#ifndef __JFIT__JLINE3ZREGRESSOR__
#define __JFIT__JLINE3ZREGRESSOR__

#include <string>

#include "JPhysics/JPDFTypes.hh"
#include "JPhysics/JPDFTable.hh"
#include "JPhysics/JNPETable.hh"
#include "JPhysics/JPDFToolkit.hh"
#include "JPhysics/JGeane.hh"
#include "JTools/JFunction1D_t.hh"
#include "JTools/JFunctionalMap_t.hh"
#include "JPhysics/JConstants.hh"
#include "JTools/JRange.hh"
#include "JGeometry3D/JPosition3D.hh"
#include "JGeometry3D/JDirection3D.hh"
#include "JMath/JZero.hh"
#include "JLang/JSharedPointer.hh"
#include "JFit/JTimeRange.hh"
#include "JFit/JLine3Z.hh"
#include "JFit/JPMTW0.hh"
#include "JFit/JSimplex.hh"
#include "JFit/JGandalf.hh"
#include "JFit/JMEstimator.hh"
#include "JFit/JRegressor.hh"
#include "Jeep/JMessage.hh"


/**
 * \file
 * Data regression method for JFIT::JLine3Z.
 * \author mdejong
 */
namespace JFIT {}
namespace JPP { using namespace JFIT; }

namespace JFIT {

  using JPHYSICS::JPDFType_t;
  using JPHYSICS::DIRECT_LIGHT_FROM_MUON;
  using JPHYSICS::SCATTERED_LIGHT_FROM_MUON;
  using JPHYSICS::DIRECT_LIGHT_FROM_DELTARAYS;
  using JPHYSICS::SCATTERED_LIGHT_FROM_DELTARAYS;
  using JPHYSICS::DIRECT_LIGHT_FROM_EMSHOWERS;
  using JPHYSICS::SCATTERED_LIGHT_FROM_EMSHOWERS;


  /**
   * Regressor function object for JLine3Z fit using JSimplex minimiser.
   */
  template<>
  struct JRegressor<JLine3Z, JSimplex> :
    public JAbstractRegressor<JLine3Z, JSimplex>
  {
    using JAbstractRegressor<JLine3Z, JSimplex>::operator();

    /**
     * Constructor.
     *
     * \param  sigma              time resolution of hit [ns]
     */
    JRegressor(double sigma) :
      estimator(new JMEstimatorNormal())
    {
      this->sigma = sigma;
    }


    /**
     * Fit function.
     * This method is used to determine the chi2 of given hit with respect to trajectory of muon.
     *
     * The template argument <tt>JHit_t</tt> refers to a data structure which should have the following member methods:
     *   - double getX();       // [m]
     *   - double getY();       // [m]
     *   - double getZ();       // [m]
     *   - double getT();       // [ns]
     *
     * \param  track              track
     * \param  hit                hit
     * \return                    chi2
     */
    template<class JHit_t>
    double operator()(const JLine3Z& track, const JHit_t& hit) const
    {
      using namespace JPP;

      JPosition3D D(hit.getX(), hit.getY(), hit.getZ());

      D.sub(track.getPosition());

      const double z  = D.getDot(track.getDirection());
      const double R  = sqrt(D.getLengthSquared() - z*z);

      const double t1 = track.getT() + (z + R * getKappaC()) * getInverseSpeedOfLight();

      const double u  = (t1 - hit.getT()) / sigma;

      return estimator->getRho(u) * hit.getW();
    }

    JLANG::JSharedPointer<JMEstimator> estimator;  //!< M-Estimator function
    double                             sigma;      //!< Time resolution [ns]
  };


  /**
   * Regressor function object for JLine3Z fit using JGandalf minimiser.
   */
  template<>
  struct JRegressor<JLine3Z, JGandalf> :
    public JAbstractRegressor<JLine3Z, JGandalf>
  {
    using JAbstractRegressor<JLine3Z, JGandalf>::operator();

    typedef JTOOLS::JSplineFunction1S_t                                   JFunction1D_t;
    typedef JTOOLS::JMAPLIST<JTOOLS::JPolint1FunctionalMap,
			     JTOOLS::JPolint0FunctionalGridMap,
			     JTOOLS::JPolint0FunctionalGridMap>::maplist  JPDFMaplist_t;
    typedef JPHYSICS::JPDFTable<JFunction1D_t, JPDFMaplist_t>             JPDF_t;  //!< time dependent PDF
    
    typedef JTOOLS::JMAPLIST<JTOOLS::JPolint1FunctionalMapH,
			     JTOOLS::JPolint1FunctionalGridMap,
			     JTOOLS::JPolint1FunctionalGridMap>::maplist  JNPEMaplist_t;
    typedef JPHYSICS::JNPETable<double, double, JNPEMaplist_t>            JNPE_t;  //!< time integrated PDF

