#include "events.h"
#include <TStyle.h>
#include <TCanvas.h>
#include <iostream>
#include <TH1F.h>
#include <TLorentzVector.h>
#include "TMinuit.h"
#include "TRandom.h"

using namespace std;

void events::Loop(){
   if (fChain == 0) return;

   Long64_t nentries = fChain->GetEntries();
   Long64_t nbytes = 0, nb = 0;
	 cout << "I have " << nentries << " events in my tree" << endl;
	 
	 // Hint 1: Here's a good spot to declare the histogram
	 
	 TLorentzVector v1;
	 TLorentzVector v2;
	 TLorentzVector v3;
	 
	 TH1F * Ztrue = new TH1F("Ztrue", "", 100, 50, 150);
	 TH1F * Zreco = new TH1F("Zreco", "", 100, 50, 150);
	 
    if (nentries>= 2000){
      nentries = 2000;
    }

   for (Long64_t jentry=0; jentry<nentries;jentry++) {
      Long64_t ientry = LoadTree(jentry);
      if (ientry < 0) break;
      nb = fChain->GetEntry(jentry);   nbytes += nb;
      //cout << "event: " << jentry << " Z mass " << Z_mass << endl;
			
      v1.SetPtEtaPhiM(mu1_pt, mu1_eta, mu1_phi, mu1_mass);
      v2.SetPtEtaPhiM(mu2_pt, mu2_eta, mu2_phi, mu2_mass);
      v3 = v1 + v2;

      Ztrue->Fill(Z_mass);
      Zreco->Fill(v3.M());
			
   }

   // Uncomment for slide 2

   //   Ztrue->Draw();
//   Zreco->SetLineColor(kRed);
//   Zreco->Draw("same");

   // first part
   //   Ztrue->Fit("gaus");

   // second part
//   TF1 *fit = Ztrue->GetFunction("gaus");
//   std::cout<<"par0 = "<<fit->GetParameter(0)<<std::endl;
   
}

events::events(TTree *tree) : fChain(0) {
   if (tree == 0) {
      TFile *f = (TFile*)gROOT->GetListOfFiles()->FindObject("mytree.root");
      if (!f || !f->IsOpen()) {
         f = new TFile("mytree.root");
      }
      f->GetObject("events",tree);

   }
   Init(tree);
}

events::~events(){
   if (!fChain) return;
   delete fChain->GetCurrentFile();
}

Int_t events::GetEntry(Long64_t entry){
// Read contents of entry.
   if (!fChain) return 0;
   return fChain->GetEntry(entry);
}

Long64_t events::LoadTree(Long64_t entry){
// Set the environment to read one entry
   if (!fChain) return -5;
   Long64_t centry = fChain->LoadTree(entry);
   if (centry < 0) return centry;
   if (fChain->GetTreeNumber() != fCurrent) {
      fCurrent = fChain->GetTreeNumber();
      Notify();
   }
   return centry;
}

void events::Init(TTree *tree){
   if (!tree) return;
   fChain = tree;
   fCurrent = -1;
   fChain->SetMakeClass(1);

   fChain->SetBranchAddress("event_number", &event_number, &b_event_number);
   fChain->SetBranchAddress("Z_mass", &Z_mass, &b_Z_mass);
   fChain->SetBranchAddress("Z_pt", &Z_pt, &b_Z_pt);
   fChain->SetBranchAddress("Z_eta", &Z_eta, &b_Z_eta);
   fChain->SetBranchAddress("Z_phi", &Z_phi, &b_Z_phi);
   fChain->SetBranchAddress("mu1_pt", &mu1_pt, &b_mu1_pt);
   fChain->SetBranchAddress("mu1_eta", &mu1_eta, &b_mu1_eta);
   fChain->SetBranchAddress("mu1_phi", &mu1_phi, &b_mu1_phi);
   fChain->SetBranchAddress("mu1_mass", &mu1_mass, &b_mu1_mass);
   fChain->SetBranchAddress("mu1_charge", &mu1_charge, &b_mu1_charge);
   fChain->SetBranchAddress("mu2_pt", &mu2_pt, &b_mu2_pt);
   fChain->SetBranchAddress("mu2_eta", &mu2_eta, &b_mu2_eta);
   fChain->SetBranchAddress("mu2_phi", &mu2_phi, &b_mu2_phi);
   fChain->SetBranchAddress("mu2_mass", &mu2_mass, &b_mu2_mass);
   fChain->SetBranchAddress("mu2_charge", &mu2_charge, &b_mu2_charge);
   Notify();
}

Bool_t events::Notify(){
   return kTRUE;
}

void events::Show(Long64_t entry){
   if (!fChain) return;
   fChain->Show(entry);
}