#ifndef _BreitWigner_
#define _BreitWigner_

#include <utility>
#include <string>
#include <complex>
#include <vector>
#include <cassert>
#include <iostream>
#include <cstdlib>

#include <TLorentzVector.h>

#include "IUAmpTools/Amplitude.h"
#include "IUAmpTools/AmpParameter.h"
#include "IUAmpTools/UserAmplitude.h"
#include "IUAmpTools/Kinematics.h"

#include "AMPTOOLS_AMPS/barrierFactor.h"
#include "AMPTOOLS_AMPS/breakupMomentum.h"

using std::complex;
using namespace std;

class Kinematics;

class BreitWigner : public UserAmplitude< BreitWigner >
{
	public:
	
		BreitWigner() : UserAmplitude< BreitWigner >() {}
		BreitWigner( const vector< string >& args );
	
		~BreitWigner(){}
	
		string name() const { return "BreitWigner"; }
	
		complex< GDouble > calcAmplitude( GDouble** pKin ) const;
		
		void updatePar( const AmpParameter& par );

	private:
	
		AmpParameter m_mass0;
		AmpParameter m_width0;
		int m_orbitL;
	
		//particle 4-vectors are sum of the particle indices set. if num == -1, is target
		int dNumParticleIndices_Product1;
		int* dParticleIndices_Product1;

		int dNumParticleIndices_Product2;
		int* dParticleIndices_Product2;
};

#endif //_BreitWigner_