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

/*

 * Copyright (c) 2005,2006 INRIA

 * All rights reserved.

 *

 * 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef TIME_H

#define TIME_H

#include <stdint.h>

#include <cassert>

#include "high-precision.h"

namespace ns3 {

/**

 * \brief keep track of time unit.

 *

 * This template class is used to keep track of the value 

 * of a specific time unit: the type TimeUnit<1> is used to 

 * keep track of seconds, the type TimeUnit<2> is used to keep

 * track of seconds squared, the type TimeUnit<-1> is used to

 * keep track of 1/seconds, etc.

 *

 * This base class defines all the functionality shared by all

 * these time unit objects: it defines all the classic arithmetic

 * operators +, -, *, /, and all the classic comparison operators:

 * ==, !=, <, >, <=, >=. It is thus easy to add, substract, or 

 * multiply multiple TimeUnit objects. The return type of any such

 * arithmetic expression is always a TimeUnit object.

 *

 * The ns3::Scalar, ns3::Time, ns3::TimeSquare, and ns3::TimeInvert classes 

 * are aliases for the TimeUnit<0>, TimeUnit<1>, TimeUnit<2> and TimeUnit<-1>

 * types respectively.

 *

 * For example:

 * \code

 * Time<1> t1 = Seconds (10.0);

 * Time<1> t2 = Seconds (10.0);

 * Time<2> t3 = t1 * t2;

 * Time<0> t4 = t1 / t2;

 * Time<3> t5 = t3 * t1;

 * Time<-2> t6 = t1 / t5;

 * TimeSquare t7 = t3;

 * Scalar s = t4;

 * \endcode

 *

 * If you try to assign the result of an expression which does not 

 * match the type of the variable it is assigned to, you will get a

 * compiler error. For example, the following will not compile:

 * \code

 * Time<1> = Seconds (10.0) * Seconds (1.5);

 * \endcode

 *

 * You can also use the following non-member functions to manipulate

 * any of these ns3::TimeUnit object:

 *  - \ref ns3-Time-Abs ns3::Abs

 *  - \ref ns3-Time-Max ns3::Max

 *  - \ref ns3-Time-Min ns3::Min

 */

template <int N>

class TimeUnit

{

public:

  TimeUnit ();

  TimeUnit (TimeUnit const &o);

  TimeUnit operator = (TimeUnit const &o);

  TimeUnit (HighPrecision data);

  /**

   * \return the ns3::HighPrecision object which holds the value 

   *         stored in this Time<N> type.

   */

  HighPrecision GetHighPrecision (void) const;

  /**

   * \return true if the time is zero, false otherwise.

   */

  bool IsZero (void) const;

  /**

   * \return true if the time is negative or zero, false otherwise.

   */

  bool IsNegative (void) const;

  /**

   * \return true if the time is positive or zero, false otherwise.

   */

  bool IsPositive (void) const;

  /**

   * \return true if the time is strictly negative, false otherwise.

   */

  bool IsStrictlyNegative (void) const;

  /**

   * \return true if the time is strictly positive, false otherwise.

   */

  bool IsStrictlyPositive (void) const;

private:

  HighPrecision m_data;

};

template <int N>

TimeUnit<N>::TimeUnit ()

  : m_data ()

{}

template <int N>

TimeUnit<N>::TimeUnit (TimeUnit const &o)

  : m_data (o.m_data)

{}

template <int N>

TimeUnit<N>

TimeUnit<N>::operator = (TimeUnit const &o)

{

  m_data = o.m_data;

  return *this;

}

template <int N>

TimeUnit<N>::TimeUnit (HighPrecision data)

  : m_data (data)

{}

template <int N>

HighPrecision

TimeUnit<N>::GetHighPrecision (void) const

{

  return m_data;

}

template <int N>

bool

TimeUnit<N>::IsZero (void) const

{

  return m_data.Compare (HighPrecision::Zero ()) == 0;

}

template <int N>

bool 

TimeUnit<N>::IsNegative (void) const

{

  return m_data.Compare (HighPrecision::Zero ()) <= 0;

