//---------- Here are two dummy classes---------------
class TarItem : public TObject{
 public:
  TarItem() : TObject(){}
  TArrayI *tarData;
};

class Tar2Item : public TObject{
 public:
  Tar2Item() : TObject(){}
  TArrayI *tar2Data; //NOT WORKING VERSION
  //TArrayI tar2Data; //VORKING VERSION
  Int_t dummy = 0;
};
//---------- Here are two dummy classes---------------

//----main routine------------
void TArrayTest()
{
  gROOT->Reset();
  

 // Create the first root file (Tar)
  TFile    *findex;
  TTree    *tindex;
  TarItem *tar = new TarItem();

  findex = new TFile("Tar.root", "CREATE");
  tindex = new TTree("Index", "Level0 Index file");
  tindex->Branch("Tar", "TarItem", &tar);

  //Insert the data into Tar
  Int_t data[] = {0,1,2,3,4,5,6,7,8,9};
  for (Int_t i = 0; i < 5; i++){
    tar = new TarItem();
    tar->tarData = new TArrayI(10, data);
    tindex->Fill();
  }
  findex->Write();
  findex->Close();
  
  // Read the root file just for test
  cout << "Start Tar scan \n";
  TFile *tf   = new TFile("Tar.root", "READ");
  TTree *tree = (TTree*)tf->Get("Index");
  TarItem *ind = new TarItem();
  tree->SetBranchAddress("Tar", &ind);

  for (Int_t i = 0; i < tree->GetEntries(); i++){
    tree->GetEntry(i);
    for (Int_t j = 0; j < 10; j++){
      cout << "indice " << j << " :     " << (Int_t)ind->tarData->At(j) << "\n";
    }
  }
  tf->Close();
  cout << "End scan Tar close \n";
  

 // create the second root file (Tar2)
  TFile    *f2index;
  TTree    *t2index;
  Tar2Item  *tar2 = new Tar2Item();

  f2index = new TFile("Tar2.root", "CREATE");
  t2index = new TTree("Index2", "Level0 Index file");
  t2index->Branch("Tar2", "Tar2Item", &tar2);

  //Insert the data into Tar2
  Int_t data[] = {10,11,12,13,14,15,16,17,18,19};
  for (Int_t i = 0; i < 5; i++){
    tar2 = new Tar2Item();

    //tar2->tar2Data = TArrayI(10, data); //WORKING VERION
    tar2->tar2Data = new TArrayI(10, data); //NOT WORKING VERION

    t2index->Fill();
  }
  f2index->Write();
  f2index->Close();
  
  
  cout << "Start Tar2 scan \n";
  TFile *tf2   = new TFile("Tar2.root", "READ");
  TTree *tree2 = (TTree*)tf2->Get("Index2");
  Tar2Item *ind2 = new Tar2Item();
  tree2->SetBranchAddress("Tar2", &ind2);
  // Read the root file just for test
  for (Int_t i = 0; i < tree2->GetEntries(); i++){
    tree2->GetEntry(i);
    for (Int_t j = 0; j < 10; j++){
      cout << "indice " << j << " :     " << (Int_t)ind2->tar2Data->At(j) << "\n";
    }
  }
  tf2->Close();
  cout << "End scan Tar close \n";
  

  //Now I want to read the two files using the FRIEND property
  cout << "--------------- Friend Start Tar scan \n";
  tf   = new TFile("Tar.root", "READ");
  tf2  = new TFile("Tar2.root", "READ");
  tree = (TTree*)tf->Get("Index");
  
  //-----------------------------------------
  // ***** the troubles begin here **********
  //-----------------------------------------
   
  //---------NOT WORKING VERSION------------
  
  tree->AddFriend("Index2", tf2);
  Tar2Item *ind2 = 0;
  tree->SetBranchAddress("Index2.Tar2", &ind2);
  for (Int_t i = 0; i < tree->GetEntries(); i++){
    tree->GetEntry(i);
    for (Int_t j = 0; j < 10; j++){
      cout << "indice " << j << " :     " << (Int_t)ind2->tar2Data->At(j) << "\n";
    }
   }
  
  //----------------------------------------

  //---------WORKING VERSION------------
  /*
  tree->AddFriend("Index2", tf2);
  Tar2Item *ind2 = 0;
  tree->SetBranchAddress("Tar2", &ind2);
  TArrayI *outTar;
  for (Int_t i = 0; i < tree->GetEntries(); i++){
    tree->GetEntry(i);
    for (Int_t j = 0; j < 10; j++){
      cout << "indice " << j << " :     " << (Int_t)ind2->tar2Data.At(j) << "\n";
    }
  }
  */
  //---------WORKING VERSION------------

  tf->Close();
  tf2->Close();
  cout << "----FRIEND End scan close \n";
}