#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooGaussian.h"
#include "RooLandau.h"
#include "RooFFTConvPdf.h"
#include "RooPlot.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"
using namespace RooFit;

void gexp_conv()
{
   // S e t u p   c o m p o n e n t   p d f s
   // ---------------------------------------

   // Construct observable
   //RooRealVar t("t", "t", -10, 30);
   RooRealVar x("x", "x", 50, 750);
   RooRealVar y("y", "y", -100, 5000);

   // Construct gauss(t,mg,sg)
   RooRealVar mg("mg", "mg", 0);
   RooRealVar sg("sg", "sg", 2, 0.1, 10);
   RooGaussian gauss("gauss", "gauss", x, mg, sg);

   // Construct exponential(t,ml,sl) ;
   // Construct exponential(t,sl) ;
   //RooRealVar ml("ml", "mean landau", 5., -20, 20);
   RooRealVar sl("sl", "slope", 1, 0.1, 10);
   RooExponential exp("exp", "exp", x, sl);
   //RooExponential exp("exp", "exp", t, ml, sl);

   // C o n s t r u c t   c o n v o l u t i o n   p d f
   // ---------------------------------------

   // Set #bins to be used for FFT sampling to 10000
   //x.setBins(14000, "cache");

   // Construct landau (x) gauss
   RooFFTConvPdf gxe("gxe", "gauss (X) exponential", x, gauss, exp);

   // S a m p l e ,   f i t   a n d   p l o t   c o n v o l u t e d   p d f
   // ----------------------------------------------------------------------

   // Sample 1000 events in x from gxlx
   //RooDataSet *data = lxg.generate(t, 10000);
   //RooDataSet *data = lxg.generate(t, 10000);
   //RooDataSet *data = RooDataSet::read("TD_401_388_bg417_v2_bgbgct10_scaled.dat",RooArgList(x,y));
   //RooDataSet *data = RooDataSet::read("TD_401_388_bg417_v2_bgbgct10_scaled.dat",RooArgList(x));
   RooDataSet *data = RooDataSet::read("test.txt",RooArgList(x,y));

   // Fit gxlx to data
   gxe.fitTo(*data);

   // Plot data, landau pdf, landau (X) gauss pdf
   RooPlot *frame = x.frame(Title("gauss (X) exponential convolution"));
   data->plotOn(frame);
   gxe.plotOn(frame);
   //landau.plotOn(frame, LineStyle(kDashed));

   // Draw frame on canvas
   new TCanvas("gxe_convolution", "gxe_convolution", 600, 600);
   gPad->SetLeftMargin(0.15);
   frame->GetYaxis()->SetTitleOffset(1.4);
   frame->Draw();
}