#pragma once
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/

/**
* @file
* @copyright MPLv2
*/
#include <mutex>
#include <queue>
#include <memory>
#include <condition_variable>
#include <BC/Message.hpp>

namespace BC{
  /**
    * @class BasicMessageQueue
    *
    * This class encapsulates shared storage which is a queue and protect it
    * with a mutex. In Addition there is a condition variable to notify other
    * threads if there is new data in the queue.
    */
  class BasicMessageQueue
  {
  private:
    std::queue<std::unique_ptr<BC::Message>> q;
    std::mutex mx;
    std::condition_variable condVar;
  public:
    /**
      * @brief default constructor for class BasicMessageQueue
      */
    BasicMessageQueue();

    /**
      * @brief appends given message to queue
      *
      * The storage is protected by a mutex. Makes a notify_one call to inform 
      * in waiting thread that there is a new message in the queue.
      *
      * @param msg - incoming message
      */
    void appendMessage( std::unique_ptr<BC::Message> msg );

    /**
      * @brief gets the fron message from the queue
      *
      * This method gets the front message in the queue and deletes it from the 
      * queue. The storage is protected by a mutex. If the queue is empty the
      * function throws an exception.
      *
      * @result msg - returns the front message from the queue
      * @throws length_error - if queue is empty this method throws length_error exception
      */
    std::unique_ptr<BC::Message> getMessage();

    /**
      * @brief waits for new message to be added
      *
      * If the queue is empty this method waits for a notfication on the condition variable.
      * It returns the front message and deletes it from the queue. This action is protected 
      * by a mutex.
      *
      * @result msg - returns the first/front message in the queue
      * @throws length_error - if queue is empty this method throws length_error exception
      */
    std::unique_ptr<BC::Message> waitForNewMessage();

    /**
      * @brief method size
      *
      * @result size - current size of the message queue
      */
    unsigned int size();

  }; //BasicMessageQueue

}; // namespace BC