#!/usr/bin/perl

# term-finder.cgi - input a word, browse more words

# Eric Lease Morgan <emorgan@nd.edu>
# November  7, 2008 - first cut; at WorldCat Hackathon (NYC)
# November 19, 2008 - removed the explicit content-type header; made it generic
# July      9, 2008 - begun extracting 450 fields -- see references
# January   5, 2010 - made the See references not clickable; changed See to Use for
# January  24, 2010 - added GNU Public License

# P.S. The entire application, complete with support files ought to be
# available (at least temporarily) from:
#
#  http://zoia.library.nd.edu/sandbox/term-finder/term_finder-2010-01-24.tar.gz

# Copyright (C) Eric Lease Morgan
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2,
# as published by the Free Software Foundation.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


# require/include
use LWP::UserAgent;
use strict;
use XML::LibXML;
use XML::LibXSLT;
use CGI;

# define
use constant SEARCH   => 'http://tspilot.oclc.org/lcsh/?query=oclcts.marcTags+%3D+%22150%22+and+oclcts.preferredTerm+%3D+%22##INPUT##%22&version=1.1&operation=searchRetrieve&recordSchema=info%3Asrw%2Fschema%2F1%2Fmarcxml-v1.1&maximumRecords=1000&startRecord=1&resultSetTTL=300&recordPacking=xml&recordXPath=&sortKeys=';
use constant TRANS    => './etc/related.xsl';
use constant TEMPLATE => './etc/template.txt';
use constant HOME     => './etc/home.txt';

# initalize
my $cgi = CGI->new;
my $query = $cgi->param( 'query' );

# display home page
if ( ! $query ) {

	# display the home page and quit
	my $html = &slurp( TEMPLATE );
	$html =~ s/##CONTENT##//e;
	$html =~ s/##QUERY##/paper work/;
	&gracefulExit ( $html );

}

else {

	# get the input
	$query =~ s/ /+/g;
	
	# create a url
	my $url = SEARCH;
	$url =~ s/##INPUT##/$query/e;
	
	# create a user agent, create a request, send it, and get a response
	my $ua       = LWP::UserAgent->new;
	my $request  = HTTP::Request->new( GET => $url );
	my $response = $ua->request( $request );
	
	# get the response
	my $parser     = XML::LibXML->new;
	my $xslt       = XML::LibXSLT->new;
	my $source     = $parser->parse_string( $response->content ) or croak $!;
	my $style      = $parser->parse_file( TRANS )                or croak $!;
	my $stylesheet = $xslt->parse_stylesheet( $style )           or croak $!;
	my $results    = $stylesheet->transform( $source )           or croak $!;
	my @responses  = split /\n/, $stylesheet->output_string( $results );
	
	# initialize output
	my $response = '';
	
	# check for responses; failure
	if ( ! @responses ) { $response = $cgi->p( 'No records found. Bummer!' ) }
	
	# success
	else {
			
		# broader
		$response .= $cgi->h2( 'Broader' );
		my $list = '';
		foreach ( split /\t/, @responses[ 0 ] ) { $list .= $cgi->li( $cgi->a({ -href => "./?query=$_" }, $_ ))}
		$response .= $cgi->ul( $list );
	
		# narrower
		$response .= $cgi->h2( 'Narrower' );
		$list = '';
		foreach ( split /\t/, @responses[ 1 ] ) { $list .= $cgi->li( $cgi->a({ -href => "./?query=$_" }, $_ ))}
		$response .= $cgi->ul( $list );
		
		# see
		$response .= $cgi->h2( 'Use for' );
		$list = '';
		foreach ( split /\t/, @responses[ 2 ] ) { $list .= $cgi->li( $_ )}
		$response .= $cgi->ul( $list );
		
	}
	
	# display the home page and quit
	my $html = &slurp( TEMPLATE );
	$html =~ s/##CONTENT##/$response/e;
	$html =~ s/##QUERY##/$cgi->param( 'query' )/e;
	&gracefulExit ( $html );

}


sub slurp {

	# open a file named by the input and return its contents
	my $f = @_[0];
	open (F, "< $f");
	my $r = do { local $/; <F> };
	close F;
	return $r;

}


sub gracefulExit {

	# get the html, send a header, send the html, and quit
	my $html = shift;
	print $cgi->header();
	print $html;
	exit;

}