#include <petsc/private/randomimpl.h>

PetscErrorCode PetscRandomSeed_Rand(PetscRandom r) {
  PetscFunctionBegin;
  srand(r->seed);
  PetscFunctionReturn(0);
}

#define RAND_WRAP ((PetscReal)((rand() / (double)((unsigned int)RAND_MAX + 1))))
PetscErrorCode PetscRandomGetValue_Rand(PetscRandom r, PetscScalar *val) {
  PetscFunctionBegin;
#if defined(PETSC_USE_COMPLEX)
  if (r->iset) *val = PetscRealPart(r->width) * RAND_WRAP + PetscRealPart(r->low) + (PetscImaginaryPart(r->width) * RAND_WRAP + PetscImaginaryPart(r->low)) * PETSC_i;
  else *val = RAND_WRAP + RAND_WRAP * PETSC_i;
#else
  if (r->iset) *val = r->width * RAND_WRAP + r->low;
  else *val = RAND_WRAP;
#endif
  PetscFunctionReturn(0);
}

PetscErrorCode PetscRandomGetValueReal_Rand(PetscRandom r, PetscReal *val) {
  PetscFunctionBegin;
#if defined(PETSC_USE_COMPLEX)
  if (r->iset) *val = PetscRealPart(r->width) * RAND_WRAP + PetscRealPart(r->low);
  else *val = RAND_WRAP;
#else
  if (r->iset) *val = r->width * RAND_WRAP + r->low;
  else *val = RAND_WRAP;
#endif
  PetscFunctionReturn(0);
}

static struct _PetscRandomOps PetscRandomOps_Values = {
  PetscDesignatedInitializer(seed, PetscRandomSeed_Rand),
  PetscDesignatedInitializer(getvalue, PetscRandomGetValue_Rand),
  PetscDesignatedInitializer(getvaluereal, PetscRandomGetValueReal_Rand),
};

/*MC
   PETSCRAND - access to the basic Unix random number generator

   Options Database Keys:
. -random_type <rand,rand48,sprng> - set the random number generator from the options database

  Level: beginner

.seealso: `PetscRandomCreate()`, `PetscRandomSetType()`, `PETSCRAND48`, `PETSCSPRNG`, `PetscRandomSetFromOptions()`
M*/

PETSC_EXTERN PetscErrorCode PetscRandomCreate_Rand(PetscRandom r) {
  PetscFunctionBegin;
  PetscCall(PetscMemcpy(r->ops, &PetscRandomOps_Values, sizeof(PetscRandomOps_Values)));
  PetscCall(PetscObjectChangeTypeName((PetscObject)r, PETSCRAND));
  PetscFunctionReturn(0);
}