program ex95f90
#include "petsc/finclude/petsc.h"
    use petsc
    implicit none
#include "exodusII.inc"

    ! Get the Fortran kind associated with PetscInt and PetscReal so that we can use literal constants.
    PetscInt                             :: dummyPetscInt
    PetscReal                            :: dummyPetscreal
    PetscBool                            :: flg
    integer,parameter                    :: kPI = kind(dummyPetscInt)
    integer,parameter                    :: kPR = kind(dummyPetscReal)
    integer                              :: nNodalVar = 4
    integer                              :: nZonalVar = 3
    integer                              :: i

    PetscErrorCode                       :: ierr
    type(tDM)                            :: dm, pdm
    character(len=PETSC_MAX_PATH_LEN)    :: ifilename,ofilename,IOBuffer
    PetscInt                             :: order = 1
    type(tPetscViewer)                   :: viewer
    character(len = MXNAME),dimension(4) :: nodalVarName = ["U_x  ", &
                                                            "U_y  ", &
                                                            "Alpha", &
                                                            "Beta "]
    character(len = MXNAME),dimension(3) :: zonalVarName = ["Sigma_11", &
                                                            "Sigma_12", &
                                                            "Sigma_22"]
    character(len = MXNAME)              :: varName

    PetscCallA(PetscInitialize(PETSC_NULL_CHARACTER,ierr))
    if (ierr /= 0) then
      print*,'Unable to initialize PETSc'
      stop
    endif

    PetscCallA(PetscOptionsBegin(PETSC_COMM_WORLD,PETSC_NULL_CHARACTER,'PetscViewer_ExodusII test','ex95f90',ierr))
    PetscCallA(PetscOptionsString("-i", "Filename to read", "ex95f90", ifilename, ifilename, flg, ierr));
    PetscCheckA(flg,PETSC_COMM_WORLD,PETSC_ERR_ARG_OUTOFRANGE,'missing input file name -i <input file name>')
    PetscCallA(PetscOptionsString("-o", "Filename to write", "ex95f90", ofilename, ofilename, flg, ierr));
    PetscCheckA(flg,PETSC_COMM_WORLD,PETSC_ERR_ARG_OUTOFRANGE,'missing output file name -o <output file name>')
    PetscCallA(PetscOptionsEnd(ierr))

    ! Read the mesh in any supported format
    PetscCallA(DMPlexCreateFromFile(PETSC_COMM_WORLD, ifilename,PETSC_NULL_CHARACTER,PETSC_TRUE,dm,ierr))
    PetscCallA(DMPlexDistributeSetDefault(dm, PETSC_FALSE,ierr));
    PetscCallA(DMSetFromOptions(dm,ierr));
    PetscCallA(PetscObjectSetName(dm, "ex95f90", ierr));
    PetscCallA(DMViewFromOptions(dm, PETSC_NULL_OBJECT,'-dm_view',ierr));

    ! enable exodus debugging information
#ifdef PETSC_USE_DEBUG
    PetscCallA(exopts(EXVRBS+EXDEBG,ierr))
#endif

    ! Create the exodus file
    PetscCallA(PetscViewerExodusIIOpen(PETSC_COMM_WORLD,ofilename,FILE_MODE_WRITE,viewer,ierr))

    ! Save the geometry to the file, erasing all previous content
    PetscCallA(PetscViewerExodusIISetOrder(viewer,order,ierr))
    PetscCallA(DMView(dm,viewer,ierr))
    PetscCallA(PetscViewerView(viewer,PETSC_VIEWER_STDOUT_WORLD,ierr))
    PetscCall(PetscViewerFlush(viewer,ierr))

    PetscCallA(DMPlexDistribute(dm,0_kPI,PETSC_NULL_SF,pdm,ierr))
    if (pdm /= PETSC_NULL_DM) Then
      pdm = dm
    end if

    ! Testing Variable Number
    PetscCallA(PetscViewerExodusIISetZonalVariable(viewer, nZonalVar, ierr))
    nZonalVar = -1
    PetscCallA(PetscViewerExodusIIGetZonalVariable(viewer, nZonalVar, ierr))
    Write(IOBuffer,'("Number of zonal variables:", I2,"\n")') nZonalVar
    PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))

