#!/usr/bin/python3
#
# Copyright (C) 2023 Canonical, Ltd.
# Authors: Lukas Märdian <slyon@ubuntu.com>
#          Danilo Egea Gondolfo <danilo.egea.gondolfo@canonical.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 3.
#
# 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 ipaddress
import json
import logging
import re
import shutil
import subprocess
import sys
from collections import defaultdict, namedtuple
from io import StringIO
from socket import AF_INET, AF_INET6, inet_ntop
from typing import Dict, List, Type, Union
from urllib import parse

import yaml

import netplan

from . import utils

JSON = Union[Dict[str, 'JSON'], List['JSON'], int, str, float, bool, Type[None]]

DEVICE_TYPES = {
    'bond': 'bond',
    'bridge': 'bridge',
    'dummy': 'dummy-device',
    'erspan': 'tunnel',
    'ether': 'ethernet',
    'gretap': 'tunnel',
    'ipgre': 'tunnel',
    'ip6gre': 'tunnel',
    'loopback': 'ethernet',
    'sit': 'tunnel',
    'tunnel': 'tunnel',
    'tun': 'tunnel',
    'tunnel6': 'tunnel',
    'wireguard': 'tunnel',
    'wlan': 'wifi',
    'wwan': 'modem',
    'veth': 'virtual-ethernet',
    'vlan': 'vlan',
    'vrf': 'vrf',
    'vxlan': 'tunnel',

    # Used for wifi testing.
    # It's the type of the interface hwsim0 created by the mac80211_hwsim driver
    'ieee80211_radiotap': 'wifi',

    # Netplan netdef types
    'wifis': 'wifi',
    'ethernets': 'ethernet',
    'bridges': 'bridge',
    'bonds': 'bond',
    'nm-devices': 'nm-device',
    'dummy-devices': 'dummy-device',
    'modems': 'modem',
    'vlans': 'vlan',
    'vrfs': 'vrf',
    }


class Interface():
    def __extract_mac(self, ip: dict) -> str:
        '''
        Extract the MAC address if it's set inside the JSON data and seems to
        have the correct format. Return 'None' otherwise.
        '''
        if len(address := ip.get('address', '')) == 17:  # 6 byte MAC (+5 colons)
            return address.lower()
        return None

    def __init__(self, ip: dict, nd_data: JSON = [], nm_data: JSON = [],
                 resolved_data: tuple = (None, None), route_data: tuple = (None, None)):
        self.idx: int = ip.get('ifindex', -1)
        self.name: str = ip.get('ifname', 'unknown')
        self.adminstate: str = 'UP' if 'UP' in ip.get('flags', []) else 'DOWN'
        self.operstate: str = ip.get('operstate', 'unknown').upper()
        self.macaddress: str = self.__extract_mac(ip)
        self.bridge: str = None
        self.bond: str = None
        self.vrf: str = None
        self.members: List[str] = []
        self.data_sources = {}

        # Filter networkd/NetworkManager data
        nm_data = nm_data or []  # avoid 'None' value on systems without NM
        self.nd: JSON = next((x for x in nd_data if x['Index'] == self.idx), None)
        self.nm: JSON = next((x for x in nm_data if x['device'] == self.name), None)

        # Map networkd data (such as IP addresses and nameservers)
        # to their sources (such as dhcp4, dhcp6, etc)
        # TODO: the same information seems to be available for Network Manager
        # through its DBus API.
        if self.nd:
            self.data_sources = self._find_data_sources(self.nd)

        # Filter resolved's DNS data
        self.dns_addresses: list = None
        if resolved_data[0]:
            self.dns_addresses = []
            for itr in resolved_data[0]:
                if int(itr[0]) == int(self.idx):
                    ipfamily = itr[1]
                    dns = itr[2]
                    self.dns_addresses.append(inet_ntop(ipfamily, b''.join([v.to_bytes(1, 'big') for v in dns])))
        self.dns_search: list = None
        if resolved_data[1]:
            self.dns_search = []
            for v in resolved_data[1]:
                if int(v[0]) == int(self.idx):
                    self.dns_search.append(str(v[1]))

