NextTime Function

FUNCTION NextTime &
!
(ncId, refTime, timeUnit, current) &
!
RESULT (time)

USE Units, ONLY: &
! Imported parameters:
minute, hour, day, month

USE StringManipulation, ONLY: &
!Imported routines:
ToString

IMPLICIT NONE

! Arguments with intent(in):
INTEGER (KIND = short), INTENT(IN)   :: ncId  !!NetCdf Id for the file
TYPE (DateTime), INTENT(IN)  :: refTime  !!reference time to calculate time index
CHARACTER (LEN = *), INTENT(IN) :: timeUnit
INTEGER (KIND = short), INTENT(IN) :: current !!current time step

!Local variables:
TYPE (DateTime)  :: time !!returned time of the next grid
INTEGER (KIND = short) :: next !!index of next time step
INTEGER (KIND = short) :: ncStatus !!error code return by NetCDF routines
INTEGER (KIND = short) :: nDims !!number of dimensions
INTEGER (KIND = short) :: nVars !!number of variables
INTEGER (KIND = short) :: nAtts !!number of global attributes
INTEGER (KIND = short) :: length !!length of time dimension
INTEGER (KIND = short) :: idTime !!Id of the variable containing 
                                 !!information on time ccordinate
CHARACTER (LEN = 80)   :: attribute
CHARACTER (LEN = 100)  :: variableName
INTEGER (KIND = short) :: i !!loop index
INTEGER                :: slice (2)
INTEGER                :: timeSpan
CHARACTER (LEN = 80)   :: string
CHARACTER (LEN = 19)   :: str
INTEGER, DIMENSION(NF90_MAX_VAR_DIMS) :: dimIDs

!------------end of declaration------------------------------------------------

!inquire dataset to retrieve number of dimensions, variables 
!and global attributes
ncStatus = nf90_inquire(ncId, nDimensions = nDims, &
                        nVariables = nVars,        &
                        nAttributes = nAtts        )
                  
CALL ncErrorHandler (ncStatus)

!search for time variable
DO i = 1, nVars
  attribute = ''
  ncStatus = nf90_get_att (ncId, varid = i, name = 'standard_name', &
                           values = attribute)
  
  IF (ncStatus == nf90_noerr) THEN 
    IF ( attribute(1:4) == 'time' ) THEN
      idTime = i 
      EXIT   
    END IF
  ELSE !standard_name is not defined: search for variable named 'time'
     !ncStatus = nf90_inq_varid (ncId, 'time', varid = i )
     ncstatus = nf90_inquire_variable(ncId, varId = i, name = variableName)
     IF (LEN_TRIM(variableName) == 4 .AND. &
         variableName(1:4) == 'time' .OR. &
         LEN_TRIM(variableName) == 4 .AND. &
         variableName(1:4) == 'Time' .OR. &
         LEN_TRIM(variableName) == 5 .AND. &
         variableName(1:5) == 'Times') THEN !variable 'time' found
       idTime = i 
       EXIT 
     END IF
  END IF
END DO

!inquire time length
ncStatus = nf90_inquire_variable(ncid, idTime, dimids = dimIDs)
CALL ncErrorHandler (ncStatus)

!ncStatus = nf90_inquire_dimension (ncId, dimid = dimIDs(2), len = length)
ncStatus = nf90_inquire_dimension (ncId, dimid = dimIDs(1), len = length)
CALL ncErrorHandler (ncStatus)

!set next time step
IF (current < length) THEN
  next = current + 1
ELSE
  next = length
END IF

!compute date corresponding to next time step
!slice(1) = 1
!slice(2) = next
slice(1) = next
slice(2) = 1

IF (DateTimeIsDefault(refTime)) THEN
  ncStatus = nf90_get_var (ncId, idTime, str , start = slice)

  CALL ncErrorHandler (ncStatus)
  string = str(1:10) // 'T' // str(12:19) // '+00:00'
  time = string  
ELSE
    ncStatus = nf90_get_var (ncId, idTime, timeSpan , start = slice)
    CALL ncErrorHandler (ncStatus)
    SELECT CASE (timeUnit)
      CASE ('minutes')
        timeSpan = timeSpan * minute
      CASE ('hours')
        timeSpan = timeSpan * hour
      CASE ('days')
        timeSpan = timeSpan * day
      CASE ('months')
        timeSpan = timeSpan * month
    END SELECT

    time = refTime + timeSpan

END IF

RETURN
END FUNCTION NextTime