#ifndef TIMER_H

#define TIMER_H

#include "ns3/fatal-error.h"

#include "nstime.h"

#include "event-id.h"

namespace ns3 {

class TimerImpl;

/**

 * \brief a simple Timer class

 *

 * A timer is used to hold together a delay, a function to invoke

 * when the delay expires, and a set of arguments to pass to the function

 * when the delay expires.

 *

 * A timer can also be used to enforce a set of predefined event lifetime

 * management policies. These policies are specified at construction time

 * and cannot be changed after.

 */

class Timer 

{

public:

  enum {

    /**

     * This policy enforces a check before each call to Timer::Schedule

     * to verify that the timer has already expired. This policy

     * is incompatible with CANCEL_ON_SCHEDULE REMOVE_ON_SCHEDULE, and,

     * GARBAGE_COLLECT.

     */

    CHECK_ON_SCHEDULE = (1<<0),

    /**

     * This policy enforces a check from the destructor of the Timer

     * to verify that the timer has already expired. This policy is

     * incompatible with CANCEL_ON_DESTROY, REMOVE_ON_DESTROY, and

     * GARBAGE_COLLECT.

     */

    CHECK_ON_DESTROY = (1<<1),

    /**

     * This policy cancels the event before scheduling a new event 

     * for each call to Timer::Schedule. This policy

     * is incompatible with CHECK_ON_SCHEDULE, REMOVE_ON_SCHEDULE, and,

     * GARBAGE_COLLECT.

     */

    CANCEL_ON_SCHEDULE = (1<<2),

    /**

     * This policy cancels the event from the destructor of the Timer

     * to verify that the event has already expired. This policy is

     * incompatible with CHECK_ON_DESTROY, REMOVE_ON_DESTROY, and

     * GARBAGE_COLLECT.

     */

    CANCEL_ON_DESTROY = (1<<3),

    /**

     * This policy removes the event from the simulation event list 

     * before scheduling a new event for each call to Timer::Schedule. 

     * This policy is incompatible with CHECK_ON_SCHEDULE,

     * CANCEL_ON_SCHEDULE, and, GARBAGE_COLLECT.

     */

    REMOVE_ON_SCHEDULE = (1<<4),

    /**

     * This policy removes the event from the simulation event list

     * when the destructor of the Timer is invoked. This policy is

     * incompatible with CHECK_ON_DESTROY, CANCEL_ON_DESTROY, and

     * GARBAGE_COLLECT.

     */

    REMOVE_ON_DESTROY = (1<<5),

    /**

     * This policy is incompatible with all other policies. Event

     * event scheduled with this policy is kept track of by an

     * event garbage collector which makes sure that all events

     * of timers with a GARBAGE_COLLECT policy are cancelled at the

     * end of the simulation.

     */

    GARBAGE_COLLECT = (1<<6),

  };

  /**

   * create a timer with a default event lifetime management policy:

   *  - CHECK_ON_SCHEDULE

   *  - CHECK_ON_DESTROY

   */

  Timer ();

  /**

   * \param flags the event lifetime management policies to use

   *

   * The set of flag combinations allowed is:

   *  - none

   *  - GARBAGE_COLLECT

   *  - one of CANCEL_ON_DESTROY, REMOVE_ON_DESTROY, or, CHECK_ON_DESTROY

   *  - one of CANCEL_ON_SCHEDULE, REMOVE_ON_SCHEDULE, or, CHECK_ON_SCHEDULE

   *  - one of CANCEL_ON_DESTROY, REMOVE_ON_DESTROY, or, CHECK_ON_DESTROY ored

   *    with one of CANCEL_ON_SCHEDULE, REMOVE_ON_SCHEDULE, or, CHECK_ON_SCHEDULE.

   */

  Timer (int flags);

  ~Timer ();

  /**

   * \param fn the function

   *

   * Store this function in this Timer for later use by Timer::Schedule.

   */

  void SetFunction (void (*fn) (void));

  /**

   * \param fn the function

   * \param a1 the first argument

   *

   * Store this function and this argument in this Timer for later use by 

   * Timer::Schedule.

   */

  template <typename U1, typename T1>

  void SetFunction (void (*fn) (U1), T1 a1);

  /**

   * \param fn the function

   * \param a1 the first argument

   * \param a2 the second argument

   *

   * Store this function and these arguments in this Timer for later use by 

   * Timer::Schedule.

