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

#ignore child processes to prevent zombies
$SIG{CHLD} = 'IGNORE';

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

## Queue for commands input from the keyboard
## That will be sent to the currrently connected device
my $qin  = Thread::Queue -> new;

## Queue for the data inbound from the device
my $qout = Thread::Queue -> new;

my $listen_socket = IO::Socket::INET->new(
    LocalPort => $port, Listen => 1,
    Proto => 'tcp', Reuse => 1
) or die "Cant't create a listening socket: $@";

warn "Server ready. Waiting for connections on $port ... \n";

async {
    ## Monitor the keyboard and forward any input
    ## to the currently connected client GPS device
    while( <STDIN> ) {
        chomp;
        $qin->enqueue( $_ );
    }
};

async{
    ## Monitor the queue and do whatever with the inbound data
    while( my $data = $qout->dequeue ) {
        ## Do something with the gps data (like write it to a database?)
    }
};

## Spawn a new connection if the device reattaches.
## Old connections clean themselves up automatically
while (my $connection = $listen_socket->accept) {
    threads->create ("read_data", $qin, $qout, $connection)->detach;
    print $connection;
}

sub read_data {
    # accept data from the socket and put it on the queue
    my( $qin, $qout, $socket ) = @_;
    while (<$socket>) {
        print "$_";
        ## Process data from connected devices
        $qout -> enqueue(time." $_");

        ## if there are any commands pending, send them to the GPS device
        while( $qin->pending ) {
            my $cmd = $qin->dequeue;
            print $socket $cmd;
        }
    }
    close $socket;
}