/* $Id$ */

// Helper macros for creating chains

TChain* CreateESDChain(const char* aDataDir, Int_t aRuns = 20, Int_t offset = 0)
{
  // creates chain of files in a given directory or file containing a list.
  // In case of directory the structure is expected as:
  // <aDataDir>/<dir0>/AliESDs.root
  // <aDataDir>/<dir1>/AliESDs.root
  // ...

  if (!aDataDir)
    return 0;

  Long_t id, size, flags, modtime;
  if (gSystem->GetPathInfo(aDataDir, &id, &size, &flags, &modtime))
  {
    print("%s not found.\n", aDataDir);
    return 0;
  }

  TChain* chain = new TChain("esdTree");
  TChain* chaingAlice = 0;

  if (flags & 2)
  {
    TString execDir(gSystem->pwd());
    TSystemDirectory* baseDir = new TSystemDirectory(".", aDataDir);
    TList* dirList            = baseDir->GetListOfFiles();
    Int_t nDirs               = dirList->GetEntries();
    gSystem->cd(execDir);

    Int_t count = 0;

    for (Int_t iDir=0; iDir<nDirs; ++iDir)
    {
      TSystemFile* presentDir = (TSystemFile*) dirList->At(iDir);
      if (!presentDir || !presentDir->IsDirectory() || strcmp(presentDir->GetName(), ".") == 0 || strcmp(presentDir->GetName(), "..") == 0)
        continue;

      if (offset > 0)
      {
        --offset;
        continue;
      }

      if (count++ == aRuns)
        break;

      TString presentDirName(aDataDir);
      presentDirName += "/";
      presentDirName += presentDir->GetName();

      chain->Add(presentDirName + "/AliESDs.root/esdTree");
    }
  }
  else
  {
    // Open the input stream
    ifstream in;
    in.open(aDataDir);

    Int_t count = 0;

    // Read the input list of files and add them to the chain
    TString esdfile;
    while(in.good()) {
      in >> esdfile;
      if (!esdfile.Contains("root")) continue; // protection

      if (offset > 0)
      {
        --offset;
        continue;
      }

      if (count++ == aRuns)
        break;

        // add esd file
      chain->Add(esdfile);
    }

    in.close();

    chain->Lookup();
  }

  return chain;
}