/*
 * Merge root histograms into one histogram file.
 * Each histogram file must contain the same histograms and ntuples
 * in the same directory structure.
 *                                       yuji@fnal.gov
 *
 * Supported objects: TH1F, TH2F, TNtuple
 *    All variables in TNtuple should be float type (probably)
 *
 * Usage: ].L hmrg.C+
 *        ]merge()
 *
 * Time-stamp: <2004-05-31 16:25:40 yuji>
 */
#include <iostream>
#include <string.h>
#include "TROOT.h"
#include "TKey.h"
#include "TF1.h"
#include "TH2.h"
#include "TFile.h"
#include "TNtuple.h"

using std::cout;
using std::cerr;
using std::endl;

//gROOT->Reset();

const char *infile[] = {
  "hoge1.root",
  "hoge2.root"
};
const char *outfile="merged.root";

// prototype declaration
void dirScan(TDirectory*);

// Global variables
TFile* fout;

//
// duplicate TNtuple object
//
TNtuple* appendTNtuple(TNtuple* ntpl0, TNtuple* ntpl)
{
  TNtuple* tnew;

  if (!ntpl0) {
    char buff[4096]; buff[0]=0;

    // make var list
    TObjArray* br=ntpl->GetListOfBranches();
    for(int idx=0; ; ++idx) {
      strncat(buff, br->At(idx)->GetName(), 4096);
      if ( idx+1 == br->GetEntries() ) break;
      strncat(buff, ":", 4096);
    }
    // create new ntuple but it's empty
    tnew= new TNtuple(ntpl->GetName(), ntpl->GetTitle(), buff);
  } else {
    tnew=ntpl0;
  }

  // append contents
  for(int idx=0; idx<ntpl->GetEntries(); ++idx) {
    ntpl->GetEvent(idx);
    tnew->Fill(ntpl->GetArgs());
  }

  return tnew;
}

//
// treat TDirectory object (output to fout)
//
void dirScan(TDirectory* dir1)
{
  // make string of same name direcotry for fout
  const char* fname1=dir1->GetFile()->GetName(); // obtain filename of dir1
  const char* path2=dir1->GetPath()+
    strlen(fname1); // obtain pathname without filename
  char buff[1024];
  strncpy(buff, fout->GetName(), 1024);
  strncat(buff, path2, 1024);

  dir1->cd(); // change searching directory
  TList* olist = gDirectory->GetListOfKeys();

  for(int oidx=0; oidx<olist->GetSize(); ++oidx) {
    // get objects in this directory
    TKey* key=(TKey*)olist->At(oidx);

    // read object from key
    dir1->cd();
    TObject* obj=key->ReadObj();

    // show the object for debug
    //    cout << dir1->GetPath() << "/" << obj->GetName()
    //	 << "(" << obj->ClassName() << ")" << endl;

    // TDirectory ////////////////
    if (!strcmp(obj->ClassName(), "TDirectory")) {
      TDirectory* tdObj=(TDirectory*)obj;

      // check if fout has the directory
      gDirectory->cd(buff);
      if (!gDirectory->GetKey(tdObj->GetName())) {
	gDirectory->mkdir(tdObj->GetName());
	cout << "Create " << buff << "/" << tdObj->GetName() << endl;
      }
      
      // recursive call of dirScan
      dirScan(tdObj);      
    } // endif TDirectory object

    // TH1F ////////////////
    if (!strcmp(obj->ClassName(), "TH1F")) {
      TH1F* th1fObj=(TH1F*)obj;

      // check if fout has the histo.
      gDirectory->cd(buff);
      TH1F* th1fObj2;
      if (!gDirectory->Get(th1fObj->GetName())) {
	th1fObj2=new TH1F(*th1fObj);
	cout << "Create " << buff << "/" << th1fObj->GetName() << endl;
      } else {
	th1fObj2=(TH1F*)(gDirectory->Get(th1fObj->GetName()));
	th1fObj2->Add(th1fObj);
      }
    } // endif TH1F object

    // TH2F ////////////////////
    if (!strcmp(obj->ClassName(), "TH2F")) {
      TH2F* th2fObj=(TH2F*)obj;

      // check if fout has the histo.
      gDirectory->cd(buff);
      TH2F* th2fObj2;
      if (!gDirectory->Get(th2fObj->GetName())) {
	th2fObj2=new TH2F(*th2fObj);
	cout << "Create " << buff << "/" << th2fObj->GetName() << endl;
      } else {
	th2fObj2=(TH2F*)(gDirectory->Get(th2fObj->GetName()));
	th2fObj2->Add(th2fObj);
      }
    } // endif TH2F object

    // Ntuple /////////////////
    if (!strcmp(obj->ClassName(), "TNtuple")) {
      TNtuple* tnObj=(TNtuple*)obj;

      // check if fout has the histo.
      gDirectory->cd(buff);
      TNtuple* tnObj2;
      if (!gDirectory->Get(tnObj->GetName())) {
	appendTNtuple(NULL, tnObj);
	cout << "Create " << buff << "/" << tnObj->GetName() << endl;
      } else {
	tnObj2=(TNtuple*)(gDirectory->Get(tnObj->GetName()));
	appendTNtuple(tnObj2, tnObj);
      }
    } // endif TH2F object

  } // for oindx
}

//
// main routine
//
int merge()
{
  int nfiles=sizeof(infile)/sizeof(char**);

  fout= new TFile(outfile, "RECREATE");

  for(int fidx=0; fidx<nfiles; ++fidx) {
    TFile* fin= new TFile(infile[fidx]);
    cout << "Processing file: " << fin->GetName() << endl;

    dirScan(gDirectory);
  }

  fout->Write();
  fout->Close();

  return 0;
}