    /**
     * Default constructor
     */
    JRegressor()
    {};


    /**
     * Constructor.
     *
     * The PDF file descriptor should contain the wild card character JPHYSICS::WILD_CARD which
     * will be replaced by the corresponding PDF types listed in JRegressor<JLine3Z, JGandalf>::pdf_t.
     *
     * The <tt>TTS</tt> corresponds to the additional time smearing applied to the PDFs.
     *
     * \param  fileDescriptor     PDF file descriptor
     * \param  TTS                TTS [ns]
     * \param  numberOfPoints     number of points for Gauss-Hermite integration of TTS
     * \param  epsilon            precision        for Gauss-Hermite integration of TTS
     */
    JRegressor(const std::string& fileDescriptor,
	       const double       TTS,
	       const int          numberOfPoints = 25,
	       const double       epsilon        = 1.0e-10) :
      E_GeV(0.0),
      estimator(new JMEstimatorNormal())
    {
      using namespace std;
      using namespace JPP;

      const JPDF_t::JSupervisor supervisor(new JPDF_t::JDefaultResult(JMATH::zero));

      for (int i = 0; i != NUMBER_OF_PDFS; ++i) {

	try {
	    
	  const string file_name = getFilename(fileDescriptor, pdf_t[i]);
	    
	  NOTICE("loading PDF from file " << file_name << "... " << flush);

	  pdf[i].load(file_name.c_str());
	  
	  NOTICE("OK" << endl);

	  pdf[i].setExceptionHandler(supervisor);
	}
	catch(const JException& error) {
	  FATAL(error.what() << endl);
	}
      }

      // Add PDFs

      for (int i = 1; i < NUMBER_OF_PDFS; i += 2) {

	pdf[ i ].add(pdf[i-1]); 

	JPDF_t buffer;

	pdf[i-1].swap(buffer);

	if        (TTS > 0.0) {
	  pdf[i].blur(TTS, numberOfPoints, epsilon);
	} else if (TTS < 0.0) {
	  ERROR("Illegal value of TTS [ns]: " << TTS << endl);
	}

	npe[ i ] = JNPE_t(pdf[i]);
      }
    }


    /**
     * Fit function.
     * This method is used to determine the chi2 and gradient of given hit with respect to trajectory of muon.
     *
     * The template argument <tt>JHit_t</tt> refers to a data structure which should have the following member methods:
     *   - double getX();       // [m]
     *   - double getY();       // [m]
     *   - double getZ();       // [m]
     *   - double getDX();      // [u]
     *   - double getDY();      // [u]
     *   - double getDZ();      // [u]
     *   - double getT();       // [ns]
     *
     * \param  track              track
     * \param  hit                hit
     * \return                    chi2 and gradient
     */
    template<class JHit_t>
    result_type operator()(const JLine3Z& track, const JHit_t& hit) const
    {
      using namespace JPP;
      
      JPosition3D  D(hit.getX(),  hit.getY(),  hit.getZ());
      JDirection3D U(hit.getDX(), hit.getDY(), hit.getDZ());

      D.sub(track.getPosition());

      const double z  = D.getDot(track.getDirection());
      const double x  = D.getX()  -  z * track.getDX();
      const double y  = D.getY()  -  z * track.getDY();
      const double R2 = D.getLengthSquared() - z*z;
      const double R  = (R2 > Rmin_m*Rmin_m ? sqrt(R2) : Rmin_m);

      const double t1 = track.getT() + (z + R * getTanThetaC()) * getInverseSpeedOfLight();

      U.rotate(JRotation3Z(-atan2(y,x)));                  // rotate PMT axis to x-z plane

      const double theta = U.getTheta();
      const double phi   = fabs(U.getPhi());

      const double E  = gWater.getE(E_GeV, z);
      const double dt = T_ns.constrain(hit.getT()  -  t1);

