#ifndef __JTRIGGER__JMATCH3G__
#define __JTRIGGER__JMATCH3G__

#include "JPhysics/JConstants.hh"

#include "JTrigger/JMatch.hh"


/**
 * \file
 *
 * Match operator for Cherenkov light from shower in any direction.
 * \author mdejong
 */
namespace JTRIGGER {}
namespace JPP { using namespace JTRIGGER; }

namespace JTRIGGER {

  using JPHYSICS::getInverseSpeedOfLight;
  using JPHYSICS::getIndexOfRefraction;


  /** 
   * 3G match criterion. 
   * This match algorithm is intented for shower signals.
   */
  template<class JHit_t>
  class JMatch3G :
    public JClonable< JMatch<JHit_t>, JMatch3G<JHit_t> >
  {
  public:
    /**
     * Constructor.
     *
     * \param  Dmax_m           maximal distance traveled by photon [m]
     * \param  Tmax_ns          maximal extra time [ns]
     */
    JMatch3G(const double Dmax_m,
	     const double Tmax_ns = 0.0) :
      DMax_m      (Dmax_m),
      TMaxExtra_ns(Tmax_ns),
      x(0.0),
      y(0.0),
      z(0.0),
      d(0.0),
      t(0.0)
    {
      TMax_ns = 0.5 * DMax_m * getIndexOfRefraction() * getInverseSpeedOfLight()  +  TMaxExtra_ns;
    }


    /**
     * Match operator.
     *
     * \param  first    hit
     * \param  second   hit
     * \return          match result
     */
    virtual bool operator()(const JHit_t& first, const JHit_t& second) const override 
    {
      t = fabs(first.getT() - second.getT());

      if (t > TMax_ns) {
	return false;
      }

      x = first.getX() - second.getX();
      y = first.getY() - second.getY();
      z = first.getZ() - second.getZ();
      d = sqrt(x*x + y*y + z*z);
      
      if      (d <= 0.5 * DMax_m)
	return t <=  d           * getIndexOfRefraction() * getInverseSpeedOfLight()  +  TMaxExtra_ns;
      else if (d <= DMax_m)
	return t <= (DMax_m - d) * getIndexOfRefraction() * getInverseSpeedOfLight()  +  TMaxExtra_ns;

      return false;
    }


    double DMax_m;
    double TMax_ns;
    double TMaxExtra_ns;

  private:
    mutable double x;
    mutable double y;
    mutable double z;
    mutable double d;
    mutable double t;
  };
}

#endif