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// $Id: G4InteractionCase.cc,v 1.2 2010/06/25 09:44:32 gunter Exp $
// GEANT4 tag: $Name: hadr-casc-V09-03-85 $
//
// 20100518  M. Kelsey -- Move code from Colliders' "bulletTargetSetter()"
//		to setBulletTarget().

#include "G4InteractionCase.hh"
#include "G4InuclParticle.hh"
#include "G4InuclElementaryParticle.hh"
#include "G4InuclNuclei.hh"


// Evaluate concrete types of input particles and assign bullet, target

void G4InteractionCase::set(G4InuclParticle* part1, 
			    G4InuclParticle* part2) {
  clear();		// Reset everything in case of failure

  // See which one of the two (or both) is a nucleus
  G4InuclNuclei* nucl1 = dynamic_cast<G4InuclNuclei*>(part1);
  G4InuclNuclei* nucl2 = dynamic_cast<G4InuclNuclei*>(part2);

  G4InuclElementaryParticle* had1 = dynamic_cast<G4InuclElementaryParticle*>(part1);
  G4InuclElementaryParticle* had2 = dynamic_cast<G4InuclElementaryParticle*>(part2);

  if (nucl1 && nucl2) { 	// Nuclear collision, lighter is projectile
    inter_case = -2;
    if (nucl2->getA() >= nucl1->getA()) {
      bullet = part1;
      target = part2;
    } else {
      bullet = part2;
      target = part1;
    } 
  } else if (nucl1 || nucl2) {	// Hadron on nucleus, hadron projectile
    inter_case = -1;
    if (nucl1 && had2) {
      bullet = part2;
      target = part1;
    } else {
      bullet = part1;
      target = part2;
    }
  } else if (had1 && had2) {	// Hadron-hadron interaction, order irrelevant
    inter_case = had1->type() * had2->type();
    bullet = part1;
    target = part2;
  }
}
