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

/*

 * Copyright (c) 2005,2006,2007 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 WIFI_REMOTE_STATION_MANAGER_H

#define WIFI_REMOTE_STATION_MANAGER_H

#include <vector>

#include <utility>

#include "ns3/mac48-address.h"

#include "ns3/traced-callback.h"

#include "ns3/packet.h"

#include "ns3/object.h"

#include "ns3/nstime.h"

#include "wifi-mode.h"

namespace ns3 {

struct WifiRemoteStation;

struct WifiRemoteStationState;

class WifiPhy;

class WifiMacHeader;

/**

 * \brief Tid independent remote station statistics

 *

 * Structure is similar to struct sta_info in Linux kernel (see

 * net/mac80211/sta_info.h)

 */

class WifiRemoteStationInfo

{

public:

  WifiRemoteStationInfo ();

  /**

   * \brief Updates average frame error rate when data or RTS

   * was transmitted successfully.

   * \param retryCounter is slrc or ssrc value at the moment of

   * success transmission.

   */

  void NotifyTxSuccess (uint32_t retryCounter);

  /// Updates average frame error rate when final data or RTS has failed.

  void NotifyTxFailed ();

  /// Returns frame error rate (probability that frame is corrupted due to transmission error).

  double GetFrameErrorRate () const;

private:

  /**

   * \brief Calculate averaging coefficient for frame error rate. Depends on time of the last update.

   * \attention Calling this method twice gives different results,

   * because it resets time of last update.

   */

  double CalculateAveragingCoefficient ();

  ///averaging coefficient depends on the memory time

  Time m_memoryTime;

  ///when last update has occured

  Time m_lastUpdate;

  /// moving percentage of failed frames

  double m_failAvg;

};

/**

 * \brief hold a list of per-remote-station state.

 *

 * \sa ns3::WifiRemoteStation.

 */

class WifiRemoteStationManager : public Object

{

public:

  static TypeId GetTypeId (void);

  WifiRemoteStationManager ();

  virtual ~WifiRemoteStationManager ();

  virtual void SetupPhy (Ptr<WifiPhy> phy);

  uint32_t GetMaxSsrc (void) const;

  uint32_t GetMaxSlrc (void) const;

  uint32_t GetRtsCtsThreshold (void) const;

  uint32_t GetFragmentationThreshold (void) const;

  void SetMaxSsrc (uint32_t maxSsrc);

  void SetMaxSlrc (uint32_t maxSlrc);

  void SetRtsCtsThreshold (uint32_t threshold);

  void SetFragmentationThreshold (uint32_t threshold);

  // Invoked in a STA upon dis-association

  // or in an AP upon reboot

  void Reset (void);

  // Invoked in a STA upon association to store

  // the set of rates which belong to the 

  // BSSBasicRateSet of the associated AP

  // and which are supported locally.

  // Invoked in an AP to configure the BSSBasicRateSet

  void AddBasicMode (WifiMode mode);

  WifiMode GetDefaultMode (void) const;

  uint32_t GetNBasicModes (void) const;

  WifiMode GetBasicMode (uint32_t i) const;

  WifiMode GetNonUnicastMode (void) const;

  /**

   * Invoked in an AP upon disassociation of a

   * specific STA.

   */

  void Reset (Mac48Address address);

  /**

   * Invoked in a STA or AP to store the set of 

   * modes supported by a destination which is

   * also supported locally.

   * The set of supported modes includes

   * the BSSBasicRateSet.

   */

  void AddSupportedMode (Mac48Address address, WifiMode mode);

  bool IsBrandNew (Mac48Address address) const;

  bool IsAssociated (Mac48Address address) const;

  bool IsWaitAssocTxOk (Mac48Address address) const;

  void RecordWaitAssocTxOk (Mac48Address address);

  void RecordGotAssocTxOk (Mac48Address address);

  void RecordGotAssocTxFailed (Mac48Address address);

  void RecordDisassociated (Mac48Address address);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to queue

   * \param fullPacketSize the size of the packet after its 802.11 MAC header has been added.

   *

   * This method is typically invoked just before queuing a packet for transmission.

