->{'dbh'}, $ctxt->{'mail_id'}, \$text);
  }
}
 
sub process_parts {
  my ($obj,$ctxt) = @_;;
  if ($obj->is_multipart) {
    foreach my $subobj ($obj->parts) {
      process_parts($subobj, $ctxt);    # recurse
    }
  }
  else {
    my $type=$obj->effective_type;
    if ($type eq "text/html") {
      my $io = $obj->bodyhandle->open("r");
      index_contents($io, $ctxt);
      $io->close;
    }
  }
}

The full source code and download link are available on the wiki