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

/*

 * Copyright (c) 2005 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 DCA_TXOP_H

#define DCA_TXOP_H

#include <stdint.h>

#include "ns3/callback.h"

#include "ns3/packet.h"

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

#include "ns3/nstime.h"

#include "wifi-mac-header.h"

#include "wifi-mode.h"

namespace ns3 {

class DcfState;

class DcfManager;

class WifiMacQueue;

class MacLow;

class MacParameters;

class MacTxMiddle;

class RandomStream;

class MacStation;

class MacStations;

/**

 * \brief handle packet fragmentation and retransmissions.

 *

 * This class implements the packet fragmentation and 

 * retransmission policy. It uses the ns3::MacLow and ns3::DcfManager

 * helper classes to respectively send packets and decide when 

 * to send them. Packets are stored in a ns3::WifiMacQueue until

 * they can be sent.

 *

 * The policy currently implemented uses a simple fragmentation

 * threshold: any packet bigger than this threshold is fragmented

 * in fragments whose size is smaller than the threshold.

 *

 * The retransmission policy is also very simple: every packet is

 * retransmitted until it is either successfully transmitted or

 * it has been retransmitted up until the ssrc or slrc thresholds.

 *

 * The rts/cts policy is similar to the fragmentation policy: when

 * a packet is bigger than a threshold, the rts/cts protocol is used.

 */

{

public:

  typedef Callback <void, WifiMacHeader const&> TxOk;

  typedef Callback <void, WifiMacHeader const&> TxFailed;

  /**

   * \param cwMin forwarded to ns3::DcfState constructor

   * \param cwMax forwarded to ns3::DcfState constructor

   * \param aifsn forwarded to ns3::DcfState constructor

   * \param manager the manager which will be responsible

   *        for controlling access to this DcaTxop.

   *

   * Initialized from \valueref{WifiMaxSsrc}, \valueref{WifiMaxSlrc},

   * \valueref{WifiRtsCtsThreshold}, and, \valueref{WifiFragmentationThreshold}.

   */

  DcaTxop (uint32_t cwMin, uint32_t cwMax, uint32_t aifsn, DcfManager *manager);

  ~DcaTxop ();

  void SetParameters (MacParameters *parameters);

  void SetStations (MacStations *stations);

  void SetTxMiddle (MacTxMiddle *txMiddle);

  /**

   * \param callback the callback to invoke when a 

   * packet transmission was completed successfully.

   */

  void SetTxOkCallback (TxOk callback);

  /**

   * \param callback the callback to invoke when a 

   * packet transmission was completed unsuccessfully.

   */

  void SetTxFailedCallback (TxFailed callback);

  void SetMaxQueueSize (uint32_t size);

  void SetMaxQueueDelay (Time delay);

  /**

   * \param packet packet to send

   * \param hdr header of packet to send.

   *

   * Store the packet in the internal queue until it

   * can be sent safely.

   */

  void Queue (Ptr<const Packet> packet, WifiMacHeader const &hdr);

private:

  class TransmissionListener;

  class NavListener;

  class PhyListener;

  class Dcf;

  friend class Dcf;

  friend class TransmissionListener;

  MacParameters *Parameters (void);

  /* dcf notifications forwarded here */

  bool NeedsAccess (void) const;

  void NotifyAccessGranted (void);

  void NotifyInternalCollision (void);

  void NotifyCollision (void);

  /* event handlers */

  void GotCts (double snr, WifiMode txMode);

  void MissedCts (void);

  void GotAck (double snr, WifiMode txMode);

  void MissedAck (void);

  void StartNext (void);

  void Cancel (void);

  void RestartAccessIfNeeded (void);

  void StartAccessIfNeeded (void);

  bool NeedRts (void);

  bool NeedFragmentation (void);

  uint32_t GetNFragments (void);

  uint32_t GetNextFragmentSize (void);

  uint32_t GetFragmentSize (void);

  MacStation *GetStation (Mac48Address to) const;

  uint32_t GetMaxSsrc (void) const;

  uint32_t GetMaxSlrc (void) const;

  bool IsLastFragment (void);

  void NextFragment (void);

  Ptr<Packet> GetFragmentPacket (WifiMacHeader *hdr);

  Dcf *m_dcf;

  DcfManager *m_manager;

  TxOk m_txOkCallback;

  TxFailed m_txFailedCallback;

  WifiMacQueue *m_queue;

  MacTxMiddle *m_txMiddle;

  MacStations *m_stations;

  MacParameters *m_parameters;

  TransmissionListener *m_transmissionListener;

  RandomStream *m_rng;

  bool m_accessOngoing;

  Ptr<const Packet> m_currentPacket;

  WifiMacHeader m_currentHdr;

  uint32_t m_ssrc;

  uint32_t m_slrc;

  uint8_t m_fragmentNumber;

  /* 80211-dca-acktimeout

   * param1: slrc

   */

  CallbackTraceSource<uint32_t> m_acktimeoutTrace;

  /* 80211-dca-ctstimeout

   * param1: ssrc

   */

  CallbackTraceSource<uint32_t> m_ctstimeoutTrace;

};

} //namespace ns3

#endif /* DCA_TXOP_H */