#ifndef __JAANET__JEVTWEIGHTHELPER__
#define __JAANET__JEVTWEIGHTHELPER__

#include <memory>

#include "km3net-dataformat/offline/Head.hh"
#include "km3net-dataformat/offline/Evt.hh"

#include "JAAnet/JHead.hh"
#include "JAAnet/JEvtWeight.hh"


/**
 * \author mdejong
 */

namespace JAANET {}
namespace JPP { using namespace JAANET; }

namespace JAANET {
  
  /**
   * Helper class for event weighing.
   */
  struct JEvtWeightHelper :
    public JHead,
    public std::shared_ptr<JEvtWeight>
  {
    /**
     * Default constructor.
     */
    JEvtWeightHelper() :
      counter(0)
    {}


    /**
     * Constructor.
     *
     * \param  weighter          event weighter
     */
    JEvtWeightHelper(const JEvtWeight& weighter) :
      counter(0)
    {
      this->configure(weighter);
    }


    /**
     * Get name.
     *
     * \return                   name
     */
    const char* const getName() const
    {
      return getEvtWeighter().getName();
    }
    
    
    /**
     * Configuration.
     *
     * \param  weighter          event weighter
     */
    void configure(const JEvtWeight& weighter)
    {
      counter = 0;
      
      reset(weighter.clone());
    }


    /**
     * Check if a given header is consistent with this event weighter.
     * 
     * \param  header             header
     * \return                    true if header is consistent with this event weighter; else false.              
     */
    bool check(const JHead& header) const
    {
      const JEvtWeight& weighter = getEvtWeighter();
      
      return weighter.check(header);
    }


    /**
     * Get reference to event-weighter.
     *
     * \return                    reference to event-weighter
     */
    JEvtWeight& getEvtWeighter() const
    {
      using namespace JPP;

      if (static_cast<const JEvtWeightHelper&>(*this)) {
	return *(this->get());
      } else {
	THROW(JNullPointerException, "JEvtWeightHelper::getEvtWeighter(): Event-weighter is not set.");
      }
    }
    
    
    /**
     * Add header.
     *
     * \param  header             header
     */
    void add(const JHead& header)
    {
      using namespace JPP;

      JEvtWeight& weighter = getEvtWeighter();
      
      if (check(header)) {
	
	if (counter == 0) {
	  JHead::setHeader(header);
	} else {
	  JHead::add(header);
	}

	++counter;

	weighter.configure(getHeader());
	
      } else {
	
	THROW(JValueOutOfRange, "JEvtWeightHelper::add(): headers do not match.");
      }
    }
    
    
    /**
     * Get weight of given event.
     *
     * \param  evt               event
     * \return                   weight [Hz]
     */
    double getWeight(const Evt& evt) const
    {
      const JEvtWeight& weighter = getEvtWeighter();

      return weighter.getWeight(evt);
    }


    /**
     * Get event-weight normalisation.
     *
     * \return                   event-weight normalisation
     */
    double getNormalisation() const
    {
      const JEvtWeight& weighter = getEvtWeighter();

      return weighter.getNormalisation();
    }


    /**
     * Get event-weight normalisation.
     *
     * \param  evt               event
     * \return                   event-weight normalisation
     */
    double getNormalisation(const Evt& evt) const
    {
      const JEvtWeight& weighter = getEvtWeighter();

      return weighter.getNormalisation(evt);
    }
    
    
  private:    
    
    int counter; //!< Counter to check how many headers have been added
  };
}

#endif