#include "TPluginManager.h"
#include "TSystem.h"
#include "TROOT.h"
#include "Minuit2/MnMatrix.h"
#include "Minuit2/FunctionMinimum.h"
#include "Minuit3Minimizer.h"
#include "Minuit2/FunctionGradient.h"
#include "RooRealVar.h"
#include "RooGaussian.h"
#include "RooExponential.h"
#include "RooDataSet.h"
#include "RooAddPdf.h"
#include "RooMinimizer.h"
#include "RooArgList.h"
#include "RooArgSet.h"

int main(){

    RooRealVar mB("mB", "mB", 5100, 5400);
    mB.setBins(75);

    RooRealVar mean("mean", "mean", 5280, 5200, 5350);
    RooRealVar sigma("sigma", "sigma", 15, 0, 50);
    RooGaussian signal("signal", "signal", mB, mean, sigma);

    RooRealVar slope("slope", "slope", -1e-3, -1e-1, 0.);
    RooExponential background("background", "background", mB, slope);

    RooRealVar nSignal("nSignal", "nSignal", 50000, 0, 100000);
    RooRealVar nBackground("nBackground", "nBackground", 25000, 0, 100000);
    RooAddPdf model(
        "model",
        "model",
        RooArgList(signal, background),
        RooArgList(nSignal, nBackground)
    );

    auto dataset = signal.generate(RooArgSet(mB), 50000);
    auto background_dataset = background.generate(RooArgSet(mB), 50000);
    dataset->append(*background_dataset);

    gSystem->Load("libMinuit3Minimizer");
    // Use Minuit3 to get better logging for first derivatives
    TPluginManager *pm = gROOT->GetPluginManager();
    pm->AddHandler("ROOT::Math::Minimizer", "Minuit2", "ROOT::Minuit2::Minuit3Minimizer", "Minuit2", "Minuit3Minimizer(const char *)");

    auto nll = model.createNLL(*dataset, RooFit::Extended(1), RooFit::Offset(1));
    RooMinimizer minimizer(*nll);
    minimizer.setMinimizerType("Minuit2");
    minimizer.migrad();

    const auto min2 = dynamic_cast<const ROOT::Minuit2::Minuit2Minimizer*>(minimizer.fitter()->GetMinimizer());
    const auto min3 = dynamic_cast<const ROOT::Minuit2::Minuit3Minimizer*>(minimizer.fitter()->GetMinimizer());
    if ( min3 == nullptr ){
        std::cout << "Cannot cast to Minuit3" << std::endl;
    }
    if ( min2 != nullptr ){
        std::cout << "It is an instantiation of Minuit2Minimizer!" << std::endl;
    }

    auto * handler = gROOT->GetPluginManager()->FindHandler("ROOT::Math::Minimizer","Minuit2");
    auto * minuit = reinterpret_cast<ROOT::Math::Minimizer *>( handler->ExecPlugin(1,"Migrad") );
    const auto minuit2 = dynamic_cast<const ROOT::Minuit2::Minuit2Minimizer*>(minuit);
    const auto minuit3 = dynamic_cast<const ROOT::Minuit2::Minuit3Minimizer*>(minuit);
    if ( minuit3 == nullptr ){
        std::cout << "From PluginManager: Cannot cast to Minuit3" << std::endl;
    }
    if ( minuit2 != nullptr ){
        std::cout << "From PluginManager: It is an instantiation of Minuit2Minimizer!" << std::endl;
    }

    return 0;   
}