   * It is a no-op unless the IsLowLatency attribute of the attached ns3::WifiRemoteStationManager

   * is set to false, in which case, the tx parameters of the packet are calculated and stored in

   * the packet as a tag. These tx parameters are later retrieved from GetDadaMode and GetRtsMode.

   */

  void PrepareForQueue (Mac48Address address, const WifiMacHeader *header,

                        Ptr<const Packet> packet, uint32_t fullPacketSize);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \param fullPacketSize the size of the packet after its 802.11 MAC header has been added.

   * \returns the transmission mode to use to send this packet

   */

  WifiMode GetDataMode (Mac48Address address, const WifiMacHeader *header,

                        Ptr<const Packet> packet, uint32_t fullPacketSize);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \returns the transmission mode to use to send the RTS prior to the

   *          transmission of the data packet itself.

   */

  WifiMode GetRtsMode (Mac48Address address, const WifiMacHeader *header,

                       Ptr<const Packet> packet);

  /**

   * Should be invoked whenever the RtsTimeout associated to a transmission

   * attempt expires.

   */

  void ReportRtsFailed (Mac48Address address, const WifiMacHeader *header);

  /**

   * Should be invoked whenever the AckTimeout associated to a transmission

   * attempt expires.

   */

  void ReportDataFailed (Mac48Address address, const WifiMacHeader *header);

  /**

   * Should be invoked whenever we receive the Cts associated to an RTS 

   * we just sent.

   */

  void ReportRtsOk (Mac48Address address, const WifiMacHeader *header,

                    double ctsSnr, WifiMode ctsMode, double rtsSnr);

  /**

   * Should be invoked whenever we receive the Ack associated to a data packet

   * we just sent.

   */

  void ReportDataOk (Mac48Address address, const WifiMacHeader *header,

                     double ackSnr, WifiMode ackMode, double dataSnr);

  /**

   * Should be invoked after calling ReportRtsFailed if 

   * NeedRtsRetransmission returns false

   */

  void ReportFinalRtsFailed (Mac48Address address, const WifiMacHeader *header);

  /**

   * Should be invoked after calling ReportDataFailed if 

   * NeedDataRetransmission returns false

   */

  void ReportFinalDataFailed (Mac48Address address, const WifiMacHeader *header);

  /**

   * \param address remote address

   * \param header MAC header

   * \param rxSnr the snr of the packet received

   * \param txMode the transmission mode used for the packet received.

   *

   * Should be invoked whenever a packet is successfully received.

   */

  void ReportRxOk (Mac48Address address, const WifiMacHeader *header,

                   double rxSnr, WifiMode txMode);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \returns true if we want to use an RTS/CTS handshake for this

   *          packet before sending it, false otherwise.

   */

  bool NeedRts (Mac48Address address, const WifiMacHeader *header,

                Ptr<const Packet> packet);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \returns true if we want to restart a failed RTS/CTS 

   *          handshake, false otherwise.

   */

  bool NeedRtsRetransmission (Mac48Address address, const WifiMacHeader *header,

                              Ptr<const Packet> packet);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \returns true if we want to resend a packet 

   *          after a failed transmission attempt, false otherwise.

   */

  bool NeedDataRetransmission (Mac48Address address, const WifiMacHeader *header,

                               Ptr<const Packet> packet);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \returns true if this packet should be fragmented, false otherwise.

   */

  bool NeedFragmentation (Mac48Address address, const WifiMacHeader *header,

                                  Ptr<const Packet> packet);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \param fragmentNumber the fragment index of the next fragment to send (starts at zero).

   * \returns the size of the corresponding fragment.

   */

  uint32_t GetFragmentSize (Mac48Address address, const WifiMacHeader *header,

                            Ptr<const Packet> packet, uint32_t fragmentNumber);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \param fragmentNumber the fragment index of the next fragment to send (starts at zero).

   * \returns the offset within the original packet where this fragment starts.

   */

  uint32_t GetFragmentOffset (Mac48Address address, const WifiMacHeader *header,

                              Ptr<const Packet> packet, uint32_t fragmentNumber);

  /**

   * \param address remote address

   * \param header MAC header

   * \param packet the packet to send

   * \param fragmentNumber the fragment index of the next fragment to send (starts at zero).

   * \returns true if this is the last fragment, false otherwise.

