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

/*

 * Copyright (c) 2004,2005,2006 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: Federico Maguolo <maguolof@dei.unipd.it>

 */

#include "aarfcd-wifi-manager.h"

#include "ns3/assert.h"

#include "ns3/log.h"

#include "ns3/simulator.h"

#include "ns3/boolean.h"

#include "ns3/double.h"

#include "ns3/uinteger.h"

#include <algorithm>

#define Min(a,b) ((a<b)?a:b)

#define Max(a,b) ((a>b)?a:b)

NS_LOG_COMPONENT_DEFINE ("Aarfcd");

namespace ns3 {

struct AarfcdWifiRemoteStation : public WifiRemoteStation

{

  uint32_t m_timer;

  uint32_t m_success;

  uint32_t m_failed;

  bool m_recovery;

  bool m_justModifyRate;

  uint32_t m_retry;

  uint32_t m_successThreshold;

  uint32_t m_timerTimeout;

  uint32_t m_rate;

  bool m_rtsOn;

  uint32_t m_rtsWnd;

  uint32_t m_rtsCounter;

  bool m_haveASuccess;

};

NS_OBJECT_ENSURE_REGISTERED(AarfcdWifiManager);

TypeId 

AarfcdWifiManager::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::AarfcdWifiManager")

    .SetParent<WifiRemoteStationManager> ()

    .AddConstructor<AarfcdWifiManager> ()

    .AddAttribute ("SuccessK", "Multiplication factor for the success threshold in the AARF algorithm.",

                   DoubleValue (2.0),

                   MakeDoubleAccessor (&AarfcdWifiManager::m_successK),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("TimerK",

                   "Multiplication factor for the timer threshold in the AARF algorithm.",

                   DoubleValue (2.0),

                   MakeDoubleAccessor (&AarfcdWifiManager::m_timerK),

                   MakeDoubleChecker<double> ())

    .AddAttribute ("MaxSuccessThreshold",

                   "Maximum value of the success threshold in the AARF algorithm.",

                   UintegerValue (60),

                   MakeUintegerAccessor (&AarfcdWifiManager::m_maxSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinTimerThreshold",

                   "The minimum value for the 'timer' threshold in the AARF algorithm.",

                   UintegerValue (15),

                   MakeUintegerAccessor (&AarfcdWifiManager::m_minTimerThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinSuccessThreshold",

                   "The minimum value for the success threshold in the AARF algorithm.",

                   UintegerValue (10),

                   MakeUintegerAccessor (&AarfcdWifiManager::m_minSuccessThreshold),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MinRtsWnd", 

                   "Minimum value for Rts window of Aarf-CD",

                   UintegerValue (1),

                   MakeUintegerAccessor (&AarfcdWifiManager::m_minRtsWnd),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("MaxRtsWnd", 

                   "Maximum value for Rts window of Aarf-CD",

                   UintegerValue (40),

                   MakeUintegerAccessor (&AarfcdWifiManager::m_maxRtsWnd),

                   MakeUintegerChecker<uint32_t> ())

    .AddAttribute ("TurnOffRtsAfterRateDecrease",

                   "If true the RTS mechanism will be turned off when the rate will be decreased",

                   BooleanValue (true),

                   MakeBooleanAccessor (&AarfcdWifiManager::m_turnOffRtsAfterRateDecrease),

                   MakeBooleanChecker ())

    .AddAttribute ("TurnOnRtsAfterRateIncrease",

                   "If true the RTS mechanism will be turned on when the rate will be increased",

                   BooleanValue (true),

                   MakeBooleanAccessor (&AarfcdWifiManager::m_turnOnRtsAfterRateIncrease),

                   MakeBooleanChecker ())

    ;

  return tid;

}

AarfcdWifiManager::AarfcdWifiManager ()

  : WifiRemoteStationManager ()

{}

AarfcdWifiManager::~AarfcdWifiManager ()

{}

WifiRemoteStation *

AarfcdWifiManager::DoCreateStation (void) const

{

  AarfcdWifiRemoteStation *station = new AarfcdWifiRemoteStation ();

  // aarf fields below

  station->m_successThreshold = m_minSuccessThreshold;

  station->m_timerTimeout = m_minTimerThreshold;

  station->m_rate = 0;

  station->m_success = 0;

  station->m_failed = 0;

  station->m_recovery = false;

  station->m_retry = 0;

  station->m_timer = 0;

  // aarf-cd specific fields below

  station->m_rtsOn = false;

  station->m_rtsWnd = m_minRtsWnd;

  station->m_rtsCounter = 0;

  station->m_justModifyRate = true;

  station->m_haveASuccess = false;

  return station;

}

void 

AarfcdWifiManager::DoReportRtsFailed (WifiRemoteStation *station)

{}

/**

 * It is important to realize that "recovery" mode starts after failure of

 * the first transmission after a rate increase and ends at the first successful

 * transmission. Specifically, recovery mode transcends retransmissions boundaries.

 * Fundamentally, ARF handles each data transmission independently, whether it

 * is the initial transmission of a packet or the retransmission of a packet.

 * The fundamental reason for this is that there is a backoff between each data

 * transmission, be it an initial transmission or a retransmission.

