/**
     * User subscribes with their subject:userId:token
     * 
     * If token does not match userId (check DB), return a 403 else...
     * 
     * Token is regenerated and placed in DB for next time the page is visited,
     * userId is retrieved that matches token.
     * 
     * New process spawned which runs looping zmq with argv being userId from
     * previous DB check. Process Id retrieved. 
     * 
     * Add conn, subject, userId, processId, ip and new token to $clients array
     * 
     * Print above details to console for debugging (or log all this)
     * 
     * @param \Ratchet\ConnectionInterface $conn
     * @param type $topic
     */
    public function onSubscribe(ConnectionInterface $conn, $subscription) 
    {
        list($subject, $userId, $token) = explode(':', $subscription->getId());
        
        $subscription->add($conn);
        
        $resourceId = $conn->resourceId;
        
        $pidArr = [];
        $cmd = sprintf('%s%s --userId=%d --subject=%s --resourceId=%s', self::CMD_PREFIX, self::CMD_TORRENTS, $userId, $subject, $resourceId);
        exec(sprintf("%s > /dev/null 2>&1 & echo $!;", $cmd), $pidArr);
        $pid = $pidArr[0];

        if (empty($pidArr) || $pid == 0)
        {
            echo sprintf("Couldn't create a new process for user: %d", $userId);
            return; 
        }
        
        if (!array_key_exists($resourceId, $this->clients)) 
        {
            $this->clients[$resourceId]['userId'] = $userId;
            $this->clients[$resourceId]['token'] = $token;
            $this->clients[$resourceId]['conn'] = $conn;
            $this->clients[$resourceId]['subject'] = $subject;
            $this->clients[$resourceId]['subscription'] = $subscription;
            $this->clients[$resourceId]['pid'] = $pid;
        }
        
        echo sprintf("Client Connected: %s, userId: %d, subject: %s" . PHP_EOL, $conn->remoteAddress, $userId, $subject);
    }

/**
     * @param string JSON'ified string we'll receive from ZeroMQ
     */
    public function onMessage($data) 
    {
        $data = json_decode($data, true);
        
        var_dump($data);

        $result = reset(array_filter($this->clients, function($client) use ($data) {
            return $client['conn']->resourceId == $data['resourceId'];
        }));
        
        if ($result)
        {
            $result['subscription']->broadcast($data);
        }
        else
        {
            echo "Couldn't find user in this->clients";
            return;
        }
    }

    public function onClose(ConnectionInterface $conn) 
    { 
        $resourceId = $conn->resourceId;
        $result = reset(array_filter($this->clients, function($client) use ($resourceId) {
            return $client['conn']->resourceId == $resourceId;
        }));
        
        posix_kill($result['pid'], SIGKILL);
        unset($this->clients[$conn->resourceId]);
        echo sprintf("Client Disconnected: %s" . PHP_EOL, $conn->remoteAddress);
    }