//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 1998      Caltech, UCSB
//
// Module: EvtSVS.cc
//
// Description: Routine to decay scalar -> vector + scalar
//
// Modification history:
//
//    RYD       November 24, 1996       Module created
//
//------------------------------------------------------------------------
// 
#include "EvtGenBase/EvtPatches.hh"
#include <stdlib.h>
#include "EvtGenBase/EvtParticle.hh"
#include "EvtGenBase/EvtGenKine.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtPDL.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenModels/EvtSVS.hh"
#include <string>

EvtSVS::~EvtSVS() {}

std::string EvtSVS::getName(){

  return "SVS";     

}


EvtDecayBase* EvtSVS::clone(){

  return new EvtSVS;

}

void EvtSVS::init(){

  // check that there are 0 arguments
  checkNArg(0);
  checkNDaug(2);
    
  checkSpinParent(EvtSpinType::SCALAR);

  checkSpinDaughter(0,EvtSpinType::VECTOR);
  checkSpinDaughter(1,EvtSpinType::SCALAR);


}



void EvtSVS::initProbMax(){

  setProbMax(1.0);

}

void EvtSVS::decay( EvtParticle *p){

  p->initializePhaseSpace(getNDaug(),getDaugs());

  EvtParticle *v;
  v = p->getDaug(0);
  double massv = v->mass();
  EvtVector4R momv = v->getP4();
  EvtVector4R moms = p->getDaug(1)->getP4();
  double m_parent = p->mass();
  EvtVector4R p4_parent = momv+moms;

  double norm=massv/(momv.d3mag()*m_parent);
  p4_parent = norm*p4_parent;
  vertex(0,p4_parent*(v->epsParent(0)));
  vertex(1,p4_parent*(v->epsParent(1)));
  vertex(2,p4_parent*(v->epsParent(2)));
  
  return ;
}