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

/*

 * Copyright (c) 2010 Network Security Lab, University of Washington, Seattle.

 *

 * 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

 *

 * Authors: Sidharth Nabar <snabar@uw.edu>, He Wu <mdzz@u.washington.edu>

 */

#ifndef BASIC_ENERGY_SOURCE_H

#define BASIC_ENERGY_SOURCE_H

#include "ns3/traced-value.h"

#include "ns3/nstime.h"

#include "ns3/event-id.h"

#include "energy-source.h"

namespace ns3 {

/**

 * BasicEnergySource decreases/increases remaining energy stored in itself in

 * linearly.

 */

class BasicEnergySource : public EnergySource

{

public:

  static TypeId GetTypeId (void);

  BasicEnergySource ();

  virtual ~BasicEnergySource ();

  /**

   * \return Initial energy stored in energy source, in Joules.

   *

   * Implements GetInitialEnergy.

   */

  virtual double GetInitialEnergy (void) const;

  /**

   * \returns Supply voltage at the energy source.

   *

   * Implements GetSupplyVoltage.

   */

  virtual double GetSupplyVoltage (void) const;

  /**

   * \return Remaining energy in energy source, in Joules

   *

   * Implements GetRemainingEnergy.

   */

  virtual double GetRemainingEnergy (void);

  /**

   * \returns Energy fraction.

   *

   * Implements GetEnergyFraction.

   */

  virtual double GetEnergyFraction (void);

  /**

   * Implements UpdateEnergySource.

   */

  virtual void UpdateEnergySource (void);

  /**

   * \param initialEnergyJ Initial energy, in Joules

   *

   * Sets initial energy stored in the energy source. Note that initial energy

   * is assumed to be set before simulation starts and is set only once per

   * simulation.

   */

  void SetInitialEnergy (double initialEnergyJ);

  /**

   * \param supplyVoltageV Supply voltage at the energy source, in Volts.

   *

   * Sets supply voltage of the energy source.

   */

  void SetSupplyVoltage (double supplyVoltageV);

  /**

   * \param interval Energy update interval.

   *

   * This function sets the interval between each energy update.

   */

  void SetEnergyUpdateInterval (Time interval);

  /**

   * \returns The interval between each energy update.

   */

  Time GetEnergyUpdateInterval (void) const;

private:

  /// Defined in ns3::Object

  void DoStart (void);

  /// Defined in ns3::Object

  void DoDispose (void);

  /**

   * Handles the remaining energy going to zero event. This function notifies

   * all the energy models aggregated to the node about the energy being

   * depleted. Each energy model is then responsible for its own handler.

   */

  void HandleEnergyDrainedEvent (void);

  /**

   * Calculates remaining energy. This function uses the total current from all

   * device models to calculate the amount of energy to decrease. The energy to

   * decrease is given by:

   *    energy to decrease = total current * supply voltage * time duration

   * This function subtracts the calculated energy to decrease from remaining

   * energy.

   */

  void CalculateRemainingEnergy (void);

private:

  double m_initialEnergyJ;                // initial energy, in Joules

  double m_supplyVoltageV;                // supply voltage, in Volts

  TracedValue<double> m_remainingEnergyJ; // remaining energy, in Joules

  EventId m_energyUpdateEvent;            // energy update event

  Time m_lastUpdateTime;                  // last update time

  Time m_energyUpdateInterval;            // energy update interval

};

} // namespace ns3

#endif /* BASIC_ENERGY_SOURCE_H */