#include <petscis.h>         /*I  "petscis.h"  I*/
#include <petsc/private/isimpl.h>
#include <petsc/private/viewerimpl.h>
#include <petsclayouthdf5.h>

PetscErrorCode ISView_Binary(IS is,PetscViewer viewer)
{
  PetscBool      skipHeader;
  PetscLayout    map;
  PetscInt       tr[2],n,s,N;
  const PetscInt *iarray;

  PetscFunctionBegin;
  PetscCall(PetscViewerSetUp(viewer));
  PetscCall(PetscViewerBinaryGetSkipHeader(viewer,&skipHeader));

  PetscCall(ISGetLayout(is,&map));
  PetscCall(PetscLayoutGetLocalSize(map,&n));
  PetscCall(PetscLayoutGetRange(map,&s,NULL));
  PetscCall(PetscLayoutGetSize(map,&N));

  /* write IS header */
  tr[0] = IS_FILE_CLASSID; tr[1] = N;
  if (!skipHeader) PetscCall(PetscViewerBinaryWrite(viewer,tr,2,PETSC_INT));

  /* write IS indices */
  PetscCall(ISGetIndices(is,&iarray));
  PetscCall(PetscViewerBinaryWriteAll(viewer,iarray,n,s,N,PETSC_INT));
  PetscCall(ISRestoreIndices(is,&iarray));
  PetscFunctionReturn(0);
}

#if defined(PETSC_HAVE_HDF5)
/*
     This should handle properly the cases where PetscInt is 32 or 64 and hsize_t is 32 or 64. These means properly casting with
   checks back and forth between the two types of variables.
*/
PetscErrorCode ISLoad_HDF5(IS is, PetscViewer viewer)
{
  hid_t           inttype;    /* int type (H5T_NATIVE_INT or H5T_NATIVE_LLONG) */
  PetscInt       *ind;
  const char     *isname;

  PetscFunctionBegin;
  PetscCheck(((PetscObject)is)->name, PetscObjectComm((PetscObject)is), PETSC_ERR_SUP, "IS name must be given using PetscObjectSetName() before ISLoad() since HDF5 can store multiple objects in a single file");
#if defined(PETSC_USE_64BIT_INDICES)
  inttype = H5T_NATIVE_LLONG;
#else
  inttype = H5T_NATIVE_INT;
#endif
  PetscCall(PetscObjectGetName((PetscObject)is, &isname));
  PetscCall(PetscViewerHDF5Load(viewer, isname, is->map, inttype, (void**)&ind));
  PetscCall(ISGeneralSetIndices(is, is->map->n, ind, PETSC_OWN_POINTER));
  PetscFunctionReturn(0);
}
#endif

PetscErrorCode ISLoad_Binary(IS is, PetscViewer viewer)
{
  PetscBool      isgeneral,skipHeader;
  PetscInt       tr[2],rows,N,n,s,*idx;
  PetscLayout    map;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)is,ISGENERAL,&isgeneral));
  PetscCheck(isgeneral,PetscObjectComm((PetscObject)is),PETSC_ERR_ARG_INCOMP,"IS must be of type ISGENERAL to load into it");
  PetscCall(PetscViewerSetUp(viewer));
  PetscCall(PetscViewerBinaryGetSkipHeader(viewer,&skipHeader));

  PetscCall(ISGetLayout(is,&map));
  PetscCall(PetscLayoutGetSize(map,&N));

  /* read IS header */
  if (!skipHeader) {
    PetscCall(PetscViewerBinaryRead(viewer,tr,2,NULL,PETSC_INT));
    PetscCheck(tr[0] == IS_FILE_CLASSID,PetscObjectComm((PetscObject)viewer),PETSC_ERR_FILE_UNEXPECTED,"Not an IS next in file");
    PetscCheck(tr[1] >= 0,PetscObjectComm((PetscObject)viewer),PETSC_ERR_FILE_UNEXPECTED,"IS size (%" PetscInt_FMT ") in file is negative",tr[1]);
    PetscCheck(N < 0 || N == tr[1],PETSC_COMM_SELF,PETSC_ERR_FILE_UNEXPECTED,"IS in file different size (%" PetscInt_FMT ") than input IS (%" PetscInt_FMT ")",tr[1],N);
    rows = tr[1];
  } else {
    PetscCheck(N >= 0,PETSC_COMM_SELF,PETSC_ERR_USER,"IS binary file header was skipped, thus the user must specify the global size of input IS");
    rows = N;
  }

  /* set IS size if not already set */
  if (N < 0) PetscCall(PetscLayoutSetSize(map,rows));
  PetscCall(PetscLayoutSetUp(map));

  /* get IS sizes and check global size */
  PetscCall(PetscLayoutGetSize(map,&N));
  PetscCall(PetscLayoutGetLocalSize(map,&n));
  PetscCall(PetscLayoutGetRange(map,&s,NULL));
  PetscCheck(N == rows,PETSC_COMM_SELF,PETSC_ERR_FILE_UNEXPECTED,"IS in file different size (%" PetscInt_FMT ") than input IS (%" PetscInt_FMT ")",rows,N);

  /* read IS indices */
  PetscCall(PetscMalloc1(n,&idx));
  PetscCall(PetscViewerBinaryReadAll(viewer,idx,n,s,N,PETSC_INT));
  PetscCall(ISGeneralSetIndices(is,n,idx,PETSC_OWN_POINTER));
  PetscFunctionReturn(0);
}

PetscErrorCode ISLoad_Default(IS is, PetscViewer viewer)
{
  PetscBool      isbinary,ishdf5;

  PetscFunctionBegin;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERHDF5,&ishdf5));
  if (isbinary) {
    PetscCall(ISLoad_Binary(is, viewer));
  } else if (ishdf5) {
#if defined(PETSC_HAVE_HDF5)
    PetscCall(ISLoad_HDF5(is, viewer));
#endif
  }
  PetscFunctionReturn(0);
}