/**************************************************************************
 * 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.                  *
 **************************************************************************/

/* $Id$ */

//-------------------------------------------------------------------------
//                Implementation of the AliKalmanTrack class
//   that is the base for AliTPCtrack, AliITStrackV2 and AliTRDtrack
//        Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
//-------------------------------------------------------------------------
#include <TGeoManager.h>
#include <TMatrixDSym.h>

#include "AliKalmanTrack.h"
#include "AliCluster3D.h"

ClassImp(AliKalmanTrack)

//_______________________________________________________________________
  AliKalmanTrack::AliKalmanTrack():AliExternalTrackParam(),
  fLab(-3141593),
  fFakeRatio(0),
  fChi2(0),
  fMass(AliPID::ParticleMass(AliPID::kPion)),
  fN(0),
  fStartTimeIntegral(kFALSE),
  fIntegratedLength(0)
{
  //
  // Default constructor
  //

  for(Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i] = 0;
}

//_______________________________________________________________________
AliKalmanTrack::AliKalmanTrack(const AliKalmanTrack &t):
  AliExternalTrackParam(t),
  fLab(t.fLab),
  fFakeRatio(t.fFakeRatio),
  fChi2(t.fChi2),
  fMass(t.fMass),
  fN(t.fN),
  fStartTimeIntegral(t.fStartTimeIntegral),
  fIntegratedLength(t.fIntegratedLength)
{
  //
  // Copy constructor
  //
  
  for (Int_t i=0; i<AliPID::kSPECIES; i++)
      fIntegratedTime[i] = t.fIntegratedTime[i];
}

//_______________________________________________________________________
Double_t AliKalmanTrack::GetPredictedChi2(const AliCluster3D *c) const {
  //
  //  Calculate the predicted Chi2 for a 3D cluster "c" 
  //
  Double_t res[3] = {
    GetX() - c->GetX(),
    GetY() - c->GetY(),
    GetZ() - c->GetZ()
  };

  Double_t f=GetSnp();
  if (TMath::Abs(f) >= kAlmost1) return kVeryBig;
  Double_t r=TMath::Sqrt(1.- f*f);
  Double_t a=f/r, b=GetTgl()/r;

  Double_t s2=333.*333.;  //something reasonably big (cm^2)
 
  TMatrixDSym v(3);
  v(0,0)=  s2;  v(0,1)=  a*s2;                 v(0,2)=  b*s2;;
  v(1,0)=a*s2;  v(1,1)=a*a*s2 + GetSigmaY2();  v(1,2)=a*b*s2 + GetSigmaZY();
  v(2,0)=b*s2;  v(2,1)=a*b*s2 + GetSigmaZY();  v(2,2)=b*b*s2 + GetSigmaZ2();

  v(0,0)+=c->GetSigmaX2(); v(0,1)+=c->GetSigmaXY(); v(0,2)+=c->GetSigmaXZ();
  v(1,0)+=c->GetSigmaXY(); v(1,1)+=c->GetSigmaY2(); v(1,2)+=c->GetSigmaYZ();
  v(2,0)+=c->GetSigmaXZ(); v(2,1)+=c->GetSigmaYZ(); v(2,2)+=c->GetSigmaZ2();

  v.Invert();
  if (!v.IsValid()) return kVeryBig;

  Double_t chi2=0.;
  for (Int_t i = 0; i < 3; i++)
    for (Int_t j = 0; j < 3; j++) chi2 += res[i]*res[j]*v(i,j);

  return chi2;  
}

//_______________________________________________________________________
void AliKalmanTrack::StartTimeIntegral() 
{
  // Sylwester Radomski, GSI
  // S.Radomski@gsi.de
  //
  // Start time integration
  // To be called at Vertex by ITS tracker
  //
  
  //if (fStartTimeIntegral) 
  //  AliWarning("Reseting Recorded Time.");

  fStartTimeIntegral = kTRUE;
  for(Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i] = 0;  
  fIntegratedLength = 0;
}

