#include "TH1.h"
#include "TMath.h"
#include "TF1.h"
#include "TLegend.h"
#include "TCanvas.h"


// Breit-Wigner peak function
Double_t bw(Double_t *x, Double_t *par) {
  return (1/(2*TMath::Pi()))*par[0]*par[2]/((x[0]-par[1])*(x[0]-par[1])+(par[2]*par[2]/4));
}

// Background function
Double_t back(Double_t *x, Double_t *par) {
  return par[0]*1/(par[1]*pow(x[0],3) + par[2]*pow(x[0],4) + par[3]*pow(x[0],5)) + par[4];
  
}

// Sum of background and peak function
Double_t fitFunction(Double_t *x, Double_t *par) {
  return bw(x,par) + back(x,&par[3]);
}

void Fit() {

  TFile *file = new TFile("teste02.root"); 
  TH1D *MuonMassInv = file->Get("MuonMassInv"); 
  gStyle->SetOptFit();
  TF1 *fitsimple = new TF1("fitsimple",fitFunction,10,200,8);
  fitsimple->SetNpx(500);
  fitsimple->SetLineWidth(4);
  fitsimple->SetLineColor(kMagenta);

  fitsimple->SetParName(0,"Constant");
  fitsimple->SetParameter(0,15000);

  fitsimple->SetParName(1,"Mean");
  fitsimple->SetParameter(1,91.38);

  fitsimple->SetParName(2,"Sigma");
  fitsimple->SetParameter(2, 3);
 
  
  fitsimple->SetParameter(3, 1e9);
  fitsimple->SetParameter(4, 2);
  fitsimple->SetParameter(5, 2.5e-2);
  fitsimple->SetParameter(6, 9e-3);
  fitsimple->SetParameter(7, -20);


  MuonMassInv->Fit("fitsimple","","",10.,200.);
  TF1 *backFcn = new TF1("backFcn",back,10,200,5);
  backFcn->SetLineColor(kRed);
  TF1 *signalFcn = new TF1("signalFcn",bw,10,200,3);
  signalFcn->SetLineColor(kBlue);
  Double_t par[8];

  // writes the fit results into the par array
  fitsimple->GetParameters(par);
  backFcn->SetParameters(&par[3]);
  signalFcn->SetParameters(&par[0]);

  //Subtract background
 TH1D *hisSignal = new TH1D(*MuonMassInv);
  hisSignal->Sumw2();
  hisSignal->Add(backFcn,-1);


  //Plot Spectra and functions
  gPad->SetLogy();
  MuonMassInv->Draw("e");
 // hisSignal->Draw("SAME");
 //signalFcn->Draw("SAME");
// backFcn->Draw("SAME");


/*
  // draw the legend
  TLegend *legend=new TLegend(0.6,0.65,0.88,0.85);
  legend->SetTextFont(72);
  legend->SetTextSize(0.04);
  legend->AddEntry(histo,"Data","lpe");
  legend->AddEntry(backFcn,"Background fit","l");
  legend->AddEntry(signalFcn,"Signal fit","l");
  legend->AddEntry(fitsimple,"Global Fit","l");
  legend->Draw();
*/

//  MuonMassInv->Draw();
}

// TF1 *back = new TF1("back","1e9/(2*pow(x,3) + 2.5e-2*pow(x,4) - 9e-5*pow(x,5)) - 21.5 ",10,200);