# Copyright 2021-2024 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/>.

# - T3391: Migrate "maximum-paths" setting from "protocols bgp asn maximum-paths"
#   under the IPv4 address-family tree. Reason is we currently have no way in
#   configuring this for IPv6 address-family. This mimics the FRR configuration.

from vyos.configtree import ConfigTree

base = ['protocols', 'bgp']

def migrate(config: ConfigTree) -> None:
    if not config.exists(base):
        # Nothing to do
        return

    # Check if BGP is actually configured and obtain the ASN
    asn_list = config.list_nodes(base)
    if asn_list:
        # There's always just one BGP node, if any
        bgp_base = base + [asn_list[0]]

        maximum_paths = bgp_base + ['maximum-paths']
        if config.exists(maximum_paths):
            for bgp_type in ['ebgp', 'ibgp']:
                if config.exists(maximum_paths + [bgp_type]):
                    new_base =  bgp_base + ['address-family', 'ipv4-unicast', 'maximum-paths']
                    config.set(new_base)
                    config.copy(maximum_paths + [bgp_type], new_base + [bgp_type])
            config.delete(maximum_paths)