        # Filter route data
        _routes: list = []
        self.routes: list = None
        if route_data[0]:
            _routes += route_data[0]
        if route_data[1]:
            _routes += route_data[1]
        if _routes:
            self.routes = []
            for obj in _routes:
                if obj.get('dev') == self.name:
                    elem = {'to': obj.get('dst')}
                    if val := obj.get('family'):
                        elem['family'] = val
                    if val := obj.get('gateway'):
                        elem['via'] = val
                    if val := obj.get('prefsrc'):
                        elem['from'] = val
                    if val := obj.get('metric'):
                        elem['metric'] = val
                    if val := obj.get('type'):
                        elem['type'] = val
                    if val := obj.get('scope'):
                        elem['scope'] = val
                    if val := obj.get('protocol'):
                        elem['protocol'] = val
                    if val := obj.get('table'):
                        elem['table'] = val
                    self.routes.append(elem)

        self.addresses: list = None
        if addr_info := ip.get('addr_info'):

            ra_networks = set()
            if self.routes:
                for route in self.routes:
                    if (route.get('protocol') == 'ra'
                            and route.get('to') != 'default'
                            and route.get('family') == AF_INET6.value):
                        ra_networks.add(ipaddress.ip_interface(route['to']).network)

            self.addresses = []
            for addr in addr_info:
                flags: list = []
                if ipaddress.ip_address(addr['local']).is_link_local:
                    flags.append('link')
                if addr.get('dynamic', False):
                    flags.append('dynamic')

                # Try to determine if the address was received via RA/DHCPv6
                # IPv6 RA addresses might not have a flag indicating it so we check
                # for a route entry (received via RA) where the destination is the same network
                # the address belongs to.
                ip_addr = ipaddress.ip_interface(f'{addr["local"]}/{addr["prefixlen"]}')
                if isinstance(ip_addr, ipaddress.IPv6Address):
                    if ip_addr.network in ra_networks:
                        flags.append('ra')

                    if ip_ds := self.data_sources.get('addresses', {}).get(str(ip_addr)):
                        if ip_ds == 'DHCPv6':
                            flags.append('dhcp')

                if ip_ds := self.data_sources.get('addresses', {}).get(str(ip_addr)):
                    if ip_ds == 'DHCPv4' and 'dhcp' not in flags:
                        flags.append('dhcp')

                if self.routes and 'dhcp' not in flags:
                    for route in self.routes:
                        if ('from' in route and
                                ipaddress.ip_address(route['from']) == ipaddress.ip_address(addr['local'])):
                            if route['protocol'] == 'dhcp' and 'dhcp' not in flags:
                                flags.append('dhcp')
                                break
                ip_addr = addr['local'].lower()
                elem = {ip_addr: {'prefix': addr['prefixlen']}}
                if flags:
                    elem[ip_addr]['flags'] = flags
                self.addresses.append(elem)

        self.iproute_type: str = None
        if info_kind := ip.get('linkinfo', {}).get('info_kind'):
            self.iproute_type = info_kind.strip()

        # workaround: query some data which is not available via networkctl's JSON output
        self._networkctl: str = self.query_networkctl(self.name) or ''

    def query_nm_ssid(self, con_name: str) -> str:
        ssid: str = None
        try:
            ssid = utils.nmcli_out(['--get-values', '802-11-wireless.ssid',
                                    'con', 'show', 'id', con_name])
            return ssid.strip()
        except Exception as e:
            logging.warning('Cannot query NetworkManager SSID for {}: {}'.format(
                            con_name, str(e)))
        return ssid

    def query_networkctl(self, ifname: str) -> str:
        output: str = None
        try:
            output = subprocess.check_output(['networkctl', 'status', '--', ifname], text=True)
        except Exception as e:
            logging.warning('Cannot query networkctl for {}: {}'.format(
                ifname, str(e)))
        return output

