// Read stdHEP data, and Run Fast MC interactively with Root
// Sample program using JetFinder (using Clusters)
//           
//                            Aug/28/2000 M. Iwasaki
//
// :: How to run ::
// 
// 1) to call the root, type   
//    
//     root
//
// 2)
//     root [0]  .x Jets_cal.C
// 
// .. that's it.
//
// For example, if you like to run 300 events, type like
//     root [0]  .x Jets_cal.C(300)
//

#include <stdlib.h>

Int_t Jets_cal(Int_t nEvent=100)
{

  gROOT->Reset();

  // In order to refer to shareable libraries in this simple form,
  // include their paths in a .rootrc file.

  gSystem->Load("libLCDEvent.so");
  gSystem->Load("libLCDRootAppsUtil.so");
  gSystem->Load("libLCDFastMC.so");
  gSystem->Load("libLCDPhUtil.so");

  // Input HEPEVT file
  char* stdFile = "test.dat";

  // Detector parameter file
  char* geomFile = 
    "/afs/slac/g/nld/RootApps/V2.1/ParFiles/Small.par";

  // Tracker smearing parameter file
  char* smearFile = 
    "/afs/slac/g/nld/RootApps/V2.1/ParFiles/lookup_small.nobmcon";

  LCDreadStdFile *source = new LCDreadStdFile(stdFile);
  LCDFastMC* fmc = new LCDFastMC(source, geomFile, smearFile, 0);
  LCDEvent*  event = 0;

  // Define histograms
  TH1F *nJets   = new TH1F("nJets","# of Jets per Event (y=0.004)",20,0.,20);
  TH1F *nJets_1 = new TH1F("nJets_1","# of Jets per Event(y=0.006)",20,0.,20);
  TH1F *nJets_2 = new TH1F("nJets_2","# of Jets per Event(y=0.006, JADE)",20,0.,20);
  TH1F *JetP    = new TH1F("JetP","Jet momentum",100,0.,200);
  TH1F *JetPhi  = new TH1F("JetPhi","JetPhi Angle",100,0.,3.14);
  TH1F *JetCosTh= new TH1F("JetCosTh","Jet Cos Theta",50,-1.0,1.0);

  // Setup of JetFinder
  LCDJetFinder* jetfind = new LCDJetFinder(0.004);  // Default.. DURHAM algorithm

  TObjArray* veclist = new TObjArray();

  // Event loop
  for (int iEvent = 0; iEvent < nEvent; iEvent++) {

    event = new LCDEvent();
    event->Create();

    Int_t ierr = fmc->FetchEvent(event);
    if (!ierr) break;

    fmc->Cleanup();
    fmc->Doit(event); //Through FastMC
    
    // Look at tracks. Can access them by the [] operator.
    int nClusters = event->ClusterLst()->GetEntries();
        
    // Event cut # cluster >= 2
    if (nClusters < 2) continue;

    veclist -> Delete(); // Clean up veclist

    // Track loop    
    for (Int_t ncls=0; ncls<nClusters; ncls++) {
      LCDCluster* cls = (LCDCluster*)event->ClusterLst()->At(ncls);

      Double_t     e     = cls->GetEnergy();

      if (e < 0.2 ) continue;  // Reject small Energy particles

      Double_t     Phi   = cls->GetEnergyPhi();
      Double_t     Theta = cls->GetEnergyTheta();


      Double_t Ex = e * sin(Theta) * cos(Phi);
      Double_t Ey = e * sin(Theta) * sin(Phi);
      Double_t Ez = e * cos(Theta);
      
      TVector3 vec3(Ex, Ey, Ez);
      TLorentzVector* vec4  = new TLorentzVector(vec3,e);
      veclist->Add(vec4);

    }
    
//  Do Jet Finding
    jetfind->SetPartList(veclist); // Input particle 4-vector list
    jetfind->SetDURHAM();          // Use DURHAM algorithm
    jetfind->SetYCut(0.004);       // Set YCut value
    jetfind->doFindJets();         // JetFindig
    
    Int_t numjets = jetfind->njets();
    nJets->Fill(numjets);

    for(Int_t j = 0; j < numjets; j++){

	TLorentzVector* Jet_vec = jetfind->jet4vec(j);
	TVector3        Pjet    = Jet_vec ->Vect();   // Jet 3 vector

	Double_t  Jet_mom = Pjet->Mag();
	Double_t  Jet_cos = (Pjet->Z())/Jet_mom;
	Double_t  Jet_phi = Pjet->Phi();

	JetP    ->Fill(Jet_mom);
	JetPhi  ->Fill(Jet_phi);
	JetCosTh->Fill(Jet_cos);
    }
    

//  Example 1  ... Do JetFindong with different Y-cut
    jetfind->SetYCut(0.0060);  // Set different YCut value
    jetfind->doFindJets();     // JetFinding

    Int_t numjets_1 = jetfind->njets();
    nJets_1->Fill(numjets_1);


//  Example 2  ... Do JetFindong with different Algorithm
    jetfind ->SetJADE();      // Use JADE algorithm
    jetfind->doFindJets();    // JetFinding

    Int_t numjets_2 = jetfind->njets();
    nJets_2->Fill(numjets_2);

    event->Clean(); delete event;

  }
  veclist->Delete(); delete veclist;    

  nJets   ->SetFillColor(4);
  nJets_1 ->SetFillColor(4);
  nJets_2 ->SetFillColor(4);
  JetP    ->SetFillColor(4);
  JetPhi  ->SetFillColor(4);
  JetCosTh->SetFillColor(4);

  TCanvas *c1 = new TCanvas("c1", "c1", 700,900);
  c1->Divide(2,3);
  c1->cd(1); nJets->Draw("B");
  c1->cd(2); nJets_1->Draw("B");
  c1->cd(3); nJets_2->Draw("B");
  c1->cd(4); JetP->Draw("B");
  c1->cd(5); JetPhi->Draw("B");
  c1->cd(6); JetCosTh->Draw("B");

  return 1;
}