/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/*
$Log$
*/

#include "AliRICHSegResV0.h"
#include "AliRun.h"
#include "TParticle.h"
#include "TMath.h"
#include "TRandom.h"


ClassImp(AliRICHsegmentation)
ClassImp(AliRICHresponse)	
//___________________________________________
ClassImp(AliRICHsegmentationV0)

void AliRICHsegmentationV0::Init(AliRICHchamber* Chamber)
{
    fNpx=(Int_t) (Chamber->ROuter()/fDpx+1);
    fNpy=(Int_t) (Chamber->ROuter()/fDpy+1);
}


Float_t AliRICHsegmentationV0::GetAnod(Float_t xhit)
{
    Float_t wire= (xhit>0)? Int_t(xhit/fWireD)+0.5:Int_t(xhit/fWireD)-0.5;
    return fWireD*wire;
}

void AliRICHsegmentationV0::SetPADSIZ(Float_t p1, Float_t p2)
{
    fDpx=p1;
    fDpy=p2;
}
void AliRICHsegmentationV0::GetPadIxy(Float_t x, Float_t y, Int_t &ix, Int_t &iy)
{
//  returns pad coordinates (ix,iy) for given real coordinates (x,y)
//
    ix = (x>0)? Int_t(x/fDpx)+1 : Int_t(x/fDpx);
    iy = (y>0)? Int_t(y/fDpy)+1 : Int_t(y/fDpy);
    if (iy >  fNpy) iy= fNpy;
    if (iy < -fNpy) iy=-fNpy;
    if (ix >  fNpx) ix= fNpx;
    if (ix < -fNpx) ix=-fNpx;
}
void AliRICHsegmentationV0::
GetPadCxy(Int_t ix, Int_t iy, Float_t &x, Float_t &y)
{
//  returns real coordinates (x,y) for given pad coordinates (ix,iy)
//
    x = (ix>0) ? Float_t(ix*fDpx)-fDpx/2. : Float_t(ix*fDpx)-fDpx/2.;
    y = (iy>0) ? Float_t(iy*fDpy)-fDpy/2. : Float_t(iy*fDpy)-fDpy/2.;
}

void AliRICHsegmentationV0::
FirstPad(Float_t xhit, Float_t yhit, Float_t dx, Float_t dy)
{
    //
    // Find the wire position (center of charge distribution)
    Float_t x0a=GetAnod(xhit);
    //
    // and take fNsigma*sigma around this center
    Float_t x01=x0a  - dx;
    Float_t x02=x0a  + dx;
    Float_t y01=yhit - dy;
    Float_t y02=yhit + dy;
    //
    // find the pads over which the charge distributes
    GetPadIxy(x01,y01,fixmin,fiymin);
    GetPadIxy(x02,y02,fixmax,fiymax);    
    // 
    // Set current pad to lower left corner
    fix=fixmin;
    fiy=fiymin;
    GetPadCxy(fix,fiy,fx,fy);
}

void AliRICHsegmentationV0::NextPad()
{
    // 
    // Step to next pad in integration region
    if (fix != fixmax) {
	fix++;
    } else if (fiy != fiymax) {
	fix=fixmin;
	fiy++;
    } else {
	printf("\n Error: Stepping outside integration region\n ");
    }
    GetPadCxy(fix,fiy,fx,fy);
}

Int_t AliRICHsegmentationV0::MorePads()
    
//
// Are there more pads in the integration region
{
    if (fix == fixmax && fiy == fiymax) {
	return 0;
    } else {
	return 1;
	
    }
}

void AliRICHsegmentationV0::SigGenInit(Float_t x,Float_t y,Float_t)
{
//
//  Initialises pad and wire position during stepping
    fxt =x;
    fyt =y;
    GetPadIxy(x,y,fixt,fiyt);
    fiwt=Int_t(x/fWireD)+1;
    
}

Int_t AliRICHsegmentationV0::SigGenCond(Float_t x,Float_t y,Float_t)
{
//
//  Signal will be generated if particle crosses pad boundary or
//  boundary between two wires. 
    Int_t ixt, iyt;
    GetPadIxy(x,y,ixt,iyt);
    Int_t iwt=Int_t(x/fWireD)+1;
    
    if ((ixt != fixt) || (iyt !=fiyt) || (iwt != fiwt)) {
	return 1;
    } else {
	return 0;
    }
}
void AliRICHsegmentationV0::
IntegrationLimits(Float_t& x1,Float_t& x2,Float_t& y1, Float_t& y2)
{
    x1=fxt-fx-fDpx/2.;
    x2=x1+fDpx;
    y1=fyt-fy-fDpy/2.;
    y2=y1+fDpy;    
    
}

void AliRICHsegmentationV0::
Neighbours(Int_t iX, Int_t iY, Int_t* Nlist, Int_t Xlist[7], Int_t Ylist[7])
{
//Is used for the cluster finder, include diagonal elements
    
    *Nlist=4;Xlist[0]=Xlist[1]=iX;Xlist[2]=iX-1;Xlist[3]=iX+1;
    Ylist[0]=iY-1;Ylist[1]=iY+1;Ylist[2]=Ylist[3]=iY;
}

void AliRICHsegmentationV0::
FitXY(AliRICHRecCluster* ,TClonesArray* )
    // Default : Centre of gravity method
{
    ;
}


//___________________________________________
ClassImp(AliRICHresponseV0)	
    Float_t AliRICHresponseV0::IntPH(Float_t eloss)
{
    // Get number of electrons and return charge
    
