// Program utilizing ROOT framework headers to process a large 
// data set and generate a ROOT output file containing an NTuple 
// file with the relevant data required for analysis
//
// Author: Shawn Havery
//   Modified: Volker Crede
//
// Creation Date: 03-31-08

#include <TNtuple.h>		// Root Ntuple header
#include <TFile.h>		// Root File Object header
#include <iostream.h>
#include <fstream.h>
#include <TLorentzVector.h>	// Lorentz vector header

// input file
ifstream fin ("/export/home/crede/data/pi0pi0_data.txt");

int main() {
  float skip;			// to accept unused data
  float Nrun, Ebeam;		// run number, beam energy
  float Px, Py, Pz, E;		// for reading momentum and energy
  TLorentzVector p[3];		// particles: 0 = proton; 1,2 = pions

  // Open a Root Data File Object
  TFile file("project10.root","RECREATE");

  // Create an instance of a TNtuple object
  TNtuple ntuple("ntp1", "Project 10 Ntuple",
   "Mppi1pi2:Mpi1pi2:Mppi1:Mppi2:Ebeam:Nrun");

  while (! fin.eof()) {
    fin >> Nrun >> skip >> Ebeam >> skip; // read event header
    for (int i = 0; i < 3; i++) {	  // for each particle
      fin >> Px >> Py >> Pz >> E;	  // read particle data
      p[i].SetPxPyPzE(Px,Py,Pz,E);	  // store in TLorentzVector
    }

    // Create the data table entry
    ntuple.Fill((p[0] + p[1] + p[2]).M(), (p[1] + p[2]).M(),
		(p[0] + p[1]).M(), (p[0] + p[2]).M(), Eb, Nr);
  }
  // Write all known objects to file
  file.Write();

  return 0;
}