#!/usr/bin/env python
# Filenames.py
#   Copyright (C) 2006 CCLRC, Graeme Winter
#
#   This code is distributed under the BSD license, a copy of which is
#   included in the root directory of this package.
#
# An expert who knows about how file names are structured on a number of
# platforms... this handles them mostly as strings, which of course they
# are...
#

import os

_original_wd = os.getcwd()

def _pathsplit(path):
  head, tail = os.path.split(path)
  if tail:
    result = _pathsplit(head)
    result.append(tail)
    return result
  return [head]

def pathsplit(path):
  return _pathsplit(os.path.normpath(path))

def windows_environment_vars_to_unix(token):
  '''Transmogrify windows environment tokens (e.g. %WINDIR%) to
  the UNIX form ($WINDIR) for python environment token replacement.'''

  if token.count('%') % 2:
    raise RuntimeError, 'must have even number of % tokens'

  in_env_variable = False

  token_list = token.split('%')
  result = ''
  for l in token_list:
    if not in_env_variable:
      result += l
      in_env_variable = True
    else:
      result += '$%s' % l
      in_env_variable = False

  return result

def expand_path(path):
  '''Expand the input to give a full path.'''

  if path is None:
    return None

  if os.name == 'nt':
    return os.path.expandvars(os.path.expanduser(
        windows_environment_vars_to_unix(path)))
  else:
    return os.path.expandvars(os.path.expanduser(path))


if __name__ == '__main__':

  if os.name == 'nt':
    print expand_path(r'%USERPROFILE%\test')
    print expand_path(r'~\test')
  else:
    print expand_path(r'~\test')