// Run Fast MC interactively with Root
//
//     Aug 29 20000    M.Iwasaki
//
// :: How to run ::
// 
// 1) to call the root, type   
//    
//     root
//
// 2)
//     root [0]  .x GoFastMC.C
// 
// .. that's it.
//
// For example, if you like to run 300 events, type like
//     root [0]  .x GoFastMC.C(300)
//

#include <stdlib.h>

int GoFastMC(int 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");

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

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

  // Tracker smearing 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 a histogram or two
  TH1F *ClsMult = new TH1F("ClsMult","Cluster Multiplicity",50, 0.0, 200.0);
  TH1F *ClsE    = new TH1F("ClsE","Cluster Energy",50, 0.0, 50.0);
  TH1F *TrkMult = new TH1F("TrkMult","Track Multiplicity",50, 0.0, 100.0);
  TH1F *TrkE    = new TH1F("TrkE","Track Energy",50, 0.0, 50.0);

  // 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 Clusters. Can access them by the [] operator.
    int nClusters = event->ClusterLst()->GetEntries();
    ClsMult->Fill(nClusters);


    for (Int_t iClus = 0; iClus < nClusters; iClus++) {
      LCDCluster* cls = (LCDCluster*)event->ClusterLst()->At(iClus);

      if (cls) {
	Double_t     eClus     = cls->GetEnergy();	
	// Histogram energies
	ClsE->Fill(eClus);
      }

    }
    

    // Look at tracks. Can access them by the [] operator.
    int nTracks = event->Tracks()->GetEntries();
    TrkMult->Fill(nTracks);

    // Track loop    
    for (Int_t ntrk=0; ntrk<nTracks; ntrk++) {
      LCDTrack* trk = (LCDTrack*)event->Tracks()->At(ntrk);
      
      if(trk) {
	Double_t* tP3 = trk->GetMomentum();
	Double_t  E_trk = 0.1396 * 0.1396; // Assume pion mass
	for (int i=0; i<3; i++) { E_trk += (*(tP3+i))*(*(tP3+i)); }
	E_trk = sqrt(E_trk);

	// Histogram energies
	TrkE->Fill(E_trk);
      }

    }

    event->Clean(); delete event;

  }

  ClsMult->SetFillColor(4);
  ClsE->SetFillColor(4);
  TrkMult->SetFillColor(4);
  TrkE->SetFillColor(4);

  TCanvas *c1 = new TCanvas("c1", "c1", 400, 600);
  c1->Divide(2,2);
  c1->cd(1); ClsMult->Draw("B");
  c1->cd(2); ClsE->Draw("B");
  c1->cd(3); TrkMult->Draw("B");
  c1->cd(4); TrkE->Draw("B");

  return 1;
}