#!/usr/bin/env python3
#
# Copyright (C) 2018-2020 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 sys import exit
from copy import deepcopy

from netifaces import interfaces
from vyos.config import Config
from vyos import ConfigError
from vyos.util import call
from vyos.template import render

from vyos import airbag
airbag.enable()

config_file = r'/etc/igmpproxy.conf'

default_config_data = {
    'disable': False,
    'disable_quickleave': False,
    'interfaces': [],
}

def get_config():
    igmp_proxy = deepcopy(default_config_data)
    conf = Config()
    base = ['protocols', 'igmp-proxy']
    if not conf.exists(base):
        return None
    else:
        conf.set_level(base)

    # Network interfaces to listen on
    if conf.exists(['disable']):
        igmp_proxy['disable'] = True

    # Option to disable "quickleave"
    if conf.exists(['disable-quickleave']):
        igmp_proxy['disable_quickleave'] = True

    for intf in conf.list_nodes(['interface']):
        conf.set_level(base + ['interface', intf])
        interface = {
            'name': intf,
            'alt_subnet': [],
            'role': 'downstream',
            'threshold': '1',
            'whitelist': []
        }

        if conf.exists(['alt-subnet']):
            interface['alt_subnet'] = conf.return_values(['alt-subnet'])

        if conf.exists(['role']):
            interface['role'] = conf.return_value(['role'])

        if conf.exists(['threshold']):
            interface['threshold'] = conf.return_value(['threshold'])

        if conf.exists(['whitelist']):
            interface['whitelist'] = conf.return_values(['whitelist'])

        # Append interface configuration to global configuration list
        igmp_proxy['interfaces'].append(interface)

    return igmp_proxy

def verify(igmp_proxy):
    # bail out early - looks like removal from running config
    if igmp_proxy is None:
        return None

    # bail out early - service is disabled
    if igmp_proxy['disable']:
        return None

    # at least two interfaces are required, one upstream and one downstream
    if len(igmp_proxy['interfaces']) < 2:
        raise ConfigError('Must define an upstream and at least 1 downstream interface!')

    upstream = 0
    for interface in igmp_proxy['interfaces']:
        if interface['name'] not in interfaces():
            raise ConfigError('Interface "{}" does not exist'.format(interface['name']))
        if "upstream" == interface['role']:
            upstream += 1

    if upstream == 0:
        raise ConfigError('At least 1 upstream interface is required!')
    elif upstream > 1:
        raise ConfigError('Only 1 upstream interface allowed!')

    return None

def generate(igmp_proxy):
    # bail out early - looks like removal from running config
    if igmp_proxy is None:
        return None

    # bail out early - service is disabled, but inform user
    if igmp_proxy['disable']:
        print('Warning: IGMP Proxy will be deactivated because it is disabled')
        return None

    render(config_file, 'igmp-proxy/igmpproxy.conf.tmpl', igmp_proxy)
    return None

def apply(igmp_proxy):
    if igmp_proxy is None or igmp_proxy['disable']:
         # IGMP Proxy support is removed in the commit
         call('systemctl stop igmpproxy.service')
         if os.path.exists(config_file):
             os.unlink(config_file)
    else:
        call('systemctl restart igmpproxy.service')

    return None

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