      JPDF_t::result_type H0 = getH0(hit.getR(), dt);
      JPDF_t::result_type H1 = getH1(E, R, theta, phi, dt);

      if (H1.V >= Vmax_npe) {
        H1 *= Vmax_npe / H1.V;
      }

      H1 += H0;                                                                                      // signal + background

      result_type result;

      result.chi2     = H1.getChi2() - H0.getChi2();                                                 // Likelihood ratio

      const double wc = 1.0  -  getTanThetaC() * z / R;                                              // d(ct1)/d(z)

      result.gradient = JLine3Z(JLine1Z(JPosition3D(-getTanThetaC() * D.getX() / R,                  // d(ct1)/d(x)
						    -getTanThetaC() * D.getY() / R,                  // d(ct1)/d(y)
						    0.0),
					getSpeedOfLight()),                                          // d(ct1)/d(t)
				JVersor3Z(wc * (D.getX() - D.getZ()*track.getDX()/track.getDZ()),    // d(ct1)/d(dx)
					  wc * (D.getY() - D.getZ()*track.getDY()/track.getDZ())));  // d(ct1)/d(dy)
      
      result.gradient.mul(getInverseSpeedOfLight() * (H1.getDerivativeOfChi2() -
						      H0.getDerivativeOfChi2()));                    // x d(chi2)/d(ct1)

      return result;
    }


    /**
     * Fit function.
     * This method is used to determine the chi2 and gradient of given PMT with respect to trajectory of muon.
     *
     * \param  track              track
     * \param  pmt                pmt
     * \return                    chi2 and gradient
     */
    result_type operator()(const JLine3Z& track, const JPMTW0& pmt) const
    {
      using namespace JGEOMETRY3D;
      using namespace JPHYSICS;
      
      JPosition3D  D(pmt.getPosition());
      JDirection3D U(pmt.getDirection());

      D.sub(track.getPosition());

      const double z  = D.getDot(track.getDirection());
      const double x  = D.getX()  -  z * track.getDX();
      const double y  = D.getY()  -  z * track.getDY();
      const double R2 = D.getLengthSquared() - z*z;
      const double R  = (R2 > Rmin_m*Rmin_m ? sqrt(R2) : Rmin_m);

      U.rotate(JRotation3Z(-atan2(y,x)));                  // rotate PMT axis to x-z plane

      const double theta = U.getTheta();
      const double phi   = fabs(U.getPhi());

      const double E  = gWater.getE(E_GeV, z);

      JNPE_t::result_type H0 = getH0(pmt.getR());
      JNPE_t::result_type H1 = getH1(E, R, theta, phi);

      if (H1.f >= Vmax_npe) {
        H1 *= Vmax_npe / H1.f;
      }

      H1 += H0;

      const bool   hit = pmt.getN() != 0;
      const double u   = H1.getChi2(hit);

      result_type result;

      result.chi2     = estimator->getRho(u);

      result.gradient = JLine3Z(JLine1Z(JPosition3D(-D.getX() / R,   // d(R)/d(x)
						    -D.getY() / R,   // d(R)/d(y)
						    0.0),
					0.0),
				JVersor3Z(-z * D.getX() / R,         // d(R)/d(dx)
					  -z * D.getY() / R));       // d(R)/d(dy)

      result.gradient.mul(estimator->getPsi(u));
      result.gradient.mul(H1.getDerivativeOfChi2(hit));              // x d(chi2)/d(R)

      return result;
    }


    /**
     * Get background hypothesis value for time differentiated PDF.
     *
     * \param  R_Hz               rate [Hz]
     * \param  t1                 time [ns]
     * \return                    hypothesis value
     */
    JPDF_t::result_type getH0(const double R_Hz,
			      const double t1) const
    {
      return JPDF_t::result_type(R_Hz * 1e-9, t1, T_ns);
    }


    /**
     * Get signal hypothesis value for time differentiated PDF.
     *
     * \param  E                  muon energy at minimum distance of approach [GeV]
     * \param  R                  minimum distance of approach [m]
     * \param  theta              PMT zenith  angle [rad]
     * \param  phi                PMT azimuth angle [rad]
     * \param  t1                 arrival time relative to Cherenkov hypothesis [ns]
     * \return                    hypothesis value
     */
    JPDF_t::result_type getH1(const double E,
			      const double R,
			      const double theta,
			      const double phi,
			      const double t1) const
    {
      using namespace std;
      using namespace JPP;

      JPDF_t::result_type h1 = zero;

      for (int i = 0; i != NUMBER_OF_PDFS; ++i) {

	if (!pdf[i].empty() && R <= pdf[i].getXmax()) {

	  JPDF_t::result_type y1 = pdf[i](max(R, pdf[i].getXmin()), theta, phi, t1);
	  