   */

  bool IsLastFragment (Mac48Address address, const WifiMacHeader *header,

                       Ptr<const Packet> packet, uint32_t fragmentNumber);

  /**

   * \param address remote address

   * \param rtsMode the transmission mode used to send an RTS we just received

   * \returns the transmission mode to use for the CTS to complete the RTS/CTS

   *          handshake.

   */

  WifiMode GetCtsMode (Mac48Address address, WifiMode rtsMode);

  /**

   * \param address

   * \param dataMode the transmission mode used to send an ACK we just received

   * \returns the transmission mode to use for the ACK to complete the data/ACK

   *          handshake.

   */

  WifiMode GetAckMode (Mac48Address address, WifiMode dataMode);

  WifiRemoteStationInfo GetInfo (Mac48Address address);

protected:

  virtual void DoDispose (void);

  // for convenience

  WifiMode GetSupported (const WifiRemoteStation *station, uint32_t i) const;

  uint32_t GetNSupported (const WifiRemoteStation *station) const;

private:

  /**

   * \param station the station with which we need to communicate

   * \param packet the packet to send

   * \param normally indicates whether the normal 802.11 rts enable mechanism would

   *        request that the rts is sent or not.

   * \returns true if we want to use an RTS/CTS handshake for this

   *          packet before sending it, false otherwise.

   *

   * Note: This method is called before a unicast packet is sent on the medium.

   */

  virtual bool DoNeedRts (WifiRemoteStation *station, 

                          Ptr<const Packet> packet, bool normally);

  /**

   * \param station the station with which we need to communicate

   * \param packet the packet to send

   * \param normally indicates whether the normal 802.11 rts enable mechanism would

   *        request that the rts is retransmitted or not.

   * \returns true if we want to restart a failed RTS/CTS 

   *          handshake, false otherwise.

   *

   * Note: This method is called after an rts/cts handshake has been attempted

   *       and has failed.

   */

  virtual bool DoNeedRtsRetransmission (WifiRemoteStation *station, 

                                        Ptr<const Packet> packet, bool normally);

  /**

   * \param station the station with which we need to communicate

   * \param packet the packet to send

   * \param normally indicates whether the normal 802.11 data retransmission mechanism

   *        would request that the data is retransmitted or not.

   * \returns true if we want to resend a packet 

   *          after a failed transmission attempt, false otherwise.

   *

   * Note: This method is called after a unicast packet transmission has been attempted

   *       and has failed.

   */

  virtual bool DoNeedDataRetransmission (WifiRemoteStation *station, 

                                         Ptr<const Packet> packet, bool normally);

  /**

   * \param station the station with which we need to communicate

   * \param packet the packet to send

   * \param normally indicates whether the normal 802.11 data fragmentation mechanism

   *        would request that the data packet is fragmented or not.

   * \returns true if this packet should be fragmented, false otherwise.

   *

   * Note: This method is called before sending a unicast packet.

   */

  virtual bool DoNeedFragmentation (WifiRemoteStation *station, 

                                    Ptr<const Packet> packet, bool normally);

  /**

   * \returns whether this manager is a manager designed to work in low-latency

   *          environments.

   *

   * Note: In this context, low vs high latency is defined in <i>IEEE 802.11 Rate Adaptation:

   * A Practical Approach</i>, by M. Lacage, M.H. Manshaei, and T. Turletti.

   */

  virtual bool IsLowLatency (void) const = 0;

  /**

   * \return a new station data structure

   */

  virtual WifiRemoteStation *DoCreateStation (void) const = 0;

  /**

   * \param station the station with which we need to communicate

   * \param size size of the packet or fragment we want to send

   * \returns the transmission mode to use to send a packet to the station

   *

   * Note: This method is called before sending a unicast packet or a fragment

   *       of a unicast packet to decide which transmission mode to use.

   */

  virtual WifiMode DoGetDataMode (WifiRemoteStation *station,

                                  uint32_t size) = 0;

  /**

   * \param station the station with which we need to communicate

   * \returns the transmission mode to use to send an rts to the station

   *

   * Note: This method is called before sending an rts to a station

   *       to decide which transmission mode to use for the rts.

