get_config_file Subroutine

subroutine get_config_file(config)

   !> Name of the configuration file
   character(len=:), allocatable, intent(out) :: config

   character(len=*), parameter :: rc = 'mctc.toml'
   character(len=:), allocatable :: tmp, prefix
   character :: sep
   logical :: exist

   if (is_windows()) then
      sep = '\'
      call get_variable('HOMEDRIVE', prefix)
      call get_variable('HOMEDIR', tmp)
      prefix = prefix // tmp
   else
      sep = '/'
      call get_variable('HOME', prefix)
   end if
   if (allocated(prefix)) then
      tmp = prefix // sep // rc
      inquire(file=tmp, exist=exist)
      if (exist) then
         config = tmp
         return
      end if

      tmp = prefix // sep // '.' // rc
      inquire(file=tmp, exist=exist)
      if (exist) then
         config = tmp
         return
      end if
   end if

   inquire(file=rc, exist=exist)
   if (exist) then
      config = rc
      return
   end if

end subroutine get_config_file