#ifndef __JDAQEVALUATOR__
#define __JDAQEVALUATOR__

#include <limits>

#include "km3net-dataformat/online/JDAQUTCExtended.hh"
#include "km3net-dataformat/online/JDAQHeader.hh"
#include "km3net-dataformat/online/JDAQEventHeader.hh"


/**
 * \author mdejong
 */

namespace KM3NETDAQ {

  /**
   * Auxiliary class to determine time of DAQ objects.
   *
   * The time is relative to the fixed time defined in JDAQUTCExtended.\n
   * For DAQ events, the time is offset by the product of the event counter and a constant weight.\n
   * To correlate DAQ events with summary data, the weight should be set to a value such that 
   * this product is strictly less than half of the frame duration.
   */
  struct JDAQEvaluator {
    /**
     * Type definition of time value.
     */
    struct value_type {

      JDAQUTCExtended   utc;
      JTriggerCounter_t counter;

      static inline JTriggerCounter_t min() { return std::numeric_limits<JTriggerCounter_t>::min(); } //!< minimal counter value
      static inline JTriggerCounter_t max() { return std::numeric_limits<JTriggerCounter_t>::max(); } //!< maximal counter value

      /**
       * Less-than operator.
       *
       * \param  first             first  value
       * \param  second            second value
       * \return                   true if first value less than second value; else false
       */
      friend inline bool operator<(const value_type& first, const value_type& second)
      {
	if (first.utc == second.utc && first.counter != max() && second.counter != max())
	  return first.counter < second.counter;
	else
	  return first.utc     < second.utc;
      }

      /**
       * Subtraction operator.
       *
       * \param  first             first  value
       * \param  second            second value
       * \return                   difference
       */
      friend inline double operator-(const value_type& first, const value_type& second)
      {
	if (first.utc == second.utc && first.counter != max() && second.counter != max())
	  return (double) first.counter - (double) second.counter;
	else
	  return getTimeDifference(second.utc, first.utc);
      }
    };

    
    /**
     * Default constructor.
     */
    JDAQEvaluator()
    {}


    /**
     * Get time of object.
     *
     * \param  object          UTC time
     * \return                 time
     */
    inline value_type operator()(const JDAQUTCExtended& object) const
    {
      return { object, JDAQEvaluator::value_type::max() };
    }


    /**
     * Get time of object.
     *
     * \param  object          DAQ header
     * \return                 time
     */
    inline value_type operator()(const JDAQHeader& object) const
    {
      return(*this)(object.getTimesliceStart());
    }


    /**
     * Get time of event.
     *
     * \param  object          event header
     * \return                 time
     */
    inline value_type operator()(const JDAQEventHeader& object) const
    {
      return { object.getTimesliceStart(), object.getCounter() };
    }
  };


  /**
   * Function object for evaluation of DAQ objects.
   */
  static const JDAQEvaluator getDAQValue;
}

#endif