/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2005,2006 INRIA

 *

 * 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef INTERFERENCE_HELPER_H

#define INTERFERENCE_HELPER_H

#include <stdint.h>

#include <vector>

#include <list>

#include "wifi-mode.h"

#include "wifi-preamble.h"

#include "wifi-phy-standard.h"

#include "ns3/nstime.h"

#include "ns3/simple-ref-count.h"

namespace ns3 {

class ErrorRateModel;

/**

 * \ingroup wifi

 * \brief handles interference calculations

 */

class InterferenceHelper

{

public:

  class Event : public SimpleRefCount<InterferenceHelper::Event>

  {

public:

    Event (uint32_t size, WifiMode payloadMode,

           enum WifiPreamble preamble,

    ~Event ();

    Time GetDuration (void) const;

    Time GetStartTime (void) const;

    Time GetEndTime (void) const;

    double GetRxPowerW (void) const;

    uint32_t GetSize (void) const;

    WifiMode GetPayloadMode (void) const;

    enum WifiPreamble GetPreambleType (void) const;

private:

    uint32_t m_size;

    WifiMode m_payloadMode;

    enum WifiPreamble m_preamble;

    Time m_startTime;

    Time m_endTime;

    double m_rxPowerW;

  };

  struct SnrPer

  {

    double snr;

    double per;

  };

  InterferenceHelper ();

  ~InterferenceHelper ();

  void SetNoiseFigure (double value);

  void SetErrorRateModel (Ptr<ErrorRateModel> rate);

  double GetNoiseFigure (void) const;

  Ptr<ErrorRateModel> GetErrorRateModel (void) const;

  /**

   * \param energyW the minimum energy (W) requested

   * \returns the expected amount of time the observed

   *          energy on the medium will be higher than

   *          the requested threshold.

   */

  Time GetEnergyDuration (double energyW);

  Ptr<InterferenceHelper::Event> Add (uint32_t size, WifiMode payloadMode,

                                      enum WifiPreamble preamble,

  struct InterferenceHelper::SnrPer CalculateSnrPer (Ptr<InterferenceHelper::Event> event);

  void NotifyRxStart ();

  void NotifyRxEnd ();

  void EraseEvents (void);

private:

  class NiChange

  {

public:

    NiChange (Time time, double delta);

    Time GetTime (void) const;

    double GetDelta (void) const;

    bool operator < (const NiChange& o) const;

private:

    Time m_time;

    double m_delta;

  };

  typedef std::vector <NiChange> NiChanges;

  typedef std::list<Ptr<Event> > Events;

  InterferenceHelper (const InterferenceHelper &o);

  InterferenceHelper &operator = (const InterferenceHelper &o);

  void AppendEvent (Ptr<Event> event);

  double CalculateNoiseInterferenceW (Ptr<Event> event, NiChanges *ni) const;

  double CalculateSnr (double signal, double noiseInterference, WifiMode mode) const;

  double CalculateChunkSuccessRate (double snir, Time delay, WifiMode mode) const;

  double CalculatePer (Ptr<const Event> event, NiChanges *ni) const;

  double m_noiseFigure; /**< noise figure (linear) */

  Ptr<ErrorRateModel> m_errorRateModel;

  /// Experimental: needed for energy duration calculation

  NiChanges m_niChanges;

  double m_firstPower;

  bool m_rxing;

  /// Returns an iterator to the first nichange, which is later than moment

  NiChanges::iterator GetPosition (Time moment);

  void AddNiChangeEvent (NiChange change);

};

} // namespace ns3

#endif /* INTERFERENCE_HELPER_H */