#define MySelector_cxx
// The class definition in MySelector.h has been generated automatically
// by the ROOT utility TTree::MakeSelector(). This class is derived
// from the ROOT class TSelector. For more information on the TSelector
// framework see $ROOTSYS/README/README.SELECTOR or the ROOT User Manual.


// The following methods are defined in this file:
//    Begin():        called every time a loop on the tree starts,
//                    a convenient place to create your histograms.
//    SlaveBegin():   called after Begin(), when on PROOF called only on the
//                    slave servers.
//    Process():      called for each event, in this function you decide what
//                    to read and fill your histograms.
//    SlaveTerminate: called at the end of the loop on the tree, when on PROOF
//                    called only on the slave servers.
//    Terminate():    called at the end of the loop on the tree,
//                    a convenient place to draw/fit your histograms.
//
// To use this file, try the following session on your Tree T:
//
// root> T->Process("MySelector.C")
// root> T->Process("MySelector.C","some options")
// root> T->Process("MySelector.C+")
//


#include "MySelector.h"
#include <TH2.h>
#include <TStyle.h>
#include <TF3.h>

#include <TCanvas.h>

using namespace  std;

void MySelector::Begin(TTree * /*tree*/)
{
    // The Begin() function is called at the start of the query.
    // When running with PROOF Begin() is only called on the client.
    // The tree argument is deprecated (on PROOF 0 is passed).

    TString option = GetOption();

    fOutputFile = new TFile("Results.root","recreate");

    hCosThetaTheo = new TH1D("CosThetaTheo","CosThetaTheo",200,-1,1);
    h_trackE = new TH1F("trackE","trackE",2000,0,2000);
}

void MySelector::SlaveBegin(TTree * /*tree*/)
{
    // The SlaveBegin() function is called after the Begin() function.
    // When running with PROOF SlaveBegin() is called on each slave server.
    // The tree argument is deprecated (on PROOF 0 is passed).

    TString option = GetOption();

}

Bool_t MySelector::Process(Long64_t entry)
{
    fReader.SetLocalEntry(entry);

    if(*nbTrack==0)
        return true;

    for(int i=0 ; i<*nbTrack ; i++) {

        // we skip the events for wich no Compton diffusion occur
        if(trackType.At(i) !=2 ) continue;

        // Real value of Theta using the real position of the gamma-ray emission:

        TVector3 Source(0.,0.,0.);
        TVector3 Int1(trackX1.At(i),trackY1.At(i),trackZ1.At(i));
        TVector3 Int2(trackX2.At(i),trackY2.At(i),trackZ2.At(i));

        if(!(abs(trackE.At(i)-600)<5)) continue;
        // to keep only gammas with two interation points
        Float_t CosThetaTheo = CalcCosTheta(0,0,0,Int1,Int2);

        h_trackE->Fill(trackE.At(i));
        hCosThetaTheo->Fill(CosThetaTheo);
    }

    return kTRUE;
}

Double_t MySelector::CalcCosTheta(Double_t X, Double_t Y, Double_t Z, TVector3 &Int1, TVector3 &Int2)
{
    TVector3 Source(X,Y,Z);

    TVector3 Vec_Source_Int1 = Int1-Source;
    TVector3 Vec_Int1_Int2 = Int2-Int1;

    Float_t CosThetaTheo = (Vec_Source_Int1 * Vec_Int1_Int2)/(Vec_Source_Int1.Mag() * Vec_Int1_Int2.Mag());

    return CosThetaTheo;
}

void MySelector::SlaveTerminate()
{
    // The SlaveTerminate() function is called after all entries or objects
    // have been processed. When running with PROOF SlaveTerminate() is called
    // on each slave server.

}

void MySelector::Terminate()
{
    // The Terminate() function is the last function to be called during
    // a query. It always runs on the client, it can be used to present
    // the results graphically or save the results to file.

    fOutputFile->Write();
    fOutputFile->Close();
}