#!/usr/bin/perl

# Copyright 2008-2009 LibLime
#
# 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

use strict;
use warnings;

=head1 NAME

unapi - implement unAPI for the OPAC

=head1 SYNOPSIS

Retrieve http://library.example.org/cgi-bin/koha/unapi?id=koha:biblionumber:123&format=oai_dc

=head1 DESCRIPTION

Implements unAPI <http://unapi.info>, a small HTTP API for retrieving structured
content from a web application.  The primary application of unAPI in Koha is to
allow tools such as Zotero to identify and grab bibliographic record metadata in
an XML format such as OAI DC, RSS2, MARCXML, or MODS.

=cut

use CGI;
use C4::Context;
use C4::Biblio;
use XML::LibXML;
use XML::LibXSLT;

my $cgi = CGI->new();
binmode(STDOUT, ":encoding(UTF-8)"); #output as utf8

=head1 VARIABLES

=head2 $format_to_stylesheet_map

This hashref of hashrefs maps from a MARC flavour and unAPI format
to the stylesheet that should be used to transform the bib MARCXML
to the desired output format.  As new MARC XSLT stylesheets are added,
(particularly for UNIMARC), this map should be updated.  Of course,
if/when we add support for emitting a format that is not genreated
by a stylesheet, the structure of this variable will have to be changed.
At present, this doubles as the list of output formats supported by
this unAPI implementation.

=cut

my $format_to_stylesheet_map = {
    'MARC21' => {
        'marcxml'      => 'identity.xsl',
        'marcxml-full' => 'identity.xsl',
        'mods'         => 'MARC21slim2MODS.xsl',
        'mods-full'    => 'MARC21slim2MODS.xsl',
        'mods3'        => 'MARC21slim2MODS3-1.xsl',
        'mods3-full'   => 'MARC21slim2MODS3-1.xsl',
        'oai_dc'       => 'MARC21slim2OAIDC.xsl',
        'rdfdc',       => 'MARC21slim2RDFDC.xsl',
        'rss2'         => 'MARC21slim2RSS2.xsl',
        'rss2-full'    => 'MARC21slim2RSS2.xsl',
        'srw_dc'       => 'MARC21slim2SRWDC.xsl',
    },
    'NORMARC' => {
        'marcxml'      => 'identity.xsl',
        'marcxml-full' => 'identity.xsl',
        'mods'         => 'MARC21slim2MODS.xsl',
        'mods-full'    => 'MARC21slim2MODS.xsl',
        'mods3'        => 'MARC21slim2MODS3-1.xsl',
        'mods3-full'   => 'MARC21slim2MODS3-1.xsl',
        'oai_dc'       => 'MARC21slim2OAIDC.xsl',
        'rdfdc',       => 'MARC21slim2RDFDC.xsl',
        'rss2'         => 'MARC21slim2RSS2.xsl',
        'rss2-full'    => 'MARC21slim2RSS2.xsl',
        'srw_dc'       => 'MARC21slim2SRWDC.xsl',
    },
    'UNIMARC' => {
        'marcxml'      => 'identity.xsl',
        'marcxml-full' => 'identity.xsl',
        'oai_dc'       => 'UNIMARCslim2OAIDC.xsl',
    },
};

=head2 $format_info

This hashref maps from unAPI output formats to the <format> elements
used to describe them in an unAPI format request.

