/**************************************************************************
 * 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.                  *
***************************************************************************/
///////////////////////////////////////////////////////////////////////////
//  Class to generate decays of particles generated by a                 //
//  previous generator. It works as a generator, but pratically it       //
//  performs only decays. It works with this scheme: first loops over    // 
//  particles on the stack, selects those to be decayed, decays them     //
//  and then pushes the decay products on the stack.                     //
//                                                                       //
//  Giuseppe E. Bruno            &    Fiorella Fionda                    //
//  (Giuseppe.Bruno@ba.infn.it)       (Fiorella.Fionda@ba.infn.it)       //
///////////////////////////////////////////////////////////////////////////

#include "AliStack.h"
#include "AliGenEvtGen.h"
#include "AliRun.h"
#include "AliLog.h"
#include <TParticle.h>

ClassImp(AliGenEvtGen)
///////////////////////////////////////////////////////////////////////////
AliGenEvtGen::AliGenEvtGen(): 
  fStack(0x0),    
  fDecayer(0x0),
  fForceDecay(kAll),
  fSwitchOff(kBeautyPart),
  fUserDecay(kFALSE),
  fUserDecayTablePath(0x0)
  {
  //
  // Default Construction
  //
  }
///////////////////////////////////////////////////////////////////////////////////////////
AliGenEvtGen::~AliGenEvtGen() 
  {
  //
  // Standard Destructor
  //
  if(fStack) {delete fStack;}
  fStack = 0; 
  if(fDecayer) {delete fDecayer;}
  fDecayer = 0;
  if(fUserDecayTablePath) {delete fUserDecayTablePath;}
  fUserDecayTablePath = 0;
  }
///////////////////////////////////////////////////////////////////////////////////////////

void AliGenEvtGen::Init() 
  {
  //
  // Standard AliGenerator Initializer - no input 
  // 1) initialize EvtGen with default decay and particle table
  // 2) set the decay mode to force particle 
  // 3) set a user decay table if defined
  //
  if(fDecayer)
  {
  AliWarning("AliGenEvtGen already initialized!!!");
  return;
  }
  fDecayer = new AliDecayerEvtGen();
  fDecayer->Init(); //read the default decay table DECAY.DEC and particle table

  //if is set a decay mode: default decay mode is kAll  
  fDecayer->SetForceDecay(fForceDecay);
  fDecayer->ForceDecay();

  //if is defined a user decay table
  if(fUserDecay) 
    {
    fDecayer->SetDecayTablePath(fUserDecayTablePath);
    fDecayer->ReadDecayTable();
    }
  }

/////////////////////////////////////////////////////////////////////////////////////////////
void AliGenEvtGen::Generate() 
  {
  //
  //Generate method - Input none - Output none
  //For each event:
  //1)return the stack of the previous generator and select particles to be decayed by EvtGen
  //2)decay particles selected and put the decay products on the stack
  //
  //
  Float_t polar[3]= {0,0,0};  // Polarisation of daughter particles 
  Float_t origin0[3];         // Origin of the parent particle 
  Float_t pc[3], och[3]; // Momentum and origin of the children particles from EvtGen
  Int_t nt;
  Float_t tof;
  Int_t nPrimsPythia;
  TLorentzVector *mom=new TLorentzVector();
  static TClonesArray *particles;
  if(!particles) particles = new TClonesArray("TParticle",1000);
  fStack = AliRunLoader::Instance()->Stack();
  if(!fStack) {Info("Generate","Error: No stack found!"); return;}
  nPrimsPythia = fStack->GetNprimary();  
  AliDebug(1,Form("nPrimsPythia = %d \n",nPrimsPythia));
  for (Int_t iTrack = 0; iTrack < nPrimsPythia; ++iTrack) {
  TParticle *part = fStack->Particle(iTrack);
  Int_t pdg=part->GetPdgCode();

  AliDebug(1,Form("GetFlavour = %d e pdg = %d \n",GetFlavour(pdg),pdg));
  
  switch(fSwitchOff)
  {
  case kAllPart: 
  break;
  case kBeautyPart:
  if(GetFlavour(pdg)!=5) continue;
  break; 
  case kCharmPart: 
  if(GetFlavour(pdg)!=4) continue;
  break;
  } 

