package Wiki::Toolkit::Feed::Atom;

use strict;

use vars qw( @ISA $VERSION );
$VERSION = '0.02';

use POSIX 'strftime';
use Time::Piece;
use URI::Escape;
use Carp qw( croak );

use Wiki::Toolkit::Feed::Listing;
@ISA = qw( Wiki::Toolkit::Feed::Listing );

sub new {
    my $class = shift;
    my $self  = {};
    bless $self, $class;

    my %args = @_;
    my $wiki = $args{wiki};

    unless ($wiki && UNIVERSAL::isa($wiki, 'Wiki::Toolkit')) {
        croak 'No Wiki::Toolkit object supplied';
    }
  
    $self->{wiki} = $wiki;
  
    # Mandatory arguments.
    foreach my $arg (qw/site_name site_url make_node_url atom_link/) {
        croak "No $arg supplied" unless $args{$arg};
        $self->{$arg} = $args{$arg};
    }

    # Must-supply-one-of arguments
    my %mustoneof = ( 'html_equiv_link' => ['html_equiv_link','recent_changes_link'] );
    $self->handle_supply_one_of(\%mustoneof,\%args);
  
    # Optional arguments.
    foreach my $arg (qw/site_description software_name software_version software_homepage encoding/) {
        $self->{$arg} = $args{$arg} || '';
    }

    # Supply some defaults, if a blank string isn't what we want
    unless($self->{encoding}) {
        $self->{encoding} = $self->{wiki}->store->{_charset};
    }

    $self->{timestamp_fmt} = $Wiki::Toolkit::Store::Database::timestamp_fmt;
    $self->{utc_offset} = strftime "%z", localtime;
    $self->{utc_offset} =~ s/(..)(..)$/$1:$2/;
  
    # Escape any &'s in the urls
    foreach my $key qw(site_url atom_link) {
        my @ands = ($self->{$key} =~ /(\&.{1,6})/g);
        foreach my $and (@ands) {
            if($and ne "&") {
                my $new_and = $and;
                $new_and =~ s/\&/\&/;
                $self->{$key} =~ s/$and/$new_and/;
            }
        }
    }

    $self;
}

=item <build_feed_start>

Internal method, to build all the stuff that will go at the start of a feed.
Outputs the feed header, and initial feed info.

=cut

sub build_feed_start {
    my ($self,$atom_timestamp) = @_;

    my $generator = '';
  
    if ($self->{software_name}) {
        $generator  = '  <generator';
        $generator .= ' uri="' . $self->{software_homepage} . '"'   if $self->{software_homepage};
        $generator .= ' version=' . $self->{software_version} . '"' if $self->{software_version};
        $generator .= ">\n";
        $generator .= $self->{software_name} . "</generator>\n";
    }                          

    my $subtitle = $self->{site_description}
                 ? '<subtitle>' . $self->{site_description} . "</subtitle>\n"
                 : '';

    $atom_timestamp ||= '';

    my $atom = qq{<?xml version="1.0" encoding="} . $self->{encoding} . qq{"?>

<feed 
 xmlns         = "http://www.w3.org/2005/Atom"
 xmlns:geo     = "http://www.w3.org/2003/01/geo/wgs84_pos#"
 xmlns:space   = "http://frot.org/space/0.1/"
>

  <link href="}            . $self->{site_url}     . qq{" />
  <title>}                 . $self->{site_name}    . qq{</title>
  <link rel="self" href="} . $self->{atom_link}    . qq{" />
  <updated>}               . $atom_timestamp       . qq{</updated>
  <id>}                    . $self->{site_url}     . qq{</id>
  $subtitle};
  
    return $atom;
}

=item <build_feed_end>

Internal method, to build all the stuff that will go at the end of a feed.

=cut

sub build_feed_end {
    my ($self,$feed_timestamp) = @_;

    return "</feed>\n";
}

=item <generate_node_list_feed>
  
Generate and return an Atom feed for a list of nodes
  
=cut

sub generate_node_list_feed {
    my ($self,$atom_timestamp,@nodes) = @_;

    my $atom = $self->build_feed_start($atom_timestamp);

    my (@urls, @items);

    foreach my $node (@nodes) {
        my $node_name = $node->{name};

        my $item_timestamp = $node->{last_modified};
    
        # Make a Time::Piece object.
        my $time = Time::Piece->strptime($item_timestamp, $self->{timestamp_fmt});

        my $utc_offset = $self->{utc_offset};
    
        $item_timestamp = $time->strftime( "%Y-%m-%dT%H:%M:%S$utc_offset" );

        my $author      = $node->{metadata}{username}[0] || $node->{metadata}{host}[0] || 'Anonymous';
        my $description = $node->{metadata}{comment}[0]  || 'No description given for node';

