#include<iostream>
#include<fstream>

//#define N 4

void beam_calibration(){
    TGraph *gr = new TGraph();
    TMultiGraph *mg = new TMultiGraph();
    Double_t slope, intercept;
    const Int_t N = 4;

    Double_t fc_current[N] = {6.912664851, 12.79845209, 18.76219677, 32.40474996};
    Double_t dose[N] = {66.19495288, 128.2179372, 185.7405073, 308.9333599};

    Int_t n = sizeof(fc_current) / sizeof(fc_current[0]);
    cout << "size = " << n << endl;

    TF1 *function = new TF1("linear", "pol1(0)");
    std::ofstream ofs("beam_calibration_cxx.txt");

    mg->Add(gr, "p");
    gr->SetMarkerStyle(8);
    gr->SetMarkerSize(1.5);
    gr->SetMarkerColor(1);
    for(Int_t i = 0; i < n; i++){
        gr->SetPoint(i, fc_current[i], dose[i]);
    }
    
    gr->Fit("linear");
    gr->GetFunction("linear")->SetLineColor(1);
    intercept = function->GetParameter(0);
    slope = function->GetParameter(1);

    ofs << "intercept = " << intercept << ", slope = " << slope << endl;
    ofs.close();
    
    TCanvas *c0 = new TCanvas("c0", "c0", 40, 40, 740, 640);
    c0->ToggleEditor();
    c0->ToggleEventStatus();
    c0->ToggleToolBar();

    c0->cd();
    //gPad.SetLogx();
    //gPad.SetLogy();
    gStyle->SetLabelFont(42, "xy");
    gStyle->SetLabelSize(0.05, "xy");
    gStyle->SetLabelOffset(1e-5, "x");
    gStyle->SetLabelOffset(5e-3, "y");
    gStyle->SetTitleFont(42, "xy");
    gStyle->SetTitleSize(0.05, "xy");
    gStyle->SetTitleOffset(1.1, "x");
    gStyle->SetTitleOffset(1.2, "y");

    mg->Draw("APL");
    //mg->GetXaxis()->SetLimits(-2*pi, 2*pi);
    mg->GetXaxis()->SetTitle("FC Current [pnA]");
    mg->GetXaxis()->CenterTitle(1);
    mg->GetYaxis()->SetTitle("Dose [#muSv/h]");
    mg->GetYaxis()->CenterTitle(1);
    //mg->GetYaxis()->SetRangeUser(0, 10);

    TPaveText *p = new TPaveText(0.40, 0.91, 0.60, 0.95, "NDC");
    p->AddText("Beam Calibration");
    p->SetTextFont(42);
    p->SetTextSize(0.05);
    p->SetBorderSize(0);
    p->SetFillColor(0);
    p->Draw("same");

    c0->Modified();
    c0->Update();


}