/**************************************************************************
 * 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.                  *
 **************************************************************************/
 
///_________________________________________________________________________
///
/// This class constructs Digits out of Hits
///
///

// --- Standard library ---

// --- ROOT system ---
#include <TTree.h>

// --- AliRoot header files ---
#include "AliVZEROConst.h"
#include "AliRun.h"
#include "AliVZERO.h"
#include "AliVZEROhit.h"
#include "AliRunLoader.h"
#include "AliLoader.h"
#include "AliRunDigitizer.h"
#include "AliVZEROdigit.h"
#include "AliVZERODigitizer.h"

ClassImp(AliVZERODigitizer)

 AliVZERODigitizer::AliVZERODigitizer()
{
  // default constructor

   fNdigits = 0;
   fDigits = 0 ;
  
   fPhotoCathodeEfficiency =   0.18;
   fPMVoltage              =  768.0;
   fPMGain = TMath::Power((fPMVoltage / 112.5) ,7.04277);     
}

//____________________________________________________________________________ 
  AliVZERODigitizer::AliVZERODigitizer(AliRunDigitizer* manager)
                    :AliDigitizer(manager)
                    
{
  // constructor
  
  fNdigits = 0;
  fDigits = 0 ;
  
  fPhotoCathodeEfficiency =   0.18;
  fPMVoltage              =  768.0;
  fPMGain = TMath::Power( (fPMVoltage / 112.5) ,7.04277 );
}
           
//____________________________________________________________________________ 
  AliVZERODigitizer::~AliVZERODigitizer()
{
  // destructor
  
  if (fDigits) {
    fDigits->Delete();
    delete fDigits;
    fDigits=0; 
  }
}

//_____________________________________________________________________________
Bool_t AliVZERODigitizer::Init()
{
  // Initialises the digitizer

  // Initialises the Digit array
  fDigits = new TClonesArray ("AliVZEROdigit", 1000);

  return kTRUE;
}

//____________________________________________________________________________
void AliVZERODigitizer::Exec(Option_t* /*option*/) 
{ 
  //
  // Creates digits from hits
  //
  
  fNdigits = 0;
  Int_t map[96];
  Float_t cPM = fPhotoCathodeEfficiency * fPMGain;
             
  for(Int_t i=0; i<96; i++) map[i] = 0; 
          
  AliRunLoader* outRunLoader = 
    AliRunLoader::GetRunLoader(fManager->GetOutputFolderName());    
  if (!outRunLoader) {
    Error("Exec", "Can not get output Run Loader");
    return;
  }
  AliLoader* outLoader = outRunLoader->GetLoader("VZEROLoader");
  if (!outLoader) {
    Error("Exec", "Can not get output VZERO Loader");
    return;
  }

  outLoader->LoadDigits("update");
  if (!outLoader->TreeD()) outLoader->MakeTree("D");
  outLoader->MakeDigitsContainer();
  TTree* treeD = outLoader->TreeD();
  Int_t bufsize = 16000;
  treeD->Branch("VZERODigit", &fDigits, bufsize); 

  for (Int_t iInput = 0; iInput < fManager->GetNinputs(); iInput++) {
    AliRunLoader* runLoader = 
      AliRunLoader::GetRunLoader(fManager->GetInputFolderName(iInput));
    AliLoader* loader = runLoader->GetLoader("VZEROLoader");
    if (!loader) {
      Error("Exec", "Can not get VZERO Loader for input %d", iInput);
      continue;
    }
    if (!runLoader->GetAliRun()) runLoader->LoadgAlice();

    AliVZERO* vzero = (AliVZERO*) runLoader->GetAliRun()->GetDetector("VZERO");
    if (!vzero) {
      Error("Exec", "No VZERO detector for input %d", iInput);
      continue;
    }
      
    loader->LoadHits();
    TTree* treeH = loader->TreeH();
    if (!treeH) {
      Error("Exec", "Cannot get TreeH for input %d", iInput);
      continue; 
    }
    TClonesArray* hits = vzero->Hits();
             
//  Now makes Digits from hits
         
    Int_t nTracks = (Int_t) treeH->GetEntries();
    for (Int_t iTrack = 0; iTrack < nTracks; iTrack++) {
      vzero->ResetHits();
      treeH->GetEvent(iTrack);
      Int_t nHits = hits->GetEntriesFast();
      for (Int_t iHit = 0; iHit < nHits; iHit++) {
	AliVZEROhit* hit = (AliVZEROhit *)hits->UncheckedAt(iHit);
	Int_t nPhot = hit->Nphot();
	Int_t cell  = hit->Cell();                                    
	map[cell] += nPhot;
      }           // hit   loop
    }             // track loop

    loader->UnloadHits();

  }               // input loop
            
  for (Int_t i=0; i<96; i++) {
    Float_t q1 = Float_t ( map[i] )* cPM * kQe;
    Float_t noise = gRandom->Gaus(10.5,3.22);
    Float_t pmResponse  =  q1/kC*TMath::Power(ktheta/kthau,1/(1-ktheta/kthau)) 
      + noise*1e-3;
    map[i] = Int_t( pmResponse * 200.0);
    if(map[i] > 3) {
//    printf(" Event, cell, adc = %d %d %d\n", outRunLoader->GetEventNumber(),i, map[i]);
      AddDigit(i, map[i]);
    } 
  }

  treeD->Fill();
  outLoader->WriteDigits("OVERWRITE");  
  outLoader->UnloadDigits();     
  ResetDigit();
}

//____________________________________________________________________________
void AliVZERODigitizer::AddDigit(Int_t cellnumber, Int_t adc) 
 { 
 
// Adds Digit 
 
  TClonesArray &ldigits = *fDigits;  
  new(ldigits[fNdigits++]) AliVZEROdigit(cellnumber,adc);
}
//____________________________________________________________________________
void AliVZERODigitizer::ResetDigit()
{
//
// Clears Digits
//
  fNdigits = 0;
  if (fDigits) fDigits->Delete();
}