#!/usr/bin/perl

use HTTP::Daemon;
use HTTP::Status;
use HTTP::Response;
use CGI;

$urisetqueueport = $ENV{'URI_SET_QUEUE_PORT'} || $urisetqueueport;

my $d = new HTTP::Daemon LocalPort => $urisetqueueport
 or die "Error: port $urisetqueueport not available.";
print "Please contact me at: <URL:", $d->url, ">\n";

$SIG{CHLD} = "IGNORE"; # do not accumulate defunct processes

my %uri_sets;
my %uri_queues;
my %overflowed;
my %size;

#NOT REENTRANT: CAN NOT FORK DUE TO THE GLOBAL VARIABLES %uri_sets & ...
#HENCE, THE "PID" ARGUMENT OF EVERY REQUEST MUST IDENTIFY THE SET OF URI
#IT WANTS TO WORK WITH. MOREOVER, EVERY CLIENT MUST WORK WITH A DIFFERENT SET
#OF URI, I.E. EVERY PID MUST BE UNIQUE.

#CSC: WHAT IF THE CLIENTS ARE ON DIFFERENT MACHINES AND HAVE THE SAME PID?

while (my $c = $d->accept) {
    while (my $r = $c->get_request) {
        if ($r->method eq 'GET' and $r->url->path eq '/add_if_not_in') {
            my $http_query = $r->url->equery;
            my $cgi = new CGI("$http_query");
            my $uri = $cgi->param('uri');
            my $pid = $cgi->param('PID');
	    print "$pid: ";
            print(@{$uri_queues{$pid}} + 0);
            print "/";
            my $tot = keys(%{$uri_sets{$pid}}) + 0;
            $tot .= "*" if defined($overflowed{$pid});
	    print "$tot $uri: ";

            my $res;
	    if (!(defined($uri_sets{$pid}->{$uri}))) {
                if ($tot + 1 > $size{$pid}) {
                   $res = "not_added_because_already_too_many";
                   $overflowed{$pid} = 1;
                } else {
	           $uri_sets{$pid}->{$uri} = 1;
                   push @{$uri_queues{$pid}},$uri;
		   $res = "added";
                }
            } else {
		$res = "already_in";
            }
	    print $res."\n";

	    my $response = new HTTP::Response;
            $response->content("<?xml version=\"1.0\"?>\n<$res/>\n");
	    $response->content_type('text/xml');
            $c->send_response($response);
        } elsif ($r->method eq 'GET' and $r->url->path eq '/is_overflowed') {
            my $http_query = $r->url->equery;
            my $cgi = new CGI("$http_query");
            my $pid = $cgi->param('PID');
	    print "$pid: ";
            print(@{$uri_queues{$pid}} + 0);
            print "/";
	    print(keys(%{$uri_sets{$pid}}) + 0);
            print "*" if defined($overflowed{$pid});
            my $res = defined($overflowed{$pid}) ? "true" : "false";
            print " is_overflowed: $res\n";
	    my $response = new HTTP::Response;
            $response->content("<?xml version=\"1.0\"?>\n<$res/>\n");
	    $response->content_type('text/xml');
            $c->send_response($response);
        } elsif ($r->method eq 'GET' and $r->url->path eq '/set_uri_set_size') {
            my $http_query = $r->url->equery;
            my $cgi = new CGI("$http_query");
            my $pid = $cgi->param('PID');
            my $size = $cgi->param('size');
	    print "$pid: size := $size\n";
            $size{$pid} = $size;
	    my $response = new HTTP::Response;
            $response->content("<?xml version=\"1.0\"?>\n<done/>\n");
	    $response->content_type('text/xml');
            $c->send_response($response);
        } elsif ($r->method eq 'GET' and $r->url->path eq '/get_next') {
            my $http_query = $r->url->equery;
            my $cgi = new CGI("$http_query");
            my $pid = $cgi->param('PID');
	    print "$pid: ";
            print(@{$uri_queues{$pid}} + 0);
            print "/";
	    print(keys(%{$uri_sets{$pid}}) + 0);
            print "*" if defined($overflowed{$pid});
            print " ";

            my $elem = shift @{$uri_queues{$pid}};
            my $mark = $overflowed{$pid};

	    my $response = new HTTP::Response;
            my $xml_header = "<?xml version=\"1.0\"?>\n";
            if (!defined($elem)) {
	       print "is now empty\n";
               $response->content("$xml_header<empty/>\n");
            } elsif ($mark == 1) {
	       print "$elem (marked) removed\n";
               $response->content("$xml_header<marked_uri value=\"$elem\"/>\n");
            } else {
	       print "$elem removed\n";
               $response->content("$xml_header<uri value=\"$elem\"/>\n");
            }
	    $response->content_type('text/xml');
            $c->send_response($response);
        } elsif ($r->method eq 'GET' and $r->url->path eq '/reset_to_empty') {
	    my $pid = $r->url->query;
	    $pid =~ s/[^=]*=//;
            # Next loop for debugging purposes only
            my $count = 1;
            while (my $e = shift @{$uri_queues{$pid}}) {
             print "#$count $e forced out of the set\n";
             $count++;
            }
	    print "************\nThe URI set $pid is now empty again\n";
	    delete($uri_sets{$pid});
            delete($overflowed{$pid});
            delete($size{$pid});
	    my $response = new HTTP::Response;
            $response->content("<?xml version=\"1.0\"?>\n<done/>\n");
	    $response->content_type('text/xml');
            $c->send_response($response);
        } elsif ($r->method eq 'GET' && $r->url->path eq "/help"){
           print "Help requested!\n";
	   my $response = new HTTP::Response;
           $response->content("URI-Set (Queue) Version: ???");
           $c->send_response($response);
        } else {
            $c->send_error(RC_FORBIDDEN)
        }
    }
    $c->close;
    undef($c);
}