/* -*-  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>

 */

#include "ns3/assert.h"

#include "ns3/packet.h"

#include "ns3/log.h"

#include "ns3/simulator.h"

#include "ns3/net-device.h"

#include "ns3/node.h"

#include "dca-txop.h"

#include "dcf-manager.h"

#include "mac-parameters.h"

#include "mac-low.h"

#include "wifi-mac-queue.h"

#include "mac-tx-middle.h"

#include "wifi-phy.h"

#include "random-stream.h"

NS_LOG_COMPONENT_DEFINE ("DcaTxop");

#define MY_DEBUG(x) \

  NS_LOG_DEBUG (Simulator::Now () << " " << m_low->GetDevice ()->GetNode ()->GetId () << ":" << \

                m_low->GetDevice ()->GetIfIndex () << " " << x)

namespace ns3 {

class DcaTxop::Dcf : public DcfState

{

public:

  Dcf (DcaTxop *txop)

    : m_txop (txop)

  {}

private:

  virtual void DoNotifyAccessGranted (void) {

    m_txop->NotifyAccessGranted ();

  }

  virtual void DoNotifyInternalCollision (void) {

    m_txop->NotifyInternalCollision ();

  }

  virtual void DoNotifyCollision (void) {

    m_txop->NotifyCollision ();

  }

  DcaTxop *m_txop;

};

class DcaTxop::TransmissionListener : public MacLowTransmissionListener {

public:

  TransmissionListener (DcaTxop *txop)

    : MacLowTransmissionListener (),

      m_txop (txop) {}

  virtual ~TransmissionListener () {}

  virtual void GotCts (double snr, WifiMode txMode) {

    m_txop->GotCts (snr, txMode);

  }

  virtual void MissedCts (void) {

    m_txop->MissedCts ();

  }

  virtual void GotAck (double snr, WifiMode txMode) {

    m_txop->GotAck (snr, txMode);

  }

  virtual void MissedAck (void) {

    m_txop->MissedAck ();

  }

  virtual void StartNext (void) {

    m_txop->StartNext ();

  }

  virtual void Cancel (void) {

    m_txop->Cancel ();

  }

private:

  DcaTxop *m_txop;

};

DcaTxop::DcaTxop (uint32_t minCw, uint32_t maxCw, uint32_t aifsn, DcfManager *manager)

  : m_manager (manager),

    m_currentPacket (0),

    m_ssrc (0),

    m_slrc (0)

{

  m_transmissionListener = new DcaTxop::TransmissionListener (this);

  m_dcf = new DcaTxop::Dcf (this);

  m_dcf->SetCwBounds (minCw, maxCw);

  m_dcf->SetAifsn (aifsn);

  m_manager->Add (m_dcf);

  m_queue = new WifiMacQueue ();

  m_rng = new RealRandomStream ();

}

DcaTxop::~DcaTxop ()

{

  delete m_transmissionListener;

  delete m_queue;

  delete m_dcf;

  delete m_rng;

  m_transmissionListener = 0;

  m_queue = 0;

  m_dcf = 0;

  m_rng = 0;

}

void 

DcaTxop::SetLow (MacLow *low)

{

  m_low = low;

}

void 

DcaTxop::SetParameters (MacParameters *parameters)

{

  m_parameters = parameters;

}

void 

DcaTxop::SetTxMiddle (MacTxMiddle *txMiddle)

{

  m_txMiddle = txMiddle;

}

void 

DcaTxop::SetTxOkCallback (TxOk callback)

{

  m_txOkCallback = callback;

}

void 

DcaTxop::SetTxFailedCallback (TxFailed callback)

{

  m_txFailedCallback = callback;

}

void 

DcaTxop::SetMaxQueueSize (uint32_t size)

{

  m_queue->SetMaxSize (size);

}

void 

DcaTxop::SetMaxQueueDelay (Time delay)

{

  m_queue->SetMaxDelay (delay);

}

void 

DcaTxop::Queue (Ptr<const Packet> packet, WifiMacHeader const &hdr)

{

  m_queue->Enqueue (packet, hdr);

  StartAccessIfNeeded ();

}

void

DcaTxop::RestartAccessIfNeeded (void)

