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

/*

 * Copyright (c) 2005,2006,2007 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: Federico Maguolo <maguolof@dei.unipd.it>

 */

#include "ns3/simulator.h"

#include "ns3/uinteger.h"

#include "ns3/double.h"

#include "ns3/random-variable.h"

#include "ns3/mobility-model.h"

#include "ns3/log.h"

#include "jakes-propagation-loss-model.h"

#include <math.h>

NS_LOG_COMPONENT_DEFINE ("Jakes");

namespace ns3 {

class JakesPropagationLossModel::PathCoefficients {

public:

  PathCoefficients (Ptr<const JakesPropagationLossModel> jakes,

                    Ptr<MobilityModel> receiver, 

                    uint8_t nRays, 

                    uint8_t nOscillators);

  ~PathCoefficients ();

  double GetLoss (void);

  Ptr<MobilityModel> GetReceiver (void);

private:

  void DoConstruct (void);

  Ptr<MobilityModel> m_receiver;

  uint8_t m_nOscillators;

  uint8_t m_nRays;

  double **m_phases;

  Time m_lastUpdate;

  Ptr<const JakesPropagationLossModel> m_jakes;

};

JakesPropagationLossModel::PathCoefficients::PathCoefficients (Ptr<const JakesPropagationLossModel> jakes, 

                                                           Ptr<MobilityModel> receiver, 

                                                           uint8_t nRays, 

							   uint8_t nOscillators)

  : m_receiver (receiver),

    m_nOscillators (nOscillators),

    m_nRays (nRays),

    m_jakes(jakes)

{

  DoConstruct ();

}

JakesPropagationLossModel::PathCoefficients::~PathCoefficients ()

{

  for (uint8_t i = 0; i < m_nRays; i++) {

    delete [] m_phases[i];

  }

  delete [] m_phases;

}

void

JakesPropagationLossModel::PathCoefficients::DoConstruct ()

{

  m_phases = new double*[m_nRays];

  for (uint8_t i = 0; i < m_nRays; i++) {

    m_phases[i] = new double[m_nOscillators + 1];

    for (uint8_t j = 0; j <= m_nOscillators; j++) {

      m_phases[i][j] = 2.0 * JakesPropagationLossModel::PI * m_jakes->m_variable.GetValue ();

    }

  }

  m_lastUpdate = Simulator::Now ();

}

Ptr<MobilityModel>

JakesPropagationLossModel::PathCoefficients::GetReceiver ()

{

  return m_receiver;

}

double

JakesPropagationLossModel::PathCoefficients::GetLoss (void)

{

  uint16_t N = 4 * m_nOscillators + 2;

  Time interval = Simulator::Now () - m_lastUpdate;

  ComplexNumber coef= {0.0, 0.0};

  ComplexNumber fading;

  double norm = 0.0;

  for (uint8_t i = 0; i < m_nRays; i++) {

    fading.real = 0.0;

    fading.imag = 0.0;

    for (uint8_t j = 0; j <= m_nOscillators; j++) {

      m_phases[i][j] += 2.0 * JakesPropagationLossModel::PI * cos (2.0 * JakesPropagationLossModel::PI * j / N) * m_jakes->m_fd * interval.GetSeconds ();

      m_phases[i][j] -= 2.0 * JakesPropagationLossModel::PI * floor (m_phases[i][j] / 2.0 / JakesPropagationLossModel::PI);

      fading.real += m_jakes->m_amp[j].real * cos (m_phases[i][j]);

      fading.imag += m_jakes->m_amp[j].imag * cos (m_phases[i][j]);

      norm += sqrt(pow (m_jakes->m_amp[j].real, 2) + pow(m_jakes->m_amp[j].imag, 2));

    }

    coef.real += fading.real;

    coef.imag += fading.imag;

  }

  m_lastUpdate = Simulator::Now ();

  double k = sqrt (pow (coef.real, 2) + pow (coef.imag, 2)) / norm;

  NS_LOG_DEBUG ("Jakes coef "<< k << " (" << 10 * log10 (k) << "dB)");

  return 10 * log10 (k);

