#!/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')