////////////////////////////////////////////////////////////////////
/// \class RAT::DecayChain_Gen
///
/// \brief Implements a GLG4Sim-style generator for a chain of radioactive
///        decays. The class we use is DecayChain, prepared by Joe Formaggio
///        and Jason Detwiler. This class is based on code in GLG4Sim/GLG4Gen.
///
/// \author Joe Formaggio and Jason Detwiler  -- not on SNO+
/// \author Logan Sibley <lsibley@ualberta.ca>
/// \author Eric Vazquez-Jauregui <ericvj@fisica.unam.mx>
///
/// REVISION HISTORY:\n
///    10 Jan 2006 : WGS \n
///    02 Nov 2009 : Aleksandra Bialek - added midchain and alpha options \n
///    28 May 2010 : Logan Sibley - added screening option to decay_chain \n
///    23 Sep 2010 : Logan Sibley - added gamma decay option \n
///    03 Jan 2013 : Logan Sibley - now adds parent info into DS
///    04 Aug 2015 : Matt Mottram - Use G4IonTable to get ions
///    07 Feb 2017 : Nuno Barros - Removing time and pos gen instances since they
///                               since they are defined in the base GLG4gen
///
/// \details  To use this generator, the command is:
///       /generator/add decaychain ISOTOPE:POSITION[:TIME][:MIDCHAIN][:SCREEN]
///          (that is, TIME, MIDCHAIN and SCREEN are optional). ISOTOPE comes
///          from the list in data/beta_decays.dat. POSITION and TIME are the
///          same as for the combo generator. For example:
///       /generator/add decaychain 208Tl:fill \n\n
///
///          To start in the middle of a decay chain at ISOTOPE, one should
///          set the command as:
///       /generator/add decaychain ISOTOPE:POSITION:TIME:midchain
///          The generator then searches through all elements in each chain and
///          creates the chain starting from that ISOTOPE. \n \n
///
///          There is also an option to have only one decay of that ISOTOPE.
///          By default, the decay for elements is beta decay. To not crash RAT
///          one should choose an ISOTOPE which undergoes beta decay, not alpha
///          or gamma decay. If an alpha or gamma decay of ISOTOPE is required,
///          one should set:
///       /generator/add decaychain ISOTOPE:POSITION:TIME:alpha     or
///       /generator/add decaychain ISOTOPE:POSITION:TIME:gamma
///          The generator will then use the information from beta_decays.dat
///          for the alpha or gamma decay of ISOTOPE. Note that gamma decays
///          include electron capture decays and internal transitions. \n \n
///
///          Note that 'chains' may also consist of a list of the various decay
///          processes a single ISOTOPE may undergo. For example, if ISOTOPE
///          may both beta decay and electron capture, then there will be two
///          entries for ISOTOPE in beta_decays.dat, one DECAY and one GAMMA
///          type. The CHAIN type for isotope will then select the appropriate
///          decay type according to the branching ratios for each.
///
///          The last option is to choose whether or not to apply a screening
///          correction to the calculation of the Fermi function in beta
///          decay. If SCREEN is not specified, or is set to 'none', then no
///          screening correction will be applied. To apply a screening
///          correction, one should set:
///       /generator/add decaychain ISOTOPE:POSITION:TIME::screen
///          One may also specify MIDCHAIN, if required. Further information
///          regarding the screening is in src/gen/FermiFunction.cc and will be
///          available in SNO+ DocDB. \n \n
///
///          For now, the implicit assumption is that all the isotopes in the
///          decay chain remain at the fixed point determined by the position
///          generator (no drifting during decays). There is also no "deferring"
///          of any tracks of emitted particles into other events. "TIME"
///          refers to the start of the selected decay chain. As with the combo
///          generator, the default is a poisson. \n \n
///
///          The location of the file path data/beta_decays.dat is assumed to be
///          relative to the directory in which we're running RAT. If you have
///          to start RAT from a different location, want to use a different
///          beta_decays.dat file, etc., you can change the file path by setting
///          the variable $RATDecayDataDir in your shell environment.
///
////////////////////////////////////////////////////////////////////

#ifndef __RAT_DecayChain_Gen__
#define __RAT_DecayChain_Gen__

#include <globals.hh>
#include <RAT/GLG4Gen.hh>

class G4Event;
class GLG4TimeGen;
class GLG4PosGen;

namespace RAT{

  // Forward declarations in RAT namespace
class DecayChain;

class DecayChain_Gen : public GLG4Gen {
  public:
    DecayChain_Gen(const G4String & name = "DecayChain");
    virtual ~DecayChain_Gen();
    virtual void GenerateEvent(G4Event *event);
    virtual void ResetTime(double offset=0.0);
    virtual bool IsRepeatable() const { return true; };

    virtual void SetState(G4String state);
    virtual G4String GetState() const;

    virtual void SetTimeState(G4String state);
    virtual G4String GetTimeState() const;
    virtual void SetPosState(G4String state);
    virtual G4String GetPosState() const;

  protected:

    // Generator initialization, specified by the user.
    G4String fStateStr;

    // The decay chain for the isotope selected by the user.
    DecayChain* fDecayChain;

    bool fInMiddle;  //to start chain from the isotope;
    bool fInAlphaDecay;// to have only alpha decay
    bool fInGammaDecay;// to have only gamma decay
    bool fScreenCorr;  // to use a screening correction in the beta decay
  };

}
#endif