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

/*

 * Copyright (c) 2005, 2006 INRIA

 * All rights reserved.

 *

 * 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 MAC_LOW_H

#define MAC_LOW_H

#include <vector>

#include <stdint.h>

#include "wifi-mac-header.h"

#include "wifi-mode.h"

#include "ns3/mac48-address.h"

#include "ns3/callback.h"

#include "ns3/callback-trace-source.h"

#include "ns3/event-id.h"

#include "ns3/packet.h"

#include "ns3/nstime.h"

namespace ns3 {

class WifiNetDevice;

class WifiPhy;

class PacketLogger;

class MacStations;

class MacStation;

class MacParameters;

class MacLowTransmissionListener {

public:

  MacLowTransmissionListener ();

  virtual ~MacLowTransmissionListener ();

  virtual void GotCts (double snr, WifiMode txMode) = 0;

  virtual void MissedCts (void) = 0;

  /* Do not rely on the gotAck method to be

   * given valid parameters when SuperFastAck is

   * enabled.

   */

  virtual void GotAck (double snr, WifiMode txMode) = 0;

  virtual void MissedAck (void) = 0;

  virtual void StartNext (void) = 0;

  /* Invoked if this transmission was canceled 

   * one way or another. When this method is invoked,

   * you can assume that the packet has not been passed

   * down the stack to the PHY. You are responsible

   * for freeing the packet if you want to.

   */

  virtual void Cancel (void) = 0;

};

class MacLowNavListener {

public:

  MacLowNavListener ();

  virtual ~MacLowNavListener ();

  virtual void NavStart (Time now, Time duration) = 0;

  virtual void NavContinue (Time now, Time duration) = 0;

  virtual void NavReset (Time now, Time duration) = 0;

};

class MacLowTransmissionParameters {

public:

  MacLowTransmissionParameters ();

  /* If ACK is enabled, we wait ACKTimeout for an ACK.

   */

  void EnableAck (void);

  /* If FastAck is enabled, we:

   *   - wait PIFS after end-of-tx. If idle, report

   *     FastAckMissed.

   *   - if busy at end-of-tx+PIFS, wait end-of-rx

   *   - if Ack ok at end-of-rx, report FastAck ok.

   *   - if Ack not ok at end-of-rx, report FastAckMissed

   *     at end-of-rx+SIFS.

   * This is really complicated but it is needed for

   * proper HCCA support.

   */

  void EnableFastAck (void);

  /* If SuperFastAck is enabled, we:

   *   - if busy at end-of-tx+PIFS, report gotAck

   *   - if idle at end-of-tx+PIFS, report missedAck

   */

  void EnableSuperFastAck (void);

  /* If RTS is enabled, we wait CTSTimeout for a CTS.

   * Otherwise, no RTS is sent.

   */

  void EnableRts (void);

  /* If NextData is enabled, we add the transmission duration

   * of the nextData to the durationId and we notify the

   * transmissionListener at the end of the current

   * transmission + SIFS.

   */

  void EnableNextData (uint32_t size);

  /* If we enable this, we ignore all other durationId 

   * calculation and simply force the packet's durationId

   * field to this value.

   */

  void EnableOverrideDurationId (Time durationId);

  void DisableAck (void);

  void DisableRts (void);

  void DisableNextData (void);

  void DisableOverrideDurationId (void);

  bool MustWaitAck (void) const;

  bool MustWaitNormalAck (void) const;

  bool MustWaitFastAck (void) const;

  bool MustWaitSuperFastAck (void) const;

  bool MustSendRts (void) const;

  bool HasDurationId (void) const;

  Time GetDurationId (void) const;

  bool HasNextPacket (void) const;

  uint32_t GetNextPacketSize (void) const;

private:

  uint32_t m_nextSize;

  enum {

    ACK_NONE,

    ACK_NORMAL,

    ACK_FAST,

    ACK_SUPER_FAST

  } m_waitAck;

  bool m_sendRts;

  Time m_overrideDurationId;

};

class MacLow {

public:

  typedef Callback<void, Packet , WifiMacHeader const*> MacLowRxCallback;

  MacLow ();

  ~MacLow ();

  void SetPhy (WifiPhy *phy);

  void SetStations (MacStations *stations);

  void SetParameters (MacParameters *parameters);

  void SetRxCallback (MacLowRxCallback callback);

  void RegisterNavListener (MacLowNavListener *listener);

  /* This transmission time includes the time required for

   * the next packet transmission if one was selected.