    def json(self) -> JSON:
        json = {
            'index': self.idx,
            'adminstate': self.adminstate,
            'operstate': self.operstate,
            }
        if self.type:
            json['type'] = self.type
        if self.ssid:
            json['ssid'] = self.ssid
        if self.tunnel_mode:
            json['tunnel_mode'] = self.tunnel_mode
        if self.backend:
            json['backend'] = self.backend
        if self.netdef_id:
            json['id'] = self.netdef_id
        if self.macaddress:
            json['macaddress'] = self.macaddress
        if self.vendor:
            json['vendor'] = self.vendor
        if self.addresses:
            json['addresses'] = self.addresses
        if self.dns_addresses:
            json['dns_addresses'] = self.dns_addresses
        if self.dns_search:
            json['dns_search'] = self.dns_search
        if self.routes:
            json['routes'] = self.routes
        if self.activation_mode:
            json['activation_mode'] = self.activation_mode
        if self.bridge:
            json['bridge'] = self.bridge
        if self.bond:
            json['bond'] = self.bond
        if self.vrf:
            json['vrf'] = self.vrf
        if self.members:
            json['interfaces'] = self.members
        return (self.name, json)

    @property
    def up(self) -> bool:
        return self.adminstate == 'UP' and self.operstate == 'UP'

    @property
    def down(self) -> bool:
        return self.adminstate == 'DOWN' and self.operstate == 'DOWN'

    @property
    def type(self) -> str:
        nd_type = self.nd.get('Type') if self.nd else None
        if nd_type == 'none':
            # If the Type is reported as 'none' by networkd, the interface still might have a Kind.
            nd_type = self.nd.get('Kind')
        if nd_type == 'ether':
            # There are different kinds of 'ether' devices, such as VRFs, veth and dummies
            if kind := self.nd.get('Kind'):
                nd_type = kind
        if device_type := DEVICE_TYPES.get(nd_type):
            return device_type
        logging.warning('Unknown device type: {}'.format(nd_type))
        return None

    @property
    def tunnel_mode(self) -> str:
        if self.type == 'tunnel' and self.iproute_type:
            return self.iproute_type
        return None

    @property
    def backend(self) -> str:
        if (self.nd and
                'unmanaged' not in self.nd.get('SetupState', '') and
                'run/systemd/network/10-netplan-' in self.nd.get('NetworkFile', '')):
            return 'networkd'
        elif self.nm and 'run/NetworkManager/system-connections/netplan-' in self.nm.get('filename', ''):
            return 'NetworkManager'
        return None

    @property
    def netdef_id(self) -> str:
        if self.backend == 'networkd':
            return self.nd.get('NetworkFile', '').split(
                'run/systemd/network/10-netplan-')[1].split('.network')[0]
        elif self.backend == 'NetworkManager':
            netdef = self.nm.get('filename', '').split(
                'run/NetworkManager/system-connections/netplan-')[1].split('.nmconnection')[0]
            if self.nm.get('type', '') == '802-11-wireless':
                ssid = self.query_nm_ssid(self.nm.get('name'))
                if ssid not in netdef:
                    # If the plain SSID in not found in the netdef here
                    # it's probably because it contains non-ascii characters that
                    # were escaped in the file name. We need to do the same here to
                    # be able to extract it from the file name.
                    # In this case, Network Manager will save the SSID using the format "b1;b2;b3...;"
                    # instead of a non-ascii string.
                    # In src/nm.c we use g_uri_escape_string() to create the file name.

                    # Transform the SSID to the same format used by Network Manager
                    ssid_encoded = ssid.encode('utf-8')
                    ssid_bytes = [str(b) for b in ssid_encoded]
                    ssid_nm_escaped = ';'.join(ssid_bytes) + ';'

                    # Escape characters in the same way we do in src/nm.c.
                    ssid = parse.quote(ssid_nm_escaped)
                if ssid:
                    netdef = netdef.split('-' + ssid)[0]
            return netdef
        return None

    @property
    def vendor(self) -> str:
        if self.nd and 'Vendor' in self.nd and self.nd['Vendor']:
            return self.nd['Vendor'].strip()
        return None

