#!/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 netifaces import interfaces
from sys import exit

from vyos.config import Config
from vyos.configdict import dict_merge
from vyos import ConfigError
from vyos.util import call
from vyos.template import render
from vyos.xml import defaults
from vyos import airbag
airbag.enable()

config_file = r'/etc/ssh/sshd_config'
systemd_override = r'/etc/systemd/system/ssh.service.d/override.conf'

def get_config():
    conf = Config()
    base = ['service', 'ssh']
    if not conf.exists(base):
        return None

    ssh = conf.get_config_dict(base, key_mangling=('-', '_'), get_first_key=True)
    # We have gathered the dict representation of the CLI, but there are default
    # options which we need to update into the dictionary retrived.
    default_values = defaults(base)
    ssh = dict_merge(default_values, ssh)

    return ssh

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

    if 'vrf' in ssh.keys() and ssh['vrf'] not in interfaces():
        raise ConfigError('VRF "{vrf}" does not exist'.format(**ssh))

    return None

def generate(ssh):
    if not ssh:
        if os.path.isfile(config_file):
            os.unlink(config_file)
        if os.path.isfile(systemd_override):
            os.unlink(systemd_override)

        return None

    render(config_file, 'ssh/sshd_config.tmpl', ssh, trim_blocks=True)
    render(systemd_override, 'ssh/override.conf.tmpl', ssh, trim_blocks=True)

    return None

def apply(ssh):
    if not ssh:
        # SSH access is removed in the commit
        call('systemctl stop ssh.service')

    # Reload systemd manager configuration
    call('systemctl daemon-reload')

    if ssh:
        call('systemctl restart ssh.service')

    return None

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