/* -*-  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/simulator.h"

#include "ns3/packet.h"

#include "wifi-mac-queue.h"

using namespace std;

namespace ns3 {

WifiMacQueue::Item::Item (Packet packet, 

                            WifiMacHeader const &hdr, 

                            Time tstamp)

  : packet (packet), hdr (hdr), tstamp (tstamp)

{}

WifiMacQueue::WifiMacQueue ()

  : m_size (0)

{}

WifiMacQueue::~WifiMacQueue ()

{

  Flush ();

}

void 

WifiMacQueue::SetMaxSize (uint32_t maxSize)

{

  m_maxSize = maxSize;

}

void 

WifiMacQueue::SetMaxDelay (Time delay)

{

  m_maxDelay = delay;

}

void 

WifiMacQueue::Enqueue (Packet packet, WifiMacHeader const &hdr)

{

  Cleanup ();

  if (m_size == m_maxSize) 

    {

      return;

    }

  Time now = Simulator::Now ();

  m_queue.push_back (Item (packet, hdr, now));

  m_size++;

}

void

WifiMacQueue::Cleanup (void)

{

  if (m_queue.empty ()) 

    {

      return;

    }

  Time now = Simulator::Now ();

  uint32_t n = 0;

  PacketQueueI end = m_queue.begin ();

  for (PacketQueueI i = m_queue.begin (); i != m_queue.end (); i++) 

    {

      if (i->tstamp + m_maxDelay > now) 

        {

          end = i;

          break;

        }

      n++;

    }

  m_size -= n;

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

}

Packet 

WifiMacQueue::Dequeue (WifiMacHeader *hdr, bool *found)

{

  Cleanup ();

  if (!m_queue.empty ()) 

    {

      Item i = m_queue.front ();

      m_queue.pop_front ();

      m_size--;

      *hdr = i.hdr;

      *found = true;

      return i.packet;

    }

  *found = false;

  return Packet ();

}

bool

WifiMacQueue::IsEmpty (void)

{

  Cleanup ();

  return m_queue.empty ();

}

uint32_t

WifiMacQueue::GetSize (void)

{

  return m_size;

}

void

WifiMacQueue::Flush (void)

{

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

  m_size = 0;

}