#!/usr/bin/env python3
#
# Copyright (C) 2024 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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/>.
#
# Adds an explicit old default for 'server topology'
# to keep old configs working as before even though the default has changed.

from vyos.configtree import ConfigTree

def migrate(config: ConfigTree) -> None:
    ovpn_intfs = config.list_nodes(['interfaces', 'openvpn'], path_must_exist=False)
    for i in ovpn_intfs:
        mode = config.return_value(['interfaces', 'openvpn', i, 'mode'])
        if mode != 'server':
            # If it's a client or a site-to-site OpenVPN interface,
            # the topology setting is not applicable
            # and will cause commit errors on load,
            # so we must not change such interfaces.
            continue
        else:
            # The default OpenVPN server topology was changed from net30 to subnet
            # because net30 is deprecated and causes problems with Windows clients.
            # We add 'net30' to old configs if topology is not set there
            # to ensure that if anyone relies on net30, their configs work as before.
            topology_path = ['interfaces', 'openvpn', i, 'server', 'topology']
            if not config.exists(topology_path):
                config.set(topology_path, value='net30', replace=False)