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

/* $Id$ */

// Event generator that using an instance of type AliGenReader
// reads particles from a file and applies cuts.
// Example: In your Config.C you can include the following lines
//   AliGenExtFile *gener = new AliGenExtFile(-1);
//  gener->SetMomentumRange(0,999);
//  gener->SetPhiRange(-180.,180.);
//  gener->SetThetaRange(0,180);
//  gener->SetYRange(-999,999);
//  AliGenReaderTreeK * reader = new AliGenReaderTreeK();
//  reader->SetFileName("myFileWithTreeK.root");
//  gener->SetReader(reader);
//  gener->Init();


#include <Riostream.h>

#include "AliGenExtFile.h"
#include "AliRun.h"

#include <TParticle.h>
#include <TFile.h>
#include <TTree.h>


ClassImp(AliGenExtFile)

AliGenExtFile::AliGenExtFile()
  :AliGenMC()
{
//  Constructor
//
//  Read all particles
    fNpart  =- 1;
    fReader =  0;
}

AliGenExtFile::AliGenExtFile(Int_t npart)
    :AliGenMC(npart)
{
//  Constructor
    fName   = "ExtFile";
    fTitle  = "Primaries from ext. File";
    fReader = 0;
}

AliGenExtFile::AliGenExtFile(const AliGenExtFile & ExtFile):
    AliGenMC(ExtFile)
{
// Copy constructor
    ExtFile.Copy(*this);
}
//____________________________________________________________
AliGenExtFile::~AliGenExtFile()
{
// Destructor
    delete fReader;
}

//___________________________________________________________
void AliGenExtFile::Init()
{
// Initialize
    if (fReader) fReader->Init();
}

    
void AliGenExtFile::Generate()
{
// Generate particles

  Float_t polar[3]  = {0,0,0};
  //
  Float_t origin[3] = {0,0,0};
  Float_t p[3];
  Float_t random[6];
  Int_t i = 0, j, nt;
  //
  for (j=0;j<3;j++) origin[j]=fOrigin[j];
  if(fVertexSmear == kPerTrack) {
    Rndm(random,6);
    for (j = 0; j < 3; j++) {
	origin[j] += fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
	    TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
    }
  }

  while(1) {
    Int_t nTracks = fReader->NextEvent(); 	
    if (nTracks == 0) {
      // printf("\n No more events !!! !\n");
      Warning("AliGenExtFile::Generate","\nNo more events in external file!!!\nLast event may be empty or incomplete.\n");
      return;
    }

    //
    // Particle selection loop
    //
    // The selction criterium for the external file generator is as follows:
    //
    // 1) All tracks are subjects to the cuts defined by AliGenerator, i.e.
    //    fThetaMin, fThetaMax, fPhiMin, fPhiMax, fPMin, fPMax, fPtMin, fPtMax,
    //    fYMin, fYMax.
    //    If the particle does not satisfy these cuts, it is not put on the
    //    stack.
    // 2) If fCutOnChild and some specific child is selected (e.g. if
    //    fForceDecay==kSemiElectronic) the event is rejected if NOT EVEN ONE
    //    child falls into the child-cuts.
    TParticle* iparticle = 0x0;
    
    if(fCutOnChild) {
      // Count the selected children
      Int_t nSelected = 0;
      while ( (iparticle=fReader->NextParticle()) ) {
	 ;
	Int_t kf = CheckPDGCode(iparticle->GetPdgCode());
	kf = TMath::Abs(kf);
	if (ChildSelected(kf) && KinematicSelection(iparticle, 1)) {
	  nSelected++;
	}
      }
      if (!nSelected) continue;    // No particle selected:  Go to next event
      fReader->RewindEvent();
    }

    //
    // Stack filling loop
    //
    for (i = 0; i < nTracks; i++) {

      TParticle* iparticle = fReader->NextParticle();
      Bool_t selected = KinematicSelection(iparticle,0); 
      if (!selected) {
	Double_t  pz   = iparticle->Pz();
	Double_t  e    = iparticle->Energy();
	Double_t  y;
	if ((e-pz) == 0) {
	  y = 20.;
	} else if ((e+pz) == 0.) {
	  y = -20.;
	} else {
	  y = 0.5*TMath::Log((e+pz)/(e-pz));	  
	}
	printf("\n Not selected %d %f %f %f %f %f", i,
	       iparticle->Theta(),
	       iparticle->Phi(),
	       iparticle->P(),
	       iparticle->Pt(),
	       y);
	//PH	delete iparticle;
	//	continue;
      }
      p[0] = iparticle->Px();
      p[1] = iparticle->Py();
      p[2] = iparticle->Pz();
      Int_t idpart = iparticle->GetPdgCode();
      if(fVertexSmear==kPerTrack) 
       {
         Rndm(random,6);
         for (j = 0; j < 3; j++) {
            origin[j]=fOrigin[j]+
                      fOsigma[j]*TMath::Cos(2*random[2*j]*TMath::Pi())*
                        TMath::Sqrt(-2*TMath::Log(random[2*j+1]));
         }
      }
      Int_t decayed = iparticle->GetFirstDaughter();
      Int_t doTracking = fTrackIt && (decayed < 0) &&
	                 (TMath::Abs(idpart) > 10) && selected;
      // printf("*** pdg, first daughter, trk = %d, %d, %d\n",
      //   idpart,decayed, doTracking);
      //PH      PushTrack(doTracking,-1,idpart,p,origin,polar,0,kPPrimary,nt);
      Int_t parent = iparticle->GetFirstMother();
      PushTrack(doTracking,parent,idpart,p,origin,polar,0,kPPrimary,nt);
      KeepTrack(nt);
    } // track loop

    break;

  } // event loop

  SetHighWaterMark(nt);
  CdEventFile();
}

void AliGenExtFile::CdEventFile()
{
// CD back to the event file
  TFile *pFile=0;
  if (!gAlice) {
      gAlice = (AliRun*)pFile->Get("gAlice");
      if (gAlice) printf("AliRun object found on file\n");
      if (!gAlice) gAlice = new AliRun("gAlice","Alice test program");
  }
  TTree *fAli=gAlice->TreeK();
  if (fAli) pFile =fAli->GetCurrentFile();
  pFile->cd();    
}


AliGenExtFile& AliGenExtFile::operator=(const  AliGenExtFile& rhs)
{
// Assignment operator
    rhs.Copy(*this);
    return *this;
}
 

void AliGenExtFile::Copy(TObject&) const
{
    //
    // Copy 
    //
    Fatal("Copy","Not implemented!\n");
}