/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * 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
 *
 * Author: George Riley <riley@ece.gatech.edu>
 */

#ifndef DISTRIBUTED_SIMULATOR_IMPL_H
#define DISTRIBUTED_SIMULATOR_IMPL_H

#include "ns3/simulator-impl.h"
#include "ns3/scheduler.h"
#include "ns3/event-impl.h"
#include "ns3/ptr.h"

#include <list>

namespace ns3 {

/**
 * \ingroup mpi
 *
 * \brief Structure used for all-reduce LBTS computation
 */
class LbtsMessage
{
public:
  LbtsMessage ()
    : m_txCount (0),
      m_rxCount (0),
      m_myId (0)
  {
  }

  /**
   * \param rxc received count
   * \param txc transmitted count
   * \param id mpi rank
   * \param t smallest time
   */
  LbtsMessage (uint32_t rxc, uint32_t txc, uint32_t id, const Time& t)
    : m_txCount (txc),
      m_rxCount (rxc),
      m_myId (id),
      m_smallestTime (t)
  {
  }

  ~LbtsMessage ();

  /**
   * \return smallest time
   */
  Time GetSmallestTime ();
  /**
   * \return transmitted count
   */
  uint32_t GetTxCount ();
  /**
   * \return receieved count
   */
  uint32_t GetRxCount ();
  /**
   * \return id which corresponds to mpi rank
   */
  uint32_t GetMyId ();

private:
  uint32_t m_txCount;
  uint32_t m_rxCount;
  uint32_t m_myId;
  Time     m_smallestTime;
};

/**
 * \ingroup mpi
 *
 * \brief distributed simulator implementation using lookahead
 */
class DistributedSimulatorImpl : public SimulatorImpl
{
public:
  static TypeId GetTypeId (void);

  DistributedSimulatorImpl ();
  ~DistributedSimulatorImpl ();

  // virtual from SimulatorImpl
  virtual void Destroy ();
  virtual bool IsFinished (void) const;
  virtual void Stop (void);
  virtual void Stop (Time const &time);
  virtual EventId Schedule (Time const &time, EventImpl *event);
  virtual void ScheduleWithContext (uint32_t context, Time const &time, EventImpl *event);
  virtual EventId ScheduleNow (EventImpl *event);
  virtual EventId ScheduleDestroy (EventImpl *event);
  virtual void Remove (const EventId &ev);
  virtual void Cancel (const EventId &ev);
  virtual bool IsExpired (const EventId &ev) const;
  virtual void Run (void);
  virtual Time Now (void) const;
  virtual Time GetDelayLeft (const EventId &id) const;
  virtual Time GetMaximumSimulationTime (void) const;
  virtual void SetScheduler (ObjectFactory schedulerFactory);
  virtual uint32_t GetSystemId (void) const;
  virtual uint32_t GetContext (void) const;

private:
  virtual void DoDispose (void);
  void CalculateLookAhead (void);

  void ProcessOneEvent (void);
  uint64_t NextTs (void) const;
  Time Next (void) const;
  typedef std::list<EventId> DestroyEvents;

  DestroyEvents m_destroyEvents;
  bool m_stop;
  Ptr<Scheduler> m_events;
  uint32_t m_uid;
  uint32_t m_currentUid;
  uint64_t m_currentTs;
  uint32_t m_currentContext;
  // number of events that have been inserted but not yet scheduled,
  // not counting the "destroy" events; this is used for validation
  int m_unscheduledEvents;

  LbtsMessage* m_pLBTS;       // Allocated once we know how many systems
  uint32_t     m_myId;        // MPI Rank
  uint32_t     m_systemCount; // MPI Size
  Time         m_grantedTime; // Last LBTS
  static Time  m_lookAhead;   // Lookahead value

};

} // namespace ns3

#endif /* DISTRIBUTED_SIMULATOR_IMPL_H */
