#include <cmath>	// for the funtion 'exp()'

#include "FCALSteppingAction.hh"
#include "FCALDetectorConstruction.hh"
#include "FCALEventAction.hh"

#include "G4ios.hh"
#include "G4Step.hh"
#include "G4ParticleDefinition.hh"
#include "G4Navigator.hh"


FCALSteppingAction::FCALSteppingAction(FCALEventAction* event_Act)
: event_Action(event_Act) {}

FCALSteppingAction::~FCALSteppingAction() {;}

void FCALSteppingAction::UserSteppingAction(const G4Step* aStep)
{
  //			-------- 1. Extract information of energy deposited in LeadGlass blocks
  G4StepPoint* pre_Step = aStep->GetPreStepPoint();
  G4StepPoint* post_Step = aStep->GetPostStepPoint();
  G4TouchableHandle pre_TouchHandle = pre_Step->GetTouchableHandle();
  G4VPhysicalVolume* pre_Volume = pre_TouchHandle->GetVolume();
  
  G4TouchableHandle post_TouchHandle = post_Step->GetTouchableHandle();
  G4VPhysicalVolume* post_Volume = post_TouchHandle->GetVolume();
  
  if (pre_Volume != NULL && pre_Volume->GetName() == "LeadGlass")
    {

      G4double energy_Deposition = aStep->GetTotalEnergyDeposit();

      //		G4double z_PrePosition = (pre_Step->GetPosition()).z();
      //		G4double z_PostPosition = (post_Step->GetPosition()).z();
      //		G4double z_AvgPosition = (z_PrePosition + z_PostPosition) / 2.;	
      //		G4double energy_Attenuate = energy_Deposition * exp(-(143.8*mm + 50.*mm - z_AvgPosition) / 1600*mm);	
      //		G4double energy_Attenuate = energy_Deposition * exp(-(318.8*mm + 225.*mm - z_AvgPosition) / 1600*mm);	
      //            318.8: the global z-position of the end of a leadglass
      
      // use local coordinate system to calculate attenuation
      
      G4ThreeVector worldPos1 = pre_Step->GetPosition();
      G4ThreeVector localPos1 =
	pre_TouchHandle->GetHistory()->GetTopTransform().TransformPoint(worldPos1);
      
      G4ThreeVector worldPos2 = post_Step->GetPosition();
      G4ThreeVector localPos2 =
	post_TouchHandle->GetHistory()->GetTopTransform().TransformPoint(worldPos2);
      
      G4double z_AvgPos = (localPos1.z()+localPos2.z())/2.; // GEANT4 uses millimeter internally
      
      // block_length - zposition  : is wrong but is the same as in GlueX-geant siumulation
      //                             should be zposition-0.5*block_length
      G4double energy_Attenuate = energy_Deposition * exp((z_AvgPos-45.0*cm) / 1600*mm);
      
      
      if (energy_Deposition > 0)
	{
	  G4int copy_Number = pre_TouchHandle->GetCopyNumber(2);
	  event_Action->addEnergyDeposit(energy_Deposition, copy_Number);
	  event_Action->addEnergyAttenuate(energy_Attenuate, copy_Number);
	}
    }
  
  //			-------- 2. Extract associated infomation of optical photons hitting the photocathode
  
  
  if (post_Volume != NULL && post_Volume->GetName() == "PMTCathode")
    {
      G4String particle_Name = aStep->GetTrack()->GetDefinition()->GetParticleName();
      if (particle_Name == "opticalphoton")	
	//////////////////////////////////////////////////////////////////////////////////////////////////		
	// Actually, the above line might be meaningless. But if you generate, for example, muons, 	//
	// you can come across some occation when the associated detector counts them.			//
	// Of course, when it comes to the comparative number, this must be meaningless			//
	// since huge number of optical photons will be detected. This is just because of rigorousness.	//
	//////////////////////////////////////////////////////////////////////////////////////////////////
	{
	  G4double photon_Energy = post_Step->GetTotalEnergy();
	  G4int copy_Number = post_TouchHandle->GetCopyNumber(2);
	  
	  event_Action->countHits(copy_Number);				// count Hits
	  event_Action->addEnergy(photon_Energy, copy_Number);	// add energy
	}
    }
}