# Blosxom Plugin: keywords
# Author(s): Gregor Rayman <rayman@grayman.de> 
# Special thanks to: Markus Theissinger <markus.theissinger@gmx.de>
# Version: 0.1
# Revision: $Id: keywords,v 1.2 2003/11/12 18:57:47 gra Exp $

package keywords;

# --- Configurable variables -----

my $maxwords = 10;

my $story_weight = 3;

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

my %wordhash;
sub start {
  1;
}

sub story {
    my($pkg, $path, $filename, $story_ref, $title_ref, $body_ref) = @_;
    
    $$body_ref =~ s:<kw>\s*(.*?)\s*</kw>:($wordhash{$1}+=$story_weight,$1):ego;
    $$body_ref =~ s:<kwx>\s*(.*?)\s*</kwx>:($wordhash{$1}+=$story_weight,""):ego;
    $$title_ref =~ s:<kw>\s*(.*?)\s*</kw>:($wordhash{$1}+=$story_weight*2,$1):ego;
    $$title_ref =~ s:<kwx>\s*(.*?)\s*</kwx>:($wordhash{$1}+=$story_weight*2,""):ego;
      
    $story_weight-- if $story_weight > 1;
    return 1;
}

sub last {
    my $i = 0;
    my $comma = "";
    my $keywords = "";
    for $word (sort { $wordhash{$b} <=> $wordhash{$a} } keys %wordhash) {
        $keywords .= "$comma$word";
        $comma = ", ";        
        $i++;
        last if $i >= $maxwords;
    }  
    
    $blosxom::output =~ s!{keywords}!$keywords!ego;
    
    return $blosxom::entries;
}

1;

__END__

=head1 NAME

Blosxom Plug-in: keywords

=head1 SYNOPSIS

Extracts marked keywords form the individual stories places them
to marked spot in the generated text. Can be used to generate
the <meta name="keywords" value="..."> in HTML header files

The keywords in the individual stories have to be enclosed
either with the <kw></kw> tag or with the <kwx></kwx> tag.
The <kw>keywords</kw> we be left in the individual stories, 
the <kwx>keywords</kwx> will be removed.

The keywords will be sorted by their weighted frequencies. 
The weight is determined by the variable $story_weight, which will 
be decremented after each displayed story until it reaches the
value 1.

Keywords in story's title get the doble weight

The place in the resulting text, where the keywords have to be placed
must be marked with the placeholder {keywords}.

Example: <meta name="keywords" content="{keywords}">

=head1 AUTHOR

Gregor Rayman  <rayman@grayman.de>, http://www.grayman.de/

=head1 BUGS

Address bug reports and comments to me
[mailto:rayman@grayman.de].

=head1 LICENSE

Blosxom and this Blosxom Plug-in
Copyright 2003, Gregor Rayman 

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.