#!/usr/bin/env python3
#
# Copyright (C) 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 ipaddress import IPv4Address
from sys import exit

from vyos import ConfigError
from vyos import frr
from vyos.config import Config
from vyos.utils.process import call
from vyos.template import render, render_to_string

from vyos import airbag
airbag.enable()

config_file = r'/tmp/static_mcast.frr'

# Get configuration for static multicast route
def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()
    mroute = {
        'old_mroute' : {},
        'mroute' : {}
    }

    base_path = "protocols static multicast"

    if not (conf.exists(base_path) or conf.exists_effective(base_path)):
        return None

    conf.set_level(base_path)

    # Get multicast effective routes
    for route in conf.list_effective_nodes('route'):
        mroute['old_mroute'][route] = {}
        for next_hop in conf.list_effective_nodes('route {0} next-hop'.format(route)):
            mroute['old_mroute'][route].update({
                next_hop : conf.return_value('route {0} next-hop {1} distance'.format(route, next_hop))
            })

    # Get multicast effective interface-routes
    for route in conf.list_effective_nodes('interface-route'):
        if not route in  mroute['old_mroute']:
            mroute['old_mroute'][route] = {}
        for next_hop in conf.list_effective_nodes('interface-route {0} next-hop-interface'.format(route)):
            mroute['old_mroute'][route].update({
                next_hop : conf.return_value('interface-route {0} next-hop-interface {1} distance'.format(route, next_hop))
            })

    # Get multicast routes
    for route in conf.list_nodes('route'):
        mroute['mroute'][route] = {}
        for next_hop in conf.list_nodes('route {0} next-hop'.format(route)):
            mroute['mroute'][route].update({
                next_hop : conf.return_value('route {0} next-hop {1} distance'.format(route, next_hop))
            })

    # Get multicast interface-routes
    for route in conf.list_nodes('interface-route'):
        if not route in  mroute['mroute']:
            mroute['mroute'][route] = {}
        for next_hop in conf.list_nodes('interface-route {0} next-hop-interface'.format(route)):
            mroute['mroute'][route].update({
                next_hop : conf.return_value('interface-route {0} next-hop-interface {1} distance'.format(route, next_hop))
            })

    return mroute

def verify(mroute):
    if mroute is None:
        return None

    for route in mroute['mroute']:
        route = route.split('/')
        if IPv4Address(route[0]) < IPv4Address('224.0.0.0'):
            raise ConfigError(route + " not a multicast network")


def generate(mroute):
    if mroute is None:
        return None

    mroute['new_frr_config'] = render_to_string('frr/static_mcast.frr.j2', mroute)
    return None


def apply(mroute):
    if mroute is None:
        return None
    static_daemon = 'staticd'

    frr_cfg = frr.FRRConfig()
    frr_cfg.load_configuration(static_daemon)

    if 'old_mroute' in mroute:
        for route_gr in mroute['old_mroute']:
            for nh in mroute['old_mroute'][route_gr]:
                if mroute['old_mroute'][route_gr][nh]:
                    frr_cfg.modify_section(f'^ip mroute {route_gr} {nh} {mroute["old_mroute"][route_gr][nh]}')
                else:
                    frr_cfg.modify_section(f'^ip mroute {route_gr} {nh}')

    if 'new_frr_config' in mroute:
        frr_cfg.add_before(frr.default_add_before, mroute['new_frr_config'])

    frr_cfg.commit_configuration(static_daemon)

    return None


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