/****************************************************************\
| This file is part of the PAX example files for CDF             |
| -------------------------------------------------------------- | 
|   Author of the last change: $Author: erdmann $                 
|   Date of last change:       $Date: 2003/11/18 15:13:17 $   
|   Revision number:           $Revision: 1.2 $        
\****************************************************************/
//
//! example pax algorithm:
//
//! MergeElectrons merges a calorimeter event interpretations and an electron
//! event interpretation into one combined event interpretation without double
//! counting of energy.
//
//! The electrons are found within the calorimeter event interpretation
//! by the eta-phi tower assignment. The calorimeter tower energy is then
//! replaced by the kinematics of the electron.
//
//! The algorithm contains an example how to access from a pax fourvector 
//! the original member function EtaPhi() of the calorimeter tower.
//
#include "TPAXAnaModule.hh"

#include "PAX/PAXexperimentclass.hh"
#include "PAX/PAXfourvector.hh"
#include "PAX/PAXinterpret.hh"
#include "PAX/PAXiterator.hh"
#include "PAX/PAXmap.hh"
#include "PAX/PAXvertex.hh"

#include <iostream>

int TPAXAnaModule::MergeElectrons( PaxEventInterpret* calorimeter,
PaxEventInterpret* electron, PaxEventInterpret* merged_event_interpretation )
{
  string name_event_interpretation = "electrons merged with caltowers";
  int number_of_electrons = 0;

  // --------------------------------------------------------------------
  // check input
  // --------------------------------------------------------------------

  // if output event interpretation is not empty: clear it

  if ( ! merged_event_interpretation->IsEmpty() ) 
    merged_event_interpretation->clear();

  // check for proper input

  if ( calorimeter->IsEmpty() && electron->IsEmpty() )
    {
      cout << "makeElectron: proper input missing" << endl;
      return number_of_electrons;;
    }

  // if calorimeter event interpretation is empty, return electrons

  if ( calorimeter->IsEmpty() )
    {
      // copy electron event interpretation

      merged_event_interpretation->copy( electron );

      // set name of event interpretation

      merged_event_interpretation->SetPaxName( name_event_interpretation );

      // get number of fourvectors from the size of the fourvector map

      number_of_electrons = merged_event_interpretation->fourvector->size();

      return number_of_electrons;
    }

  // fill output event interpretation with calorimeter event interpretation
  // and correct the electron towers below

  merged_event_interpretation->copy( calorimeter );

  // set name of event interpretation

  merged_event_interpretation->SetPaxName( name_event_interpretation );

  // if electron event interpretation is empty, return calorimeter

  if ( electron->IsEmpty() )
    return number_of_electrons;;

  // --------------------------------------------------------------------
  // for fast match between calorimeter towers and electrons:
  // fill map of calorimeter towers with integer eta-phi key and pointer 
  // to the calorimeter PaxFourVector
  // --------------------------------------------------------------------

  PaxFourVectorMap* calomap = new PaxFourVectorMap;

  // for eta-phi-key need to access original CDF class

  string experiment_class_manager="TCalTower"; 

  // iterator for fourvectors

  PaxIterator<PaxFourVector*>* iter_calo 
    = merged_event_interpretation->fourvector->GetIterator();

  // loop over all calorimeter towers

  for ( iter_calo->First(); !iter_calo->IsDone(); iter_calo->Next() )
    {
      // check if manager for experiment class relation exists

      if ( iter_calo->CurrentItem()->map_experimentclass_relations
	   ->findItemByKey( experiment_class_manager )) 
	{ 
	  // loop over the relations to the CDF class (here only one)

	  PaxIterator<PaxExperimentClass* >* iter_ec 
	    = iter_calo->CurrentItem()->map_experimentclass_relations
	    ->findItemByKey( experiment_class_manager )->GetIterator(); 

	  for (iter_ec->First(); !iter_ec->IsDone(); iter_ec->Next() ) 
	    { 
	      // downcast from pax experiment class to detector class 

	      PaxExperiment<TCalTower>* calorimeter_tower 
		= dynamic_cast<PaxExperiment<TCalTower>* >
		(iter_ec->CurrentItem()); 

	      // get the eta-phi key

	      int ietaphi = calorimeter_tower->data->EtaPhi();

              // fill calorimeter map according to the eta-phi key

      	      calomap->add( ietaphi, iter_calo->CurrentItem() );
	    }
	}
    }

  // --------------------------------------------------------------------
  // for all electrons find the corresponding calorimeter tower 
  // using the eta-phi-key, and correct the tower energy
  // --------------------------------------------------------------------

  // loop over the electron fourvectors

  PaxIterator<PaxFourVector*>* iter_electron 
    = electron->fourvector->GetIterator();

  for ( iter_electron->First(); !iter_electron->IsDone(); iter_electron->Next())
    {
      PaxFourVector* fv_electron = iter_electron->CurrentItem();

      // check if manager for experiment class relation exists

      if (fv_electron->map_experimentclass_relations
	  ->findItemByKey( experiment_class_manager ) )
	{
	  // loop over the relations to the CDF class (here only one)

	  PaxIterator<PaxExperimentClass* >* iter_ec 
	    = fv_electron->map_experimentclass_relations
	    ->findItemByKey( experiment_class_manager )->GetIterator(); 

	  for (iter_ec->First(); !iter_ec->IsDone(); iter_ec->Next() ) 
	    { 
	      // downcast from pax experimentclass to detector class 

	      PaxExperiment<TCalTower>* electron_tower 
		= dynamic_cast<PaxExperiment<TCalTower>* >
		(iter_ec->CurrentItem()); 

	      // get the eta-phi key

	      int ietaphi = electron_tower->data->EtaPhi();

	      // find the corresponding tower in the calorimeter map

	      PaxFourVector* fv_calo = calomap->findItemByKey( ietaphi );

	      if ( fv_calo ) 
		{
		  // replace kinematics of calorimeter tower 
		  // by the electron kinematics

		  fv_calo->setPx        ( fv_electron->px()            );
		  fv_calo->setPy        ( fv_electron->py()            );
		  fv_calo->setPz        ( fv_electron->pz()            );
		  fv_calo->setE         ( fv_electron->e ()            );
		  fv_calo->setCharge    ( fv_electron->getCharge ()    );
		  fv_calo->setPaxName   ( fv_electron->getPaxName()    );
		  fv_calo->setParticleId( fv_electron->getParticleId() );
		  fv_calo->addExperimentClassRelations( fv_electron    );

		  // increment number of electrons
		  
		  number_of_electrons++;
		}
	    }
	}
    }
  // clear memory

  delete calomap;

  return number_of_electrons;
}

//_____________________________________________________________________________