#!/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.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'/tmp/pimd.frr'

def get_config(config=None):
    if config:
        conf = config
    else:
        conf = Config()
    pim_conf = {
        'pim_conf' : False,
        'old_pim' : {
            'ifaces' : {},
            'rp'     : {}
        },
        'pim' : {
            'ifaces' : {},
            'rp'     : {}
        }
    }
    if not (conf.exists('protocols pim') or conf.exists_effective('protocols pim')):
        return None

    if conf.exists('protocols pim'):
        pim_conf['pim_conf'] = True

    conf.set_level('protocols pim')

    # Get interfaces
    for iface in conf.list_effective_nodes('interface'):
        pim_conf['old_pim']['ifaces'].update({
            iface : {
                'hello' : conf.return_effective_value('interface {0} hello'.format(iface)),
                'dr_prio' : conf.return_effective_value('interface {0} dr-priority'.format(iface))
            }
        })

    for iface in conf.list_nodes('interface'):
        pim_conf['pim']['ifaces'].update({
            iface : {
                'hello' : conf.return_value('interface {0} hello'.format(iface)),
                'dr_prio' : conf.return_value('interface {0} dr-priority'.format(iface)),
            }
        })

    conf.set_level('protocols pim rp')

    # Get RPs addresses
    for rp_addr in conf.list_effective_nodes('address'):
        pim_conf['old_pim']['rp'][rp_addr] = conf.return_effective_values('address {0} group'.format(rp_addr))

    for rp_addr in conf.list_nodes('address'):
        pim_conf['pim']['rp'][rp_addr] = conf.return_values('address {0} group'.format(rp_addr))

    # Get RP keep-alive-timer
    if conf.exists_effective('rp keep-alive-timer'):
        pim_conf['old_pim']['rp_keep_alive'] = conf.return_effective_value('rp keep-alive-timer')
    if conf.exists('rp keep-alive-timer'):
        pim_conf['pim']['rp_keep_alive'] = conf.return_value('rp keep-alive-timer')

    return pim_conf

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

    if pim['pim_conf']:
        # Check interfaces
        if not pim['pim']['ifaces']:
            raise ConfigError(f"PIM require defined interfaces!")

        if not pim['pim']['rp']:
            raise ConfigError(f"RP address required")

        # Check unique multicast groups
        uniq_groups = []
        for rp_addr in pim['pim']['rp']:
            if not pim['pim']['rp'][rp_addr]:
                raise ConfigError(f"Group should be specified for RP " + rp_addr)
            for group in pim['pim']['rp'][rp_addr]:
                if (group in uniq_groups):
                    raise ConfigError(f"Group range " + group + " specified cannot exact match another")

                # Check, is this multicast group
                gr_addr = group.split('/')
                if IPv4Address(gr_addr[0]) < IPv4Address('224.0.0.0'):
                    raise ConfigError(group + " not a multicast group")

            uniq_groups.extend(pim['pim']['rp'][rp_addr])

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

    render(config_file, 'frr/pimd.frr.tmpl', pim)
    return None

def apply(pim):
    if pim is None:
        return None

    if os.path.exists(config_file):
        call("vtysh -d pimd -f " + config_file)
        os.remove(config_file)

    return None

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