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#include <time.h>

#include "Randomize.hh"
#include "G4TransportationManager.hh"

#include "G4ExplicitEuler.hh"
#include "G4ImplicitEuler.hh"
#include "G4SimpleRunge.hh"
#include "G4SimpleHeum.hh"
#include "G4ClassicalRK4.hh"
#include "G4CashKarpRKF45.hh"

#include "F04GlobalField.hh"

F04GlobalField* F04GlobalField::object = 0;

F04GlobalField::F04GlobalField() : G4ElectroMagneticField(),
                             minStep(0.01*mm), deltaChord(3.0*mm),
                             deltaOneStep(0.01*mm), deltaIntersection(0.1*mm),
                             epsMin(2.5e-7*mm), epsMax(0.05*mm),
                             fEquation(0), fFieldManager(0), 
                             fFieldPropagator(0), fStepper(0), fChordFinder(0)
//F04GlobalField::F04GlobalField() : G4MagneticField(),
//                             minStep(0.01*mm), deltaChord(3.0*mm),
//                             deltaOneStep(0.01*mm), deltaIntersection(0.1*mm),
//                             epsMin(2.5e-7*mm), epsMax(0.05*mm),
//                             fEquation(0), fFieldManager(0),
//                             fFieldPropagator(0), fStepper(0), fChordFinder(0)
{
  fFieldMessenger = new F04FieldMessenger(this);

  fields = new FieldList();

  fStepperType = 4 ;       // ClassicalRK4 is default stepper

  //  set object

  object = this;

  updateField();
}

F04GlobalField::~F04GlobalField()
{
  clear();

  delete fFieldMessenger;

  if (fEquation)        delete fEquation;
  if (fFieldManager)    delete fFieldManager;
  if (fFieldPropagator) delete fFieldPropagator;
  if (fStepper)         delete fStepper;
  if (fChordFinder)     delete fChordFinder;
}

void F04GlobalField::updateField()
{
  first = true;

  nfp = 0;
  fp = 0;

  clear();

  //  Construct equ. of motion of particles through B fields
//  fEquation = new G4Mag_EqRhs(this);
  //  Construct equ. of motion of particles through e.m. fields
//  fEquation = new G4EqMagElectricField(this);
  //  Construct equ. of motion of particles including spin through B fields
//  fEquation = new G4Mag_SpinEqRhs(this);
  //  Construct equ. of motion of particles including spin through e.m. fields
  fEquation = new G4EqEMFieldWithSpin(this);

  //  Get transportation, field, and propagator managers
  G4TransportationManager* fTransportManager =
         G4TransportationManager::GetTransportationManager();

  fFieldManager = GetGlobalFieldManager();

  fFieldPropagator = fTransportManager->GetPropagatorInField();

  //  Need to SetFieldChangesEnergy to account for a time varying electric
  //  field (r.f. fields)
  fFieldManager->SetFieldChangesEnergy(true);

  //  Set the field
  fFieldManager->SetDetectorField(this);

  //  Choose a stepper for integration of the equation of motion
  SetStepper();

  //  Create a cord finder providing the (global field, min step length,
  //  a pointer to the stepper)
  fChordFinder = new G4ChordFinder((G4MagneticField*)this,minStep,fStepper);

  // Set accuracy parameters
  fChordFinder->SetDeltaChord( deltaChord );

  fFieldManager->SetAccuraciesWithDeltaOneStep(deltaOneStep);

  fFieldManager->SetDeltaIntersection(deltaIntersection);

  fFieldPropagator->SetMinimumEpsilonStep(epsMin);
  fFieldPropagator->SetMaximumEpsilonStep(epsMax);

  G4cout << "Accuracy Parameters:" <<
            " MinStep=" << minStep <<
            " DeltaChord=" << deltaChord <<
            " DeltaOneStep=" << deltaOneStep << G4endl;
  G4cout << "                    " <<
            " DeltaIntersection=" << deltaIntersection <<
            " EpsMin=" << epsMin <<
            " EpsMax=" << epsMax <<  G4endl;

  fFieldManager->SetChordFinder(fChordFinder);

}

F04GlobalField* F04GlobalField::getObject()
{
  if (!object) new F04GlobalField();
  return object;
}

void F04GlobalField::SetStepper()
{
  if(fStepper) delete fStepper;

  switch ( fStepperType )
  {
    case 0:
//      fStepper = new G4ExplicitEuler( fEquation, 8 ); // no spin tracking
      fStepper = new G4ExplicitEuler( fEquation, 12 ); // with spin tracking
      G4cout << "G4ExplicitEuler is called" << G4endl;
      break;
    case 1:
//      fStepper = new G4ImplicitEuler( fEquation, 8 ); // no spin tracking
      fStepper = new G4ImplicitEuler( fEquation, 12 ); // with spin tracking
      G4cout << "G4ImplicitEuler is called" << G4endl;
      break;
    case 2:
//      fStepper = new G4SimpleRunge( fEquation, 8 ); // no spin tracking
      fStepper = new G4SimpleRunge( fEquation, 12 ); // with spin tracking
      G4cout << "G4SimpleRunge is called" << G4endl;
      break;
    case 3:
//      fStepper = new G4SimpleHeum( fEquation, 8 ); // no spin tracking
      fStepper = new G4SimpleHeum( fEquation, 12 ); // with spin tracking
      G4cout << "G4SimpleHeum is called" << G4endl;
      break;
    case 4:
//      fStepper = new G4ClassicalRK4( fEquation, 8 ); // no spin tracking
      fStepper = new G4ClassicalRK4( fEquation, 12 ); // with spin tracking
      G4cout << "G4ClassicalRK4 (default) is called" << G4endl;
      break;
    case 5:
//      fStepper = new G4CashKarpRKF45( fEquation, 8 ); // no spin tracking
      fStepper = new G4CashKarpRKF45( fEquation, 12 ); // with spin tracking
      G4cout << "G4CashKarpRKF45 is called" << G4endl;
      break;
    default: fStepper = 0;
  }
}

G4FieldManager* F04GlobalField::GetGlobalFieldManager()
{
  return G4TransportationManager::GetTransportationManager()
                                ->GetFieldManager();
}

void F04GlobalField::GetFieldValue(const G4double* point, G4double* field) const
{
  // NOTE: this routine dominates the CPU time for tracking.
  // Using the simple array fp[] instead of fields[] 
  // directly sped it up

  field[0] = field[1] = field[2] = field[3] = field[4] = field[5] = 0.0;

  // protect against Geant4 bug that calls us with point[] NaN.
  if(point[0] != point[0]) return;

  // (can't use nfp or fp, as they may change)
  if (first) ((F04GlobalField*)this)->setupArray();   // (cast away const)

  for (int i=0; i<nfp; ++i) {
      const F04ElementField* p = fp[i];
      if (p->isInBoundingBox(point)) {
         p->addFieldValue(point,field);
      }
  }

}

void F04GlobalField::clear()
{
  if (fields) {
     if (fields->size()>0) {
        FieldList::iterator i;
        for (i=fields->begin(); i!=fields->end(); ++i) delete *i;
        fields->clear();
     }
  }

  if (fp) delete[] fp;

  first = true;

  nfp = 0;
  fp = NULL;
}

void F04GlobalField::setupArray()
{
  first = false;
  nfp = fields->size();
  fp = new const F04ElementField* [nfp+1]; // add 1 so it's never 0
  for (int i=0; i<nfp; ++i) fp[i] = (*fields)[i];
}