# vim: ft=perl
# Blosxom Plugin: previous_next
# Author(s): Jason Thaxter <sseye@ahab.com>
# Version: 1.0
# Documentation: See the bottom of this file or type: perldoc previous_next

package previous_next;

# --- Configurable variables -----

# enabled: use or no (for config plugin, etc)
# default: yes
$enabled;

# sprintf format for the "previous" link
# default: <a href="%s">previous</a>
$previous_tmpl;

# sprintf format for the "next" link
# default: <a href="%s">next</a>
$next_tmpl;

# sprintf format for the "previous/next" link
# default: %s::%s
$previous_next_tmpl;

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

$enabled  = 1 unless defined $enabled;
$previous_tmpl ||= '<a href="%s">previous</a>';
$next_tmpl ||= '<a href="%s">next</a>';
$previous_next_tmpl = "%s::%s";

# here's what the variables for template use
use vars qw( $next $previous $previous_next );
$next; # use as $previous_next::next in story.flavour templates
$previous; # use as $previous_next::previous in story.flavour templates
$previous_next; # use as $previous_next::previous_next in story.flavour templates

use CGI qw(:standard);

sub start {
    return $enabled;
}

sub story {
    my ($pkg, $path, $filename, $story_ref, $title_ref, $body_ref) = @_;

    # only operate when showing an individual story
    return unless path_info() =~ m/$path\/$filename/;
    # and make it a real one
    my $story_entry = "$blosxom::datadir$path/$filename.$blosxom::file_extension";
    next unless -f $story_entry;
    my $story_mtime = $blosxom::files{$story_entry};

    # find the previous and next entries in %blosxom::files
    my ( $previous_entry, $next_entry );
    foreach my $entry ( sort keys %blosxom::files ) {
        # *this* story is not "previous" or next"
        next if $entry eq $story_entry;
        my $mtime = $blosxom::files{$entry};

        # set previous and next
        if (
            $story_mtime > $mtime
            and
            ( $mtime > $blosxom::files{$previous_entry} or not $previous_entry )
          )
        {
            $previous_entry = $entry;
        }
        elsif ( $story_mtime < $mtime
            and ( $mtime < $blosxom::files{$next_entry} or not $next_entry ) )
        {
            $next_entry = $entry;
        }

    }

    #
    # Make links for substitution
    #
    if ($previous_entry){
        $previous_href = $previous_entry;
        $previous_href =~ s/$blosxom::file_extension$/$blosxom::flavour/;
        $previous_href =~ s/^$blosxom::datadir/$blosxom::url/;
        $previous = sprintf($previous_tmpl,$previous_href);
    }

    if ($next_entry){
        $next_href = $next_entry;
        $next_href =~ s/$blosxom::file_extension$/$blosxom::flavour/;
        $next_href =~ s/^$blosxom::datadir/$blosxom::url/;
        $next = sprintf($next_tmpl,$next_href);
    }

    $previous_next = sprintf($previous_next_tmpl,$previous,$next);
}

1;

__END__

=head1 NAME

Blosxom Plug-in: previous_next

=head1 SYNOPSIS

This is intended for use in story templates.  It should work in C<foot.$flavour>
as well. When showing aggregate entries - by date or by category - this will do
nothing. When showing individual stories, it has a purpose.

Populates some template variables with previous and next links for the previous
and next story.  C<$previous_next::previous> links to the previous story,
C<$previous_next::next> links to the next story, and
C<$previous_next::previous_next> links to both.

When files have the same nodifi same modification time, it goes alphabetically.

=head1 VERSION

Version 1.0

=head1 AUTHOR

Jason Thaxter <sseye@ahab.com>, http://ahab.com/

=head1 SEE ALSO

Blosxom Home/Docs/Licensing: http://www.raelity.org/apps/blosxom/

Blosxom Plugin Docs: http://www.raelity.org/apps/blosxom/plugin.shtml

=head1 BUGS

Address bug reports and comments to the Blosxom mailing list
[http://www.yahoogroups.com/group/blosxom] or to the author.

=head1 LICENSE

This Blosxom Plug-in
Copyright 2004, Jason Thaxter

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.