/*
Copyright_License {

  XCSoar Glide Computer - http://www.xcsoar.org/
  Copyright (C) 2000-2015 The XCSoar Project
  A detailed list of copyright holders can be found in the file "AUTHORS".

  This program is free software; you can redistribute it and/or
  modify it under the terms of the GNU General Public License
  as published by the Free Software Foundation; either version 2
  of the License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
}
*/

#ifndef XCSOAR_EVENT_DELAYED_NOTIFY_HPP
#define XCSOAR_EVENT_DELAYED_NOTIFY_HPP

#include "Event/Timer.hpp"

/**
 * This class is similar to #Notify, but it delivers the notification
 * with a certain delay, to limit the rate of redundant notifications.
 * To use it, subclass it and implement the abstract method
 * OnNotification().
 */
class DelayedNotify : private Timer {
  const unsigned delay_ms;

public:
  DelayedNotify(unsigned _delay_ms):delay_ms(_delay_ms) {}

  ~DelayedNotify() {
    ClearNotification();
  }

  /**
   * Send a notification to this object.  This method can be called
   * from any thread.
   */
  void SendNotification() {
    SchedulePreserve(delay_ms);
  }

  /**
   * Clear any pending notification.
   */
  void ClearNotification() {
    Cancel();
  }

protected:
  /**
   * Called after SendNotification() has been called at least once.
   * This method runs in the main thread.
   */
  virtual void OnNotification() = 0;

private:
  /* virtual methods from class Timer */
  virtual void OnTimer();
};

#endif