  //check if particle is already decayed by Pythia  
  if(part->GetStatusCode() != 1 || part->GetNDaughters()>0) 
    {
    AliDebug(1,Form("Attention: particle %d is already decayed by Pythia!",pdg));
    continue;
    }
  
  part->SetStatusCode(11); //Set particle as decayed : change the status code
  part->SetBit(kDoneBit);
  part->ResetBit(kTransportBit);

  mom->SetPxPyPzE(part->Px(),part->Py(),part->Pz(),part->Energy());
  Int_t np;

   do{
     fDecayer->Decay(part->GetPdgCode(),mom);
     np = fDecayer->ImportParticles(particles);
     }while(np<0);

  Int_t* trackIt    = new Int_t[np];
  Int_t* pParent   = new Int_t[np];
  AliDebug(1,Form("np = %d \n",np)); 
  
  for (int i = 0; i < np; i++) {
             pParent[i]   = -1;
             trackIt[i]   =  0;
         }
  //select trackable particle  
  if (np >1) {
    TParticle* iparticle =  0;//(TParticle *) particles->At(0);//parent particle
   for (int i = 1; i<np ; i++) { 
     iparticle = (TParticle*) particles->At(i);
     Int_t ks = iparticle->GetStatusCode();

     //track last decay products
     if(ks==1) trackIt[i]=1; 
   
     }//decay particles loop

  }// if decay products   
 
  origin0[0]=part->Vx(); //[cm]
  origin0[1]=part->Vy(); //[cm]
  origin0[2]=part->Vz(); //[cm]
  //
  // Put decay products on the stack
  //
  for (int i = 1; i < np; i++) {
         TParticle* iparticle = (TParticle *) particles->At(i);
         Int_t kf   = iparticle->GetPdgCode();
         Int_t ksc  = iparticle->GetStatusCode();
         Int_t jpa  = iparticle->GetFirstMother()-1; //jpa = 0 for daughters of beauty particles
         Int_t iparent = (jpa > 0) ? pParent[jpa] : iTrack;      

         och[0] = origin0[0]+iparticle->Vx(); //[cm]
         och[1] = origin0[1]+iparticle->Vy(); //[cm]
         och[2] = origin0[2]+iparticle->Vz(); //[cm]
         pc[0]  = iparticle->Px(); //[GeV/c]
         pc[1]  = iparticle->Py(); //[GeV/c]
         pc[2]  = iparticle->Pz(); //[GeV/c]
         tof = part->T()+iparticle->T(); 

         AliDebug(1,Form("FirstMother = %d e indicePart = %d e pdg = %d \n",jpa,i,kf));         
          
         PushTrack(trackIt[i], iparent, kf, pc, och, polar,tof, kPDecay, nt, 1., ksc); 
         if(trackIt[i]==1) AliDebug(1,Form("Trackable particles: %d e pdg %d \n",i,kf));
         pParent[i] = nt;
         KeepTrack(nt);
         SetHighWaterMark(nt);
         }// Particle loop
         particles->Clear();
     	 if (trackIt)    delete[] trackIt;
         if (pParent)    delete[] pParent;
       }
  Info("Generate","AliGenEvtGen DONE");  
  }

//////////////////////////////////////////////////////////////////////////////////////////
Int_t AliGenEvtGen::GetFlavour(Int_t pdgCode)  
  { 
  //
  // return the flavour of a particle
  // input: pdg code of the particle
  // output: Int_t 
  //         3 in case of strange (open and hidden)
  //         4 in case of charm (")
  //         5 in case of beauty (")
  //
  Int_t pdg = TMath::Abs(pdgCode);
  //Resonance
  if (pdg > 100000) pdg %= 100000;
  if(pdg > 10000)  pdg %= 10000;
  // meson ?
  if(pdg > 10) pdg/=100;
  // baryon ?
  if(pdg > 10) pdg/=10;
  return pdg;
  }

/////////////////////////////////////////////////////////////////////////////////////////
Bool_t AliGenEvtGen::SetUserDecayTable(Char_t *path)
  {
  //
  //Set the path of user decay table if it is defined
  //
  //put a comment to control if path exists 
  if(gSystem->AccessPathName(path))
    {
    AliWarning("Attention: This path not exist!\n");
    return kFALSE;
    }
  fUserDecayTablePath = path;
  fUserDecay = kTRUE;
  return kTRUE;
  }