{

  if ((m_currentPacket != 0 ||

       !m_queue->IsEmpty ()) &&

      !m_dcf->IsAccessRequested ())

    {

      m_manager->RequestAccess (m_dcf);

    }

}

void

DcaTxop::StartAccessIfNeeded (void)

{

  if (m_currentPacket == 0 &&

      !m_queue->IsEmpty () &&

      !m_dcf->IsAccessRequested ())

    {

      m_manager->RequestAccess (m_dcf);

    }

}

MacLow *

DcaTxop::Low (void)

{

  return m_low;

}

MacParameters *

DcaTxop::Parameters (void)

{

  return m_parameters;

}

bool

DcaTxop::NeedRts (void)

{

  if (m_currentPacket->GetSize () > Parameters ()->GetRtsCtsThreshold ()) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

bool

DcaTxop::NeedFragmentation (void)

{

  if (m_currentPacket->GetSize () > Parameters ()->GetFragmentationThreshold ()) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

uint32_t

DcaTxop::GetNFragments (void)

{

  uint32_t nFragments = m_currentPacket->GetSize () / Parameters ()->GetFragmentationThreshold () + 1;

  return nFragments;

}

void

DcaTxop::NextFragment (void)

{

  m_fragmentNumber++;

}

uint32_t

DcaTxop::GetLastFragmentSize (void)

{

  uint32_t lastFragmentSize = m_currentPacket->GetSize () %

    Parameters ()->GetFragmentationThreshold ();

  return lastFragmentSize;

}

uint32_t

DcaTxop::GetFragmentSize (void)

{

  return Parameters ()->GetFragmentationThreshold ();

}

bool

DcaTxop::IsLastFragment (void) 

{

  if (m_fragmentNumber == (GetNFragments () - 1)) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

uint32_t

DcaTxop::GetNextFragmentSize (void) 

{

  if (IsLastFragment ()) 

    {

      return 0;

    }

  uint32_t nextFragmentNumber = m_fragmentNumber + 1;

  if (nextFragmentNumber == (GetNFragments () - 1)) 

    {

      return GetLastFragmentSize ();

    } 

  else 

    {

      return GetFragmentSize ();

    }

}

Ptr<Packet>

DcaTxop::GetFragmentPacket (WifiMacHeader *hdr)

{

  *hdr = m_currentHdr;

  hdr->SetFragmentNumber (m_fragmentNumber);

  uint32_t startOffset = m_fragmentNumber * GetFragmentSize ();

  Ptr<Packet> fragment;

  if (IsLastFragment ()) 

    {

      hdr->SetNoMoreFragments ();

      fragment = m_currentPacket->CreateFragment (startOffset, 

                                                 GetLastFragmentSize ());

    } 

  else 

    {

      hdr->SetMoreFragments ();

      fragment = m_currentPacket->CreateFragment (startOffset, 

                                                 GetFragmentSize ());

    }

  return fragment;

}

bool 

DcaTxop::NeedsAccess (void) const

{

  return !m_queue->IsEmpty () || m_currentPacket != 0;

}

void 

DcaTxop::NotifyAccessGranted (void)

{

  if (m_currentPacket == 0) 

    {

      if (m_queue->IsEmpty ()) 

        {

          MY_DEBUG ("queue empty");

          return;

        }

      m_currentPacket = m_queue->Dequeue (&m_currentHdr);

      NS_ASSERT (m_currentPacket != 0);

      uint16_t sequence = m_txMiddle->GetNextSequenceNumberfor (&m_currentHdr);

      m_currentHdr.SetSequenceNumber (sequence);

      m_currentHdr.SetFragmentNumber (0);

      m_currentHdr.SetNoMoreFragments ();

      m_currentHdr.SetNoRetry ();

      m_ssrc = 0;

      m_slrc = 0;

      m_fragmentNumber = 0;

      MY_DEBUG ("dequeued size="<<m_currentPacket->GetSize ()<<

                    ", to="<<m_currentHdr.GetAddr1 ()<<

                    ", seq="<<m_currentHdr.GetSequenceControl ()); 

    }

  MacLowTransmissionParameters params;

  params.DisableOverrideDurationId ();

  if (m_currentHdr.GetAddr1 ().IsBroadcast ()) 

    {

      params.DisableRts ();

      params.DisableAck ();

      params.DisableNextData ();