}

template <int N>

bool 

TimeUnit<N>::IsPositive (void) const

{

  return m_data.Compare (HighPrecision::Zero ()) >= 0;

}

template <int N>

bool 

TimeUnit<N>::IsStrictlyNegative (void) const

{

  return m_data.Compare (HighPrecision::Zero ()) < 0;

}

template <int N>

bool 

TimeUnit<N>::IsStrictlyPositive (void) const

{

  return m_data.Compare (HighPrecision::Zero ()) > 0;

}

template <int N>

bool 

operator == (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  return lhs.GetHighPrecision ().Compare (rhs.GetHighPrecision ()) == 0;

}

template <int N>

bool 

operator <= (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  return lhs.GetHighPrecision ().Compare (rhs.GetHighPrecision ()) <= 0;

}

template <int N>

bool 

operator >= (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  return lhs.GetHighPrecision ().Compare (rhs.GetHighPrecision ()) >= 0;

}

template <int N>

bool 

operator < (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  return lhs.GetHighPrecision ().Compare (rhs.GetHighPrecision ()) < 0;

}

template <int N>

bool 

operator > (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  return lhs.GetHighPrecision ().Compare (rhs.GetHighPrecision ()) > 0;

}

template <int N>

TimeUnit<N> operator + (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  HighPrecision retval = lhs.GetHighPrecision ();

  bool overflow = retval.Add (rhs.GetHighPrecision ());

  assert (!overflow);

  return TimeUnit<N> (retval);

}

template <int N>

TimeUnit<N> operator - (TimeUnit<N> const &lhs, TimeUnit<N> const &rhs)

{

  HighPrecision retval = lhs.GetHighPrecision ();

  bool overflow = retval.Sub (rhs.GetHighPrecision ());

  assert (!overflow);

  return TimeUnit<N> (retval);

}

template <int N1, int N2>

TimeUnit<N1+N2> operator * (TimeUnit<N1> const &lhs, TimeUnit<N2> const &rhs)

{

  HighPrecision retval = lhs.GetHighPrecision ();

  bool overflow = retval.Mul (rhs.GetHighPrecision ());

  assert (!overflow);

  return TimeUnit<N1+N2> (retval);

}

template <int N1, int N2>

TimeUnit<N1-N2> operator / (TimeUnit<N1> const &lhs, TimeUnit<N2> const &rhs)

{

  HighPrecision retval = lhs.GetHighPrecision ();

  bool underflow = retval.Div (rhs.GetHighPrecision ());

  assert (!underflow);

  return TimeUnit<N1-N2> (retval);

}

/**

 * \anchor ns3-Time-Abs

 * \relates ns3::TimeUnit

 * \param time the input value

 * \returns the absolute value of the input value.

 */

template <int N>

TimeUnit<N> Abs (TimeUnit<N> const &time)

{

  return TimeUnit<N> (Abs (time.GetHighPrecision ()));

}

/**

 * \anchor ns3-Time-Max

 * \relates ns3::TimeUnit

 * \param ta the first value

 * \param tb the seconds value

 * \returns the max of the two input values.

 */

template <int N>

TimeUnit<N> Max (TimeUnit<N> const &ta, TimeUnit<N> const &tb)

{

  HighPrecision a = ta.GetHighPrecision ();

  HighPrecision b = tb.GetHighPrecision ();  

  return TimeUnit<N> (Max (a, b));

}

/**

 * \anchor ns3-Time-Min

 * \relates ns3::TimeUnit

 * \param ta the first value

 * \param tb the seconds value

 * \returns the min of the two input values.

 */

template <int N>

TimeUnit<N> Min (TimeUnit<N> const &ta, TimeUnit<N> const &tb)

{

  HighPrecision a = ta.GetHighPrecision ();

  HighPrecision b = tb.GetHighPrecision ();  

  return TimeUnit<N> (Max (a, b));

}

/**

 * \brief keep track of seconds.

