#!/usr/bin/python3
# SPDX-License-Identifier: AGPL-3.0-or-later
"""
Configures or runs unattended-upgrades
"""

import argparse
import os
import pathlib
import re
import subprocess
import sys

from plinth.action_utils import run_apt_command
from plinth.modules.apache.components import check_url
from plinth.modules.upgrades import (get_current_release, is_backports_current,
                                     SOURCES_LIST)

AUTO_CONF_FILE = '/etc/apt/apt.conf.d/20auto-upgrades'
LOG_FILE = '/var/log/unattended-upgrades/unattended-upgrades.log'
DPKG_LOG_FILE = '/var/log/unattended-upgrades/unattended-upgrades-dpkg.log'
BACKPORTS_RELEASE_FILE_URL = \
    'https://deb.debian.org/debian/dists/{}-backports/Release'

APT_PREFERENCES_FREEDOMBOX = '''Explanation: This file is managed by FreedomBox, do not edit.
Explanation: Allow carefully selected updates to 'freedombox' from backports.
Package: freedombox
Pin: release a={}-backports
Pin-Priority: 500
'''

# Whenever these preferences needs to change, increment the version number
# upgrades app. This ensures that setup is run again and the new contents are
# overwritten on the old file.
APT_PREFERENCES_APPS = '''Explanation: This file is managed by FreedomBox, do not edit.
Explanation: matrix-synapse 0.99.5 introduces room version 4. Older version
Explanation: 0.99.2 in buster won't be able join newly created rooms.
Package: matrix-synapse
Pin: release a=buster-backports
Pin-Priority: 500

Explanation: matrix-synapse >= 1.2 requires python3-service-identity >= 18.1
Package: python3-service-identity
Pin: release a=buster-backports
Pin-Priority: 500

Explanation: matrix-synapse >= 1.5 requires python3-typing-extensions >= 3.7.4
Package: python3-typing-extensions
Pin: release a=buster-backports
Pin-Priority: 500

Explanation: matrix-synapse >= 1.11 requires python3-signedjson >= 1.1.0
Package: python3-signedjson
Pin: release a=buster-backports
Pin-Priority: 500

Explanation: matrix-synapse >= 1.12 requires python3-twisted >= 18.9.0-8~
Package: python3-twisted
Pin: release a=buster-backports
Pin-Priority: 500

Explanation: python3-twisted requires matching version of python3-twisted-bin
Package: python3-twisted-bin
Pin: release a=buster-backports
Pin-Priority: 500
'''


def parse_arguments():
    """Return parsed command line arguments as dictionary"""
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers(dest='subcommand', help='Sub command')

    subparsers.add_parser('run', help='Upgrade packages on the system')
    subparsers.add_parser('check-auto',
                          help='Check if automatic upgrades are enabled')
    subparsers.add_parser('enable-auto', help='Enable automatic upgrades')
    subparsers.add_parser('disable-auto', help='Disable automatic upgrades.')
    subparsers.add_parser('get-log', help='Print the automatic upgrades log')

    subparsers.add_parser('setup', help='Setup apt preferences')
    setup_repositories = subparsers.add_parser(
        'setup-repositories',
        help='Setup software repositories for FreedomBox')
    setup_repositories.add_argument('--develop', required=False, default=False,
                                    action='store_true',
                                    help='Development mode')

    subparsers.required = True
    return parser.parse_args()


def subcommand_run(_):
    """Run unattended-upgrades"""
    subprocess.run(['dpkg', '--configure', '-a'])
    run_apt_command(['--fix-broken', 'install'])
    try:
        subprocess.Popen(['systemctl', 'start', 'freedombox-manual-upgrade'],
                         stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
                         stderr=subprocess.DEVNULL, close_fds=True,
                         start_new_session=True)
    except FileNotFoundError:
        print('Error: systemctl is not available.', file=sys.stderr)
        sys.exit(2)
    except Exception as error:
        print('Error: {0}'.format(error), file=sys.stderr)
        sys.exit(3)


def subcommand_check_auto(_):
    """Check if automatic upgrades are enabled"""
    arguments = [
        'apt-config', 'shell', 'UpdateInterval',
        'APT::Periodic::Update-Package-Lists'
    ]
    try:
        output = subprocess.check_output(arguments).decode()
    except subprocess.CalledProcessError as error:
        print('Error: {0}'.format(error), file=sys.stderr)
        sys.exit(1)

    update_interval = 0
    match = re.match(r"UpdateInterval='(.*)'", output)
    if match:
        update_interval = int(match.group(1))

    print(bool(update_interval))


def subcommand_enable_auto(_):
    """Enable automatic upgrades"""
    with open(AUTO_CONF_FILE, 'w') as conffile:
        conffile.write('APT::Periodic::Update-Package-Lists "1";\n')
        conffile.write('APT::Periodic::Unattended-Upgrade "1";\n')