    PetscCallA(PetscViewerExodusIISetNodalVariable(viewer, nNodalVar, ierr))
    nNodalVar = -1
    PetscCallA(PetscViewerExodusIIGetNodalVariable(viewer, nNodalVar, ierr))
    Write(IOBuffer,'("Number of nodal variables:", I2,"\n")') nNodalVar
    PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))
    PetscCallA(PetscViewerView(viewer, PETSC_VIEWER_STDOUT_WORLD, ierr))

    ! Test of PetscViewerExodusIISet[Nodal/Zonal]VariableName
    PetscCallA(PetscPrintf(PETSC_COMM_WORLD, "Testing PetscViewerExodusIISet[Nodal/Zonal]VariableName\n", ierr))
    do i = 1, nZonalVar
        PetscCallA(PetscViewerExodusIISetZonalVariableName(viewer, i-1, zonalVarName(i), ierr))
    end do
    do i = 1, nNodalVar
        PetscCallA(PetscViewerExodusIISetNodalVariableName(viewer, i-1, nodalVarName(i), ierr))
    end do
    PetscCall(PetscViewerFlush(viewer,ierr))
    PetscCallA(PetscViewerView(viewer, PETSC_VIEWER_STDOUT_WORLD, ierr))

    do i = 1, nZonalVar
        PetscCallA(PetscViewerExodusIIGetZonalVariableName(viewer, i-1, varName, ierr))
        Write(IOBuffer,'("   zonal variable:", I2,": ",A,"\n")') i,varName
        PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))
    end do
    do i = 1, nNodalVar
        PetscCallA(PetscViewerExodusIIGetNodalVariableName(viewer, i-1, varName, ierr))
        Write(IOBuffer,'("   nodal variable:", I2,": ",A,"\n")') i,varName
        PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))
    end do
    PetscCallA(PetscViewerDestroy(viewer, ierr))

    ! Test of PetscViewerExodusIIGet[Nodal/Zonal]VariableName
    nZonalVar = -1
    nNodalVar = -1
    PetscCallA(PetscPrintf(PETSC_COMM_WORLD, "\n\nReopenning the output file in Read-only mode\n", ierr))
    PetscCallA(PetscPrintf(PETSC_COMM_WORLD, "Testing PetscViewerExodusIIGet[Nodal/Zonal]VariableName\n", ierr))
    PetscCallA(PetscViewerExodusIIOpen(PETSC_COMM_WORLD, ofilename, FILE_MODE_APPEND, viewer, ierr))
    PetscCallA(PetscViewerExodusIISetOrder(viewer, order, ierr))
    PetscCallA(PetscViewerExodusIIGetZonalVariable(viewer, nZonalVar, ierr))
    PetscCallA(PetscViewerExodusIIGetNodalVariable(viewer, nNodalVar, ierr))

    do i = 1, nZonalVar
        PetscCallA(PetscViewerExodusIIGetZonalVariableName(viewer, i-1, varName, ierr))
        Write(IOBuffer,'("   zonal variable:", I2,": ",A,"\n")') i,varName
        PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))
    end do
    do i = 1, nNodalVar
        PetscCallA(PetscViewerExodusIIGetNodalVariableName(viewer, i-1, varName, ierr))
        Write(IOBuffer,'("   nodal variable:", I2,": ",A,"\n")') i,varName
        PetscCallA(PetscPrintf(PETSC_COMM_WORLD,IOBuffer,ierr))
    end do

    PetscCallA(DMDestroy(dm,ierr))
    PetscCallA(PetscViewerDestroy(viewer, ierr))
    PetscCallA(PetscFinalize(ierr))
end program ex95f90

/*TEST

  build:
    requires: exodusii pnetcdf !complex
  test:
    suffix: 0
    nsize: 1
    args: -i ${wPETSC_DIR}/share/petsc/datafiles/meshes/FourSquareT-large.exo -o FourSquareT-large_out.exo

TEST*/