//
// ********************************************************************
// * 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.          *
// ********************************************************************
//
// 
// class G4ITPathFinder 
//
// Class description:
// 
// G4ITPathFinder is a duplicated version of G4ITPathFinder
// 
// This class directs the lock-stepped propagation of a track in the 
// 'mass' and other parallel geometries.  It ensures that tracking 
// in a magnetic field sees these parallel geometries at each trial step, 
// and that the earliest boundary limits the step.
// 
// For the movement in field, it relies on the class G4PropagatorInField
//
// History:
// -------
//  7.10.05 John Apostolakis,  Draft design 
// 26.04.06 John Apostolakis,  Revised design and first implementation 
// ---------------------------------------------------------------------------

#ifndef G4ITPATHFINDER_HH  
#define G4ITPATHFINDER_HH  1

#include <vector>
#include "G4Types.hh"

#include "G4FieldTrack.hh"

class G4ITTransportationManager;
class G4ITNavigator;

#include "G4ITMultiNavigator.hh"
#include "G4TouchableHandle.hh"
#include "G4TrackState.hh"

class G4PropagatorInField;
class G4ITPathFinder;

// Global state (retained during stepping for one track)
// State changed in a step computation
template<>
class G4TrackState<G4ITPathFinder> : public G4TrackStateBase<G4ITPathFinder>
{
	friend class G4ITPathFinder;

protected:
	G4bool  fNewTrack;               // Flag a new track (ensure first step)

	ELimited      fLimitedStep[G4ITNavigator::fMaxNav];
	G4bool        fLimitTruth[G4ITNavigator::fMaxNav];
	G4double      fCurrentStepSize[G4ITNavigator::fMaxNav];
	G4int         fNoGeometriesLimiting;  //  How many processes contribute to limit

	G4ThreeVector fPreSafetyLocation;    //  last initial position for which safety evaluated
	G4double      fPreSafetyMinValue;    //   /\ corresponding value of full safety
	G4double      fPreSafetyValues[ G4ITNavigator::fMaxNav ]; //   Safeties for the above point
	// This part of the state can be retained for severall calls --> CARE

	G4ThreeVector fPreStepLocation;      //  point where last ComputeStep called
	G4double      fMinSafety_PreStepPt;  //   /\ corresponding value of full safety
	G4double      fCurrentPreStepSafety[ G4ITNavigator::fMaxNav ]; //   Safeties for the above point
	// This changes at each step,
	//   so it can differ when steps inside min-safety are made

	G4bool        fPreStepCenterRenewed;   // Whether PreSafety coincides with PreStep point

	G4double      fMinStep;      // As reported by Navigators -- can be kInfinity
	G4double      fTrueMinStep;  // Corrected in case >= proposed

	// State after calling 'locate'

	G4VPhysicalVolume* fLocatedVolume[G4ITNavigator::fMaxNav];
	G4ThreeVector      fLastLocatedPosition;

	// State after calling 'ComputeStep' (others member variables will be affected)
	G4FieldTrack    fEndState;           // Point, velocity, ... at proposed step end
	G4bool          fFieldExertedForce{false};  // In current proposed step

	G4bool fRelocatedPoint{true};   //  Signals that point was or is being moved
	//  from the position of the last location
	//   or the endpoint resulting from ComputeStep
	//   -- invalidates fEndState

	// State for 'ComputeSafety' and related methods
	G4ThreeVector fSafetyLocation;       //  point where ComputeSafety is called
	G4double      fMinSafety_atSafLocation; // /\ corresponding value of safety
	G4double      fNewSafetyComputed[ G4ITNavigator::fMaxNav ];  // Safeties for last ComputeSafety

	// State for Step numbers
	G4int         fLastStepNo{-1}, fCurrentStepNo{-1};

public:
	~G4TrackState() override= default;