        $description .= " [$author]" if $author;

        my $version = $node->{version};
        my $status  = (1 == $version) ? 'new' : 'updated';

        my $major_change = $node->{metadata}{major_change}[0];
        $major_change = 1 unless defined $major_change;
        my $importance = $major_change ? 'major' : 'minor';

        my $url = $self->{make_node_url}->($node_name, $version);

        # make XML-clean
        my $title =  $node_name;
        $title =~ s/&/&amp;/g;
        $title =~ s/</&lt;/g;
        $title =~ s/>/&gt;/g;

        # Pop the categories into atom:category elements (4.2.2)
        # We can do this because the spec says:
        #   "This specification assigns no meaning to the content (if any) 
        #    of this element."
        # TODO: Decide if we should include the "all categories listing" url
        #        as the scheme (URI) attribute?
        my $category_atom = "";
        if ($node->{metadata}->{category}) {
            foreach my $cat (@{ $node->{metadata}->{category} }) {
                $category_atom .= "    <category term=\"$cat\" />\n";
            }
        }

        # Include geospacial data, if we have it
        my $geo_atom = $self->format_geo($node->{metadata});

        # TODO: Find an Atom equivalent of ModWiki, so we can include more info

    
        push @items, qq{
  <entry>
    <title>$title</title>
    <link href="$url" />
    <id>$url</id>
    <summary>$description</summary>
    <updated>$item_timestamp</updated>
    <author><name>$author</name></author>
$category_atom
$geo_atom
  </entry>
};

    }
  
    $atom .= join('', @items) . "\n";
    $atom .= $self->build_feed_end($atom_timestamp);

    return $atom;   
}

=item <generate_node_name_distance_feed>
  
Generate a very cut down atom feed, based just on the nodes, their locations
(if given), and their distance from a reference location (if given).

Typically used on search feeds.
  
=cut

sub generate_node_name_distance_feed {
    my ($self,$atom_timestamp,@nodes) = @_;

    my $atom = $self->build_feed_start($atom_timestamp);

    my (@urls, @items);

    foreach my $node (@nodes) {
        my $node_name = $node->{name};

        my $url = $self->{make_node_url}->($node_name);

        # make XML-clean
        my $title =  $node_name;
        $title =~ s/&/&amp;/g;
        $title =~ s/</&lt;/g;
        $title =~ s/>/&gt;/g;

        # What location stuff do we have?
        my $geo_atom = $self->format_geo($node);

        push @items, qq{
  <entry>
    <title>$title</title>
    <link href="$url" />
    <id>$url</id>
$geo_atom
  </entry>
};

    }
  
    $atom .= join('', @items) . "\n";
    $atom .= $self->build_feed_end($atom_timestamp);

    return $atom;   
}

=item B<feed_timestamp>

Generate the timestamp for the Atom, based on the newest node (if available).
Will return a timestamp for now if no node dates are available

=cut

sub feed_timestamp {
    my ($self, $newest_node) = @_;
  
    my $time;
    if ($newest_node->{last_modified}) {
        $time = Time::Piece->strptime( $newest_node->{last_modified}, $self->{timestamp_fmt} );
    } else {
        $time = localtime;
    }

    my $utc_offset = $self->{utc_offset};
    
    return $time->strftime( "%Y-%m-%dT%H:%M:%S$utc_offset" );
}


=item B<parse_feed_timestamp>

Take a feed_timestamp and return a Time::Piece object. 

=cut

sub parse_feed_timestamp {
    my ($self, $feed_timestamp) = @_;
   
    $feed_timestamp = substr($feed_timestamp, 0, -length( $self->{utc_offset}));
    return Time::Piece->strptime( $feed_timestamp, '%Y-%m-%dT%H:%M:%S' );
}
1;

__END__

=head1 NAME

  Wiki::Toolkit::Feed::Atom - A Wiki::Toolkit plugin to output RecentChanges Atom.

=head1 DESCRIPTION

This is an alternative access to the recent changes of a Wiki::Toolkit
wiki. It outputs the Atom Syndication Format as described at
L<http://www.atomenabled.org/developers/syndication/>.

This module is a straight port of L<Wiki::Toolkit::Feed::RSS>.

