#ifndef __GenGamma_H
#define __GenGamma_H

// c/c++ includes
#include <iostream.h>


// ROOT includes
#include "TF1.h"
#include "TRandom.h"

extern TRandom *gRandom;

// this is a class that generates photons hitting the exit window
// it containes all the parameters needed to set-up
// the splitting and the radiation is included as well


// Author: Miroslav Helbich
// Date: Oct. 1 2001
//
// Modified 0ct.19.01 
// radiation in the exit window added

class GenGamma {

  //data members
 private:

  // event variables
  float fEnergy;    // photon energy
  float fXPos;      // photon x-position
  float fYPos;      // photon y-position
  float fZ;          // z = Eelec/Egamma
  float fx1;        // fractional energy loss 1
  float fx2;        // fractional energy loss 2

  // setup variables
  float fEnergyMin; //minimum energy for generated photons
  float fXTilt;     // x position tilt
  float fYTilt;     // y position tilt
  float fXWidth;    // x distribution width
  float fYWidth;    // y distribution width
  
  float fEproton;   // Proton beam energy
  float fEelectron; // Electron beam energy

  // parameters for the radiation in the window
  float fRadXmean; // mean energy loss
  float fRadXmin;  // minimum energy loss for MC generation
  
  // generic distribution function
  TF1 *fEdist; // Energy distribution of photons: Bethe-Heitler formula
  TF1 *fydist; // y hit distribution
  TF1 *fxdist; // x hit distribution
  TF1 *fzdist; // zdistribution

  // default distribution functions
  TF1 *fBethe; // Bethe-Heitler
  TF1 *fydistgaus;
  TF1 *fxdistgaus;
  
  // methods
protected:

  float EnergyFracLoss(); //fractional energy loss of electrons in the window
  
public:

  // constructors  GenGamma();
  GenGamma();
  
  // destructor
  ~GenGamma();

  // getters
  float GetEnergyMin() {return fEnergyMin;};
  float GetXTilt() {return fXTilt;};
  float GetYTilt() {return fYTilt;};
  float GetEProton() {return fEproton;};
  float GetEElectron() {return fEelectron;};

  // advanced getters
  TF1* GetEDist() {return fEdist;};
  TF1* GetYDist() {return fydist;};
  TF1* GetXDist() {return fxdist;};
  TF1* GetZDist() {return fzdist;};

  //setters
  void SetEnergyMin(float Emin);
  void SetXTilt(float xtilt);
  void SetYTilt(float ytilt);
  void SetXWidth(float xwidth);
  void SetYWidth(float ywidth);
  void SetEProton(float eproton);
  void SetEElectron(float Eelectron);
  void SetRadXMean (float newmean) {fRadXmean = newmean;};
  void SetRadXMin  (float newmin) {fRadXmin = newmin;};
  
  // advanced setters
  void SetEdist(TF1 *newf) {fEdist = newf;};
  void SetYDist(TF1 *newf) {fydist = newf;};
  void SetXDist(TF1 *newf) {fxdist = newf;};
  void SetZDist(TF1 *newf) {fzdist = newf;};
  
  //derived getters
  float GetXsec(); // get cross-section 
  float GetEnergy() {return fEnergy;};
  float GetXPos()   {return fXPos;};
  float GetYPos()   {return fYPos;};
  float GetZ()      {return fZ;};
  float GetX1()     {return fx1;};
  float GetX2()     {return fx2;};


  // executive stuff
  void MakeEvent(); //generate event
  void Show();      //display event

};





#endif