#!/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 netifaces import interfaces

from vyos.ifconfig import MACsecIf
from vyos.configdict import list_diff
from vyos.config import Config
from vyos.validate import is_member
from vyos import ConfigError

default_config_data = {
    'address': [],
    'address_remove': [],
    'cipher': 'gcm-aes-128',
    'deleted': False,
    'description': '',
    'disable': False,
    'encrypt': 'off',
    'intf': '',
    'source_interface': '',
    'is_bridge_member': False,
    'vrf': ''
}

def get_config():
    macsec = deepcopy(default_config_data)
    conf = Config()

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

    macsec['intf'] = os.environ['VYOS_TAGNODE_VALUE']

    # check if we are a member of any bridge
    macsec['is_bridge_member'] = is_member(conf, macsec['intf'], 'bridge')

    # Check if interface has been removed
    if not conf.exists('interfaces macsec ' + macsec['intf']):
        macsec['deleted'] = True
        return macsec

    # set new configuration level
    conf.set_level('interfaces macsec ' + macsec['intf'])

    # retrieve configured interface addresses
    if conf.exists('address'):
        macsec['address'] = conf.return_values('address')

    # retrieve interface cipher
    if conf.exists('cipher'):
        macsec['cipher'] = conf.return_value('cipher')

    # retrieve interface description
    if conf.exists('description'):
        macsec['description'] = conf.return_value('description')

    # Disable this interface
    if conf.exists('disable'):
        macsec['disable'] = True

    # Enable optional MACsec encryption
    if conf.exists('encrypt'):
        macsec['encrypt'] = 'on'

    # Physical interface
    if conf.exists(['source-interface']):
        macsec['source_interface'] = conf.return_value(['source-interface'])

    # Determine interface addresses (currently effective) - to determine which
    # address is no longer valid and needs to be removed from the interface
    eff_addr = conf.return_effective_values('address')
    act_addr = conf.return_values('address')
    macsec['address_remove'] = list_diff(eff_addr, act_addr)

    # retrieve VRF instance
    if conf.exists('vrf'):
        macsec['vrf'] = conf.return_value('vrf')

    return macsec

def verify(macsec):
    if macsec['deleted']:
        if macsec['is_bridge_member']:
            raise ConfigError((
                f'Interface "{macsec["intf"]}" cannot be deleted as it is a '
                f'member of bridge "{macsec["is_bridge_member"]}"!'))

        return None

    if not macsec['source_interface']:
        raise ConfigError((
            f'Physical source interface must be set for MACsec "{macsec["intf"]}"'))

    if macsec['vrf']:
        if macsec['vrf'] not in interfaces():
            raise ConfigError(f'VRF "{macsec["vrf"]}" does not exist')

        if macsec['is_bridge_member']:
            raise ConfigError((
                f'Interface "{macsec["intf"]}" cannot be member of VRF '
                f'"{macsec["vrf"]}" and bridge "{macsec["is_bridge_member"]}" '
                f'at the same time!'))

    if macsec['is_bridge_member'] and macsec['address']:
        raise ConfigError((
            f'Cannot assign address to interface "{macsec["intf"]}" '
            f'as it is a member of bridge "{macsec["is_bridge_member"]}"!'))

    return None

def generate(macsec):
    return None

def apply(macsec):
    # Remove macsec interface
    if macsec['deleted']:
        MACsecIf(macsec['intf']).remove()
    else:
        # MACsec interfaces require a configuration when they are added using
        # iproute2. This static method will provide the configuration
        # dictionary used by this class.
        conf = deepcopy(MACsecIf.get_config())

        # Assign MACsec instance configuration parameters to config dict
        conf['source_interface'] = macsec['source_interface']
        conf['cipher'] = macsec['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['intf'], **conf)

        # Configure optional encryption
        i.set_encryption(macsec['encrypt'])

        # update interface description used e.g. within SNMP
        i.set_alias(macsec['description'])

        # Configure interface address(es)
        # - not longer required addresses get removed first
        # - newly addresses will be added second
        for addr in macsec['address_remove']:
            i.del_addr(addr)
        for addr in macsec['address']:
            i.add_addr(addr)

        # assign/remove VRF (ONLY when not a member of a bridge,
        # otherwise 'nomaster' removes it from it)
        if not macsec['is_bridge_member']:
            i.set_vrf(macsec['vrf'])

        # Interface is administratively down by default, enable if desired
        if not macsec['disable']:
            i.set_admin_state('up')

    return None

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