//-----------------------------------------------------------------------------
//  May 2006 T.Kuhr: SAM STNTUPLE input module
//-----------------------------------------------------------------------------
#include "TChain.h"
#include "TFile.h"

#include "diskcache_i/TSam.hh"

#include "Stntuple/obj/TStnEvent.hh"

#include "Stntuple/loop/TStnSamInputModule.hh"

ClassImp(TStnSamInputModule)

//_____________________________________________________________________________
TStnSamInputModule::TStnSamInputModule(const char* dataset):
  TStnRun2InputModule(),
  fSam(new TSam(dataset)),
  fOffset(-1)
{
  SetName("SamInputModule");
  SetTitle("SAM Input module");
  fChain = new TChain("STNTUPLE");
}


//_____________________________________________________________________________
TStnSamInputModule::~TStnSamInputModule()
{
  delete fSam;
  delete fChain;
}


//_____________________________________________________________________________
Int_t TStnSamInputModule::RegisterInputBranches(TStnEvent* Event) 
{
  if (!OpenNextFile()) return -1;
  return TStnRun2InputModule::RegisterInputBranches(Event);
}


//_____________________________________________________________________________
Double_t TStnSamInputModule::GetEntries()
{
  Warning("GetEntries",
	  "The total number of entries in unknown because of sequential file access");
  return 99999999;
}


//_____________________________________________________________________________
Int_t TStnSamInputModule::NextEvent(Int_t IEntry)
{
  if (!fSam || !fChain) return -5;

  if (fOffset < 0) {
    SetBranches();
    fOffset = 0;
  }

  Int_t entry = IEntry - fOffset;
  if (entry < 0) {
    Error("NextEvent", "Can not go back in sequential file access");
    return -5;
  }

  while (entry >= fChain->GetEntries()) {
    fOffset += (Int_t)fChain->GetEntries();
    entry = IEntry - fOffset;
    if (!OpenNextFile()) return -5;
  }

  fChain->LoadTree(entry);
  GetEvent()->SetCurrentEntry(IEntry);
  GetEvent()->SetCurrentTreeEntry(entry);

  return entry;
}

//_____________________________________________________________________________
Bool_t TStnSamInputModule::OpenNextFile()
{
  delete fChain;
  fChain = new TChain("STNTUPLE");

  if (!fSam) return false;
  TFile* file = fSam->OpenNextFile();
  if (!file) return false;

  fChain->Add(file->GetName());
  if (fOffset >= 0) SetBranches();

  return true;
}