/* -*-  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/nstime.h"

#include "ns3/object.h"

#include "wifi-mac-header.h"

#include "wifi-mode.h"

#include "wifi-remote-station-manager.h"

#include "dcf.h"

namespace ns3 {

class DcfState;

class DcfManager;

class WifiMacQueue;

class MacLow;

class WifiMacParameters;

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.

 */

class DcaTxop : public Dcf

{

public:

  static TypeId GetTypeId (void);

  typedef Callback <void, const WifiMacHeader&> TxOk;

  typedef Callback <void, const WifiMacHeader&> TxFailed;

  DcaTxop ();

  ~DcaTxop ();

  void SetLow (Ptr<MacLow> low);

  void SetManager (DcfManager *manager);

  void SetWifiRemoteStationManager (Ptr<WifiRemoteStationManager> remoteManager);

  /**

   * \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);

  virtual void SetMinCw (uint32_t minCw);

  virtual void SetMaxCw (uint32_t maxCw);

  virtual void SetAifsn (uint32_t aifsn);

  virtual uint32_t GetMinCw (void) const;

  virtual uint32_t GetMaxCw (void) const;

  virtual uint32_t GetAifsn (void) const;

  /**

   * \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, const WifiMacHeader &hdr);

private:

  class TransmissionListener;

  class NavListener;

  class PhyListener;

  class Dcf;

  friend class Dcf;

  friend class TransmissionListener;

  friend class WifiRemoteStation;

  DcaTxop &operator = (const DcaTxop &);

  DcaTxop (const DcaTxop &o);

  // Inherited from ns3::Object

  Ptr<MacLow> Low (void);

  /* dcf notifications forwarded here */

  bool NeedsAccess (void) const;

  void NotifyAccessGranted (void);

  void NotifyInternalCollision (void);

  void NotifyCollision (void);

  /**

  * When a channel switching occurs, enqueued packets are removed.

  */

  void NotifyChannelSwitching (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 (Ptr<const Packet> packet);

  bool NeedRtsRetransmission (void);

  bool NeedDataRetransmission (void);

  bool NeedFragmentation (void);

  uint32_t GetNextFragmentSize (void);

  uint32_t GetFragmentSize (void);

  uint32_t GetFragmentOffset (void);

  WifiRemoteStation *GetStation (Mac48Address to) const;

  bool IsLastFragment (void);

  void NextFragment (void);

  Ptr<Packet> GetFragmentPacket (WifiMacHeader *hdr);

  virtual void DoDispose (void);

  Dcf *m_dcf;

  DcfManager *m_manager;

  TxOk m_txOkCallback;

  TxFailed m_txFailedCallback;

  Ptr<WifiMacQueue> m_queue;

  MacTxMiddle *m_txMiddle;

  Ptr <MacLow> m_low;

  Ptr<WifiRemoteStationManager> m_stationManager;

  TransmissionListener *m_transmissionListener;

  RandomStream *m_rng;

  bool m_accessOngoing;

  Ptr<const Packet> m_currentPacket;

  WifiMacHeader m_currentHdr;

  uint8_t m_fragmentNumber;

};

} //namespace ns3

#endif /* DCA_TXOP_H */