   */

  Time CalculateTransmissionTime (uint32_t payloadSize,

                                  Mac48Address to,

                                  MacLowTransmissionParameters const&parameters) const;

  /* start the transmission of the currently-stored data. */

  void StartTransmission (Packet packet, 

                          WifiMacHeader const*hdr, 

                          MacLowTransmissionParameters parameters,

                          MacLowTransmissionListener *listener);

private:

  void CancelAllEvents (void);

  uint32_t GetAckSize (void) const;

  uint32_t GetRtsSize (void) const;

  uint32_t GetCtsSize (void) const;

  Time GetSifs (void) const;

  Time GetPifs (void) const;

  Time GetAckTimeout (void) const;

  Time GetCtsTimeout (void) const;

  uint32_t GetCurrentSize (void) const;

  Time NowUs (void) const;

  MacStation *GetStation (Mac48Address to) const;

  void ForwardDown (Packet const packet, WifiMacHeader const *hdr, 

                    WifiMode txMode);

  Time CalculateOverallTxTime (uint32_t size,

                               Mac48Address to,

                               MacLowTransmissionParameters const &params) const;

  WifiMode GetRtsTxMode (Mac48Address to) const;

  WifiMode GetDataTxMode (Mac48Address to, uint32_t size) const;

  WifiMode GetCtsTxModeForRts (Mac48Address to, WifiMode rtsTxMode) const;

  WifiMode GetAckTxModeForData (Mac48Address to, WifiMode dataTxMode) const;

  void NotifyNav (Time at, WifiMacHeader const*hdr);

  bool IsNavZero (Time at);

  void MaybeCancelPrevious (void);

  void NormalAckTimeout (void);

  void FastAckTimeout (void);

  void SuperFastAckTimeout (void);

  void FastAckFailedTimeout (void);

  void CtsTimeout (void);

  void SendCtsAfterRts (Mac48Address source, Time duration, WifiMode txMode, double rtsSnr);

  void SendAckAfterData (Mac48Address source, Time duration, WifiMode txMode, double rtsSnr);

  void SendDataAfterCts (Mac48Address source, Time duration, WifiMode txMode);

  void WaitSifsAfterEndTx (void);

  void SendRtsForPacket (void);

  void SendDataPacket (void);

  void SendCurrentTxPacket (void);

  void StartDataTxTimers (void);

  WifiPhy *m_phy;

  MacStations *m_stations;

  MacParameters *m_parameters;

  MacLowRxCallback m_rxCallback;

  typedef std::vector<MacLowNavListener *>::const_iterator NavListenersCI;

  typedef std::vector<MacLowNavListener *> NavListeners;

  NavListeners m_navListeners;

  EventId m_normalAckTimeoutEvent;

  EventId m_fastAckTimeoutEvent;

  EventId m_superFastAckTimeoutEvent;

  EventId m_fastAckFailedTimeoutEvent;

  EventId m_ctsTimeoutEvent;

  EventId m_sendCtsEvent;

  EventId m_sendAckEvent;

  EventId m_sendDataEvent;

  EventId m_waitSifsEvent;

  Packet m_currentPacket;

  bool m_hasCurrent;

  WifiMacHeader m_currentHdr;

  MacLowTransmissionParameters m_txParams;

  MacLowTransmissionListener *m_listener;

  Time m_lastNavStart;

  Time m_lastNavDuration;

  CallbackTraceSource<Packet> m_dropError;

};

}; // namespace ns3

#endif /* MAC_LOW_H */