 */

void 

AarfcdWifiManager::DoReportDataFailed (WifiRemoteStation *st)

{

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *)st;

  station->m_timer++;

  station->m_failed++;

  station->m_retry++;

  station->m_success = 0;

  if (!station->m_rtsOn) 

    {

      TurnOnRts (station);

      if (!station->m_justModifyRate && !station->m_haveASuccess) 

        {

          IncreaseRtsWnd (station);

        }

      else 

        {

          ResetRtsWnd (station);

        }

      station->m_rtsCounter = station->m_rtsWnd;

      if (station->m_retry >= 2) 

        {

          station->m_timer = 0;

        }

    }

  else if (station->m_recovery) 

    {

      NS_ASSERT (station->m_retry >= 1);

      station->m_justModifyRate = false;

      station->m_rtsCounter = station->m_rtsWnd;

      if (station->m_retry == 1)

        {

          // need recovery fallback

          if (m_turnOffRtsAfterRateDecrease) 

            {

              TurnOffRts (station);

            }

          station->m_justModifyRate = true;

          station->m_successThreshold = (int)(Min (station->m_successThreshold * m_successK,

                                                   m_maxSuccessThreshold));

          station->m_timerTimeout = (int)(Max (station->m_timerTimeout * m_timerK,

                                               m_minSuccessThreshold));

          if (station->m_rate != 0)

            {

              station->m_rate--;

            }

        }

      station->m_timer = 0;

    } 

  else 

    {

      NS_ASSERT (station->m_retry >= 1);

      station->m_justModifyRate = false;

      station->m_rtsCounter = station->m_rtsWnd;

      if (((station->m_retry - 1) % 2) == 1)

        {

          // need normal fallback

          if (m_turnOffRtsAfterRateDecrease) 

            {

              TurnOffRts (station);

            }

          station->m_justModifyRate = true;

          station->m_timerTimeout = m_minTimerThreshold;

          station->m_successThreshold = m_minSuccessThreshold;

          if (station->m_rate != 0)

            {

              station->m_rate--;

            }

        }

      if (station->m_retry >= 2) 

        {

          station->m_timer = 0;

        }

    }

  CheckRts (station);

}

void 

AarfcdWifiManager::DoReportRxOk (WifiRemoteStation *station,

                              double rxSnr, WifiMode txMode)

{}

void 

AarfcdWifiManager::DoReportRtsOk (WifiRemoteStation *st,

                                double ctsSnr, WifiMode ctsMode, double rtsSnr)

{

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *) st;

  NS_LOG_DEBUG ("station=" << station << " rts ok");

  station->m_rtsCounter--;

}

void 

AarfcdWifiManager::DoReportDataOk (WifiRemoteStation *st,

                                 double ackSnr, WifiMode ackMode, double dataSnr)

{

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *) st;

  station->m_timer++;

  station->m_success++;

  station->m_failed = 0;

  station->m_recovery = false;

  station->m_retry = 0;

  station->m_justModifyRate = false;

  station->m_haveASuccess = true;

  NS_LOG_DEBUG ("station=" << station << " data ok success=" << station->m_success << ", timer=" << station->m_timer);

  if ((station->m_success == station->m_successThreshold ||

       station->m_timer == station->m_timerTimeout) &&

      (station->m_rate < (GetNSupported (station) - 1))) 

    {

      NS_LOG_DEBUG ("station="<<station<<" inc rate");

      station->m_rate++;

      station->m_timer = 0;

      station->m_success = 0;

      station->m_recovery = true;

      station->m_justModifyRate = true;

      if (m_turnOnRtsAfterRateIncrease) 

        {

          TurnOnRts (station);

          ResetRtsWnd (station);

          station->m_rtsCounter = station->m_rtsWnd;

        }

    }

  CheckRts (station);

}

void 

AarfcdWifiManager::DoReportFinalRtsFailed (WifiRemoteStation *station)

{}

void 

AarfcdWifiManager::DoReportFinalDataFailed (WifiRemoteStation *station)

{}

WifiMode

AarfcdWifiManager::DoGetDataMode (WifiRemoteStation *st, uint32_t size)

{

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *) st;

  return GetSupported (station, station->m_rate);

}

WifiMode

AarfcdWifiManager::DoGetRtsMode (WifiRemoteStation *st)

{

  // XXX: we could/should implement the Aarf algorithm for

  // RTS only by picking a single rate within the BasicRateSet.

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *) st;

  return GetSupported (station, 0);

}

bool

AarfcdWifiManager::DoNeedRts (WifiRemoteStation *st,

                              Ptr<const Packet> packet, bool normally)

{

  AarfcdWifiRemoteStation *station = (AarfcdWifiRemoteStation *) st;

  NS_LOG_INFO ("" << station << " rate=" << station->m_rate << " rts=" << (station->m_rtsOn?"RTS":"BASIC") << 

               " rtsCounter=" << station->m_rtsCounter);

  return station->m_rtsOn;

}

bool 

AarfcdWifiManager::IsLowLatency (void) const

{

  return true;

}

void

AarfcdWifiManager::CheckRts (AarfcdWifiRemoteStation *station)

{

  if (station->m_rtsCounter == 0 && station->m_rtsOn) 

    {

      TurnOffRts (station);

    }

}

void

AarfcdWifiManager::TurnOffRts (AarfcdWifiRemoteStation *station)

{

  station->m_rtsOn = false;

  station->m_haveASuccess = false;

}

void

AarfcdWifiManager::TurnOnRts (AarfcdWifiRemoteStation *station)

{

  station->m_rtsOn = true;

}

void

AarfcdWifiManager::IncreaseRtsWnd (AarfcdWifiRemoteStation *station)

{

  if (station->m_rtsWnd == m_maxRtsWnd)

    {

      return;

    }

  station->m_rtsWnd *= 2;

  if (station->m_rtsWnd > m_maxRtsWnd)

    {

      station->m_rtsWnd = m_maxRtsWnd;

    }

}

void

AarfcdWifiManager::ResetRtsWnd (AarfcdWifiRemoteStation *station)

{

  station->m_rtsWnd = m_minRtsWnd;

}

} // namespace ns3