//_______________________________________________________________________
void AliKalmanTrack:: AddTimeStep(Double_t length) 
{
  // 
  // Add step to integrated time
  // this method should be called by a sublasses at the end
  // of the PropagateTo function or by a tracker
  // each time step is made.
  //
  // If integration not started function does nothing
  //
  // Formula
  // dt = dl * sqrt(p^2 + m^2) / p
  // p = pT * (1 + tg^2 (lambda) )
  //
  // pt = 1/external parameter [4]
  // tg lambda = external parameter [3]
  //
  //
  // Sylwester Radomski, GSI
  // S.Radomski@gsi.de
  // 
  
  static const Double_t kcc = 2.99792458e-2;

  if (!fStartTimeIntegral) return;
  
  fIntegratedLength += length;

  Double_t xr, param[5];
  Double_t pt, tgl;
  
  GetExternalParameters(xr, param);
  pt =  1/param[4] ;
  tgl = param[3];

  Double_t p = TMath::Abs(pt * TMath::Sqrt(1+tgl*tgl));

  if (length > 100) return;

  for (Int_t i=0; i<AliPID::kSPECIES; i++) {
    
    Double_t mass = AliPID::ParticleMass(i);
    Double_t correction = TMath::Sqrt( pt*pt * (1 + tgl*tgl) + mass * mass ) / p;
    Double_t time = length * correction / kcc;

    fIntegratedTime[i] += time;
  }
}

//_______________________________________________________________________
Double_t AliKalmanTrack::GetIntegratedTime(Int_t pdg) const 
{
  // Sylwester Radomski, GSI
  // S.Radomski@gsi.de
  //
  // Return integrated time hypothesis for a given particle
  // type assumption.
  //
  // Input parameter:
  // pdg - Pdg code of a particle type
  //


  if (!fStartTimeIntegral) {
    AliWarning("Time integration not started");
    return 0.;
  }

  for (Int_t i=0; i<AliPID::kSPECIES; i++)
    if (AliPID::ParticleCode(i) == TMath::Abs(pdg)) return fIntegratedTime[i];

  AliWarning(Form("Particle type [%d] not found", pdg));
  return 0;
}

void AliKalmanTrack::GetIntegratedTimes(Double_t *times) const {
  for (Int_t i=0; i<AliPID::kSPECIES; i++) times[i]=fIntegratedTime[i];
}

void AliKalmanTrack::SetIntegratedTimes(const Double_t *times) {
  for (Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i]=times[i];
}

Double_t AliKalmanTrack::MeanMaterialBudget(Double_t *start, Double_t *end, Double_t *mparam)
{
  // 
  // calculate mean material budget and material properties beween point start and end
  // mparam - returns parameters used for dEdx and multiple scatering
  //
  // mparam[0] - density mean
  // mparam[1] - rad length
  // mparam[2] - A mean
  // mparam[3] - Z mean
  // mparam[4] - length
  // mparam[5] - Z/A mean
  // mparam[6] - number of boundary crosses
  //
    mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0, mparam[4]=0, mparam[5]=0; mparam[6]=0;
  //
  Double_t bparam[6], lparam[6];          // bparam - total param - lparam - local parameters
  for (Int_t i=0;i<6;i++) bparam[i]=0;    //

