//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
// G4StateManager
//
// Class description:
//
// Class responsible for handling and updating the running state
// of the Geant4 application during its different phases.
// The class is a singleton, it can be accessed via the public
// method G4StateManager::GetStateManager().
//
// States of Geant4 are defined in G4ApplicationState.

// Authors: G.Cosmo, M.Asai - November 1996
// --------------------------------------------------------------------
#ifndef G4StateManager_hh
#define G4StateManager_hh 1

#include "G4ApplicationState.hh"
#include "G4String.hh"
#include "G4Types.hh"
#include "G4VExceptionHandler.hh"
#include "G4VStateDependent.hh"
#include <vector>

class G4Run;
class G4Event;

class G4StateManager
{
 public:
  static G4StateManager* GetStateManager();
  // The G4StateManager class is a singleton class and the pointer
  // to the only one existing object can be obtained by this static
  // method.

  ~G4StateManager();

  G4StateManager(const G4StateManager&) = delete;
  G4StateManager& operator=(const G4StateManager&) = delete;
  G4bool operator==(const G4StateManager&) const   = delete;
  G4bool operator!=(const G4StateManager&) const   = delete;

  const G4ApplicationState& GetCurrentState() const;
  // Returns the current state
  const G4ApplicationState& GetPreviousState() const;
  // Returns the previous state
  G4bool SetNewState(const G4ApplicationState& requestedState);
  // Set Geant4 to a new state.
  // In case the request is illegal, false will be returned
  // and the state of Geant4 will not be changed
  G4bool SetNewState(const G4ApplicationState& requestedState, const char* msg);
  // Set Geant4 to a new state.
  // In case the request is illegal, false will be returned
  // and the state of Geant4 will not be changed.
  // "msg" is the information associated to the state change
  G4bool RegisterDependent(G4VStateDependent* aDependent,
                           G4bool bottom = false);
  // Register a concrete class of G4VStateDependent.
  // Registered concrete classes will be notified via
  // G4VStateDependent::Notify() method when the state of Geant4 changes.
  // False will be returned if registration fails
  G4bool DeregisterDependent(G4VStateDependent* aDependent);
  // Remove the registration.
  // False will be returned if aDependent has not been registered
  G4VStateDependent* RemoveDependent(const G4VStateDependent* aDependent);
  // Remove the registration.
  // Removed pointer is returned
  G4String GetStateString(const G4ApplicationState& aState) const;
  // Utility method which returns a string of the state name

  void NotifyDeletion(const G4Event*);
  void NotifyDeletion(const G4Run*);
  // Notifying when an event or a run is deleted for the sake of avoiding
  // a state-dependent class from accessing to an obsolete event/run object.

  inline void SetSuppressAbortion(G4int i);
  inline G4int GetSuppressAbortion() const;
  inline const char* GetMessage() const;
  inline void SetExceptionHandler(G4VExceptionHandler* eh);
  inline G4VExceptionHandler* GetExceptionHandler() const;
  static void SetVerboseLevel(G4int val);

 private:
  G4StateManager();

 private:
  static G4ThreadLocal G4StateManager* theStateManager;
  G4ApplicationState theCurrentState  = G4State_PreInit;
  G4ApplicationState thePreviousState = G4State_PreInit;
  std::vector<G4VStateDependent*> theDependentsList;
  G4VStateDependent* theBottomDependent = nullptr;
  G4int suppressAbortion                = 0;
  const char* msgptr                    = nullptr;
  G4VExceptionHandler* exceptionHandler = nullptr;
  static G4int verboseLevel;
};

#include "G4StateManager.icc"

#endif