/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2009 CTTC
 *
 * 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: Nicola Baldo <nbaldo@cttc.es>
 */


#include "spectrum-interference.h"
#include "spectrum-error-model.h"

#include <ns3/simulator.h>
#include <ns3/log.h>


NS_LOG_COMPONENT_DEFINE ("SpectrumInterference");

namespace ns3 {


SpectrumInterference::SpectrumInterference ()
  : m_receiving (false),
    m_rxSignal (0),
    m_allSignals (0),
    m_noise (0),
    m_errorModel (0)
{
  NS_LOG_FUNCTION (this);
}

SpectrumInterference::~SpectrumInterference ()
{
  NS_LOG_FUNCTION (this);
}

void
SpectrumInterference::DoDispose ()
{
  NS_LOG_FUNCTION (this);
  m_rxSignal = 0;
  m_allSignals = 0;
  m_noise = 0;
  m_errorModel = 0;  
  Object::DoDispose ();
}

void
SpectrumInterference::StartRx (Ptr<const Packet> p, Ptr<const SpectrumValue> rxPsd)
{ 
  NS_LOG_FUNCTION (this << p << *rxPsd);
  m_rxSignal = rxPsd;
  m_lastChangeTime = Now ();
  m_receiving = true;
  m_errorModel->StartRx (p);
}


bool
SpectrumInterference::EndRx ()
{
  NS_LOG_FUNCTION (this);
  ConditionallyEvaluateChunk ();
  m_receiving = false;
  return m_errorModel->IsRxCorrect ();
}


void
SpectrumInterference::AddSignal (Ptr<const SpectrumValue> spd, const Time duration)
{
  NS_LOG_FUNCTION (this << *spd << duration);
  DoAddSignal (spd);
  Simulator::Schedule (duration, &SpectrumInterference::DoSubtractSignal, this, spd);
}


void
SpectrumInterference::DoAddSignal  (Ptr<const SpectrumValue> spd)
{ 
  NS_LOG_FUNCTION (this << *spd);
  ConditionallyEvaluateChunk ();
  (*m_allSignals) += (*spd);
  m_lastChangeTime = Now ();
}

void
SpectrumInterference::DoSubtractSignal  (Ptr<const SpectrumValue> spd)
{ 
  NS_LOG_FUNCTION (this << *spd);
  ConditionallyEvaluateChunk ();
  (*m_allSignals) -= (*spd);
  m_lastChangeTime = Now ();
}


void
SpectrumInterference::ConditionallyEvaluateChunk ()
{
  NS_LOG_FUNCTION (this);
  if (m_receiving && (Now () > m_lastChangeTime))
    {
      SpectrumValue sinr = (*m_rxSignal) / ((*m_allSignals) - (*m_rxSignal) + (*m_noise));
      Time duration = Now () - m_lastChangeTime;
      m_errorModel->EvaluateChunk (sinr, duration);
    }
}

void
SpectrumInterference::SetNoisePowerSpectralDensity (Ptr<const SpectrumValue> noisePsd)
{
  NS_LOG_FUNCTION (this << noisePsd);
  m_noise = noisePsd;
  // we can initialize m_allSignal only now, because earlier we
  // didn't know what spectrum model was going to be used.
  // we'll now create a zeroed SpectrumValue using the same
  // SpectrumModel which is being specified for the noise.
  m_allSignals = Create<SpectrumValue> (noisePsd->GetSpectrumModel ());
}

void
SpectrumInterference::SetErrorModel (Ptr<SpectrumErrorModel> e)
{
  NS_LOG_FUNCTION (this << e);
  m_errorModel = e;
}




} // namespace ns3


