// Plot C2_exponentialDecayOverlapping.dat

#include "TGraph.h"

#include <fstream>
#include <iostream>
#include <vector>


int fit(){
  using namespace std;
  // controls
  const char *inputFileName = "C2_exponentialDecayOverlapping.dat";
  bool WantToFit = true; // switch for fitting
	
  const char *GraphTitle = "C2";
  const char *GraphXLabel = "X";
  const char *GraphYLabel = "Y";
	
  const char *FitFunc =  "expo"; // "[0] * exp ( t * [1] )";
  const char *DrawOption = "AP" ; // see https://root.cern.ch/doc/master/classTGraphPainter.html
  int xmin = 0;
  int xmax = 100;

  // create the coordinate arrays
  vector<double> x;
  vector<double> y;

  // create the error arrays
  // Double_t dx[5] = {0};
  //  Double_t dy[nArray];

  ifstream inFile(inputFileName);

  if(inFile.is_open()){
    cout<<"Input File was opened successfully"<<endl;
  }

  //Main loop filling arrays from file//
  double linex, liney;
  while (inFile>>linex>>liney) {
    x.emplace_back(linex);
    y.emplace_back(liney);
    //cout<<x[line]<<setw(20)<<y[line]<<endl;
  }
  cout << "Read " << x.size() << " lines\n";

  cout << "Creating canvas" << endl;
  // create the canvas
  TCanvas *c1 = new TCanvas("c1",GraphTitle,200,10,700,500);
  c1->SetGrid();

  // create the TGraphErrors and draw it
  TGraphErrors *gr = new TGraphErrors(x.size(),&x[0],&y[0]);
  // change title and axes titles here
  gr->SetTitle("C2;X;Y");
  gr->SetMarkerColor(4);
  gr->SetMarkerStyle(21);
  TAxis *axis = gr->GetXaxis();
  axis->SetLimits(x[0],100);
  gr->Draw(DrawOption); 
   
  // Define Fit Function
  if (WantToFit){
    TF1 *f = new TF1("f", FitFunc, xmin, xmax);
    //f->SetParNames("A0","A1","A2");
    f->SetParameters(100,-0.02);
			
    gr->Fit(f, "B");
    cout << "Fitting" << endl;
  }
	

  c1->Update();
   
  return 0;
}