#!/usr/bin/perl
use strict;
use warnings;
use IO::Socket;
use threads;
use Thread::Queue;

#get the port to bind to or default to 8000
my $port = $ARGV[0] || 8000;
my $listeners = 10;

# a hash to record client machines and thread queue for internal comunication
my %clients;
my $mqueue = Thread::Queue -> new;
my $squeue = Thread::Queue -> new;
threads->create ("monitor", $mqueue);
for (1..$listeners) {
    threads->create ("read_data", $mqueue, $squeue)->detach;
}

#create the listen socket
my $listen_socket = IO::Socket::INET->new(LocalPort => $port,
                                          Listen => 20,
                                          Proto => 'tcp',
                                          Reuse => 1);
#make sure we are bound to the port
die "Cant't create a listening socket: $@" unless $listen_socket;
warn "Server ready. Waiting for connections on $port ... \n";

#wait for connections at the accept call
while (my $connection = $listen_socket->accept) {
    # put the connection on the queue for a reader thread
    $squeue -> enqueue($connection);
}

sub read_data {
    # accept data from the socket and put it on the queue
    my ($mqueue, $squeue) = @_;
    while (my $socket = $squeue -> dequeue) {
        while (<$socket>) {
            print "listener got: $_";
            $mqueue -> enqueue(time." $_");
	}
        close $socket;
    }
}

sub monitor {
    my $mqueue = shift;
    while (1) {
        while ($mqueue -> pending) {
            my $data = $mqueue -> dequeue;
            print "monitor got: $data";
            $data =~ /(\d+) Heartbeat from (\S+) next one in (\d+) minutes/;
            my $time   = $1;
            my $client = $2;
            my $cycle  = $3;
            if (defined $clients{$client} and $clients{$client} -> [0] eq 'NAK') {
                print "$client sent a beat again\n";
            }
            $clients{$client} = [ 'OK', $time + $cycle * 60 ];
        }
        for my $client (keys %clients) {
            next if $clients{$client}->[0] eq 'NAK';
            next if $clients{$client}->[1] > time;
            print "$client missed a heartbeat, expected at $clients{$client}->[1], now it is ".time."\n";
            $clients{$client}->[0] = 'NAK';
        }
        sleep 30;
    }
}