      Low ()->StartTransmission (m_currentPacket,

                                 &m_currentHdr,

                                 params,

                                 m_transmissionListener);

      m_currentPacket = 0;

      m_dcf->ResetCw ();

      m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

      MY_DEBUG ("tx broadcast");

    } 

  else 

    {

      params.EnableAck ();

      if (NeedFragmentation ()) 

        {

          params.DisableRts ();

          WifiMacHeader hdr;

          Ptr<Packet> fragment = GetFragmentPacket (&hdr);

          if (IsLastFragment ()) 

            {

              MY_DEBUG ("fragmenting last fragment size="<<fragment->GetSize ());

              params.DisableNextData ();

            } 

          else 

            {

              MY_DEBUG ("fragmenting size="<<fragment->GetSize ());

              params.EnableNextData (GetNextFragmentSize ());

            }

          Low ()->StartTransmission (fragment, &hdr, params, 

                                     m_transmissionListener);

        } 

      else 

        {

          if (NeedRts ()) 

            {

              params.EnableRts ();

              MY_DEBUG ("tx unicast rts");

            } 

          else 

            {

              params.DisableRts ();

              MY_DEBUG ("tx unicast");

            }

          params.DisableNextData ();

          Low ()->StartTransmission (m_currentPacket, &m_currentHdr,

                                     params, m_transmissionListener);

        }

    }

}

void 

DcaTxop::NotifyInternalCollision (void)

{

  NotifyCollision ();

}

void 

DcaTxop::NotifyCollision (void)

{

  MY_DEBUG ("collision");

  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

  RestartAccessIfNeeded ();

}

void 

DcaTxop::GotCts (double snr, WifiMode txMode)

{

  MY_DEBUG ("got cts");

  m_ssrc = 0;

}

void 

DcaTxop::MissedCts (void)

{

  MY_DEBUG ("missed cts");

  m_ssrc++;

  m_ctstimeoutTrace (m_ssrc);

  if (m_ssrc > Parameters ()->GetMaxSsrc ()) 

    {

      // to reset the dcf.

      m_currentPacket = 0;

      m_dcf->ResetCw ();

    } 

  else 

    {

      m_dcf->UpdateFailedCw ();

    }

  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

  RestartAccessIfNeeded ();

}

void 

DcaTxop::GotAck (double snr, WifiMode txMode)

{

  m_slrc = 0;

  if (!NeedFragmentation () ||

      IsLastFragment ()) 

    {

      MY_DEBUG ("got ack. tx done.");

      if (!m_txOkCallback.IsNull ()) 

        {

          m_txOkCallback (m_currentHdr);

        }

      /* we are not fragmenting or we are done fragmenting

       * so we can get rid of that packet now.

       */

      m_currentPacket = 0;

      m_dcf->ResetCw ();

      m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

      RestartAccessIfNeeded ();

    } 

  else 

    {

      MY_DEBUG ("got ack. tx not done, size="<<m_currentPacket->GetSize ());

    }

}

void 

DcaTxop::MissedAck (void)

{

  MY_DEBUG ("missed ack");

  m_slrc++;

  m_acktimeoutTrace (m_slrc);

  if (m_slrc > Parameters ()->GetMaxSlrc ()) 

    {

      // to reset the dcf.    

      m_currentPacket = 0;

      m_dcf->ResetCw ();

    } 

  else 

    {

      m_currentHdr.SetRetry ();

      if (!m_txFailedCallback.IsNull ()) 

        {

          m_txFailedCallback (m_currentHdr);

        }

      m_dcf->UpdateFailedCw ();

    }

  m_dcf->StartBackoffNow (m_rng->GetNext (0, m_dcf->GetCw ()));

  RestartAccessIfNeeded ();

}

void 

DcaTxop::StartNext (void)

{

  MY_DEBUG ("start next packet fragment");

  /* this callback is used only for fragments. */

  NextFragment ();

  WifiMacHeader hdr;

  Ptr<Packet> fragment = GetFragmentPacket (&hdr);

  MacLowTransmissionParameters params;

  params.EnableAck ();

  params.DisableRts ();

  params.DisableOverrideDurationId ();

  if (IsLastFragment ()) 

    {

      params.DisableNextData ();

    } 

  else