# Copyright 2023-2024 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library.  If not, see <http://www.gnu.org/licenses/>.

# - move all pool to named pools
#       'start-stop' migrate to namedpool 'default-range-pool'
#       'subnet' migrate to namedpool 'default-subnet-pool'
#       'default-subnet-pool' is the next pool for 'default-range-pool'
# - There is only one gateway-address, take the first which is configured
# - default-pool by migration.
#       1. If authentication mode = 'local' then it is first named pool.
#       If there are not named pools, namedless pool will be default.
#       2. If authentication mode = 'radius' then namedless pool will be default

from vyos.configtree import ConfigTree
from vyos.base import Warning

base = ['service', 'pppoe-server']
pool_base = base + ['client-ip-pool']

def migrate(config: ConfigTree) -> None:
    if not config.exists(base):
        return

    if not config.exists(pool_base):
        return

    default_pool = ''
    range_pool_name = 'default-range-pool'

    #Default nameless pools migrations
    if config.exists(pool_base + ['start']) and config.exists(pool_base + ['stop']):
        def is_legalrange(ip1: str, ip2: str, mask: str):
            from ipaddress import IPv4Interface
            interface1 = IPv4Interface(f'{ip1}/{mask}')
            interface2 = IPv4Interface(f'{ip2}/{mask}')
            return interface1.network.network_address == interface2.network.network_address and interface2.ip > interface1.ip

        start_ip = config.return_value(pool_base + ['start'])
        stop_ip = config.return_value(pool_base + ['stop'])
        if is_legalrange(start_ip, stop_ip, '24'):
            ip_range = f'{start_ip}-{stop_ip}'
            config.set(pool_base + [range_pool_name, 'range'], value=ip_range, replace=False)
            default_pool = range_pool_name
        else:
            Warning(
                f'PPPoE client-ip-pool range start-ip:{start_ip} and stop-ip:{stop_ip} can not be migrated.')
        config.delete(pool_base + ['start'])
        config.delete(pool_base + ['stop'])

    if config.exists(pool_base + ['subnet']):
        default_pool = range_pool_name
        for subnet in config.return_values(pool_base + ['subnet']):
            config.set(pool_base + [range_pool_name, 'range'], value=subnet, replace=False)
        config.delete(pool_base + ['subnet'])

    gateway = ''
    if config.exists(base + ['gateway-address']):
        gateway = config.return_value(base + ['gateway-address'])

    #named pool migration
    namedpools_base = pool_base + ['name']
    if config.exists(namedpools_base):
        if config.exists(base + ['authentication', 'mode']):
            if config.return_value(base + ['authentication', 'mode']) == 'local':
                if config.list_nodes(namedpools_base):
                    default_pool = config.list_nodes(namedpools_base)[0]

        for pool_name in config.list_nodes(namedpools_base):
            pool_path = namedpools_base + [pool_name]
            if config.exists(pool_path + ['subnet']):
                subnet = config.return_value(pool_path + ['subnet'])
                config.set(pool_base + [pool_name, 'range'], value=subnet, replace=False)
            if config.exists(pool_path + ['next-pool']):
                next_pool = config.return_value(pool_path + ['next-pool'])
                config.set(pool_base + [pool_name, 'next-pool'], value=next_pool)
            if not gateway:
                if config.exists(pool_path + ['gateway-address']):
                    gateway = config.return_value(pool_path + ['gateway-address'])

        config.delete(namedpools_base)

    if gateway:
        config.set(base + ['gateway-address'], value=gateway)
    if default_pool:
        config.set(base + ['default-pool'], value=default_pool)
    # format as tag node
    config.set_tag(pool_base)