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

/*

 * Copyright (c) 2007 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

 */

#include "ns3/log.h"

#include "energy-model.h"

NS_LOG_COMPONENT_DEFINE("EnergyModel");

namespace ns3 {

//

// Some dimensional analysis ...

//

// 1 [watt] = 1 [joule] / [second]

// 1 [watt] = 1 [volt] * 1 [amp]

// 1 [amp] = 1 [coulomb] / 1 [second]

// 1 [watt-second] = 1 [joule] / [second] * [second] = 1 [joule]

//

// A watt has dimensions of energy per second.  A watt-second has dimensions

// of energy.

//

// 1 [amp-hour] = 1 [coulomb] / 1 [second] * 1 [hour]

// 1 [amp-hour] = 1 [coulomb] / 1 [second] * 3600 [seconds]

// 1 [amp-hour] = 3600 [amp-seconds]

// 1 [watt-second] = 1 [amp-seconds] * 1 [volt]

//

// To get the energy capacity of your battery in watt-seconds from its 

// amp-hour rating, multiply by 3600 and then the voltage.  For example, your

// Alkaline AAA battery may be rated at 1.5 volts and 900 milli-amp-hours;

// so the energy capacity will be .9 * 3600 * 1.5 = 4860 watt-seconds.

//

// In a very simple battery model, we'll take this naively to mean that this

// battery can supply one watt continuously for 4860 seconds and then will die

// instantaneously.

//

// We'll assume our transmitter is measured in watts.  When it is turned on

// it draws some amount of power, 100 milliwatts for example.  If it transmits

// for one second, it will suck up .1 watt-seconds of our precious energy.

// 

const InterfaceId EnergyModel::iid = 

  MakeInterfaceId ("EnergyModel", Object::iid);

EnergyModel::EnergyModel (

  double ampHours, 

  double volts,

  double idlePower,

  double receivePower,

  double transmitPower)

:

  m_capacity (ampHours * 3600. * volts),

  m_idlePower (idlePower),

  m_receivePower (receivePower),

  m_transmitPower (transmitPower),

  m_totalTransmitPower (0.),

  m_totalReceivePower (0.)

{

  NS_LOG_FUNCTION;

  SetInterfaceId (EnergyModel::iid);

}

EnergyModel::~EnergyModel ()

{

  NS_LOG_FUNCTION;

}

  double

EnergyModel::GetCapacity (Time t)

{

  NS_LOG_FUNCTION;

  double c = m_capacity - m_idlePower * t.GetSeconds ();

  return c >= 0. ? c : 0.;

}

  double

EnergyModel::GetTotalIdlePower (Time t)

{

  NS_LOG_FUNCTION;

  return m_idlePower * t.GetSeconds ();

}

  double

EnergyModel::GetTotalReceivePower (void)

{

  NS_LOG_FUNCTION;

  return m_totalReceivePower;

}

  double

EnergyModel::GetTotalTransmitPower (void)

{

  NS_LOG_FUNCTION;

  return m_totalTransmitPower;

}

  bool

EnergyModel::DrawTransmitPower (Time t)

{

  NS_LOG_FUNCTION;

  double power = m_transmitPower * t.GetSeconds ();

  m_totalTransmitPower += power;

  m_capacity -= power;

  return m_capacity - m_idlePower * t.GetSeconds () >= 0. ? true : false;

}

  bool

EnergyModel::DrawReceivePower (Time t)

{

  NS_LOG_FUNCTION;

  double power = m_receivePower * t.GetSeconds ();

  m_totalReceivePower += power;

  m_capacity -= power;

  return m_capacity - m_idlePower * t.GetSeconds () >= 0. ? true : false;

}

}; // namespace ns3