/* -*-  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 "mac-rx-middle.h"

#include "wifi-mac-header.h"

#include "ns3/assert.h"

#include <list>

namespace ns3 {

class OriginatorRxStatus {

private:

  typedef std::list<Packet> Fragments;

  typedef std::list<Packet>::const_iterator FragmentsCI;

  bool m_defragmenting;

  uint16_t m_lastSequenceControl;

  Fragments m_fragments;

public:

  OriginatorRxStatus () {

    /* this is a magic value necessary. */

    m_lastSequenceControl = 0xffff;

    m_defragmenting = false;

  }

  ~OriginatorRxStatus () {

    for (FragmentsCI i = m_fragments.begin (); i != m_fragments.end (); i++) 

      {

        // XXX ?

      }

    m_fragments.erase (m_fragments.begin (), m_fragments.end ());

  }

  bool IsDeFragmenting (void) {

    return m_defragmenting;

  }

  void AccumulateFirstFragment (Packet const packet) {

    NS_ASSERT (!m_defragmenting);

    m_defragmenting = true;

    m_fragments.push_back (packet);

  }

  Packet AccumulateLastFragment (Packet const packet) {

    NS_ASSERT (m_defragmenting);

    m_fragments.push_back (packet);

    m_defragmenting = false;

    Packet full;

    for (FragmentsCI i = m_fragments.begin (); i != m_fragments.end (); i++) 

      {

        full.AddAtEnd (*i);

      }

    m_fragments.erase (m_fragments.begin (), m_fragments.end ());

    return full;

  }

  void AccumulateFragment (Packet const packet) {

    NS_ASSERT (m_defragmenting);

    m_fragments.push_back (packet);

  }

  bool IsNextFragment (uint16_t sequenceControl) {

    if ((sequenceControl >> 4) == (m_lastSequenceControl >> 4) &&

        (sequenceControl & 0x0f) == ((m_lastSequenceControl & 0x0f)+1)) 

      {

        return true;

      } 

    else 

      {

        return false;

      }

  }

  uint16_t GetLastSequenceControl (void) 

  {

    return m_lastSequenceControl;

  }

  void SetSequenceControl (uint16_t sequenceControl) 

  {

    m_lastSequenceControl = sequenceControl;

  }

};

MacRxMiddle::MacRxMiddle ()

{}

MacRxMiddle::~MacRxMiddle ()

{

  for (OriginatorsI i = m_originatorStatus.begin ();

       i != m_originatorStatus.end (); i++) 

    {

      delete (*i).second;

    }

  m_originatorStatus.erase (m_originatorStatus.begin (),

                            m_originatorStatus.end ());

  for (QosOriginatorsI i = m_qosOriginatorStatus.begin ();

       i != m_qosOriginatorStatus.end (); i++) 

    {

      delete (*i).second;

    }

  m_qosOriginatorStatus.erase (m_qosOriginatorStatus.begin (),

                               m_qosOriginatorStatus.end ());

}

void 

MacRxMiddle::SetForwardCallback (ForwardUpCallback callback)

{

  m_callback = callback;

}

bool

MacRxMiddle::SequenceControlSmaller (int seqca, int seqcb)

{

  int seqa = seqca >> 4;

  int seqb = seqcb >> 4;

  int delta = seqb - seqa;

  TRACE ("seqb="<<seqb<<", seqa="<<seqa<<", delta="<<delta);

  if (delta <= 0 && delta < -2048) 

    {

      return true;

    } 

  else if (delta >= 0 && delta < 2048) 

    {

      return true;

    } 

  else 

    {

      return false;

    }

}

OriginatorRxStatus *

MacRxMiddle::Lookup (WifiMacHeader const *hdr)

{

  OriginatorRxStatus *originator;

  Mac48Address source = hdr->GetAddr2 ();

  if (hdr->IsQosData () &&

      !hdr->GetAddr2 ().IsBroadcast ()) 

    {

      /* only for qos data non-broadcast frames */

      originator = m_qosOriginatorStatus[std::make_pair(source, hdr->GetQosTid ())];

      if (originator == 0) 