	  // safety measures
	  
	  if (y1.f <= 0.0) {
	    y1.f  = 0.0;
	    y1.fp = 0.0;
	  }
	  
	  if (y1.v <= 0.0) {
	    y1.v  = 0.0;
	  }
	  
	  // energy dependence
	  
	  if        (is_deltarays(pdf_t[i])) {
	    y1 *= getDeltaRaysFromMuon(E);
	  } else if (is_bremsstrahlung(pdf_t[i])) {
	    y1 *= E;
	  }
	  
	  h1 += y1;
	}
      }

      return h1;
    }


    /**
     * Get background hypothesis value for time integrated PDF.
     *
     * \param  R_Hz               rate [Hz]
     * \return                    hypothesis value
     */
    JNPE_t::result_type getH0(const double R_Hz) const
    {
      return JNPE_t::result_type(R_Hz * 1e-9 * T_ns.getLength(), 0.0);
    }


    /**
     * Get signal hypothesis value for time integrated PDF.
     *
     * \param  E                  muon energy at minimum distance of approach [GeV]
     * \param  R                  minimum distance of approach [m]
     * \param  theta              PMT zenith  angle [rad]
     * \param  phi                PMT azimuth angle [rad]
     * \return                    hypothesis value
     */
    JNPE_t::result_type getH1(const double E,
			      const double R,
			      const double theta,
			      const double phi) const
    {
      using namespace std;
      using namespace JPP;

      JNPE_t::result_type h1 = JMATH::zero;
	
      for (int i = 0; i != NUMBER_OF_PDFS; ++i) {

	if (!npe[i].empty() && R <= npe[i].getXmax()) {

	  try {

	    JNPE_t::result_type y1 = npe[i](max(R, npe[i].getXmin()), theta, phi);
	  
	    // safety measures
	    
	    if (y1.f > 0.0) {
	    
	      // energy dependence
	    
	      if        (is_deltarays(pdf_t[i])) {
		y1 *= getDeltaRaysFromMuon(E);
	      } else if (is_bremsstrahlung(pdf_t[i])) {
		y1 *= E;
	      }
	  
	      h1 += y1;
	    }
	  }
	  catch(JException& error) {
	    ERROR(error << endl);
	  }
	}
      }

      return h1;
    }
    

    /**
     * Get maximal road width of PDF.
     *
     * \return                    road width [m]
     */
    inline double getRmax() const
    {
      double xmax = 0.0;

      for (int i = 0; i != NUMBER_OF_PDFS; ++i) {
	if (!pdf[i].empty() && pdf[i].getXmax() > xmax) {
	  xmax = pdf[i].getXmax();
	}
      }

      return xmax;
    }


    /**
     * Set maximal road width of PDF.
     *
     * \param  Rmax               road width [m]
     */
    inline void setRmax(const double Rmax)
    {
      for (int i = 0; i != NUMBER_OF_PDFS; ++i) {
	if (!pdf[i].empty()) {
	  pdf[i].compress(JTOOLS::JRange<typename JFunction1D_t::abscissa_type>(0.0, Rmax));
	}
      }
    }


    static JTimeRange   T_ns;                      //!< Time window with respect to Cherenkov hypothesis [ns]
    static double       Vmax_npe;                  //!< Maximal integral of PDF [npe]
    static double       Rmin_m;                    //!< Minimal distance of [m]

    static const int    NUMBER_OF_PDFS = 6;

    static const JPDFType_t pdf_t[NUMBER_OF_PDFS];

    JPDF_t              pdf[NUMBER_OF_PDFS];       //!< PDF
    JNPE_t              npe[NUMBER_OF_PDFS];       //!< PDF
    double              E_GeV;                     //!< Energy of muon at vertex [GeV]

    JLANG::JSharedPointer<JMEstimator> estimator;  //!< M-Estimator function
  };

  
  /**
   * PDF types.
   */
  const JPDFType_t JRegressor<JLine3Z, JGandalf>::pdf_t[] = { DIRECT_LIGHT_FROM_MUON,
							      SCATTERED_LIGHT_FROM_MUON,
							      DIRECT_LIGHT_FROM_DELTARAYS,
							      SCATTERED_LIGHT_FROM_DELTARAYS,
							      DIRECT_LIGHT_FROM_EMSHOWERS,
							      SCATTERED_LIGHT_FROM_EMSHOWERS };


  /**
   * Default values.
   */
  JTimeRange JRegressor<JLine3Z, JGandalf>::T_ns;
  double     JRegressor<JLine3Z, JGandalf>::Vmax_npe = std::numeric_limits<double>::max();
  double     JRegressor<JLine3Z, JGandalf>::Rmin_m   = 0.1;
}

#endif