# path.py - functions for handling file paths
#
# Copyright (C) 2015 Arthur de Jong
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
#
# The files produced as output from the software do not automatically fall
# under the copyright of the software, unless explicitly stated otherwise.

import os
import re


def pattern2re(pattern):
    res = ''
    if pattern.startswith('/'):
        pattern.lstrip('/')
        res += '\A/?'
    else:
        res += '\A(.*/)?'
    i, n = 0, len(pattern)
    while i < n:
        c = pattern[i]
        i += 1
        if c == '*':
            if i < n and pattern[i] == '*':
                res = res + '.*'
                i += 1
            else:
                res = res + '[^/]*'
        elif c == '?':
            res = res + '[^/]'
        elif c == '[':
            j = i
            if j < n and pattern[j] == '!':
                j += 1
            if j < n and pattern[j] == ']':
                j += 1
            while j < n and pattern[j] != ']':
                j += 1
            if j >= n:
                res = res + '\\['
            else:
                stuff = pattern[i:j].replace('\\', '\\\\')
                i = j + 1
                if stuff[0] == '!':
                    stuff = '^' + stuff[1:]
                elif stuff[0] == '^':
                    stuff = '\\' + stuff
                res = '%s[%s]' % (res, stuff)
        else:
            res = res + re.escape(c)
    # TODO: do something special with patterns ending with /
    return re.compile(res + '\Z(?ms)')


def parents(path):
    """Generator that yields parent directories of the specified path."""
    path = os.path.dirname(path)
    while path not in ('', '/'):
        yield path
        path = os.path.dirname(path)