	G4TrackState() :
        
			fEndState( G4ThreeVector(), G4ThreeVector(), 0., 0., 0., 0., 0.)
			  {

		G4ThreeVector  Big3Vector( kInfinity, kInfinity, kInfinity );
		fLastLocatedPosition= Big3Vector;
		fSafetyLocation= Big3Vector;
		fPreSafetyLocation= Big3Vector;
		fPreStepLocation= Big3Vector;

		fPreSafetyMinValue=  -1.0;
		fMinSafety_PreStepPt= -1.0;
		fMinSafety_atSafLocation= -1.0;
		fMinStep=   -1.0;
		fTrueMinStep= -1.0;
		fPreStepCenterRenewed= false;
		fNewTrack= false;
		fNoGeometriesLimiting= 0;

		for( G4int num=0; num< G4ITNavigator::fMaxNav; ++num )
		{
			fLimitTruth[num] = false;
			fLimitedStep[num] = kUndefLimited;
			fCurrentStepSize[num] = -1.0;
			fLocatedVolume[num] = nullptr;
			fPreSafetyValues[num]= -1.0;
			fCurrentPreStepSafety[num] = -1.0;
			fNewSafetyComputed[num]= -1.0;
		}
	}
};

class G4ITPathFinder : public G4TrackStateDependent<G4ITPathFinder>
{

public:  // with description

	static G4ITPathFinder* GetInstance();
	//
	// Retrieve singleton instance

	G4double ComputeStep( const G4FieldTrack &pFieldTrack,
			G4double  pCurrentProposedStepLength,
			G4int     navigatorId, // Identifies the geometry
			G4int     stepNo,      // See next step/check
			G4double &pNewSafety,  // Only for this geometry
			ELimited &limitedStep,
			G4FieldTrack       &EndState,
			G4VPhysicalVolume*  currentVolume );
	//
	// Compute the next geometric Step  -- Curved or linear
	//   If it is called with a larger 'stepNo' it will execute a new step;
	//   if 'stepNo' is same as last call, then the results for
	//   the geometry with Id. number 'navigatorId' will be returned.

	void Locate( const G4ThreeVector& position,
			const G4ThreeVector& direction,
			G4bool  relativeSearch=true);
	//
	// Make primary relocation of global point in all navigators,
	// and update them.

	void ReLocate( const G4ThreeVector& position );
	//
	// Make secondary relocation of global point (within safety only)
	// in all navigators, and update them.

	void PrepareNewTrack( const G4ThreeVector& position,
			const G4ThreeVector& direction,
			G4VPhysicalVolume* massStartVol=nullptr);
	//
	// Check and cache set of active navigators.

	G4TouchableHandle CreateTouchableHandle( G4int navId ) const;
	inline G4VPhysicalVolume* GetLocatedVolume( G4int navId ) const;

	// -----------------------------------------------------------------

	inline G4bool   IsParticleLooping() const;

	inline G4double GetCurrentSafety() const;
	// Minimum value of safety after last ComputeStep
	inline G4double GetMinimumStep() const;
	// Get the minimum step size from the last ComputeStep call
	//   - in case full step is taken, this is kInfinity
	inline unsigned int  GetNumberGeometriesLimitingStep() const;

	G4double ComputeSafety( const G4ThreeVector& globalPoint);
	// Recompute safety for the relevant point the endpoint of the last step!!
	// Maintain vector of individual safety values (for next method)

	G4double ObtainSafety( G4int navId, G4ThreeVector& globalCenterPoint );
	// Obtain safety for navigator/geometry navId for last point 'computed'
	//   --> last point for which ComputeSafety was called
	//   Returns the point (center) for which this safety is valid

	void EnableParallelNavigation( G4bool enableChoice=true );
	//
	// Must call it to ensure that G4ITNavigator is prepared,
	// especially for curved tracks. If true it switches PropagatorInField
	// to use MultiNavigator. Must call it with false to undo (=PiF use
	// Navigator for tracking!)

	inline G4int  SetVerboseLevel(G4int lev=-1);

public:  // with description

	inline G4int   GetMaxLoopCount() const;
	inline void    SetMaxLoopCount( G4int new_max );
	//
	// A maximum for the number of steps that a (looping) particle can take.

public:  // without description

	inline void MovePoint();
	//
	// Signal that location will be moved -- internal use primarily

