#!/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 vyos.config import Config
from vyos.configdict import get_accel_dict
from vyos.configverify import verify_accel_ppp_base_service
from vyos.template import render
from vyos.util import call
from vyos.util import dict_search
from vyos.util import get_interface_config
from vyos.range_regex import range_to_regex
from vyos import ConfigError
from vyos import airbag
airbag.enable()

pppoe_conf = r'/run/accel-pppd/pppoe.conf'
pppoe_chap_secrets = r'/run/accel-pppd/pppoe.chap-secrets'

def convert_pado_delay(pado_delay):
    new_pado_delay = {'delays_without_sessions': [],
                      'delays_with_sessions': []}
    for delay, sessions in pado_delay.items():
        if not sessions:
            new_pado_delay['delays_without_sessions'].append(delay)
        else:
            new_pado_delay['delays_with_sessions'].append((delay, int(sessions['sessions'])))
    return new_pado_delay

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

    # retrieve common dictionary keys
    pppoe = get_accel_dict(conf, base, pppoe_chap_secrets)

    if dict_search('pado_delay', pppoe):
        pado_delay = dict_search('pado_delay', pppoe)
        pppoe['pado_delay'] = convert_pado_delay(pado_delay)

    return pppoe

def verify_pado_delay(pppoe):
    if 'pado_delay' in pppoe:
        pado_delay = pppoe['pado_delay']

        delays_without_sessions = pado_delay['delays_without_sessions']
        if len(delays_without_sessions) > 1:
            raise ConfigError(
                f'Cannot add more then ONE pado-delay without sessions, '
                f'but {len(delays_without_sessions)} were set'
            )

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

    verify_accel_ppp_base_service(pppoe)
    verify_pado_delay(pppoe)

    if 'wins_server' in pppoe and len(pppoe['wins_server']) > 2:
        raise ConfigError('Not more then two IPv4 WINS name-servers can be configured')

    if 'interface' not in pppoe:
        raise ConfigError('At least one listen interface must be defined!')

    # Check is interface exists in the system
    for iface in pppoe['interface']:
        if not get_interface_config(iface):
            raise ConfigError(f'Interface {iface} does not exist!')

    # local ippool and gateway settings config checks
    if not (dict_search('client_ip_pool.subnet', pppoe) or
           (dict_search('client_ip_pool.start', pppoe) and
            dict_search('client_ip_pool.stop', pppoe))):
        print('Warning: No PPPoE client pool defined')

    if dict_search('authentication.radius.dynamic_author.server', pppoe):
        if not dict_search('authentication.radius.dynamic_author.key', pppoe):
            raise ConfigError('DA/CoE server key required!')

    return None


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

    # Generate special regex for dynamic interfaces
    for iface, iface_options in pppoe['interface'].items():
        if 'vlan_range' in iface_options:
            pppoe['interface'][iface]['regex'] = []
            for vlan_range in iface_options['vlan_range']:
                pppoe['interface'][iface]['regex'].append(range_to_regex(vlan_range))

    render(pppoe_conf, 'accel-ppp/pppoe.config.tmpl', pppoe)

    if dict_search('authentication.mode', pppoe) == 'local':
        render(pppoe_chap_secrets, 'accel-ppp/chap-secrets.config_dict.tmpl',
               pppoe, permission=0o640)
    else:
        if os.path.exists(pppoe_chap_secrets):
            os.unlink(pppoe_chap_secrets)

    return None


def apply(pppoe):
    if not pppoe:
        call('systemctl stop accel-ppp@pppoe.service')
        for file in [pppoe_conf, pppoe_chap_secrets]:
            if os.path.exists(file):
                os.unlink(file)

        return None

    call('systemctl restart accel-ppp@pppoe.service')

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