#include "TFile.h"
#include "TTree.h"
#include "TRef.h"
#include "TRefArray.h"

class Track : public TObject {
public:  
  Int_t id ;
  TRef ref;

  Track(){}
  ~Track(){}

  ClassDef(Track,1)
};

class Vertex : public TObject {
public:  
  Int_t id ;
  TRefArray tks;

  Vertex(){}
  ~Vertex(){}

  ClassDef(Vertex,1)
};

ClassImp(Track)
ClassImp(Vertex)

//--------------------------------------------------------------
void writeref()
{
  printf("------- write ------------\n");
  TFile f("reftree.root","RECREATE");

  TTree *t = new TTree("reftree","ref tree");

  Vertex    *vtx = new Vertex();
  Track     *trk = new Track();

  t->Branch("vtx","Vertex", &vtx);
  //t->BranchRef();

  //Int_t ObjectNumber = TProcessID::GetObjectCount();

  for(int iv=0; iv<3; iv++) {
    vtx->id=iv;
    vtx->tks.Clear();

    for(int it=0; it<2; it++) {
      TObjString *str = new TObjString( Form("ev = %d  track = %d",iv,it));
      trk->id = iv*1000+it;
      trk->ref=str;
      vtx->tks.Add(trk);
      printf("trk id = %d \t",trk->id);
      trk->ref.GetObject()->Print();
    }

    int ntr = vtx->tks.GetEntries();
    printf("vertex = %d  ntr = %d\n\n", iv, ntr );
    t->Fill();
  }

  //TProcessID::SetObjectCount(ObjectNumber);

  t->Write();
  f.Close();
}

//--------------------------------------------------------------
void readref()
{
  printf("------- read ------------\n");

  TFile f("reftree.root");

  TTree *t = (TTree*)(f.Get("reftree"));
  //t->Print();

  Track   *trk = 0;
  Vertex  *vtx = 0;

  t->SetBranchAddress("vtx", &vtx);

  int nentr = t->GetEntries();
  printf("tree with %d entries\n", nentr);

  for(int iv=0; iv<nentr; iv++) {
    t->GetEntry(iv);
    int ntr = vtx->tks.GetEntries();
    printf("vertex %d  ntr = %d\n",vtx->id, ntr);
    for(int it=0; it<ntr; it++) {
      trk = (Track*)(vtx->tks.At(it));
      printf("iv = %d it=%d  trk id = %d\t",iv, it, trk->id);
      trk->ref.GetObject()->Print();
     }
  }

  f.Close();
}

//--------------------------------------------------------------
void testref_tree()
{
  writeref();
  readref();
}