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/// \file XTRTransparentRegRadModel.cc
/// \brief Implementation of the XTRTransparentRegRadModel class

#include "XTRTransparentRegRadModel.hh"

#include "G4Gamma.hh"
#include "G4Integrator.hh"
#include "G4PhysicalConstants.hh"
#include "Randomize.hh"

#include <complex>

using namespace std;

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

////////////////////////////////////////////////////////////////////////////
//
// Constructor, destructor

XTRTransparentRegRadModel::XTRTransparentRegRadModel(G4LogicalVolume* anEnvelope,
                                                     G4Material* foilMat, G4Material* gasMat,
                                                     G4double a, G4double b, G4int n,
                                                     const G4String& processName)
  : G4VXTRenergyLoss(anEnvelope, foilMat, gasMat, a, b, n, processName)
{
  G4cout << "Regular transparent X-ray TR  radiator EM process is called" << G4endl;

  // Build energy and angular integral spectra of X-ray TR photons from
  // a radiator
  fExitFlux = true;
  fAlphaPlate = 10000;
  fAlphaGas = 1000;

  //  BuildTable();
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

XTRTransparentRegRadModel::~XTRTransparentRegRadModel()
{
  ;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

G4double XTRTransparentRegRadModel::SpectralXTRdEdx(G4double energy)
{
  G4double result, sum = 0., tmp, cof1, cof2, cofMin, cofPHC, aMa, bMb, sigma;
  G4int k, kMax, kMin;

  aMa = GetPlateLinearPhotoAbs(energy);
  bMb = GetGasLinearPhotoAbs(energy);

  // if(fCompton)
  {
    aMa += GetPlateCompton(energy);
    bMb += GetGasCompton(energy);
  }
  aMa *= fPlateThick;
  bMb *= fGasThick;

  sigma = aMa + bMb;

  cofPHC = 4 * pi * hbarc;
  cofPHC *= 200. / 197.;
  tmp = (fSigma1 - fSigma2) / cofPHC / energy;
  cof1 = fPlateThick * tmp;
  cof2 = fGasThick * tmp;

  cofMin = energy * (fPlateThick + fGasThick) / fGamma / fGamma;
  cofMin += (fPlateThick * fSigma1 + fGasThick * fSigma2) / energy;
  cofMin /= cofPHC;

  //  if (fGamma < 1200) kMin = G4int(cofMin);  // 1200 ?
  // else               kMin = 1;

  kMin = G4int(cofMin);
  if (cofMin > kMin) kMin++;

  // tmp  = (fPlateThick + fGasThick)*energy*fMaxThetaTR;
  // tmp /= cofPHC;
  // kMax = G4int(tmp);
  // if(kMax < 0) kMax = 0;
  // kMax += kMin;

  kMax = kMin + 9;  // 5; // 9; //   kMin + G4int(tmp);

  // tmp /= fGamma;
  // if( G4int(tmp) < kMin ) kMin = G4int(tmp);
  // G4cout<<"kMin = "<<kMin<<";    kMax = "<<kMax<<G4endl;

  for (k = kMin; k <= kMax; k++) {
    tmp = pi * fPlateThick * (k + cof2) / (fPlateThick + fGasThick);
    result = (k - cof1) * (k - cof1) * (k + cof2) * (k + cof2);

    if (k == kMin && kMin == G4int(cofMin)) {
      sum += 0.5 * sin(tmp) * sin(tmp) * std::abs(k - cofMin) / result;
    }
    else {
      sum += sin(tmp) * sin(tmp) * std::abs(k - cofMin) / result;
    }
    //  G4cout<<"k = "<<k<<";    sum = "<<sum<<G4endl;
  }
  result = 4. * (cof1 + cof2) * (cof1 + cof2) * sum / energy;
  result *= (1. - exp(-fPlateNumber * sigma)) / (1. - exp(-sigma));
  return result;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//
// Approximation for radiator interference factor for the case of
// fully Regular radiator. The plate and gas gap thicknesses are fixed .
// The mean values of the plate and gas gap thicknesses
// are supposed to be about XTR formation zones but much less than
// mean absorption length of XTR photons in coresponding material.

G4double XTRTransparentRegRadModel::GetStackFactor(G4double energy, G4double gamma,
                                                   G4double varAngle)
{
  /*
  G4double result, Za, Zb, Ma, Mb, sigma;

  Za = GetPlateFormationZone(energy,gamma,varAngle);
  Zb = GetGasFormationZone(energy,gamma,varAngle);
  Ma = GetPlateLinearPhotoAbs(energy);
  Mb = GetGasLinearPhotoAbs(energy);
  sigma = Ma*fPlateThick + Mb*fGasThick;

  G4complex Ca(1.0+0.5*fPlateThick*Ma/fAlphaPlate,fPlateThick/Za/fAlphaPlate);
  G4complex Cb(1.0+0.5*fGasThick*Mb/fAlphaGas,fGasThick/Zb/fAlphaGas);

  G4complex Ha = pow(Ca,-fAlphaPlate);
  G4complex Hb = pow(Cb,-fAlphaGas);
  G4complex H  = Ha*Hb;
  G4complex F1 =   (1.0 - Ha)*(1.0 - Hb )/(1.0 - H)
                 * G4double(fPlateNumber) ;
  G4complex F2 =   (1.0-Ha)*(1.0-Ha)*Hb/(1.0-H)/(1.0-H)
                 * (1.0 - exp(-0.5*fPlateNumber*sigma)) ;
  //    *(1.0 - pow(H,fPlateNumber)) ;
    G4complex R  = (F1 + F2)*OneInterfaceXTRdEdx(energy,gamma,varAngle);
  // G4complex R  = F2*OneInterfaceXTRdEdx(energy,gamma,varAngle);
  result       = 2.0*real(R);
  return      result;
  */
  // numerically unstable result

  G4double result, Qa, Qb, Q, aZa, bZb, aMa, bMb, D, sigma;

  aZa = fPlateThick / GetPlateFormationZone(energy, gamma, varAngle);
  bZb = fGasThick / GetGasFormationZone(energy, gamma, varAngle);
  aMa = fPlateThick * GetPlateLinearPhotoAbs(energy);
  bMb = fGasThick * GetGasLinearPhotoAbs(energy);
  sigma = aMa * fPlateThick + bMb * fGasThick;
  Qa = exp(-0.5 * aMa);
  Qb = exp(-0.5 * bMb);
  Q = Qa * Qb;

  G4complex Ha(Qa * cos(aZa), -Qa * sin(aZa));
  G4complex Hb(Qb * cos(bZb), -Qb * sin(bZb));
  G4complex H = Ha * Hb;
  G4complex Hs = conj(H);
  D = 1.0 / ((1 - Q) * (1 - Q) + 4 * Q * sin(0.5 * (aZa + bZb)) * sin(0.5 * (aZa + bZb)));
  G4complex F1 = (1.0 - Ha) * (1.0 - Hb) * (1.0 - Hs) * G4double(fPlateNumber) * D;
  G4complex F2 = (1.0 - Ha) * (1.0 - Ha) * Hb * (1.0 - Hs)
                 * (1.0 - Hs)
                 // * (1.0 - pow(H,fPlateNumber)) * D*D;
                 * (1.0 - exp(-0.5 * fPlateNumber * sigma)) * D * D;
  G4complex R = (F1 + F2) * OneInterfaceXTRdEdx(energy, gamma, varAngle);
  result = 2.0 * real(R);
  return result;
}