def subcommand_disable_auto(_):
    """Disable automatic upgrades"""
    with open(AUTO_CONF_FILE, 'w') as conffile:
        conffile.write('APT::Periodic::Update-Package-Lists "0";\n')
        conffile.write('APT::Periodic::Unattended-Upgrade "0";\n')


def subcommand_get_log(_):
    """Print the automatic upgrades log."""
    try:
        print('==> ' + os.path.basename(LOG_FILE))
        with open(LOG_FILE, 'r') as file_handle:
            print(file_handle.read())
    except IOError:
        pass

    try:
        print('==> ' + os.path.basename(DPKG_LOG_FILE))
        with open(DPKG_LOG_FILE, 'r') as file_handle:
            print(file_handle.read())
    except IOError:
        pass


def _get_protocol():
    """Return the protocol to use for newly added repository sources."""
    try:
        from plinth.modules.tor import utils
        if utils.is_apt_transport_tor_enabled():
            return 'tor+http'
    except Exception:
        pass

    return 'http'


def _is_release_file_available(protocol, dist):
    """Return whether the release for backports is available."""
    wrapper = None
    if protocol == 'tor+http':
        wrapper = 'torsocks'

    result = check_url(BACKPORTS_RELEASE_FILE_URL.format(dist),
                       wrapper=wrapper)
    return result == 'passed'


def _add_backports_sources(sources_list, protocol, dist):
    """Add backports sources to freedombox repositories list."""
    sources = '''# This file is managed by FreedomBox, do not edit.
# Allow carefully selected updates to 'freedombox' from backports.

deb {protocol}://deb.debian.org/debian {dist}-backports main
deb-src {protocol}://deb.debian.org/debian {dist}-backports main
'''
    sources = sources.format(protocol=protocol, dist=dist)
    with open(sources_list, 'w') as file_handle:
        file_handle.write(sources)


def _check_and_backports_sources(develop=False):
    """Add backports sources after checking if it is available."""
    old_sources_list = '/etc/apt/sources.list.d/freedombox.list'
    if os.path.exists(old_sources_list):
        os.remove(old_sources_list)

    if is_backports_current():
        print('Repositories list up-to-date. Skipping update.')
        return

    try:
        with open('/etc/dpkg/origins/default', 'r') as default_origin:
            matches = [
                re.match(r'Vendor:\s+Debian', line, flags=re.IGNORECASE)
                for line in default_origin.readlines()
            ]
    except FileNotFoundError:
        print('Could not open /etc/dpkg/origins/default')
        return

    if not any(matches):
        print('System is running a derivative of Debian. Skip enabling '
              'backports.')
        return

    release, dist = get_current_release()
    if release == 'unstable' or (release == 'testing' and not develop):
        print(f'System release is {release}. Skip enabling backports.')
        return

    protocol = _get_protocol()
    if protocol == 'tor+http':
        print('Package download over Tor is enabled.')

    if not _is_release_file_available(protocol, dist):
        print(f'Release file for {dist}-backports is not available yet.')
        return

    print(f'{dist}-backports is now available. Adding to sources.')
    _add_backports_sources(SOURCES_LIST, protocol, dist)
    # In case of dist upgrade, rewrite the preferences file.
    _add_apt_preferences()


def _add_apt_preferences():
    """Setup APT preferences to upgrade selected packages from backports."""
    base_path = pathlib.Path('/etc/apt/preferences.d')
    for file_name in ['50freedombox.pref', '50freedombox2.pref']:
        full_path = base_path / file_name
        if full_path.exists():
            full_path.unlink()

    # Don't try to remove 50freedombox3.pref as this file is shipped with the
    # Debian package and is removed using maintainer scripts.

    _, dist = get_current_release()
    if dist == 'sid':
        print(f'System distribution is {dist}. Skip setting apt preferences '
              'for backports.')
    else:
        print(f'Setting apt preferences for {dist}-backports.')
        with open(base_path / '50freedombox4.pref', 'w') as file_handle:
            file_handle.write(APT_PREFERENCES_FREEDOMBOX.format(dist))
        with open(base_path / '51freedombox-apps.pref', 'w') as file_handle:
            file_handle.write(APT_PREFERENCES_APPS)


def subcommand_setup(_):
    """Setup apt preferences."""
    _add_apt_preferences()


def subcommand_setup_repositories(arguments):
    """Setup software repositories needed for FreedomBox.

    Repositories list for now only contains the backports. If the file exists,
    assume that it contains backports.

    """
    _check_and_backports_sources(arguments.develop)


def main():
    """Parse arguments and perform all duties"""
    arguments = parse_arguments()

    subcommand = arguments.subcommand.replace('-', '_')
    subcommand_method = globals()['subcommand_' + subcommand]
    subcommand_method(arguments)


if __name__ == '__main__':
    main()