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//
// Structs used by G4QSStepper
//
// Author: Mattias Portnoy (Univ. Buenos Aires), 2024
// --------------------------------------------------------------------

inline Substep::Substep()  
{
  for (G4int i = 1; i < MAX_QSS_ORDER; ++i)
  {
    std::fill_n(state_x[i], NUMBER_OF_VARIABLES_QSS, 0.0);
    std::fill_n(state_q[i], NUMBER_OF_VARIABLES_QSS, 0.0);
  }
  std::fill_n(state_x[MAX_QSS_ORDER], NUMBER_OF_VARIABLES_QSS, 0.0);

  std::fill_n(state_tx, NUMBER_OF_VARIABLES_QSS, 0.0);
  std::fill_n(state_tq, NUMBER_OF_VARIABLES_QSS, 0.0);
}

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

inline Substeps::Substeps()
{
  _substeps = static_cast<Substep *>(malloc((_arrlength) * sizeof(Substep)));    
}

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

inline Substeps::~Substeps()
{
  free(_substeps);
}

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

// Mimics the functionality of GNU method reallocarray 
inline void* Substeps::safe_reallocarray(void* ptr, size_t numMembers, size_t size)
{
  if (size != 0 && numMembers > std::numeric_limits<size_t>::max() / size)
  {
    return nullptr;
  }
  return realloc(ptr, numMembers * size);
}
 
// ----------------------------------------------------------------------------

inline void Substeps::resize()
{
  _arrlength = std::fmax(_arrlength*2, 1500);
  _substeps = static_cast<Substep *>(safe_reallocarray(_substeps, _arrlength, sizeof(Substep)));
  if( _substeps == nullptr )
  { 
     G4ExceptionDescription ermsg;
     ermsg << "QSS2: Size of state exceed available memory : number of elemets = " << _arrlength
           << " size of each element= " << sizeof(Substep) << G4endl;
     G4Exception( "G4QSSubstepStruct::resize", "GeomField0008", FatalException, ermsg ); 
  }
}

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

inline Substep* Substeps::create_substep()
{
  current_substep_index++;

  if (unlikely( current_substep_index >= _arrlength ))
  {
    resize();
  }
  return &(_substeps[current_substep_index]);
}

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

inline void Substeps::save_substep(Substep* substep)
{
  memcpy(create_substep(), substep, sizeof(Substep));
}

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

inline void Substeps::reset()
{
  current_substep_index = -1;
}