}

NS_OBJECT_ENSURE_REGISTERED (JakesPropagationLossModel);

const double JakesPropagationLossModel::PI = 3.1415;

TypeId

JakesPropagationLossModel::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::JakesPropagationLossModel")

    .SetParent<PropagationLossModel> ()

    .AddConstructor<JakesPropagationLossModel> ()

    .AddAttribute ("NumberOfRaysPerPath",

                   "The number of rays to use by default for compute the fading coeficent for a given path (default is 1)",

		   MakeUintegerAccessor (&JakesPropagationLossModel::m_nRays),

		   MakeUintegerChecker<uint8_t> ())

    .AddAttribute ("NumberOfOscillatorsPerRay",

                   "The number of oscillators to use by default for compute the coeficent for a given ray of a given path (default is 4)",

		   MakeUintegerAccessor (&JakesPropagationLossModel::m_nOscillators),

		   MakeUintegerChecker<uint8_t> ())

    .AddAttribute ("DopplerFreq",

                   "The doppler frequency in Hz (f_d = v / lambda = v * f / c, the defualt is 0)",

		   MakeDoubleAccessor (&JakesPropagationLossModel::m_fd),

		   MakeDoubleChecker<double> ())

    .AddAttribute ("Distribution",

                   "The distribution to choose the initial phases.",

                   MakeRandomVariableAccessor (&JakesPropagationLossModel::m_variable),

                   MakeRandomVariableChecker ())

    ;

  return tid;

}

JakesPropagationLossModel::JakesPropagationLossModel ()

{

  DoConstruct ();

}

JakesPropagationLossModel::~JakesPropagationLossModel ()

{

  delete [] m_amp;

  for (PathsList::iterator i = m_paths.end (); i != m_paths.begin (); i--) {

    PathsSet *ps = *i;

    for (DestinationList::iterator r = ps->receivers.begin (); r != ps->receivers.end (); r++) {

      PathCoefficients *pc = *r;

      delete pc;

    }

    delete ps;

  }

}

void

JakesPropagationLossModel::DoConstruct ()

{

  uint16_t N = 4 * m_nOscillators + 2;

  m_amp = new ComplexNumber[m_nOscillators + 1];

  m_amp[0].real = 2.0 * sqrt(2.0 / N) * cos (PI / 4.0);

  m_amp[0].imag = 2.0 * sqrt(2.0 / N) * sin (PI / 4.0);

  for (uint8_t i = 1; i <= m_nOscillators; i++) {

    double beta = PI * (double)i / m_nOscillators;

    m_amp[i].real = 4.0 * cos (beta) / sqrt(N);

    m_amp[i].imag = 4.0 * sin (beta) / sqrt(N);

  }

}

void

JakesPropagationLossModel::SetNRays (uint8_t nRays)

{

  m_nRays = nRays;

}

void

JakesPropagationLossModel::SetNOscillators (uint8_t nOscillators)

{

  m_nOscillators = nOscillators;

}

double

JakesPropagationLossModel::GetLoss (Ptr<MobilityModel> a,

				    Ptr<MobilityModel> b) const

{

  PathsList::iterator i = m_paths.end ();

  while (i != m_paths.begin ()) {

    i--;

    PathsSet *ps = *i;

    if (PeekPointer (ps->sender) == PeekPointer(a)) {

      m_paths.erase (i);

      m_paths.push_back (ps);

      for (DestinationList::iterator r = ps->receivers.begin (); r != ps->receivers.end (); r++) {

        PathCoefficients *pc = *r;

      	if (PeekPointer (pc->GetReceiver ()) == PeekPointer (b)) {

          ps->receivers.erase (r);

	  ps->receivers.push_back (pc);

	  return pc->GetLoss ();

	}

      }

      PathCoefficients *pc = new PathCoefficients (this, b, m_nRays, m_nOscillators);

      ps->receivers.push_back (pc);

      return pc->GetLoss ();

    }

  }

  PathsSet *ps = new PathsSet;

  ps->sender = a;

  PathCoefficients *pc = new PathCoefficients (this, b, m_nRays, m_nOscillators);

  ps->receivers.push_back (pc);

  m_paths.push_back (ps);

  return pc->GetLoss ();

}

} // namespace ns3