#!/usr/bin/python
from __future__ import division, print_function
from distutils.version import LooseVersion
import posixpath
import re
import subprocess
import sys


def proc_version():
    with open('/proc/version', 'r') as v:
        proc_version = v.next()
    return proc_version


def running_kernel_version():
    m = re.findall('(?<=Debian )\S+', proc_version())
    if m:
        # Note: it's the _second_ match
        version = clean_kernel_version(m[1])
        return version

    m = re.search('(?<=Linux version )\S+', proc_version())
    if m:
        version = clean_kernel_version(m.group(0))
        return version


def is_debian():
    return posixpath.exists('/etc/debian_version')


def is_fedora():
    return posixpath.exists('/etc/fedora-release')


def installed_kernel_versions():
    if is_debian():
        return installed_kernel_versions_debian()
    if is_fedora():
        return installed_kernel_versions_fedora()


def installed_kernel_versions_debian():
    dpkg_out = subprocess.check_output(
        ['dpkg-query', '--show', '--showformat', '${Package} ${Version}\n', 'linux-image*'])
    dpkg_out = dpkg_out.strip()

    versions = dpkg_out.split('\n')
    versions = [v for v in versions if re.search('^linux-image-\d', v)]
    versions = [clean_kernel_version(v.split(' ')[1]) for v in versions]

    return versions


def installed_kernel_versions_fedora():
    rpm_out = subprocess.check_output(
        ['rpm', '--queryformat=%{VERSION}-%{RELEASE}\n', '-q', 'kernel'])
    rpm_out = rpm_out.strip()

    versions = rpm_out.split('\n')
    versions = [clean_kernel_version(v) for v in versions]

    return versions


def installed_kernel_version():
    return sorted(installed_kernel_versions())[-1]


def clean_kernel_version(version):
    # arch
    version = re.sub('\.(x86_64|i[3-6]86)', '', version)
    # Fedora release
    version = re.sub('\.fc\d+', '', version)

    return LooseVersion(version)


def main():
    running = running_kernel_version()
    installed = installed_kernel_version()

    if running == installed:
        print('KERNEL OK - running version {}'.format(running))
        sys.exit(0)
    else:
        print('KERNEL WARNING - running version {}, installed: {}'
              .format(running, installed))
        sys.exit(1)


if __name__ == '__main__':
    main()