# Copyright 2016  Lars Wirzenius
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
# =*= License: GPL-3+ =*=


import re


patterns = {
    'debian_codename': r'^VERSION="\d+ \((.*)\)"$',
    'debian_release': r'^VERSION="(\d+) ',
    'pretty_codename': r'^PRETTY_NAME="Debian GNU/Linux .*/(sid)"$',
}


def parse_os_release(text):
    o = OsRelease()

    found_anything = False
    for line in text.splitlines():
        for name, pattern in patterns.items():
            m = re.match(pattern, line)
            if m:
                setattr(o, name, m.group(1))
                found_anything = True

    if found_anything:
        return o
    raise NoOsReleaseInformation(text)


class OsRelease(object):

    def __init__(self):
        self.debian_codename = None
        self.pretty_codename = None
        self.debian_release = None


class NoOsReleaseInformation(Exception):

    def __init__(self, text):
        super(NoOsReleaseInformation, self).__init__(
            "Can't parse /etc/os-release: %r" % text)