#!/bin/perl 
# 
# Rudolf demo: URI resolution - Handle2Rdf 
# daniel.brickley@bristol.ac.uk


use CGI;
require LWP::UserAgent;

package HandleRDFDS; # A trivial subclass that doesn't follow redirects
@HandleRDFDS::ISA = qw(LWP::UserAgent);
sub redirect_ok() { return 0; } # magic of subclassing...

## Output our response as plain text for now (easier to demo)
print "Content-type: text/plain\n\n"; # Issue: send text/x-rdf instead?

my $data;
my $cgi = new CGI;
$cgi->import_names("WEB");

## Get a Handle to de-reference
my $handle = '/10.1045/january98-kirriemuir';	# Default test handle
$handle = $WEB::URI || $handle; # get query string from web if running as CGI
$handle =~ s/\s+//g;     ## Strip whitespace from handle
$handle =~ s/^hdl://;    ## strip initial URI bit (if there is one) 
my $uri= 'hdl:'.$handle; ## the URI-shaped version for RDF use

$handle =~ s/^\///g;

## Hardcoded knowledge of RDF Description Service for Handles
## (there are several of these; these could be described in RDF)
my $URI= "http://hdl.handle.net/$handle"; 

## Go get the (meta)data
##
my $ua = new HandleRDFDS; 
my @locations = 
	$ua->request(new HTTP::Request('HEAD', "$URI"))->header('Location');



## If we got resolution information for this URI, reflect into RDF
##
if (@locations) {
print '<web:RDF xmlns:web="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:dc="http://purl.org/dc/elements/1.1/"  
     xmlns:demo="http://rdf.desire.org/vocab/">';
	print "\n\n<web:Description about=\"$uri\">\n";
	foreach my $u (@locations) {
		print "  <demo:webLoc web:resource=\"$u\"/>\n";#eg;
		}
	print "</web:Description>\n";
	print "\n</web:RDF>\n";
	}
else 	{
## Otherwise... ?
## Duck the issue of handling unknown resource descriptions
	print "<!-- Issue: Handle $URI not found. should we send a 404 error? What makes sense here... -->";
	}


print '

<!-- 
RDF Handle Resolution
a demo service; see http://www.ilrt.bris.ac.uk/discovery/rdf-dev/rudolf/handles/ for a bit more background. 
contact: daniel.brickley@bristol.ac.uk 
-->';