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

// Network topology
//
//       n0    n1   n2   n3
//       |     |    |    |
//       =================
//              LAN
//
// - UDP flows from n0 to n1 and back
// - DropTail queues 
// - Tracing of queues and packet receptions to file "udp-echo.tr"

#include <fstream>
#include "ns3/core-module.h"
#include "ns3/simulator-module.h"
#include "ns3/helper-module.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("RealtimeUdpEchoExample");

int 
main (int argc, char *argv[])
{
  //
  // Make the random number generators generate reproducible results.
  //
  RandomVariable::UseGlobalSeed (1, 1, 2, 3, 5, 8);

  //
  // Allow the user to override any of the defaults and the above Bind() at
  // run-time, via command-line arguments
  //
  CommandLine cmd;
  cmd.Parse (argc, argv);

  //
  // But since this is a realtime script, don't allow the user to mess with
  // that.
  //
  GlobalValue::Bind ("SimulatorImplementationType", 
    StringValue ("ns3::RealtimeSimulatorImpl"));

  //
  // Explicitly create the nodes required by the topology (shown above).
  //
  NS_LOG_INFO ("Create nodes.");
  NodeContainer n;
  n.Create (4);

  InternetStackHelper internet;
  internet.Install (n);

  //
  // Explicitly create the channels required by the topology (shown above).
  //
  NS_LOG_INFO ("Create channels.");
  CsmaHelper csma;
  csma.SetChannelAttribute ("DataRate", DataRateValue (DataRate(5000000)));
  csma.SetChannelAttribute ("Delay", TimeValue (MilliSeconds (2)));
  csma.SetDeviceAttribute ("MTU", UintegerValue (1400));
  NetDeviceContainer d = csma.Install (n);

  //
  // We've got the "hardware" in place.  Now we need to add IP addresses.
  //
  NS_LOG_INFO ("Assign IP Addresses.");
  Ipv4AddressHelper ipv4;
  ipv4.SetBase ("10.1.1.0", "255.255.255.0");
  Ipv4InterfaceContainer i = ipv4.Assign (d);

  NS_LOG_INFO ("Create Applications.");

  //
  // Create a UdpEchoServer application on node one.
  //
  uint16_t port = 9;  // well-known echo port number
  UdpEchoServerHelper server (port);
  ApplicationContainer apps = server.Install (n.Get(1));
  apps.Start (Seconds (1.0));
  apps.Stop (Seconds (10.0));

  //
  // Create a UdpEchoClient application to send UDP datagrams from node zero to
  // node one.
  //
  uint32_t packetSize = 1024;
  uint32_t maxPacketCount = 500;
  Time interPacketInterval = Seconds (0.01);
  UdpEchoClientHelper client (i.GetAddress (1), port);
  client.SetAttribute ("MaxPackets", UintegerValue (maxPacketCount));
  client.SetAttribute ("Interval", TimeValue (interPacketInterval));
  client.SetAttribute ("PacketSize", UintegerValue (packetSize));
  apps = client.Install (n.Get (0));
  apps.Start (Seconds (2.0));
  apps.Stop (Seconds (10.0));

  std::ofstream ascii;
  ascii.open ("realtime-udp-echo.tr");
  CsmaHelper::EnablePcapAll ("realtime-udp-echo");
  CsmaHelper::EnableAsciiAll (ascii);

  //
  // Now, do the actual simulation.
  //
  NS_LOG_INFO ("Run Simulation.");
  Simulator::Run ();
  Simulator::Destroy ();
  NS_LOG_INFO ("Done.");
}