/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2015 Universita' degli Studi di Napoli "Federico II"
 *
 * 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: Pasquale Imputato <p.imputato@gmail.com>
 * Author: Stefano Avallone <stefano.avallone@unina.it>
 */

#include "ns3/core-module.h"
#include "ns3/network-module.h"
#include "ns3/internet-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/applications-module.h"
#include "ns3/traffic-control-module.h"

// This simple example shows how to use TrafficControlHelper to install a 
// QueueDisc on a device.
//
// The default QueueDisc is a pfifo_fast with max number of packets equal to 
// 1000 (as in Linux).   However, in this example, we change from the default 
// to instead use a ns3::RedQueueDisc with a MaxPackets value of 10000.
//
// Network topology
//
//       10.1.1.0
// n0 -------------- n1
//    point-to-point
//
// The output will consist of a number of traced changes to queue lengths
// such as:
//
//    DevicePacketsInQueue 0 to 1
//    TcPacketsInQueue 5 to 4
//    TcPacketsInQueue 4 to 5
//    DevicePacketsInQueue 1 to 0
//
// and an average throughput: 
//
//    Average throughput: 8.72854 Mbit/s
//
// The final output displays the number of drops at the TC layer and the
// netdevice layer.  These statistics highlight the fact that for
// PointToPointNetDevice, the drops at the device layer are actually
// requeued at the TC layer, so the true packet drops (39 in this case)
// must be traced at the TC layer.
//
//    *** Source stats ***
//    Number of packets dropped by the TC layer: 39
//    Number of packets dropped by the netdevice: 3914
//    Number of packets requeued by the TC layer: 3914
//    Number of actually lost packets: 39
//
// If one were to increase the size of the PointToPointNetDevice's
// DropTailQueue from 1 to a larger number (e.g. 1000), one would observe
// that the number of packets dropped would go to zero, but the latency
// and QoS would not be controllable.  This is the so-called bufferbloat
// problem, and illustrates the importance of having a small device queue
// so that the standing queues build in the traffic control layer where
// they can be managed by advanced queue discs rather than in the 
// device layer.

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("TrafficControlExample");

void
TcPacketsInQueueTrace (uint32_t oldValue, uint32_t newValue)
{
  std::cout << "TcPacketsInQueue " << oldValue << " to " << newValue << std::endl;
}

void
DevicePacketsInQueueTrace (uint32_t oldValue, uint32_t newValue)
{
  std::cout << "DevicePacketsInQueue " << oldValue << " to " << newValue << std::endl;
}

int
main (int argc, char *argv[])
{
  double simulationTime = 10; //seconds
  std::string transportProt = "Tcp";
  std::string socketType;

  CommandLine cmd;
  cmd.AddValue ("transportProt", "Transport protocol to use: Tcp, Udp", transportProt);
  cmd.Parse (argc, argv);

  if (transportProt.compare ("Tcp") == 0)
    {
      socketType = "ns3::TcpSocketFactory";
    }
  else
    {
      socketType = "ns3::UdpSocketFactory";
    }

  NodeContainer nodes;
  nodes.Create (2);

  PointToPointHelper pointToPoint;
  pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("10Mbps"));
  pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
  pointToPoint.SetQueue ("ns3::DropTailQueue", "Mode", StringValue ("QUEUE_MODE_PACKETS"), "MaxPackets", UintegerValue (1));

  NetDeviceContainer devices;
  devices = pointToPoint.Install (nodes);

  InternetStackHelper stack;
  stack.Install (nodes);

  TrafficControlHelper tch;
  uint16_t handle = tch.SetRootQueueDisc ("ns3::RedQueueDisc");
  // Add the internal queue used by Red
  tch.AddInternalQueues (handle, 1, "ns3::DropTailQueue", "MaxPackets", UintegerValue (10000));
  QueueDiscContainer qdiscs = tch.Install (devices);

  Ptr<QueueDisc> q = qdiscs.Get (1);
  q->TraceConnectWithoutContext ("PacketsInQueue", MakeCallback (&TcPacketsInQueueTrace));

  Ptr<NetDevice> nd = devices.Get (1);
  Ptr<PointToPointNetDevice> ptpnd = DynamicCast<PointToPointNetDevice> (nd);
  Ptr<Queue> queue = ptpnd->GetQueue ();
  queue->TraceConnectWithoutContext ("PacketsInQueue", MakeCallback (&DevicePacketsInQueueTrace));

  Ipv4AddressHelper address;
  address.SetBase ("10.1.1.0", "255.255.255.0");

  Ipv4InterfaceContainer interfaces = address.Assign (devices);

  //Flow
  uint16_t port = 7;
  Address localAddress (InetSocketAddress (Ipv4Address::GetAny (), port));
  PacketSinkHelper packetSinkHelper (socketType, localAddress);
  ApplicationContainer sinkApp = packetSinkHelper.Install (nodes.Get (0));

  sinkApp.Start (Seconds (0.0));
  sinkApp.Stop (Seconds (simulationTime + 0.1));

  uint32_t payloadSize = 1448;
  Config::SetDefault ("ns3::TcpSocket::SegmentSize", UintegerValue (payloadSize));

  OnOffHelper onoff (socketType, Ipv4Address::GetAny ());
  onoff.SetAttribute ("OnTime",  StringValue ("ns3::ConstantRandomVariable[Constant=1]"));
  onoff.SetAttribute ("OffTime", StringValue ("ns3::ConstantRandomVariable[Constant=0]"));
  onoff.SetAttribute ("PacketSize", UintegerValue (payloadSize));
  onoff.SetAttribute ("DataRate", StringValue ("50Mbps")); //bit/s
  ApplicationContainer apps;

  AddressValue remoteAddress (InetSocketAddress (interfaces.GetAddress (0), port));
  onoff.SetAttribute ("Remote", remoteAddress);
  apps.Add (onoff.Install (nodes.Get (1)));
  apps.Start (Seconds (1.0));
  apps.Stop (Seconds (simulationTime + 0.1));

  Simulator::Stop (Seconds (simulationTime + 0.1));
  Simulator::Run ();
  Simulator::Destroy ();

  double thr = 0;
  uint32_t totalPacketsThr = DynamicCast<PacketSink> (sinkApp.Get (0))->GetTotalRx ();
  thr = totalPacketsThr * 8 / (simulationTime * 1000000.0); //Mbit/s
  std::cout << "Average throughput: " << thr << " Mbit/s" <<std::endl;
  std::cout << "*** Source stats ***" << std::endl;
  std::cout << "Number of packets dropped by the TC layer: " << q->GetTotalDroppedPackets () << std::endl;
  std::cout << "Number of packets dropped by the netdevice: " << queue->GetTotalDroppedPackets () << std::endl;
  std::cout << "Number of packets requeued by the TC layer: " << q->GetTotalRequeuedPackets () << std::endl;
  std::cout << "Number of actually lost packets: " << q->GetTotalDroppedPackets ()
                                                      + queue->GetTotalDroppedPackets ()
                                                      - q->GetTotalRequeuedPackets () << std::endl;

  return 0;
}