#include "TCanvas.h"
#include "TPad.h"
#include "TMultiGraph.h"
#include "TGraph.h"
#include "TGraphErrors.h"
#include "TAxis.h"
#include "TLegend.h"
#include "TLatex.h"
#include "TROOT.h"

#include <cstdlib> // for "exit"

//const char *labelsgamma[] = {"30.53 GeV", "69.34 GeV", "138.70 GeV", "260.98 GeV", "453.25 GeV", "765.59 GeV"};

void drawlabels(TGraph *g = 0,
                const char *labels[] = 0)
{
  if ((!g) || (!labels) || (!gPad)) return; // just a precaution
  
  for (Int_t i = 0; i < g->GetN(); i++) {
    Double_t x, y;
    g->GetPoint(i, x, y);
    if (gPad->GetLogx()) x *= 1.25; else x+= 0.0;
    if (gPad->GetLogy()) y *= 1.25; else y+= 0.0;
    TLatex *l = new TLatex(x, y, labels[i]);
    l->SetTextSize(0.025);
    l->SetTextFont(42);
    l->SetTextAlign(21);
    l->SetTextColor(g->GetMarkerColor());
    l->Draw();
  }
}

void corona()
{
#if 1 /* 0 or 1 */
  const char *datagamma = "C:/corona.txt";
  const char *dataout = "C:/root_v6.18.04/corona.pdf";
#else /* 0 or 1 */
  const char *datagamma = "corona.txt";
  const char *dataout = "corona.pdf";
#endif /* 0 or 1 */
  
  TCanvas *c36 = new TCanvas("c36","multigraph",1280,1024);
  //c36->SetLogx();
  //c36->SetLogy();
  float offx=1.3;
  float offy=1.7;
  float margr=0.08;
  float w=3;
  float margl=0.12;
  gPad->SetLeftMargin(margl);
  gPad->SetRightMargin(margr);
  TMultiGraph *mg = new TMultiGraph();
  
  TGraphErrors *gamma = new TGraphErrors(datagamma,"%lg %lg");
  gamma->SetMarkerColor(kBlue);
  gamma->SetLineColor(kBlue);
  gamma->SetMarkerStyle(23);
   TF1 *fitspettro = new TF1("fitspettro", "[0] * (1+[1]*TMath::Exp(-x/[2]))/(1+[3]*TMath::Exp(-x/[2]))", 0,15);
   fitspettro->SetParName(0,"a");
    fitspettro->SetParName(1,"m");
   fitspettro->SetParName(2,"\tau");
   fitspettro->SetParName(3,"n");
   fitspettro->SetParameter(0,1);
   fitspettro->SetParameter(1,1);
   fitspettro->SetParameter(2,1);
   fitspettro->SetParameter(3,1);
   //TF1 *fitspettro = new TF1("fitspettro", "gaus");
   gamma->Fit("fitspettro");
   mg->Add(gamma);
   mg->Draw("AP");
  mg->SetTitle("Covid-19 cases");
  mg->GetXaxis()->SetTitle("Day");
  mg->GetYaxis()->SetTitle("Cases");
  mg->GetYaxis()->SetTitleOffset(offy);
  mg->GetXaxis()->SetTitleOffset(offx);
  mg->GetXaxis()->SetRange(0,200);
  c36->Modified();
  //force drawing of canvas to generate the fit TPaveStats
  c36->Update();
  c36->Modified();
  //drawlabels(gamma, labelsgamma);
  c36->Print(dataout);
  delete c36;
  exit(0);
}