#!/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 copy import deepcopy
from sys import exit

from vyos.config import Config
from vyos.configdict import dict_merge
from vyos.ifconfig import MACsecIf
from vyos.template import render
from vyos.util import call
from vyos.validate import is_member
from vyos.configverify import verify_bridge_vrf
from vyos.configverify import verify_bridge_address
from vyos.configverify import verify_bridge_delete
from vyos.configverify import verify_source_interface
from vyos.xml import defaults
from vyos import ConfigError
from vyos import airbag
airbag.enable()

# XXX: wpa_supplicant works on the source interface
wpa_suppl_conf = '/run/wpa_supplicant/{source_interface}.conf'

def get_config():
    """ Retrive CLI config as dictionary. Dictionary can never be empty,
    as at least the interface name will be added or a deleted flag """
    conf = Config()

    # determine tagNode instance
    if 'VYOS_TAGNODE_VALUE' not in os.environ:
        raise ConfigError('Interface (VYOS_TAGNODE_VALUE) not specified')

    # retrieve interface default values
    base = ['interfaces', 'macsec']
    default_values = defaults(base, flat=False)

    ifname = os.environ['VYOS_TAGNODE_VALUE']
    base = base + [ifname]

    macsec = conf.get_config_dict(base, key_mangling=('-', '_'))
    # Check if interface has been removed
    if macsec == {}:
        tmp = {
            'deleted' : '',
            'source_interface' : conf.return_effective_value(
                base + ['source-interface'])
        }
        macsec.update(tmp)

    # We have gathered the dict representation of the CLI, but there are
    # default options which we need to update into the dictionary
    # retrived.
    macsec = dict_merge(default_values, macsec)

    # Add interface instance name into dictionary
    macsec.update({'ifname': ifname})

    # Check if we are a member of any bridge
    bridge = is_member(conf, ifname, 'bridge')
    if bridge:
        tmp = {'is_bridge_member' : bridge}
        macsec.update(tmp)

    return macsec


def verify(macsec):
    if 'deleted' in macsec.keys():
        verify_bridge_delete(macsec)
        return None

    verify_source_interface(macsec)
    verify_bridge_vrf(macsec)
    verify_bridge_address(macsec)

    if not (('security' in macsec.keys()) and
            ('cipher' in macsec['security'].keys())):
        raise ConfigError(
            'Cipher suite must be set for MACsec "{ifname}"'.format(**macsec))

    if (('security' in macsec.keys()) and
        ('encrypt' in macsec['security'].keys())):
        tmp = macsec.get('security')

        if not (('mka' in tmp.keys()) and
                ('cak' in tmp['mka'].keys()) and
                ('ckn' in tmp['mka'].keys())):
            raise ConfigError('Missing mandatory MACsec security '
                              'keys as encryption is enabled!')

    return None


def generate(macsec):
    render(wpa_suppl_conf.format(**macsec),
           'macsec/wpa_supplicant.conf.tmpl', macsec)
    return None


def apply(macsec):
    # Remove macsec interface
    if 'deleted' in macsec.keys():
        call('systemctl stop wpa_supplicant-macsec@{source_interface}'
             .format(**macsec))

        MACsecIf(macsec['ifname']).remove()

        # delete configuration on interface removal
        if os.path.isfile(wpa_suppl_conf.format(**macsec)):
            os.unlink(wpa_suppl_conf.format(**macsec))

    else:
        # MACsec interfaces require a configuration when they are added using
        # iproute2. This static method will provide the configuration
        # dictionary used by this class.

        # XXX: subject of removal after completing T2653
        conf = deepcopy(MACsecIf.get_config())
        conf['source_interface'] = macsec['source_interface']
        conf['security_cipher'] = macsec['security']['cipher']

        # It is safe to "re-create" the interface always, there is a sanity
        # check that the interface will only be create if its non existent
        i = MACsecIf(macsec['ifname'], **conf)
        i.update(macsec)

        call('systemctl restart wpa_supplicant-macsec@{source_interface}'
             .format(**macsec))

    return None


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