#!/usr/bin/env python3
#
# Copyright (C) 2017-2023 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/>.

import os

from glob import glob
from netifaces import AF_INET
from sys import exit

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

config_file_base = r'/etc/default/udp-broadcast-relay'

def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()
    base = ['service', 'broadcast-relay']

    relay = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
    return relay

def verify(relay):
    if not relay or 'disabled' in relay:
        return None

    for instance, config in relay.get('id', {}).items():
        # we don't have to check this instance when it's disabled
        if 'disabled' in config:
            continue

        # we certainly require a UDP port to listen to
        if 'port' not in config:
            raise ConfigError(f'Port number is mandatory for UDP broadcast relay "{instance}"')

        # Relaying data without two interface is kinda senseless ...
        if len(config.get('interface', [])) < 2:
            raise ConfigError('At least two interfaces are required for UDP broadcast relay "{instance}"')

        for interface in config.get('interface', []):
            verify_interface_exists(relay, interface)
            if not is_afi_configured(interface, AF_INET):
                raise ConfigError(f'Interface "{interface}" has no IPv4 address configured!')

    return None

def generate(relay):
    if not relay or 'disabled' in relay:
        return None

    for config in glob(config_file_base + '*'):
        os.remove(config)

    for instance, config in relay.get('id').items():
        # we don't have to check this instance when it's disabled
        if 'disabled' in config:
            continue

        config['instance'] = instance
        render(config_file_base + instance, 'bcast-relay/udp-broadcast-relay.j2',
               config)

    return None

def apply(relay):
    # first stop all running services
    call('systemctl stop udp-broadcast-relay@*.service')

    if not relay or 'disable' in relay:
        return None

    # start only required service instances
    for instance, config in relay.get('id').items():
        # we don't have to check this instance when it's disabled
        if 'disabled' in config:
            continue

        call(f'systemctl start udp-broadcast-relay@{instance}.service')

    return None

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