 *

 * This is an instance of type ns3::TimeUnit<1>: it is

 * the return value of the ns3::Simulator::Now method

 * and is needed for the Simulator::Schedule methods

 *

 * Time instances can be created through any of the following classes:

 *  - ns3::Seconds

 *  - ns3::MilliSeconds

 *  - ns3::MicroSeconds

 *  - ns3::NanoSeconds

 *  - ns3::Now

 *

 * Time instances can be added, substracted, multipled and divided using

 * the standard C++ operators (if you make sure to obey the rules

 * of the ns3::TimeUnit class template)

 * To scale a Time instance, you can multiply it with an instance of

 * the ns3::Scalar class.

 * Time instances can also be manipulated through the following non-member 

 * functions:

 *  - \ref ns3-Time-Abs ns3::Abs

 *  - \ref ns3-Time-Max ns3::Max

 *  - \ref ns3-Time-Min ns3::Min

 */

class Time : public TimeUnit<1>

{

public:

  Time ();

  Time (TimeUnit<1> time);

  /**

   * \returns an approximation in seconds of the time stored in this

   *          instance.

   */

  /**

   * \returns an approximation in milliseconds of the time stored in this

   *          instance.

   */

  /**

   * \returns an approximation in microseconds of the time stored in this

   *          instance.

   */

  /**

   * \returns an approximation in nanoseconds of the time stored in this

   *          instance.

   */

};

/**

 * \brief create ns3::Time instances in units of seconds.

 *

 * For example:

 * \code

 * Time t = Seconds (2.0);

 * Simulator::Schedule (NanoSeconds (5.0), ...);

 * \endcode

 */

class Seconds : public TimeUnit<1>

{

public:

  Seconds ();

  Seconds (double seconds);

};

/**

 * \brief create ns3::Time instances in units of milliseconds.

 *

 * For example:

 * \code

 * Time t = MilliSeconds (2);

 * Simulator::Schedule (MilliSeconds (5), ...);

 * \endcode

 */

class MilliSeconds : public TimeUnit<1>

{

public:

  MilliSeconds ();

  MilliSeconds (uint32_t ms);

};

/**

 * \brief create ns3::Time instances in units of microseconds.

 *

 * For example:

 * \code

 * Time t = MicroSeconds (2);

 * Simulator::Schedule (MicroSeconds (5), ...);

 * \endcode

 */

class MicroSeconds : public TimeUnit<1>

{

public:

  MicroSeconds ();

  MicroSeconds (uint32_t ms);

};

/**

 * \brief create ns3::Time instances in units of nanoseconds.

 *

 * For example:

 * \code

 * Time t = NanoSeconds (2);

 * Simulator::Schedule (NanoSeconds (5), ...);

 * \endcode

 */

class NanoSeconds : public TimeUnit<1>

{

public:

  NanoSeconds ();

  NanoSeconds (uint32_t ms);

};

/**

 * \brief create an ns3::Time instance which contains the

 *        current simulation time.

 *

 * This is really a shortcut for the ns3::Simulator::Now method.

 * It is typically used as shown below to schedule an event

 * which expires in 2 seconds from now:

 * \code

 * Simulator::Schedule (Seconds (2.0), &my_function);

 * \endcode

 */

class Now : public Time

{

public:

  Now ();

};

/**

 * \brief hold scalar values

 *

 * This class is used both to construct scalar values to multiply

 * ns3::Time instances and to hold the return value of

 * an expression which returns a scalar. For example, the 

 * following code will output on your terminal 1.5:

 * \code

 * Scalar s0 = Scalar (1.5);

 * Time t1 = Seconds (10.0) * s0;

 * Time t2 = Seconds (10.0) * Scalar (2.5);

 * Scalar s1 = Seconds (15.0) / Seconds (10.0);

 * std::cout << s1.GetDouble () << std::endl;

 * \endcode

 */

class Scalar : public TimeUnit<0>

{

public:

  Scalar ();

  Scalar (double scalar);

  Scalar (TimeUnit<0> scalar);

  double GetDouble (void) const;

};

typedef TimeUnit<-1> TimeInvert;

typedef TimeUnit<2> TimeSquare;

}; // namespace ns3

#endif /* TIME_H */