check_restart_file_writeable Subroutine

  subroutine check_restart_file_writeable(check_writable, need_restart, extra_files)
    use init_g, only: get_restart_dir
    use gs2_save, only: restart_writable
    use mp, only: proc0, mp_abort, broadcast
    implicit none
    !> Has the user requested this check
    logical, intent(in) :: check_writable
    !> Has the user requested restart files
    logical, intent(in) :: need_restart
    !> Has the user requested distribution function to be written
    logical, intent(inout) :: extra_files

    ! Error message from trying to open restart file
    character(len=:), allocatable :: error_message
    ! GS2 error message to show user
    character(len=:), allocatable :: abort_message

    ! Assume everything's fine if we're not checking, or if it's not needed
    if (.not. check_writable) return
    if (.not. (need_restart .or. extra_files)) return

    ! If we can write the restart files, we're done
    if (restart_writable(error_message=error_message)) return

    abort_message = " Cannot write restart files! Error message was:" // new_line('a') &
         // "    " // error_message // new_line('a') &
         // " Please check that `init_g_knobs::restart_dir = " // trim(get_restart_dir()) &
         // "` exists and has the correct permissions."

    ! User has requested restart files, but we can't write them => abort
    if (need_restart) then
      abort_message = abort_message // new_line('a') // "    --> Aborting"
      call mp_abort(trim(abort_message), to_screen=.true.)
    end if

    ! If it's just a case of save_distfn, then we can carry on but
    ! disable `save_distfn` and print a useful mesasge
    if (extra_files) then
      if(proc0) write(*, '(a, a, a)') abort_message, new_line('a'), "    --> Setting `save_distfn = F`"
      extra_files = .false.
    endif
  end subroutine check_restart_file_writeable