#include <string>
#include <TH1D.h>
#include <TROOT.h>
#include <TRandom3.h>
#include <TCanvas.h>
#include <omp.h>
#include <iostream>

// Use:
// Compile -> g++ -fopenmp -o tryMacro tryMacro.cpp `root-config --cflags --libs`
// Run     -> ./tryMacro

const Int_t kMax = 1000;
const Int_t numThreads = 4;

void savePlot(TH1D *hist);

int main(int argc, char *argv[]){
  // Enable thread safety for ROOT
  ROOT::EnableThreadSafety();
  // Print
  std::cout << "Starting!" << std::endl;
  // Create a Model histogram
  TH1D *model = new TH1D("model", "", 100, 0, 10);
  TRandom3 *rand = new TRandom3();
  for(int i=0; i<1000; i++){
    model->Fill(rand->Gaus(5,2));
  }
  // Create a new histogram to fill
  TH1D *result = new TH1D("result", "", 100, 0, 10);
  // Extract some data from the histogram model and get the average. Then fill
  omp_set_num_threads(numThreads);
  #pragma omp parallel for
  for(Int_t k=0; k<kMax; k++){
    std::string histName = "randhist_"+std::to_string(k);
    std::string histName2 = "randhist2_"+std::to_string(k);
    TH1D *randHist  = new TH1D(histName.c_str(), "", 100, 4, 6);
    TH1D *randHist2 = new TH1D(histName2.c_str(), "", 100, 4, 6);
    randHist->FillRandom(model, 20000);
    randHist2->FillRandom(model, 20000);
    #pragma omp critical
    {
      std::cout << k << "\t";
      result->Fill(randHist->GetMean());
    }
    randHist->Delete();
    randHist2->Delete();
  }
  std::cout << "\nEnding!" << std::endl;
  savePlot(model);
  savePlot(result);
  // Close and return
  model->Delete();
  result->Delete();
  rand->Delete();
  return 0;
}

void savePlot(TH1D *hist){
    TCanvas *c1 = new TCanvas("c1", "", 700,500);
    hist->Draw();
    std::string name = std::string(hist->GetName())+".png";
    c1->Print(name.c_str());
    delete c1;
}