  if (!gGeoManager) {
    printf("ERROR: no TGeo\n");
    return 0.;
  }
  //
  Double_t length;
  Double_t dir[3];
  length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
                       (end[1]-start[1])*(end[1]-start[1])+
                       (end[2]-start[2])*(end[2]-start[2]));
  mparam[4]=length;
  if (length<TGeoShape::Tolerance()) return 0.0;
  Double_t invlen = 1./length;
  dir[0] = (end[0]-start[0])*invlen;
  dir[1] = (end[1]-start[1])*invlen;
  dir[2] = (end[2]-start[2])*invlen;
  // Initialize start point and direction
  TGeoNode *currentnode = 0;
  TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
  //  printf("%s length=%f\n",gGeoManager->GetPath(),length);
  if (!startnode) {
    printf("ERROR: start point out of geometry\n");
    return 0.0;
  }
  TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
  lparam[0] = material->GetDensity();
  lparam[1]   = material->GetRadLen();
  lparam[2]   = material->GetA();
  lparam[3]   = material->GetZ();
  lparam[4]   = length;
  lparam[5]   = lparam[3]/lparam[2];
  if (material->IsMixture()) {
    lparam[1]*=lparam[0];  // different normalization in the modeler for mixture
    TGeoMixture * mixture = (TGeoMixture*)material;
    lparam[5] =0;
    Double_t sum =0;
    for (Int_t iel=0;iel<mixture->GetNelements();iel++){
      sum  += mixture->GetWmixt()[iel];
      lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
    }
    lparam[5]/=sum;
  }
  gGeoManager->FindNextBoundary(length);
  Double_t snext = gGeoManager->GetStep();
  Double_t step = 0.0;
  // If no boundary within proposed length, return current density
  if (snext>=length) {
    for (Int_t ip=0;ip<5;ip++) mparam[ip] = lparam[ip];
    return lparam[0];
  }
  // Try to cross the boundary and see what is next
  while (length>TGeoShape::Tolerance()) {
    mparam[6]+=1.;
    currentnode = gGeoManager->Step();
    step += snext+1.E-6;
    bparam[1]    += snext*lparam[1];
    bparam[2]    += snext*lparam[2];
    bparam[3]    += snext*lparam[3];
    bparam[5]    += snext*lparam[5];
    bparam[0]    += snext*lparam[0];

    if (snext>=length) break;
    if (!currentnode) break;
    //    printf("%s snext=%f  density=%f bparam[0]=%f\n", gGeoManager->GetPath(),snext,density,bparam[0]);
    if (!gGeoManager->IsEntering()) {
      gGeoManager->SetStep(1.E-3);
      currentnode = gGeoManager->Step();
      if (!gGeoManager->IsEntering() || !currentnode) {
        //      printf("ERROR: cannot cross boundary\n");
        mparam[0] = bparam[0]/step;
        mparam[1] = bparam[1]/step;
        mparam[2] = bparam[2]/step;
        mparam[3] = bparam[3]/step;
        mparam[5] = bparam[5]/step;
        mparam[4] = step;
        mparam[0] = 0.;             // if crash of navigation take mean density 0
        mparam[1] = 1000000;        // and infinite rad length
        return bparam[0]/step;
      }
      step += 1.E-3;
      snext += 1.E-3;
      bparam[0] += lparam[0]*1.E-3;
      bparam[1]    += lparam[1]*1.E-3;
      bparam[2]    += lparam[2]*1.E-3;
      bparam[3]    += lparam[3]*1.E-3;
      bparam[5]    += lparam[5]*1.E-3;
    }
    length -= snext;
    material = currentnode->GetVolume()->GetMedium()->GetMaterial();
    lparam[0] = material->GetDensity();
    lparam[1]  = material->GetRadLen();
    lparam[2]  = material->GetA();
    lparam[3]  = material->GetZ();
    lparam[5]   = lparam[3]/lparam[2];
    if (material->IsMixture()) {
      lparam[1]*=lparam[0];
      TGeoMixture * mixture = (TGeoMixture*)material;
      lparam[5]=0;
      Double_t sum =0;
      for (Int_t iel=0;iel<mixture->GetNelements();iel++){
        sum+= mixture->GetWmixt()[iel];
        lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
      }
      lparam[5]/=sum;
    }
    gGeoManager->FindNextBoundary(length);
    snext = gGeoManager->GetStep();
  }
  mparam[0] = bparam[0]/step;
  mparam[1] = bparam[1]/step;
  mparam[2] = bparam[2]/step;
  mparam[3] = bparam[3]/step;
  mparam[5] = bparam[5]/step;
  return bparam[0]/step;

}