////////////////////////////////////////////////////////////////////
/// \class RAT::PosGen_FillExp
///
/// \brief  Generates exponential distribution of events in given volume(s).
///         distribution depends on radius see documentation: SNO+-doc-2153-v1
///
/// \author Aleksandra Bialek <abialek@ualberta.ca> -- contact person
///
/// REVISION HISTORY:
///     - 23 Aug 2013 : A.Bialek - new position generator that generates events
///                              within the volume with an exponential distribution
///                              that depends on the radius see documentation: SNO+-doc-2153-v1
///     - 26 Nov 2014 : Matt Strait -doxygen fixes
///     - 21 Oct 2016 : Nuno Barros - Fixed position generator that incorrectly sampled the center
///                                   if there were off-center daughter volumes like the NCD anchors in the inner_av.
///                                   Closed issue #1392.
///     - 10 Dec 2016 : Nuno Barros - Fixed a bug in the previous bug fix. A transformation to global coordinates was missing
///
/// \details
/// Arguments of the generator:\n
///   /generator/pos/set x y z dr \n
/// or \n
///   /generator/pos/set volName dr  \n
/// if 'dr' not given it will take the default value
///
////////////////////////////////////////////////////////////////////

#ifndef __RAT_PosGen_FillExp__
#define __RAT_PosGen_FillExp__

#include <RAT/GLG4PosGen.hh>
#include <RAT/VolumeList.hh>
#include <G4ThreeVector.hh>
#include <TF1.h>
#include <vector>

class G4VPhysicalVolume;
class G4VSolid;
class G4Navigator;

namespace RAT {
class PosGen_FillExp : public GLG4PosGen
{
    public:
        /// Constructor sets the default db name
        PosGen_FillExp(const std::string& dbname = std::string("fillexp")) :
                   GLG4PosGen(dbname) {}
        /// Destructor
        virtual ~PosGen_FillExp() {}
        /// Abstract interface for generating the position
        virtual void GeneratePosition(G4ThreeVector& argResult);
        /// Abstract interface for setting the state
        virtual void SetState(G4String newValues);
        /// Abstract interface for getting the state
        virtual G4String GetState() const;
    protected:
        VolumeList fVolumes; ///< List of volumes to generate events in
        std::vector<std::string> fStates; ///< List of states to build fVolumes
        std::vector<std::string> fStateDR;///< List of decay rates of radial distribution per state
        std::vector<double> fDecayRates;  ///< List of decay rates of radial distributions
         ///exponential function
        TF1 *fRdecay;
        /// The total volume of all the physical volumes to fill, in mm^3
        double fTotalVolume;
        /// A flag marking whether the list of volumes needs to be regenerated
        bool fListValid;
    private:

};
} // namespace RAT

#endif