#include "TChain.h"
#include "TList.h"
#include "TH1F.h"
#include "TROOT.h"

#include "AliAODEvent.h"
#include "AliAnalysisTaskSE.h"
#include "AliAnalysisManager.h"

#include "AliAODTrack.h"
#include "AliAODInputHandler.h"

#include "AliAnalysisTaskPtSpectra.h"
#include <iostream>


// Analysis task for pT spectrum

using std::cout;
using std::endl;

ClassImp(AliAnalysisTaskPtSpectra)

//________________________________________________________________________
AliAnalysisTaskPtSpectra::AliAnalysisTaskPtSpectra(const char *name) 
: AliAnalysisTaskSE(name),
  fList(0),
  fHistPt(0) {
  // Constructor
  // Define input and output slots here
  // Input slot #0 works with a TChain

  DefineInput(0, TChain::Class());
  // Output slot #0 writes into a TH1 container
  DefineOutput(1, TList::Class());
}

//________________________________________________________________________
AliAnalysisTaskPtSpectra::~AliAnalysisTaskPtSpectra() {
  //
}

//________________________________________________________________________
void AliAnalysisTaskPtSpectra::UserCreateOutputObjects() {
  // Create histograms
  // Called once

  // global switch disabling the reference 
  // (to avoid "Replacing existing TH1" if several wagons are created in train)
  Bool_t oldStatus = TH1::AddDirectoryStatus();
  TH1::AddDirectory(kFALSE);

  ///Output list
  fList = new TList();
  fList->SetName("outputList");
  fList->SetOwner();

  fHistPt = new TH1F("fHistPt","pT spectrum; p_{T} (GeV/c);",100,0,10.);
  fList->Add(fHistPt);
  
  PostData(1, fList);
}

//________________________________________________________________________
void AliAnalysisTaskPtSpectra::UserExec(Option_t *) {
  // Main loop
  // Called for each event

  // get the event (for generator level: MCEvent())
  //AliVEvent* eventMain = NULL;
  //eventMain = dynamic_cast<AliVEvent*>(InputEvent());     
  AliAODEvent *event = dynamic_cast<AliAODEvent*>(InputEvent());     
  if(!event) {
    AliError("eventMain not available");
    return;
  }
  
  // Loop over tracks in event
  for (Int_t iTracks = 0; iTracks < event->GetNumberOfTracks(); iTracks++) {
    AliAODTrack* aodTrack = dynamic_cast<AliAODTrack *>(event->GetTrack(iTracks));
    if (!aodTrack) {
      AliError(Form("Could not receive track %d", iTracks));
      continue;
    }
    
    // AOD track cuts
    //if(!aodTrack->TestFilterBit(fnAODtrackCutBit)) continue;
    
    fHistPt->Fill(aodTrack->Pt());
  }//loop over AOD tracks
  
  PostData(1, fList);
}


//________________________________________________________________________
void  AliAnalysisTaskPtSpectra::FinishTaskOutput(){
  //

}

//________________________________________________________________________
void AliAnalysisTaskPtSpectra::Terminate(Option_t *) {
  // Draw result to the screen
  // Called once at the end of the query

  // not implemented ...

}