   */

  template <typename U1, typename U2,

            typename T1, typename T2>

  void SetFunction (void (*fn) (U1, U2), T1 a1, T2 a2);

  /**

   * \param fn the function

   * \param a1 the first argument

   * \param a2 the second argument

   * \param a3 the third argument

   *

   * Store this function and these arguments in this Timer for later use by 

   * Timer::Schedule.

   */

  template <typename U1, typename U2, typename U3,

            typename T1, typename T2, typename T3>

  void SetFunction (void (*fn) (U1, U2, U3), T1 a1, T2 a2, T3 a3);

  /**

   * \param a1 the first argument

   *

   * Store this argument in this Timer for later use by Timer::Schedule.

   */

  template <typename T1>

  void SetArguments (T1 a1);

  /**

   * \param a1 the first argument

   * \param a2 the second argument

   *

   * Store these arguments in this Timer for later use by Timer::Schedule.

   */

  template <typename T1, typename T2>

  void SetArguments (T1 a1, T2 a2);

  /**

   * \param a1 the first argument

   * \param a2 the second argument

   * \param a3 the third argument

   *

   * Store these arguments in this Timer for later use by Timer::Schedule.

   */

  template <typename T1, typename T2, typename T3>

  void SetArguments (T1 a1, T2 a2, T3 a3);

  /**

   * \param delay the delay

   *

   * The next call to Schedule will schedule the timer with this delay.

   */

  void SetDelay (const Time &delay);

  /**

   * \returns the currently-configured delay for the next Schedule.

   */

  Time GetDelay (void) const;

  /**

   * Cancel the currently-running event if there is one. Do nothing

   * otherwise.

   */

  void Cancel (void);

  /**

   * Remove from the simulation event-list the currently-running event 

   * if there is one. Do nothing otherwise.

   */

  void Remove (void);

  /**

   * \return true if there is no currently-running event, false otherwise.

   */

  bool IsExpired (void) const;

  /**

   * \return true if there is a currently-running event, false otherwise.

   */

  bool IsRunning (void) const;

  /**

   * Schedule a new event using the currently-configured delay, function, 

   * and arguments.

   */

  void Schedule (void);

private:

  int m_flags;

  Time m_delay;

  EventId m_event;

  TimerImpl *m_impl;

};

} // namespace ns3

// The actual implementation.

#include "simulator.h"

#include "ns3/type-traits.h"

namespace ns3 {

template <typename T>

struct TimerTraits;

template <typename T>

struct TimerTraits

{

  typedef typename TypeTraits<typename TypeTraits<T>::ReferencedType>::NonConstType StoredType;

  typedef const StoredType &ParameterType;

};

class TimerImpl

{

public:

  virtual ~TimerImpl () {}

  virtual EventId Schedule (const Time &delay) = 0;

};

template <typename T1>

struct TimerImplOne : public TimerImpl

{

  virtual void SetArguments (T1 a1) = 0;

};

template <typename U1, typename T1>

void 

Timer::SetFunction (void (*fn) (U1), T1 a1)

{

  struct FnTimerImplOne : public TimerImplOne<typename TimerTraits<U1>::ParameterType>

  {

    typedef void (*FN) (U1);

    FnTimerImplOne (FN fn) 

      : m_fn (fn) {}

    virtual void SetArguments (typename TimerTraits<U1>::ParameterType a1) {

      m_a1 = a1;

    }

    virtual EventId Schedule (const Time &delay) {

      return Simulator::Schedule (delay, m_fn, m_a1);

    }

    FN m_fn;

    typename TimerTraits<T1>::StoredType m_a1;

  } *function = new FnTimerImplOne (fn);

  function->SetArguments (a1);

  delete m_impl;

  m_impl = function;  

}

template <typename T1>

void 

Timer::SetArguments (T1 a1)

{

  if (m_impl == 0)

    {

      NS_FATAL_ERROR ("You cannot set the arguments of a Timer before setting its function.");

      return;

    }

  struct TimerImplOne<typename TimerTraits<T1>::ParameterType> *impl =

    dynamic_cast<struct TimerImplOne<typename TimerTraits<T1>::ParameterType> *> (m_impl);

  if (impl == 0)

    {

      NS_FATAL_ERROR ("You tried to set Timer arguments incompatible with its function.");

      return;

    }

  impl->SetArguments (a1);

}

} // namespace ns3

#endif /* TIMER_H */