#include "omp.h"

#include "TROOT.h"
#include "TFile.h"
#include "TDirectory.h"
#include "TH2S.h"
#include "TCanvas.h"
#include "TKey.h"
#include "TRandom.h"

int main(int argc, char** argv) {
    // Set to batch mode, to avoid the GUI to pop up
    gROOT->SetBatch(1);

    // Enable thread safety
    ROOT::EnableThreadSafety();

    // Number of histograms
    int num_hists = 10;

    // Retrieve all histograms in the ROOT file
    std::vector<TH2S*> vec(num_hists);
    for(int i = 0; i < num_hists; i++) {
    	std::string name = "h" + std::to_string(i);
    	TH2S *h = new TH2S(name.c_str(),"",40,-4,4,40,-20,20);
    		Float_t px, py;
    		for (Int_t i = 0; i < 2500000; i++) {
    		    gRandom->Rannor(px,py);
    		    h->Fill(px,5*py);
    		}
    		vec[i] = h;
    }

  #pragma omp parallel for
    for (size_t i = 0; i < vec.size(); i++) {
        TH2S* h = vec[i];
        TCanvas *c = new TCanvas(std::to_string(i).c_str());
        h->Draw("colz");
        std::string name = std::string(h->GetName());
        c->Print((name + ".png").c_str());
        delete c;
    }

    return 0;
}