    Int_t nel;
//E9/26=magic number should parameter
    nel= Int_t(eloss*1.e9/26.);
    Float_t charge=0;
    if (nel == 0) nel=1;
    for (Int_t i=1;i<=nel;i++) {
	charge -= fChslope*TMath::Log(gRandom->Rndm());    
    }
    return charge;
}
// -------------------------------------------
Float_t AliRICHresponseV0::IntXY(AliRICHsegmentation * segmentation)
{
    
    const Float_t invpitch = 1/fPitch;
    Float_t response;
//
//  Integration limits defined by segmentation model
//  
    
    Float_t xi1, xi2, yi1, yi2;
    segmentation->IntegrationLimits(xi1,xi2,yi1,yi2);
    xi1=xi1*invpitch;
    xi2=xi2*invpitch;
    yi1=yi1*invpitch;
    yi2=yi2*invpitch;
    
    //
// The Mathieson function 
    Double_t ux1=fSqrtKx3*TMath::TanH(fKx2*xi1);
    Double_t ux2=fSqrtKx3*TMath::TanH(fKx2*xi2);
    
    Double_t uy1=fSqrtKy3*TMath::TanH(fKy2*yi1);
    Double_t uy2=fSqrtKy3*TMath::TanH(fKy2*yi2);
    
    response=4.*fKx4*(TMath::ATan(ux2)-TMath::ATan(ux1))*fKy4*(TMath::ATan(uy2)-TMath::ATan(uy1));

    return response;       
    
}
//___________________________________________
Int_t AliRICHresponseV0::FeedBackPhotons(Float_t source[3], Float_t qtot)
{
  //
  // Generate FeedBack photons
  //
  Int_t j, ipart, nt;
    
  //Probability of feedback
  Float_t fAlphaFeed=0.05;
    
  Int_t sNfeed=0;
  
  // Local variables 
  Float_t cthf, ranf[2], phif, enfp = 0, sthf, weight;
  Int_t i, ifeed;
  Float_t e1[3], e2[3], e3[3];
  Float_t vmod, uswop;
  Float_t fp, random;
  Float_t dir[3], phi;
  Int_t nfp;
  Float_t pol[3], mom[3];
  TLorentzVector position;
  //
  // Determine number of feedback photons

  //  Get weight of current particle
  TParticle *current = (TParticle*) 
    (*gAlice->Particles())[gAlice->CurrentTrack()];
    
  ifeed = Int_t(current->GetWeight()/100+0.5);
  ipart = gMC->TrackPid();
  fp = fAlphaFeed * qtot;
  nfp = gRandom->Poisson(fp);
  
  // This call to fill the time of flight
  gMC->TrackPosition(position);
  //
  // Generate photons
  for (i = 0; i <nfp; ++i) {
	
    // Direction
    gMC->Rndm(ranf, 2);
    cthf = ranf[0] * 2 - 1.;
    if (cthf < 0)  continue;
    sthf = TMath::Sqrt((1 - cthf) * (1 + cthf));
    phif = ranf[1] * 2 * TMath::Pi();
    //
    gMC->Rndm(&random, 1);
    if (random <= .57) {
      enfp = 7.5e-9;
    } else if (random <= .7) {
      enfp = 6.4e-9;
    } else {
      enfp = 7.9e-9;
    }

    dir[0] = sthf * TMath::Sin(phif);
    dir[1] = cthf;
    dir[2] = sthf * TMath::Cos(phif);
    gMC->Gdtom(dir, mom, 2);
    mom[0]*=enfp;
    mom[1]*=enfp;
    mom[2]*=enfp;
    
    // Polarisation
    e1[0] = 0;
    e1[1] = -dir[2];
    e1[2] = dir[1];
    
    e2[0] = -dir[1];
    e2[1] = dir[0];
    e2[2] = 0;
    
    e3[0] = dir[1];
    e3[1] = 0;
    e3[2] = -dir[0];
    
    vmod=0;
    for(j=0;j<3;j++) vmod+=e1[j]*e1[j];
    if (!vmod) for(j=0;j<3;j++) {
      uswop=e1[j];
      e1[j]=e3[j];
      e3[j]=uswop;
    }
    vmod=0;
    for(j=0;j<3;j++) vmod+=e2[j]*e2[j];
    if (!vmod) for(j=0;j<3;j++) {
      uswop=e2[j];
      e2[j]=e3[j];
      e3[j]=uswop;
    }
    
    vmod=0;
    for(j=0;j<3;j++) vmod+=e1[j]*e1[j];
    vmod=TMath::Sqrt(1/vmod);
    for(j=0;j<3;j++) e1[j]*=vmod;
    
    vmod=0;
    for(j=0;j<3;j++) vmod+=e2[j]*e2[j];
    vmod=TMath::Sqrt(1/vmod);
    for(j=0;j<3;j++) e2[j]*=vmod;
    
    gMC->Rndm(ranf, 1);
    phi = ranf[0] * 2 * TMath::Pi();
    for(j=0;j<3;j++) pol[j]=e1[j]*TMath::Sin(phi)+e2[j]*TMath::Cos(phi);
    gMC->Gdtom(pol, pol, 2);
    
    // Put photon on the stack and label it as feedback (51, 52) 
    ++sNfeed;
    if (ipart == 50000050 && ifeed != 50000052) {
      weight = 5000;
    } else {
      weight = 5000;
    }
    gAlice->SetTrack(1, gAlice->CurrentTrack(), gMC->PDGFromId(50),
		     mom,source,pol,position[3],
		     "Cherenkov", nt, weight);
  }
  return(sNfeed);
}