#!/usr/bin/perl

use strict;    # always use

use XML::RSS;
use Digest::MD5 qw(md5_base64);
use POSIX qw(ceil floor);
use Date::Calc qw(Today_and_Now Delta_YMDHMS);
use C4::Context;
use C4::Search;
use C4::Koha;
use C4::Biblio;

# Copyright 2007 Paul POULAIN
#
# This file is part of Koha
#
# Koha 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.
#
# Koha 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.
#
# You should have received a copy of the GNU General Public License along with
# Koha; if not, write to the Free Software Foundation, Inc., 59 Temple Place,
# Suite 330, Boston, MA  02111-1307 USA

=head1 NAME

opac-search.pl : script to have RSS feeds automatically on each OPAC search

=head1 SYNOPSIS

on each query (on OPAC), a link to this script is automatically added. The user can save it's queries as RSS feeds.
This script :

=over 4

  - build the RDF file from the query
  - save the RDF file in a opac/rss directory for caching : the RDF is calculated only once every 30mn, and the cache file name is calculated by a md5_base64 of the query (each user registering the same query will use the same cache : speed improvement)
  - let the user specify it's query (q parameter : opac-rss.pl?q=ti:hugo)
  - let the user specify the number of results returned (by default 20, but there are no limits : opac-rss.pl?q=ti:hugo&size=9999)

This script auto calculates the website URL

the RDF contains : 

=over 4

  - Koha: $query as RSS title
  - Koha as subject
  - LibraryName systempreference as RDF description and creator
  - copyright currentyear
  - biblio title as RSS "title" and biblio author as RSS description

=cut

# create a new CGI object
# not sure undef_params option is working, need to test
use CGI qw('-no_undef_params');
my $cgi = new CGI;

# the query to use
my $query = $cgi->param('q');
$query =~ s/:/=/g;

# the number of lines to retrieve
my $size=$cgi->param('size') || 50;

# the filename of the cached rdf file.
my $filename = md5_base64($query);
my $rss = new XML::RSS (version => '1.0');

# the site URL
my $url = $cgi->url();
$url =~ s/opac-rss\.pl.*//;
$url =~ /(http:\/\/.*?)\//;
my $short_url=$1;

my $RDF_update_needed=1;
    my ($year,$month,$day, $hour,$min,$sec) = Today_and_Now();

if (-e "rss/$filename") {
    $rss->parsefile("rss/$filename");
    # check if we have to rebuild the RSS feed (once every 30mn), or just return the actual rdf
    my $rdf_stamp = $rss->{'channel'}->{'dc'}->{'date'};
    $rdf_stamp =~ /(.*)-(.*)-(.*):(.*):(.*):(.*)/;
    my ($stamp_year,$stamp_month,$stamp_day,$stamp_hour,$stamp_min,$stamp_sec) = ($1,$2,$3,$4,$5,$6);
    # if more than 30 mn since the last RDF update, rebuild the RDF. Otherwise, just return it
    unless (($year-$stamp_year >0) or ($month-$stamp_month >0) or ($day-$stamp_day >0) or ($hour-$stamp_hour >0) or ($min-$stamp_min >30)) {
        $RDF_update_needed =0;
    }
}

if ($RDF_update_needed) {
#     warn "RDF update in progress";
    $rss->channel(
                title        => "Koha : $query",
                description  => C4::Context->preference("LibraryName"),
                link => $short_url,
                dc => {
                    date       => "$year-$month-$day:$hour:$min:$sec",
                    subject    => "Koha",
                    creator    => C4::Context->preference("LibraryName"),
                    rights     => "Copyright $year" ,
                    language   => C4::Context->preference("opaclanguages"),
                },
    );
    
    my $total;    # the total results for the whole set
    my ($error, $marcresults) = SimpleSearch($query);
    
    my $hits = scalar @$marcresults;
    $hits=$size if $hits > $size;
    my @results;
    for(my $i=0;$i<$hits;$i++) {
        my %resultsloop;
        my $marcrecord = MARC::File::USMARC::decode($marcresults->[$i]);
        my $biblio = TransformMarcToKoha(C4::Context->dbh,$marcrecord,'');
        # check if the entry is already in the feed. Otherwise, pop the $line th line and add this new one.
        my $already_in_feed=0;
        foreach (@{$rss->{'items'}}) {
            if ($_->{'link'} =~ /biblionumber=$biblio->{'biblionumber'}/) {
                $already_in_feed=1;
            }
        }
        unless ($already_in_feed) {
            pop(@{$rss->{'items'}}) if (@{$rss->{'items'}} >= $size);
            $rss->add_item(title => $biblio->{'title'},
                            description => $biblio->{'author'},
                            link        => "$url/opac-detail.pl?biblionumber=".$biblio->{'biblionumber'},
                            mode =>'insert',
            );
        }
    }
    # save the rss feed.
    $rss->save("rss/$filename");
} else {
#     warn "RDF CACHE used"
}
print $cgi->header(-type => "application/rss+xml");
print $rss->as_string;