#!/usr/bin/env python3
#
# Copyright (C) 2017 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 sys
import os
import fnmatch
import subprocess

from vyos.config import Config
from vyos import ConfigError

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

def get_config():
    conf = Config()
    conf.set_level("service broadcast-relay id")
    relay_id = conf.list_nodes("")
    relays = []

    for id in relay_id:
        interface_list = []
        address = conf.return_value("{0} address".format(id))
        description = conf.return_value("{0} description".format(id))
        port = conf.return_value("{0} port".format(id))

        # split the interface name listing and form a list
        if conf.exists("{0} interface".format(id)):
            intfs_names = []
            intfs_names = conf.return_values("{0} interface".format(id))

            for name in intfs_names:
                interface_list.append(name)

        relay = {
            "id": id,
            "address": address,
            "description": description,
            "interfaces" : interface_list,
            "port": port
            }
        relays.append(relay)

    return relays

def verify(relays):
    for relay in relays:
        if not relay["port"]:
            raise ConfigError("UDP broadcast relay 'id {0}' requires a port number".format(relay["id"]))

        if len(relay["interfaces"]) < 2:
            raise ConfigError("UDP broadcast relay 'id {0}' requires at least 2 interfaces".format(relay["id"]))

    return None

def generate(relays):
    config_header = '### Autogenerated by bcast_relay.py ###\n'

    config_dir = os.path.dirname(config_file)
    config_filename = os.path.basename(config_file)
    active_configs = []

    for config in fnmatch.filter(os.listdir(config_dir), config_filename + '*'):
        # determine prefix length to identify service instance
        prefix_len = len(config_filename)
        active_configs.append(config[prefix_len:])

    # sort our list
    active_configs.sort()

    for id in active_configs[:]:
        os.unlink(config_file + id)

    for relay in relays:
         file = config_file + str(relay["id"])
         interfaces = ' '.join(str(intf) for intf in relay["interfaces"])
         config_args = 'DAEMON_ARGS="{0} {1}"\n'.format(relay["port"], interfaces)

         f = open(file, 'w')
         f.write(config_header)
         if relay["description"]:
             f.write('# ' + relay["description"] + '\n')
         f.write(config_args)
         f.close()

    return None

def apply(relays):
    # first stop all running services
    cmd = "sudo systemctl stop udp-broadcast-relay@{1..99}"
    os.system(cmd)

    # start only required service instances
    for relay in relays:
        cmd = "sudo systemctl start udp-broadcast-relay@{0}".format(relay["id"])
        os.system(cmd)

    return None

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