#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> 
void corona() {
   
   gStyle->SetOptFit();
   const char *datain = "C:/corona.txt";
   const char *dataout = "C:/root_v6.20.00/corona.png";

   TCanvas *c01 = new TCanvas("c01","multigraph",1280,1024);
   c01->SetGrid();
   float offx=1.3;
   float offy=1.3;
   float margr=0.08;
   float w=3;
   float margl=0.12;
   float ymax=1.E8;
   gPad->SetLeftMargin(margl);
   gPad->SetRightMargin(margr);
   TGraphErrors *gamma = new TGraphErrors(datain,"%lg %lg");
   for(int i = 0; i < gamma->GetN(); i++) 	{
      gamma->SetPointError(i, 0.0, TMath::Sqrt(gamma->GetY()[i]));
   } // ex = 0.0 or 0.3 or 0.5
   gamma->SetMarkerColor(kBlue);
   gamma->SetLineColor(kBlue);
   gamma->SetMarkerStyle(23);
   gamma->SetMarkerSize(1.3);
   gamma->SetLineWidth(3);
   TF1 *fitspettro = new TF1("fitspettro", "[0] * (1+[1]*TMath::Exp(-x/[2]))/(1+[3]*TMath::Exp(-x/[2]))", 0,25);
   TPaveText *t=new TPaveText(0.7,0.15,0.75,0.2,"brNDC");
   TF1 *fitspettroexpo = new TF1("fitspettroexpo", "expo", 0,25);
   TF1 *fitspettrogaus = new TF1("fitspettrogaus", "gaus", 0,25);
    TGraphErrors *gamma2 = (TGraphErrors*)(gamma->Clone());
    TGraphErrors *gamma3 = (TGraphErrors*)(gamma->Clone());
   fitspettro->SetParName(0,"a");
   fitspettro->SetParName(1,"m");
   fitspettro->SetParName(2,"#tau");
   fitspettro->SetParName(3,"n");
   fitspettro->SetParameter(0,2);
   fitspettro->SetParameter(1,60);
   fitspettro->SetParameter(2,5);
   fitspettro->SetParameter(3,300);
   fitspettro->SetParLimits(0,0,1.E10);
   fitspettro->SetParLimits(2,-1,50000);
   fitspettro->SetLineColor(kRed+2);
   fitspettrogaus->SetLineColor(kGreen+2);
   // need to increase number of function calls for avoiding call limit error
   ROOT::Math::MinimizerOptions::SetDefaultMaxFunctionCalls(1000000); 

   gamma->Fit("fitspettro","+");
   gamma2->Fit("fitspettroexpo","","sames");
   gamma3->Fit("fitspettrogaus","","sames");
   
   
   fitspettro->SetLineWidth(3);
   fitspettro->SetMaximum(ymax);
   fitspettroexpo->SetRange(0.,70);
   fitspettrogaus->SetRange(0.,70);
   fitspettroexpo->SetLineWidth(3);
   

   // draw first function to have then data put on top
   fitspettro->SetRange(0.,70);
   fitspettro->Draw();
   fitspettroexpo->Draw("SAME ");
   fitspettrogaus->Draw("SAME ");
   gamma->Draw("PL");   // drow graph data on top of function
   //gamma->Draw("L");
   fitspettro->SetTitle("Covid-19 cases in Italy, February 24-March 13 2020- Logistic, Exponential and Gaussian fits until May 4 2020");
   fitspettro->GetXaxis()->SetTitle("Day");
   fitspettro->GetYaxis()->SetTitle("Cases");
   fitspettro->GetYaxis()->SetTitleOffset(offy);
   fitspettro->GetXaxis()->SetTitleOffset(offx);
   gamma->SetTitle("Covid-19 cases");
   gamma->GetXaxis()->SetTitle("Day");
   gamma->GetYaxis()->SetTitle("Cases");
   gamma->GetYaxis()->SetTitleOffset(offy);
   gamma->GetXaxis()->SetTitleOffset(offx);
   TLegend* leg = new TLegend(0.15, 0.75, .25, .85);
   leg->SetHeader("Legend");
   leg->SetNColumns(1);
   leg->AddEntry(gamma, "Data", "lp");
   leg->AddEntry(fitspettro, "Logistic Fit", "l");  
   leg->AddEntry(fitspettroexpo, "Exponential Fit", "l");  
    leg->AddEntry(fitspettrogaus, "Gaussian Fit", "l");  
   leg->Draw();
   gPad->SetLogy(true);
   gPad->Update();
  TPaveStats *stat = (TPaveStats*)(gamma->FindObject("stats"));
  TPaveStats *stat1 = (TPaveStats*)(gamma2->FindObject("stats"));
  TPaveStats *stat2 = (TPaveStats*)(gamma3->FindObject("stats"));
  if(stat && stat1 && stat2) {
    stat->SetTextColor(kRed+2);
    stat1->SetTextColor(kRed);
    stat2->SetTextColor(kGreen+2);
    float height = stat1->GetY2NDC() - stat1->GetY1NDC();
    stat1->SetY1NDC(stat->GetY1NDC() - height);
    stat1->SetY2NDC(stat->GetY1NDC() );
    stat1->Draw();
    float height2 = stat2->GetY2NDC() - stat2->GetY1NDC();
    stat2->SetY1NDC(stat1->GetY1NDC() - height);
    stat2->SetY2NDC(stat1->GetY1NDC() );
    stat2->Draw();
  }
    gPad->Update();
   t->AddText("COVID-19");
  t->Draw();
   gPad->Update();
   c01->Print(dataout);

}