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

/*

 * Copyright (c) 2005,2006 INRIA

 * All rights reserved.

 *

 * 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:  Craig Dowell <craigdo@ee.washington.edu>

 * Revised: George Riley <riley@ece.gatech.edu>

 */

#include <iostream>

#include <cassert>

#include "ns3/debug.h"

#include "ns3/queue.h"

#include "ns3/simulator.h"

#include "ns3/composite-trace-resolver.h"

#include "ns3/eui48-address.h"

#include "ns3/llc-snap-header.h"

#include "point-to-point-net-device.h"

#include "point-to-point-channel.h"

NS_DEBUG_COMPONENT_DEFINE ("PointToPointNetDevice");

namespace ns3 {

DataRateDefaultValue PointToPointNetDevice::g_defaultRate(

           "PointToPointLinkDataRate", 

           "The default data rate for point to point links",

           DataRate ("10Mb/s"));

PointToPointNetDevice::PointToPointNetDevice (Ptr<Node> node,

                                              const DataRate& rate) 

: 

  NetDevice(node, Eui48Address::Allocate ().ConvertTo ()), 

  m_txMachineState (READY),

  m_bps (rate),

  m_tInterframeGap (Seconds(0)),

  m_channel (0), 

  m_queue (0),

  m_rxTrace ()

{

  NS_DEBUG ("PointToPointNetDevice::PointToPointNetDevice (" << node << ")");

  // BUGBUG FIXME

  //

  // You _must_ support broadcast to get any sort of packet from the ARP layer.

  EnableBroadcast (Eui48Address ("ff:ff:ff:ff:ff:ff").ConvertTo ());

  EnableMulticast();

  EnablePointToPoint();

}

PointToPointNetDevice::~PointToPointNetDevice()

{

  NS_DEBUG ("PointToPointNetDevice::~PointToPointNetDevice ()");

  m_queue = 0;

}

void 

PointToPointNetDevice::AddHeader(Packet& p, uint16_t protocolNumber)

{

  LlcSnapHeader llc;

  llc.SetType (protocolNumber);

  p.AddHeader (llc);

}

bool 

PointToPointNetDevice::ProcessHeader(Packet& p, uint16_t& param)

{

  LlcSnapHeader llc;

  p.RemoveHeader (llc);

  param = llc.GetType ();

  return true;

}

void PointToPointNetDevice::DoDispose()

{

  m_channel = 0;

  NetDevice::DoDispose ();

}

void PointToPointNetDevice::SetDataRate(const DataRate& bps)

{

  m_bps = bps;

}

void PointToPointNetDevice::SetInterframeGap(const Time& t)

{

  m_tInterframeGap = t;

}

bool PointToPointNetDevice::SendTo (Packet& p, const Address& dest, 

                                    uint16_t protocolNumber)

{

  NS_DEBUG ("PointToPointNetDevice::SendTo (" << &p << ", " << &dest << ")");

  NS_DEBUG ("PointToPointNetDevice::SendTo (): UID is " << p.GetUid () << ")");

  // GFR Comment. Why is this an assertion? Can't a link legitimately

  // "go down" during the simulation?  Shouldn't we just wait for it

  // to come back up?

  NS_ASSERT (IsLinkUp ());

  AddHeader(p, protocolNumber);

//

// This class simulates a point to point device.  In the case of a serial

// link, this means that we're simulating something like a UART.

//

//

// If there's a transmission in progress, we enque the packet for later

// trnsmission; otherwise we send it now.

  if (m_txMachineState == READY) 

    {

      return TransmitStart (p);

    }

  else

    {

      return m_queue->Enqueue(p);

    }

}

  bool

PointToPointNetDevice::TransmitStart (Packet &p)

{

  NS_DEBUG ("PointToPointNetDevice::TransmitStart (" << &p << ")");

  NS_DEBUG (

    "PointToPointNetDevice::TransmitStart (): UID is " << p.GetUid () << ")");

//

// This function is called to start the process of transmitting a packet.

// We need to tell the channel that we've started wiggling the wire and

// schedule an event that will be executed when the transmission is complete.

//

  NS_ASSERT_MSG(m_txMachineState == READY, "Must be READY to transmit");

  m_txMachineState = BUSY;

  Time txTime = Seconds (m_bps.CalculateTxTime(p.GetSize()));

  Time txCompleteTime = txTime + m_tInterframeGap;

  NS_DEBUG ("PointToPointNetDevice::TransmitStart (): " <<

    "Schedule TransmitCompleteEvent in " << 

    txCompleteTime.GetSeconds () << "sec");

  // Schedule the tx complete event

  Simulator::Schedule (txCompleteTime, 

                       &PointToPointNetDevice::TransmitComplete, 

                       this);

  return m_channel->TransmitStart(p, this, txTime); 

}

void PointToPointNetDevice::TransmitComplete (void)

{

  NS_DEBUG ("PointToPointNetDevice::TransmitCompleteEvent ()");

//

// This function is called to finish the  process of transmitting a packet.

// We need to tell the channel that we've stopped wiggling the wire and

// get the next packet from the queue.  If the queue is empty, we are

// done, otherwise transmit the next packet.

//

  NS_ASSERT_MSG(m_txMachineState == BUSY, "Must be BUSY if transmitting");

  m_txMachineState = READY;

  Packet p;

  if (!m_queue->Dequeue(p)) return; // Nothing to do at this point

  TransmitStart(p);

}

TraceResolver* PointToPointNetDevice::DoCreateTraceResolver (

                                      TraceContext const &context)

{

  CompositeTraceResolver *resolver = new CompositeTraceResolver (context);

  resolver->Add ("queue", 

                 MakeCallback (&Queue::CreateTraceResolver, PeekPointer (m_queue)),

                 PointToPointNetDevice::QUEUE);

  resolver->Add ("rx",

                 m_rxTrace,

                 PointToPointNetDevice::RX);

  return resolver;

}

bool PointToPointNetDevice::Attach (Ptr<PointToPointChannel> ch)

{

  NS_DEBUG ("PointToPointNetDevice::Attach (" << &ch << ")");

  m_channel = ch;

  m_channel->Attach(this);

  m_bps = m_channel->GetDataRate ();

  // GFR Comment.  Below is definitely wrong.  Interframe gap

  // is unrelated to channel delay.

  //m_tInterframeGap = m_channel->GetDelay ();

  /* 

   * For now, this device is up whenever a channel is attached to it.

   * In fact, it should become up only when the second device

   * is attached to the channel. So, there should be a way for

   * a PointToPointChannel to notify both of its attached devices

   * that the channel is 'complete', hence that the devices are

   * up, hence that they can call NotifyLinkUp. 

   */

  NotifyLinkUp ();

  return true;

}

void PointToPointNetDevice::AddQueue (Ptr<Queue> q)

{

  NS_DEBUG ("PointToPointNetDevice::AddQueue (" << q << ")");

  m_queue = q;

}

void PointToPointNetDevice::Receive (Packet& p)

{

  NS_DEBUG ("PointToPointNetDevice::Receive (" << &p << ")");

  Packet packet = p;

  m_rxTrace (packet);

}

Ptr<Queue> PointToPointNetDevice::GetQueue(void) const 

{ 

    return m_queue;

}

Ptr<Channel> PointToPointNetDevice::DoGetChannel(void) const 

{ 

    return m_channel;

}

bool PointToPointNetDevice::DoNeedsArp (void) const

{

  return false;

}

} // namespace ns3