//   - create a simple TTree
//   - create a clone of the tree
//   - add a branch of the tree
//mpkansasuni  18.05.2016 

#include "TFile.h"
#include "TTree.h"
#include "TRandom.h"
#include "TTree.h"
#include "TMath.h"

#include <iostream>

Int_t Run, Event;
Float_t x,y,z;

void CreateParentTree() {
   // create a simple TTree with 5 branches
   // Two branches ("Run" and "Event") will be used to index the Tree
   TFile *f = new TFile("treeparent.root","recreate");
   TTree *T = new TTree("T","test friend trees");
   T->Branch("Run",&Run,"Run/I");
   T->Branch("Event",&Event,"Event/I");
   T->Branch("x",&x,"x/F");
   T->Branch("y",&y,"y/F");
   T->Branch("z",&z,"z/F");
 //  T->Branch("d", &d, "d/F");
   TRandom r;
   for (Int_t i=0;i<10000;i++) {
      if (i < 5000) Run = 1;
      else          Run = 2;
      Event = i;
      x = r.Gaus(10,1);
      y = r.Gaus(20,2);
      z = r.Landau(2,1);
      T->Fill();
   }
   T->Print();
   T->Write();
   delete f;
}

void  AddaBranchTree(){
	//Get old file
	TString treefile = "treeparent.root";
	TFile *ftree = new TFile(treefile);
	TTree *vesseltree = (TTree*)ftree->Get("T");
	vesseltree->Print();

	Float_t x, y, z, rsph;
	vesseltree->SetBranchAddress("x", &x);
	vesseltree->SetBranchAddress("y", &y);
	vesseltree->SetBranchAddress("z", &z);

	//create the new file
	TFile *g = new TFile("treeparentNew.root", "RECREATE");
	TTree *newtree = vesseltree->CloneTree(0); // 
	newtree->Branch("rsph", &rsph, "rsph/F");

	int nentries = vesseltree->GetEntries();
	std::cout << nentries << std::endl;

	for (int i = 0; i < nentries; i++){
		vesseltree->GetEntry(i);
		if ((x + y + z) == 0.0) rsph = 0.0; // just a precaution
		else rsph = (x + y) / (x + y + z);
		newtree->Fill();
	}

	newtree->Print();
	newtree->Write();
	delete g;

	delete ftree;
}

void treefriendtest() {
   CreateParentTree();
   AddaBranchTree();
}