#ifndef __JPHYSICS__JACOEFFSOURCE__
#define __JPHYSICS__JACOEFFSOURCE__

#include "JLang/JSharedPointer.hh"

#include "JPhysics/JRadiation.hh"


/**
 * \author mdejong
 */

namespace JPHYSICS {}
namespace JPP { using namespace JPHYSICS; }

namespace JPHYSICS {

  using JLANG::JSharedPointer;
  

  /**
   * Interface for calculation of ionization constant.
   */
  class JACoeffInterface {
  public:
    /**
     * Virtual destructor.
     */
    virtual ~JACoeffInterface()
    {}

    /**
     * Get ionization constant a.
     *
     * \param  E      muon energy [GeV]
     * \return        ionization constant [GeV/m]
     */
    virtual double getA(const double E) const = 0;
  };
  
  
  /**
   * Implementation for calculation of ionization constant.

   * This class implements the JACoeffInterface interface.\n
   * N.B: This class owns the object pointed to using JLANG::JSharedPointer.
   */
  class JACoeffSource : 
    public JACoeffInterface,
    public JSharedPointer<JRadiation>
  {
  public:
    /**
     * Constructor.
     *
     * \param  radiation       pointer to valid JRadition object
     * \param  density         mass density of radiation material [gr/cm³]
     */
    JACoeffSource(const JSharedPointer<JRadiation>& radiation,
		  const double                      density) :
      JSharedPointer<JRadiation>(radiation),
      rho(density)
    {}

    
    /**
     * Get ionization constant a.
     *
     * \param  E      muon energy [GeV]
     * \return        ionization constant [GeV/m]
     */
    virtual double getA(const double E) const override 
    {
      return (*this)->CalculateACoeff(E) * rho * 1.0e6; 
    }

  protected:
    const double rho;
  };
}    

#endif