//--------------------------------------------------------------------------
// File and Version Information:
// 	$Id: BtaThrust.cc,v 1.2 1997/1/20 10:05:13 
//
// Description:
//      Class BtaThrust - a simple object to calculate thrust
//      There are three modes:
//              BTAllParticles (0) (default) - use both charged and neutrals
//              BTChargedOnly (1) - use only charged particles
//              BTNeutralOnly (2) - use only neutral particles
//
// Environment:
//      Software developed for the BaBar Detector at the SLAC B-Factory.
//
// Author List:
//      Scott Metzler           original author
//      G. Hamel de Monchenault Implement in terms of BtaThrustVector
//      John Back               Re-written to be used without BtaSelectors.
//
//------------------------------------------------------------------------

#include "BaBar/BaBar.hh"
 
#include <math.h>
#include "BetaCoreTools/BtaThrust.hh"
#include "CLHEP/Alist/AList.h"
#include "Beta/EventInfo.hh"
#include "Beta/BtaCandidate.hh"
#include "BetaCoreTools/BtaBooster.hh"

BtaThrust::BtaThrust(const HepAList<BtaCandidate>& list,
		     const EventInfo& evtinfo,
		     BetaParticles mode, bool cutInCms,
		     BetaFitter fitter)
  : _charged( false )
{

  _theFitter = fitter;

  _cutInCms = cutInCms;
  _checkCharge = false;
  // create first the BtaCandidate selector
  if( mode != BtaThrust::BTAllParticles ) {
    if( mode == BtaThrust::BTChargedOnly) {
      _checkCharge = true;
      _charged = true;
    } else if( mode == BtaThrust::BTNeutralOnly ) {
      _checkCharge = true;
      _charged = false;
    }
  }
  init( list, evtinfo);
}

BtaThrust::~BtaThrust() 
{
}

void
BtaThrust::init( const HepAList<BtaCandidate>& list , 
		 const EventInfo& eventInfo) {

  // create the Y(4S) candidate, and the corresponding BtaBooster
  BtaCandidate theUps( eventInfo.cmFrame() );
  BtaBooster theBooster( &theUps );

  if (_theFitter == BtaThrust::BTVector) {
    // compute the thrust vector
    _theThrustVector.boostAndCompute(list, &theBooster, _cutInCms, 
				     _checkCharge, _charged);

  } else if (_theFitter == BtaThrust::BTFitter) {

    _theThrustFitter.boostAndCompute(list, &theBooster, _cutInCms, 
				     _checkCharge, _charged);

  } else {
    // compute the thrust vector
    _theThrustVector.boostAndCompute(list, &theBooster, _cutInCms, 
				     _checkCharge, _charged);
  }

}

double BtaThrust::thrust() const {

  double value(0.0);

  if (_theFitter == BtaThrust::BTVector) {
    
    value = _theThrustVector.thrust();

  } else if (_theFitter == BtaThrust::BTFitter) {

    value = _theThrustFitter.thrust();

  } else {

    value = _theThrustVector.thrust();

  }

  return value;
}

Hep3Vector BtaThrust::thrust_axis() const {

  Hep3Vector theVector(0.0, 0.0, 0.0);

  if (_theFitter == BtaThrust::BTVector) {
    
    theVector = _theThrustVector.thrustAxis();

  } else if (_theFitter == BtaThrust::BTFitter) {

    theVector = _theThrustFitter.thrustAxis();

  } else {

    theVector = _theThrustVector.thrustAxis();

  }

  return theVector;
  
}