=cut

my $format_info = {
    'marcxml' => q(<format name="marcxml" type="application/xml" namespace_uri="http://www.loc.gov/MARC21/slim" docs="http://www.loc.gov/marcxml/" schema_location="http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd"/>),
    'marcxml-full' => q(<format name="marcxml-full" type="application/xml" namespace_uri="http://www.loc.gov/MARC21/slim" docs="http://www.loc.gov/marcxml/" schema_location="http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd"/>),
    'mods' => q(<format name="mods" type="application/xml" namespace_uri="http://www.loc.gov/mods/" docs="http://www.loc.gov/mods/" schema_location="http://www.loc.gov/standards/mods/mods.xsd"/>),
    'mods-full' => q(<format name="mods-full" type="application/xml" namespace_uri="http://www.loc.gov/mods/" docs="http://www.loc.gov/mods/" schema_location="http://www.loc.gov/standards/mods/mods.xsd"/>),
    'mods3' => q(<format name="mods3" type="application/xml" namespace_uri="http://www.loc.gov/mods/v3" docs="http://www.loc.gov/mods/" schema_location="http://www.loc.gov/standards/mods/v3/mods-3-1.xsd"/>),
    'mods3-full' => q(<format name="mods3-full" type="application/xml" namespace_uri="http://www.loc.gov/mods/v3" docs="http://www.loc.gov/mods/" schema_location="http://www.loc.gov/standards/mods/v3/mods-3-1.xsd"/>),
    'oai_dc' => q(<format name="oai_dc" type="application/xml" namespace_uri="http://www.openarchives.org/OAI/2.0/oai_dc/" schema_location="http://www.openarchives.org/OAI/2.0/oai_dc.xsd"/>),
    'rdfdc' => q(<format name="rdfdc" type="application/xml" namespace_uri="http://purl.org/dc/elements/1.1/" schema_location="http://purl.org/dc/elements/1.1/"/>),
    'rss2' => q(<format name="rss2" type="application/xml"/>),
    'rss2-full' => q(<format name="rss2-full" type="application/xml"/>),
    'srw_dc' => q(<format name="srw_dc" type="application/xml" namespace_uri="info:srw/schema/1/dc-schema" schema_location="http://www.loc.gov/z3950/agency/zing/srw/dc-schema.xsd"/>),
};

my $id     = $cgi->param('id');
my $format = $cgi->param('format');

if (not defined $format) {
    emit_formats($id, $format_to_stylesheet_map, $format_info, $cgi);
} elsif ($id) {

    # koha:biblionumber:0152018484
    if ($id =~ /koha:biblionumber:(\d+)/) {
        my $biblionumber = $1;

        my $content;
        eval {
            my $marcxml = GetXmlBiblio($biblionumber);
            unless (defined $marcxml) {
                # no bib, so 404
                print $cgi->header( -status => '404 record not found');
                exit 0;
            }

            my $transformer = get_transformer($format, $format_to_stylesheet_map, $format_info);
            unless (defined $transformer) {
                print $cgi->header( -status => '406 invalid format requested' );
                exit 0;
            }
            my $parser = XML::LibXML->new();
            my $record_dom = $parser->parse_string( $marcxml );
            $record_dom = $transformer->transform( $record_dom );
            $content = $record_dom->toString();
        };
        if ($@) {
            print $cgi->header( -status => '500 internal error ' . $@->code() . ": " . $@->message() );
            exit 0;
        }

        print $cgi->header( -type =>'application/xml' );
        print $content;
    } else {
        # ID is obviously wrong, so 404
        print $cgi->header( -status => '404 record not found');
        exit 0;
    }
} else {
    # supplied a format but no id - caller is doing it wrong
    print $cgi->header( -status => '400 bad request - if you specify format, must specify id');
    exit 0;
}

exit 0;

sub emit_formats {
    my ($id, $format_to_stylesheet_map, $format_info, $cgi) = @_;

    if (defined $id) {
        print $cgi->header( -type =>'application/xml', -status => '300 multiple choices' );
    } else {
        print $cgi->header( -type =>'application/xml' );
    }

    print "<?xml version='1.0' encoding='utf-8'  ?>\n";
    if (defined $id) {
        print qq(<formats id="$id">\n);
    } else {
        print "<formats>\n";
    }

    my $marcflavour = uc(C4::Context->preference('marcflavour'));
    foreach my $format (sort keys %{ $format_to_stylesheet_map->{$marcflavour} }) {
        print $format_info->{$format}, "\n";
    }
    print "</formats>\n";
    return;
}


sub get_transformer {
    my ($format, $format_to_stylesheet_map, $format_info) = @_;
    $format = lc $format;

    my $marcflavour = uc(C4::Context->preference('marcflavour'));
    return unless $format_to_stylesheet_map->{$marcflavour}->{$format};

    my $xslt_file = C4::Context->config('intranetdir') .
                    "/koha-tmpl/intranet-tmpl/prog/en/xslt/" .
                    $format_to_stylesheet_map->{$marcflavour}->{$format};

    my $parser = XML::LibXML->new();
    my $xslt = XML::LibXSLT->new();
    my $style_doc = $parser->parse_file( $xslt_file );
    my $stylesheet = $xslt->parse_stylesheet( $style_doc );

    return $stylesheet;
}

=head1 AUTHOR

Koha Development Team <http://koha-community.org/>

Originally written by Joshua Ferraro <jmf@liblime.com>

Improved by Galen Charlton <galen.charlton@liblime.com>

=cut