#include <TH2F.h>
#include <TFile.h>
#include <TChain.h>
#include <TROOT.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TCutG.h>
#include <TString.h>
#include <TObjArray.h>

void PIDCutCreator(TH2F* hist, 
                   TString saveFileName = "PIDCuts.root", 
                   bool isLogz = false
                  ){
   
   printf("================ Graphic Cut Creator for PID ============== \n");
   
   gStyle->SetOptStat("neiou");

   TCanvas * cCutCreator = new TCanvas("cCutCreator", "PID Cut Creator", 100, 100, 800, 800);
   if( !cCutCreator->GetShowToolBar() ) cCutCreator->ToggleToolBar();

   cCutCreator->Update();
   if( isLogz ) cCutCreator->cd()->SetLogz();
   hist->Draw("colz");
   
   TFile * cutFile;
   TCutG * cut = NULL;
   TObjArray * cutList;

   ///===================== load the cutFile and load the cutList

   int numCut = 0;
   cutFile = new TFile(saveFileName, "UPDATE");
   if( cutFile == NULL ){
     cutFile = new TFile(saveFileName, "recreate");
   }
   bool listExist = cutFile->GetListOfKeys()->Contains("cutList");
   if( !listExist ) {
      cutList = new TObjArray();
   }else{
      cutList = (TObjArray*) cutFile->FindObjectAny("cutList");
      numCut = cutList->GetLast()+1;
      printf("----- found %d cuts \n", numCut);
      for( int k = 0; k < numCut; k++){
         if( cutList->At(k) != NULL ){
            printf("found a cut at %2d \n", k);
            cut = (TCutG*) cutList->At(k);
            cut->Draw("same");
         }else{
            printf("     No cut at %2d \n", k);
         }
      }
   }
  cCutCreator->Modified(); cCutCreator->Update();

  int countCut = 0;
  while (true){
      
    printf("======== make a graphic cut on the plot (double click to stop), %2d-th cut: ", countCut );

    gPad->WaitPrimitive();

    cut = (TCutG*) gROOT->FindObject("CUTG");
      
    if( cut == NULL ){
      printf(" stopped by user.\n");
      break;
    }

    TString name; name.Form("cut%2d", countCut);
    cut->SetName(name);
    cut->SetVarX("AoQ");
    cut->SetVarY("Z");
    cut->SetTitle(Form("cut%2d", countCut));
    cut->SetLineColor(countCut+1);
    printf(" cut-%d \n", countCut);

    cutList->AddAtAndExpand(cut, countCut);
    countCut ++;

  }

  ///================= Summary

  cutList->Write("cutList", TObject::kSingleKey);
  printf("====> saved %d cuts into %s\n", countCut, saveFileName.Data());
  gROOT->ProcessLine(".q");

}