text: <?php
  
  namespace Enqueue\Client;
  
  use Enqueue\Rpc\Promise;
  
  class SpoolProducer implements ProducerInterface
  {
      /**
       * @var ProducerInterface
       */
      private $realProducer;
  
      /**
       * @var array
       */
      private $events;
  
      /**
       * @var array
       */
      private $commands;
  
      public function __construct(ProducerInterface $realProducer)
      {
          $this->realProducer = $realProducer;
  
          $this->events = new \SplQueue();
          $this->commands = new \SplQueue();
      }
  
      public function sendCommand(string $command, $message, bool $needReply = false): ?Promise
      {
          if ($needReply) {
              return $this->realProducer->sendCommand($command, $message, $needReply);
          }
  
          $this->commands->enqueue([$command, $message]);
  
          return null;
      }
  
      public function sendEvent(string $topic, $message): void
      {
          $this->events->enqueue([$topic, $message]);
      }
  
      /**
       * When it is called it sends all previously queued messages.
       */
      public function flush(): void
      {
          while (false == $this->events->isEmpty()) {
              list($topic, $message) = $this->events->dequeue();
  
              $this->realProducer->sendEvent($topic, $message);
          }
  
          while (false == $this->commands->isEmpty()) {
              list($command, $message) = $this->commands->dequeue();
  
              $this->realProducer->sendCommand($command, $message);
          }
      }
  }
  