# Copyright (C) VyOS Inc.
#
# 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/>.

# T8223: remove "advertise-all-vni" from named VRFs where it conflicts with
# a default BGP instance or another named VRF

from vyos.configtree import ConfigTree

base = ['vrf', 'name']
bgp_base = ['protocols', 'bgp']
bgp_l2vpn_evpn = bgp_base + ['address-family', 'l2vpn-evpn']


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

    def _cleanup_address_family(config: ConfigTree, vrf) -> None:
        """Remove advertise-all-vni from the named VRF and clean up any
        empty parent nodes left behind."""
        config.delete(base + [vrf] + bgp_l2vpn_evpn + ['advertise-all-vni'])
        if len(config.list_nodes(base + [vrf] + bgp_l2vpn_evpn)) == 0:
            config.delete(base + [vrf] + bgp_l2vpn_evpn)
            if len(config.list_nodes(base + [vrf] + ['protocols', 'bgp', 'address-family'])) == 0:
                config.delete(base + [vrf] + ['protocols', 'bgp', 'address-family'])

    # Collect named VRFs that have advertise-all-vni configured.
    advertise_all_vni_vrfs = []

    for vrf in config.list_nodes(base):
        if config.exists(base + [vrf] + bgp_l2vpn_evpn + ['advertise-all-vni']):
            if config.exists(bgp_base):
                # A default BGP instance exists. FRR always starts it before
                # named VRFs, so the named VRF's advertise-all-vni would be
                # silently rejected on every boot. Remove it.
                _cleanup_address_family(config, vrf)
            else:
                advertise_all_vni_vrfs.append(vrf)

    # No default BGP instance, but multiple named VRFs hold advertise-all-vni.
    # FRR only allows one instance to hold it at a time. Keep the first VRF
    # and remove it from the rest.
    if len(advertise_all_vni_vrfs) > 1:
        for vrf in advertise_all_vni_vrfs[1:]:
            _cleanup_address_family(config, vrf)