=head1 SYNOPSIS

  use Wiki::Toolkit;
  use Wiki::Toolkit::Feed::Atom;

  my $wiki = Wiki::Toolkit->new( ... );  # See perldoc Wiki::Toolkit

  # Set up the RSS feeder with the mandatory arguments - see
  # C<new()> below for more, optional, arguments.
  my $atom = Wiki::Toolkit::Feed::Atom->new(
    wiki                => $wiki,
    site_name           => 'My Wiki',
    site_url            => 'http://example.com/',
    make_node_url       => sub
                           {
                             my ($node_name, $version) = @_;
                             return 'http://example.com/?id=' . uri_escape($node_name) . ';version=' . uri_escape($version);
                           },
    html_equiv_link => 'http://example.com/?RecentChanges',
    atom_link => 'http://example.com/?action=rc;format=atom',
  );

  print "Content-type: application/atom+xml\n\n";
  print $atom->recent_changes;

=head1 METHODS

=head2 C<new()>

  my $atom = Wiki::Toolkit::Feed::Atom->new(
    # Mandatory arguments:
    wiki                 => $wiki,
    site_name            => 'My Wiki',
    site_url             => 'http://example.com/',
    make_node_url        => sub
                            {
                              my ($node_name, $version) = @_;
                              return 'http://example.com/?id=' . uri_escape($node_name) . ';version=' . uri_escape($version);
                            },
    html_equiv_link  => 'http://example.com/?RecentChanges',,
    atom_link => 'http://example.com/?action=rc;format=atom',

    # Optional arguments:
    site_description     => 'My wiki about my stuff',
    software_name        => $your_software_name,     # e.g. "Wiki::Toolkit"
    software_version     => $your_software_version,  # e.g. "0.73"
    software_homepage    => $your_software_homepage, # e.g. "http://search.cpan.org/dist/CGI-Wiki/"
    encoding             => 'UTF-8'
  );

C<wiki> must be a L<Wiki::Toolkit> object. C<make_node_url>, if supplied, must 
be a coderef.

The mandatory arguments are:

=over 4

=item * wiki

=item * site_name

=item * site_url

=item * make_node_url

=item * html_equiv_link or recent_changes_link

=item * atom_link

=back

The three optional arguments

=over 4

=item * software_name

=item * software_version

=item * software_homepage

=back

are used to generate the C<generator> part of the feed.

The optional argument

=over 4

=item * encoding

=back

will be used to specify the character encoding in the feed. If not set,
will default to the wiki store's encoding.

=head2 C<recent_changes()>

  $wiki->write_node(
                     'About This Wiki',
                     'blah blah blah',
                         $checksum,
                         {
                           comment  => 'Stub page, please update!',
                           username => 'Fred',
                         }
  );

  print "Content-type: application/atom+xml\n\n";
  print $atom->recent_changes;

  # Or get something other than the default of the latest 15 changes.
  print $atom->recent_changes( items => 50 );
  print $atom->recent_changes( days => 7 );

  # Or ignore minor edits.
  print $atom->recent_changes( ignore_minor_edits => 1 );

  # Personalise your feed further - consider only changes
  # made by Fred to pages about bookshops.
  print $atom->recent_changes(
             filter_on_metadata => {
                         username => 'Fred',
                         category => 'Bookshops',
                       },
              );

If using C<filter_on_metadata>, note that only changes satisfying
I<all> criteria will be returned.

B<Note:> Many of the fields emitted by the Atom generator are taken
from the node metadata. The form of this metadata is I<not> mandated
by L<Wiki::Toolkit>. Your wiki application should make sure to store some or
all of the following metadata when calling C<write_node>:

=over 4

=item B<comment> - a brief comment summarising the edit that has just been made; will be used in the summary for this item.  Defaults to the empty string.

=item B<username> - an identifier for the person who made the edit; will be used as the Dublin Core contributor for this item, and also in the RDF description.  Defaults to 'No description given for change'.

=item B<host> - the hostname or IP address of the computer used to make the edit; if no username is supplied then this will be used as the author for this item.  Defaults to 'Anonymous'.

=back

=head2 C<feed_timestamp()>

  print $atom->feed_timestamp();

Returns the timestamp of the feed in POSIX::strftime style ("Tue, 29 Feb 2000 
12:34:56 GMT"), which is equivalent to the timestamp of the most recent item 
in the feed. Takes the same arguments as recent_changes(). You will most likely
need this to print a Last-Modified HTTP header so user-agents can determine
whether they need to reload the feed or not.
  
=head1 SEE ALSO

=over 4

=item * L<Wiki::Toolkit>

=item * L<http://www.atomenabled.org/developers/syndication/>

=back

=head1 MAINTAINER

The Wiki::Toolkit team, http://www.wiki-toolkit.org/.

=head1 COPYRIGHT AND LICENSE

Copyright 2006-2008 Earle Martin and the Wiki::Toolkit team.

This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

=head1 THANKS

Kake Pugh for originally writing Wiki::Toolkit::Feed::RSS and indeed 
Wiki::Toolkit itself.

=cut