/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright 2013 University of Washington
 *
 * 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
 *
 * Simple M/M/1 queue example (Tom Henderson, tomh@tomh.org)
 */

#include <fstream>
#include <sstream>
#include <iostream>
#include <string>
#include <vector>

#include "ns3/packet.h"
#include "ns3/drop-tail-queue.h"
#include "ns3/uinteger.h"
#include "ns3/simulator.h"
#include "ns3/nstime.h"
#include "ns3/log.h"
#include "ns3/double.h"
#include "ns3/abort.h"
#include "ns3/command-line.h"
#include "ns3/random-variable-stream.h"
#include "ns3/gnuplot.h"

using namespace ns3;

// Run as 'NS_LOG="MM1Queue" ./waf --run mm1-queue' for logging output

NS_LOG_COMPONENT_DEFINE ("MM1Queue");

class Enqueuer
{
public:
  void SetQueue (Ptr<Queue> queue) { m_queue = queue; }
  void SetGenerator (Ptr<RandomVariableStream> var) { m_var = var; }
  void Start (void) { Simulator::Schedule (Seconds (m_var->GetValue ()), &Enqueuer::Generate, this); }
  
private:
  void Generate (void);
  Ptr<Queue> m_queue;
  Ptr<RandomVariableStream> m_var;
};

void
Enqueuer::Generate (void)
{
  NS_LOG_DEBUG ("Generating a packet at time " << Simulator::Now ().GetSeconds ());
  Ptr<Packet> p = Create<Packet> ();
  m_queue->Enqueue (p);
  Simulator::Schedule (Seconds (m_var->GetValue ()), &Enqueuer::Generate, this);
}

class Dequeuer
{
public:
  void SetQueue (Ptr<Queue> queue) { m_queue = queue; }
  void SetGenerator (Ptr<RandomVariableStream> var) { m_var = var; }
  void Start (void) { Simulator::Schedule (Seconds (m_var->GetValue ()), &Dequeuer::Consume, this); }
  
private:
  void Consume (void);
  Ptr<Queue> m_queue;
  Ptr<RandomVariableStream> m_var;
};

void
Dequeuer::Consume (void)
{
  NS_LOG_DEBUG ("Consuming a packet at time " << Simulator::Now ().GetSeconds ());
  Ptr<Packet> p = m_queue->Dequeue ();
  p = 0;
  Simulator::Schedule (Seconds (m_var->GetValue ()), &Dequeuer::Consume, this);
}

class QueueTracer
{
public:
  void SetQueue (Ptr<Queue> queue);
protected:
  virtual void EnqueueTracer (Ptr<const Packet> p);  
  virtual void DequeueTracer (Ptr<const Packet> p);  
  virtual void DropTracer (Ptr<const Packet> p);  
private:
  Ptr<Queue> m_queue;
};

void
QueueTracer::SetQueue (Ptr<Queue> queue)
{
  m_queue = queue;
  bool ok = queue->TraceConnectWithoutContext ("Enqueue", MakeCallback (&QueueTracer::EnqueueTracer, this));
  NS_ABORT_MSG_UNLESS (ok == true, "Could not hook Enqueue trace source");
  ok = queue->TraceConnectWithoutContext ("Dequeue", MakeCallback (&QueueTracer::DequeueTracer, this));
  NS_ABORT_MSG_UNLESS (ok == true, "Could not hook Dequeue trace source");
  ok = queue->TraceConnectWithoutContext ("Drop", MakeCallback (&QueueTracer::DropTracer, this));
  NS_ABORT_MSG_UNLESS (ok == true, "Could not hook Drop trace source");
}

void
QueueTracer::EnqueueTracer (Ptr<const Packet> p)
{
  NS_LOG_DEBUG ("Trace enqueue at time " << Simulator::Now ().GetSeconds ());
}

void
QueueTracer::DequeueTracer (Ptr<const Packet> p)
{
  NS_LOG_DEBUG ("Trace dequeue at time " << Simulator::Now ().GetSeconds ());
}

void
QueueTracer::DropTracer (Ptr<const Packet> p)
{
  NS_LOG_DEBUG ("Trace drop at time " << Simulator::Now ().GetSeconds ());
}

class QueueSampler
{
public:
  void SetQueue (Ptr<Queue> queue) { m_queue = queue;}
  void SetGenerator (Ptr<RandomVariableStream> var) { m_var = var; }
  void Start (void) { Simulator::Schedule (Seconds (m_var->GetValue ()), &QueueSampler::Sample, this); }
  void MakePlots (double lambda, double mu);
  
private:
  void Sample (void);
  Ptr<Queue> m_queue;
  Ptr<RandomVariableStream> m_var;
  std::vector<double> m_times;
  std::vector<uint32_t> m_queueDepths;
};

void
QueueSampler:: MakePlots (double lambda, double mu)
{
  using namespace std;

  ostringstream lambdastr;
  lambdastr << lambda;
  ostringstream mustr;
  mustr << mu;