	// To provide best compatibility between Coupled and Old Transportation
	//   the next two methods are provided:
	G4double LastPreSafety( G4int navId, G4ThreeVector& globalCenterPoint, G4double& minSafety );
	// Obtain last safety needed in ComputeStep (for geometry navId)
	//   --> last point at which ComputeStep recalculated safety
	//   Returns the point (center) for which this safety is valid
	//    and also the minimum safety over all navigators (ie full)

	void PushPostSafetyToPreSafety();
	// Tell G4ITNavigator to copy PostStep Safety to PreSafety (for use at next step)

	G4String& LimitedString( ELimited lim );
	// Convert ELimited to string

protected:  // without description

	G4double  DoNextLinearStep(  const G4FieldTrack  &FieldTrack,
			G4double            proposedStepLength);

	G4double  DoNextCurvedStep(  const G4FieldTrack  &FieldTrack,
			G4double            proposedStepLength,
			G4VPhysicalVolume*  pCurrentPhysVolume);

	void WhichLimited();
	void PrintLimited();
	//
	// Print key details out - for debugging

	// void ClearState();
	//
	// Clear all the State of this class and its current associates

	inline G4bool UseSafetyForOptimization( G4bool );
	//
	// Whether use safety to discard unneccesary calls to navigator

	void ReportMove( const G4ThreeVector& OldV, const G4ThreeVector& NewV, const G4String& Quantity ) const;
	// Helper method to report movement (likely of initial point)

protected:

	G4ITPathFinder();  //  Singleton
	~G4ITPathFinder() override;

	inline G4ITNavigator* GetNavigator(G4int n) const;

private:

	// ----------------------------------------------------------------------
	//  DATA Members
	// ----------------------------------------------------------------------

	G4ITMultiNavigator *fpMultiNavigator;
	//
	//  Object that enables G4PropagatorInField to see many geometries

	G4int   fNoActiveNavigators;

	G4ITNavigator*  fpNavigator[G4ITNavigator::fMaxNav];

	G4int         fVerboseLevel{0};            // For debuging purposes

	G4ITTransportationManager* fpTransportManager; // Cache for frequent use
	// G4PropagatorInField* fpFieldPropagator;

	G4double kCarTolerance;

	static G4ThreadLocal G4ITPathFinder* fpPathFinder;

};

// ********************************************************************
// Inline methods.
// ********************************************************************

inline G4VPhysicalVolume* G4ITPathFinder::GetLocatedVolume( G4int navId ) const
{
	G4VPhysicalVolume* vol=nullptr;
	if( (navId < G4ITNavigator::fMaxNav) && (navId >=0) ) { vol= fpTrackState->fLocatedVolume[navId]; }
	return vol;
}

inline G4int  G4ITPathFinder::SetVerboseLevel(G4int newLevel)
{
	G4int old= fVerboseLevel;  fVerboseLevel= newLevel; return old;
}

inline G4double G4ITPathFinder::GetMinimumStep() const
{ 
	return fpTrackState->fMinStep;
} 

inline unsigned int G4ITPathFinder::GetNumberGeometriesLimitingStep() const
{
	unsigned int noGeometries=fpTrackState->fNoGeometriesLimiting;
	return noGeometries;
}

inline G4double G4ITPathFinder::GetCurrentSafety() const
{
	return fpTrackState->fMinSafety_PreStepPt;
}

inline void G4ITPathFinder::MovePoint()
{
	fpTrackState->fRelocatedPoint= true;
}

inline G4ITNavigator* G4ITPathFinder::GetNavigator(G4int n) const
{ 
	if( (n>fNoActiveNavigators)||(n<0)) { n=0; }
	return fpNavigator[n];
}

inline G4double      G4ITPathFinder::ObtainSafety( G4int navId, G4ThreeVector& globalCenterPoint )
{
	globalCenterPoint= fpTrackState->fSafetyLocation;
	//  navId = std::min( navId, fMaxNav-1 );
	return  fpTrackState->fNewSafetyComputed[ navId ];
}

inline G4double  G4ITPathFinder::LastPreSafety( G4int navId,
		G4ThreeVector& globalCenterPoint,
		G4double& minSafety )
{
	globalCenterPoint= fpTrackState->fPreSafetyLocation;
	minSafety=         fpTrackState->fPreSafetyMinValue;
	//  navId = std::min( navId, fMaxNav-1 );
	return  fpTrackState->fPreSafetyValues[ navId ];
}
#endif