   */

  virtual WifiMode DoGetRtsMode (WifiRemoteStation *station) = 0;

  virtual void DoReportRtsFailed (WifiRemoteStation *station) = 0;

  virtual void DoReportDataFailed (WifiRemoteStation *station) = 0;

  virtual void DoReportRtsOk (WifiRemoteStation *station,

                              double ctsSnr, WifiMode ctsMode, double rtsSnr) = 0;

  virtual void DoReportDataOk (WifiRemoteStation *station,

                               double ackSnr, WifiMode ackMode, double dataSnr) = 0;

  virtual void DoReportFinalRtsFailed (WifiRemoteStation *station) = 0;

  virtual void DoReportFinalDataFailed (WifiRemoteStation *station) = 0;

  virtual void DoReportRxOk (WifiRemoteStation *station,

                             double rxSnr, WifiMode txMode) = 0;

  WifiRemoteStationState *LookupState (Mac48Address address) const;

  WifiRemoteStation *Lookup (Mac48Address address, uint8_t tid) const;

  /// Find a remote station by its remote address and TID taken from MAC header

  WifiRemoteStation *Lookup (Mac48Address address, const WifiMacHeader *header) const;

  WifiMode GetControlAnswerMode (Mac48Address address, WifiMode reqMode);

  uint32_t GetNFragments (Ptr<const Packet> packet);

  typedef std::vector <WifiRemoteStation *> Stations;

  typedef std::vector <WifiRemoteStationState *> StationStates;

  StationStates m_states;

  Stations m_stations;

  /**

   * This is a pointer to the WifiPhy associated with this

   * WifiRemoteStationManager that is set on call to

   * WifiRemoteStationManager::SetupPhy(). Through this pointer the

   * station manager can determine PHY characteristics, such as the

   * set of all transmission rates that may be supported (the

   * "DeviceRateSet").

   */

  Ptr<WifiPhy> m_wifiPhy;

  WifiMode m_defaultTxMode;

  /**

   * This member is the list of WifiMode objects that comprise the

   * BSSBasicRateSet parameter. This list is constructed through calls

   * to WifiRemoteStationManager::AddBasicMode(), and an API that

   * allows external access to it is available through

   * WifiRemoteStationManager::GetNBasicModes() and

   * WifiRemoteStationManager::GetBasicMode().

   */

  WifiModeList m_bssBasicRateSet;

  bool m_isLowLatency;

  uint32_t m_maxSsrc;

  uint32_t m_maxSlrc;

  uint32_t m_rtsCtsThreshold;

  uint32_t m_fragmentationThreshold;

  WifiMode m_nonUnicastMode;

  double m_avgSlrcCoefficient;

  /**

   * The trace source fired when the transmission of a single RTS has failed

   */

  TracedCallback<Mac48Address> m_macTxRtsFailed;

  /**

   * The trace source fired when the transmission of a single data packet has failed 

   */

  TracedCallback<Mac48Address> m_macTxDataFailed;

  /**

   * The trace source fired when the transmission of a RTS has

   * exceeded the maximum number of attempts

   */

  TracedCallback<Mac48Address> m_macTxFinalRtsFailed;

  /**

   * The trace source fired when the transmission of a data packet has

   * exceeded the maximum number of attempts

   */

  TracedCallback<Mac48Address> m_macTxFinalDataFailed;

};

struct WifiRemoteStationState

{

  enum 

    {

      BRAND_NEW,

      DISASSOC,

      WAIT_ASSOC_TX_OK,

      GOT_ASSOC_TX_OK

    } m_state;

  /**

   * This member is the list of WifiMode objects that comprise the

   * OperationalRateSet parameter for this remote station. This list

   * is constructed through calls to

   * WifiRemoteStationManager::AddSupportedMode(), and an API that

   * allows external access to it is available through

   * WifiRemoteStationManager::GetNSupported() and

   * WifiRemoteStationManager::GetSupported().

   */

  WifiModeList m_operationalRateSet;

  Mac48Address m_address;

  WifiRemoteStationInfo m_info;

};

/**

 * \brief hold per-remote-station state.

 *

 * The state in this class is used to keep track

 * of association status if we are in an infrastructure

 * network and to perform the selection of tx parameters

 * on a per-packet basis.

 */

struct WifiRemoteStation

{

  WifiRemoteStationState *m_state;

  uint32_t m_ssrc;

  uint32_t m_slrc;