#!/usr/bin/env python3
#
# Copyright VyOS maintainers and contributors <maintainers@vyos.io>
#
# 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/>.

import os

from sys import exit

from vyos.config import Config
from vyos.configverify import verify_interface_exists
from vyos.utils.process import call
from vyos.template import render
from vyos import ConfigError
from vyos import airbag
airbag.enable()

systemd_service = 'ndppd.service'
ndppd_config = '/run/ndppd/ndppd.conf'

def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()
    base = ['service', 'ndp-proxy']
    if not conf.exists(base):
        return None

    ndpp = conf.get_config_dict(base, key_mangling=('-', '_'),
                                get_first_key=True,
                                with_recursive_defaults=True)

    return ndpp

def verify(ndpp):
    if not ndpp:
        return None

    if 'interface' not in ndpp:
        return None

    for interface, interface_config in ndpp['interface'].items():
        if 'disable' in interface_config:
            continue

        verify_interface_exists(ndpp, interface)

        if 'prefix' not in interface_config:
            continue

        for prefix, prefix_config in interface_config['prefix'].items():
            if 'disable' in prefix_config:
                continue

            mode = prefix_config.get('mode')
            prefix_interface = prefix_config.get('interface')

            if mode == 'interface':
                if not prefix_interface:
                    raise ConfigError(f'Prefix "{prefix}" uses interface mode but no interface defined!')
                verify_interface_exists(ndpp, prefix_interface)
                continue

            if prefix_interface:
                raise ConfigError(f'Prefix "{prefix}" does not use interface mode, thus interface cannot be defined!')

    return None

def generate(ndpp):
    if not ndpp:
        return None

    render(ndppd_config, 'ndppd/ndppd.conf.j2', ndpp)
    return None

def apply(ndpp):
    if not ndpp:
        call(f'systemctl stop {systemd_service}')
        if os.path.isfile(ndppd_config):
            os.unlink(ndppd_config)
        return None

    call(f'systemctl reload-or-restart {systemd_service}')
    return None

if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print(e)
        exit(1)