        {

          originator = new OriginatorRxStatus ();

          m_qosOriginatorStatus[std::make_pair(source, hdr->GetQosTid ())] = originator;

        }

    } 

  else 

    {

      /* - management frames

       * - qos data broadcast frames

       * - nqos data frames

       * see section 7.1.3.4.1

       */

      originator = m_originatorStatus[source];

      if (originator == 0) 

        {

          originator = new OriginatorRxStatus ();

          m_originatorStatus[source] = originator;

        }

    }

  return originator;

}

bool

MacRxMiddle::IsDuplicate (WifiMacHeader const*hdr, 

         OriginatorRxStatus *originator) const

{

  if (originator->GetLastSequenceControl () == hdr->GetSequenceControl ()) 

    {

      return true;

    }

  return false;

}

Packet 

MacRxMiddle::HandleFragments (Packet packet, WifiMacHeader const*hdr,

             OriginatorRxStatus *originator, bool *complete)

{

  if (originator->IsDeFragmenting ()) 

    {

      if (hdr->IsMoreFragments ()) 

        {

          if (originator->IsNextFragment (hdr->GetSequenceControl ())) 

            {

              TRACE ("accumulate fragment seq="<<hdr->GetSequenceNumber ()<<

                     ", frag="<<hdr->GetFragmentNumber ()<<

                     ", size="<<packet.GetSize ());

              originator->AccumulateFragment (packet);

              originator->SetSequenceControl (hdr->GetSequenceControl ());

            } 

          else 

            {

              TRACE ("non-ordered fragment");

            }

          *complete = false;

          return Packet ();

        } 

      else 

        {

          if (originator->IsNextFragment (hdr->GetSequenceControl ())) 

            {

              TRACE ("accumulate last fragment seq="<<hdr->GetSequenceNumber ()<<

                     ", frag="<<hdr->GetFragmentNumber ()<<

                     ", size="<<hdr->GetSize ());

              packet = originator->AccumulateLastFragment (packet);

              originator->SetSequenceControl (hdr->GetSequenceControl ());

              *complete = true;

              return packet;

            } 

          else 

            {

              TRACE ("non-ordered fragment");

              *complete = false;

              return Packet ();

            }

        }

    } 

  else 

    {

      if (hdr->IsMoreFragments ()) 

        {

          TRACE ("accumulate first fragment seq="<<hdr->GetSequenceNumber ()<<

                 ", frag="<<hdr->GetFragmentNumber ()<<

                 ", size="<<packet.GetSize ());

          originator->AccumulateFirstFragment (packet);

          originator->SetSequenceControl (hdr->GetSequenceControl ());

          *complete = false;

          return Packet ();

        } 

      else 

        {

          *complete = true;

          return packet;

        }

    }

}

void

MacRxMiddle::Receive (Packet packet, WifiMacHeader const *hdr)

{

  OriginatorRxStatus *originator = Lookup (hdr);

  if (hdr->IsData ()) 

    {

      NS_ASSERT (SequenceControlSmaller (originator->GetLastSequenceControl (), 

                                      hdr->GetSequenceControl ()));

      // filter duplicates.

      if (IsDuplicate (hdr, originator)) 

        {

          TRACE ("duplicate from="<<hdr->GetAddr2 ()<<

                 ", seq="<<hdr->GetSequenceNumber ()<<

                 ", frag="<<hdr->GetFragmentNumber ());

          return;

        }

      bool complete;

      Packet agregate = HandleFragments (packet, hdr, originator, &complete);

      if (!complete) 

        {

          return;

        }

      TRACE ("forwarding data from="<<hdr->GetAddr2 ()<<

             ", seq="<<hdr->GetSequenceNumber ()<<

             ", frag="<<hdr->GetFragmentNumber ());

      originator->SetSequenceControl (hdr->GetSequenceControl ());

      m_callback (agregate, hdr);

    } 

  else 

    {

      TRACE ("forwarding "<<hdr->GetTypeString ()<<

             ", seq="<<hdr->GetSequenceNumber ()<<

             ", frag="<<hdr->GetFragmentNumber ());

      originator->SetSequenceControl (hdr->GetSequenceControl ());

      m_callback (packet, hdr);

    }

}

} // namespace ns3