  // Plot the queue depth as a function of time.
  string fileNameWithNoExtension = "mm1-queue-depth-plot";
  string graphicsFileName        = fileNameWithNoExtension + ".png";
  string plotFileName            = fileNameWithNoExtension + ".plt";
  string plotTitle               = "Queue Depth vs. Time (lambda=" + lambdastr.str () + ", mu=" + mustr.str () + ")";
  string dataTitle               = "Queue Depth (packets)";

  // Instantiate the plot and set its title.
  Gnuplot plot (graphicsFileName);
  plot.SetTitle (plotTitle);

  // Make the graphics file, which the plot file will create when it
  // is used with Gnuplot, be a PNG file.
  plot.SetTerminal ("png");

  // Set the labels for each axis.
  plot.SetLegend ("Time (seconds)", "Queue Depth");

  // Instantiate the dataset, set its title, and make the points be
  // plotted along with connecting lines.
  Gnuplot2dDataset dataset;
  dataset.SetTitle (dataTitle);
  dataset.SetStyle (Gnuplot2dDataset::LINES_POINTS);

  unsigned long count = m_queueDepths.size ();
  unsigned long i;

  // Populate the 2-D dataset.
  for (i = 0; i < count; i++)
    {
      // Add this point.
      dataset.Add (m_times[i], m_queueDepths[i]);
    }

  // Add the dataset to the plot.
  plot.AddDataset (dataset);

  // Open the plot file.
  ofstream plotFile (plotFileName.c_str());

  // Write the plot file.
  plot.GenerateOutput (plotFile);

  // Close the plot file.
  plotFile.close ();
}

void
QueueSampler::Sample (void)
{
  m_times      .push_back (Simulator::Now ().GetSeconds ());
  m_queueDepths.push_back (m_queue->GetNPackets ());
  NS_LOG_DEBUG ("Sampling queue depth at time " << Simulator::Now ().GetSeconds () << " depth = " << m_queue->GetNPackets ());
  Simulator::Schedule (Seconds (m_var->GetValue ()), &QueueSampler::Sample, this);
}

int main (int argc, char *argv[])
{
  uint32_t numInitialPackets = 10;
  double lambda = 1;
  double mu = 2;
  uint32_t plot = 0;
  Time stopTime = Seconds (10000.0);

  CommandLine cmd;
  cmd.AddValue ("lambda", "arrival rate", lambda);
  cmd.AddValue ("mu", "departure rate", mu);
  cmd.AddValue ("plot", "whether to plot (gnuplot)", plot);
  cmd.AddValue ("initial", "initial packets in the system", numInitialPackets);

  cmd.Parse (argc, argv);

  Ptr<DropTailQueue> queue = CreateObject<DropTailQueue> ();
  bool ok = queue->SetAttributeFailSafe ("MaxPackets", UintegerValue (1000));
  NS_ABORT_MSG_UNLESS (ok == true, "Could not set MaxPackets");
  NS_ASSERT_MSG (lambda < mu, "Stability only if lamdba < mu");
  NS_ASSERT (lambda > 0);
  NS_ASSERT (mu > 0);

  Enqueuer enq;
  enq.SetQueue (queue);
  Ptr<ExponentialRandomVariable> enqrv = CreateObject<ExponentialRandomVariable> ();
  enqrv->SetAttribute ("Mean", DoubleValue (1/lambda));
  enq.SetGenerator (enqrv);
  enq.Start ();

  Dequeuer deq;
  deq.SetQueue (queue);
  Ptr<ExponentialRandomVariable> deqrv = CreateObject<ExponentialRandomVariable> ();
  deqrv->SetAttribute ("Mean", DoubleValue (1/mu));
  deq.SetGenerator (deqrv);
  deq.Start ();

  QueueTracer qt;
  qt.SetQueue (queue);

  QueueSampler qs;
  qs.SetQueue (queue);
  Ptr<ConstantRandomVariable> qsrv = CreateObject<ConstantRandomVariable> ();
  qsrv->SetAttribute ("Constant", DoubleValue (1));
  qs.SetGenerator (qsrv);
  qs.Start ();

  Simulator::Stop (stopTime);

  //
  // Pre-simulation stage
  //

  // Seed the queue with initial packets
  for (uint32_t i = 0; i < numInitialPackets; i++)
    {
      Ptr<Packet> p = Create<Packet> ();
      queue->Enqueue (p);
    }

  //
  // Simulation stage
  //

  Simulator::Run ();

  //
  // Post-simulation stage
  //

  NS_LOG_DEBUG ("Final queue depth = " << queue->GetNPackets ());

  if (plot)
    {
      // Make some plots for the sampler.
      qs.MakePlots (lambda, mu);
    }

  Simulator::Destroy ();

  return 0;
}