    @property
    def ssid(self) -> str:
        if self.type == 'wifi':
            if self.backend == "NetworkManager":
                return self.query_nm_ssid(self.nm.get('name', ''))
            # XXX: available from networkctl's JSON output as of v250:
            #      https://github.com/systemd/systemd/commit/da7c995
            # TODO: Retrieving the SSID from systemd seems to not be reliable.
            #       Sometimes it will return "(null)".
            for line in self._networkctl.splitlines():
                line = line.strip()
                key = r'^Wi-?Fi access point: (.*) \(.*\)'
                if match := re.match(key, line):
                    ssid = match.group(1)
                    # TODO: Find a better way to retrieve the SSID
                    # networkctl will return a non-ascii SSID using the octal notation below:
                    # '\\303\\241\\303\\251\\303\\255\\303\\263\\303...
                    # Here we handle the escaping, the encoding of individual bytes and the final decoding to utf-8
                    ssid = ssid.encode('latin1').decode('unicode-escape').encode('latin1').decode('utf-8')
                    return ssid if ssid else None
        return None

    @property
    def activation_mode(self) -> str:
        if self.backend == 'networkd':
            # XXX: available from networkctl's JSON output as of v250:
            #      https://github.com/systemd/systemd/commit/3b60ede
            for line in self._networkctl.splitlines():
                line = line.strip()
                key = 'Activation Policy: '
                if line.startswith(key):
                    mode = line[len(key):].strip()
                    return mode if mode != 'up' else None
        # XXX: this is not fully supported on NetworkManager, only 'manual'/'up'
        elif self.backend == 'NetworkManager':
            return 'manual' if self.nm['autoconnect'] == 'no' else None
        return None

    def _find_data_sources(self, data: JSON) -> dict:

        # The list of networkd data sources can be found here:
        # https://github.com/systemd/systemd/blob/v256/src/network/networkd-util.c#L15

        sources = {}

        # DNS nameservers
        if addresses := data.get('DNS', []):
            sources['dns'] = {}
            for dns in addresses:
                addr = ipaddress.ip_interface(bytes(dns['Address']))
                addr_str = str(addr.ip)
                source = dns['ConfigSource']
                sources['dns'][addr_str] = source

        # DNS search domains
        if domains := data.get('SearchDomains', []):
            sources['search'] = {}
            for search in domains:
                domain = search['Domain']
                source = search['ConfigSource']
                sources['search'][domain] = source

        # IP addresses
        if addresses := data.get('Addresses', []):
            sources['addresses'] = {}
            for ip in addresses:
                addr = ipaddress.ip_interface(bytes(ip['Address']))
                prefix = ip['PrefixLength']
                full_addr = ipaddress.ip_interface(str(addr.ip) + f'/{prefix}')
                addr_str = str(full_addr)
                source = ip['ConfigSource']
                sources['addresses'][addr_str] = source

        return sources


class SystemConfigState():
    ''' Collects the system's network configuration '''

    def __init__(self, ifname=None, all=False):
        # Make sure sd-networkd is running, as we need the data it provides.
        if not utils.systemctl_is_active('systemd-networkd.service'):
            if utils.systemctl_is_masked('systemd-networkd.service'):
                logging.error('\'netplan status\' depends on networkd, '
                              'but systemd-networkd.service is masked. '
                              'Please start it.')
                sys.exit(1)
            if not utils.systemctl_is_installed('systemd-networkd.service'):
                logging.error('systemd-networkd is required for \'netplan status\' functionality')
                sys.exit(1)
            logging.debug('systemd-networkd.service is not active. Starting...')
            utils.systemctl('start', ['systemd-networkd.service'], True)

        # required data: iproute2 and sd-networkd can be expected to exist,
        # due to hard package dependencies
        iproute2 = self.query_iproute2()
        networkd = self.query_networkd()
        if not iproute2 or not networkd:
            logging.error('Could not query iproute2 or systemd-networkd')
            sys.exit(1)

        # optional data
        nmcli = self.query_nm()
        route4, route6 = self.query_routes()
        dns_addresses, dns_search = self.query_resolved()

        self.interface_list = [Interface(itf, networkd, nmcli, (dns_addresses, dns_search),
                                         (route4, route6)) for itf in iproute2]

        # get bridge/bond/vrf data
        self.correlate_members_and_uplink(self.interface_list)

        # show only active interfaces by default
        filtered = [itf for itf in self.interface_list if itf.operstate != 'DOWN']
        # down interfaces do not contribute anything to the online state
        online_state = self.query_online_state(filtered)
        # show only a single interface, if requested
        # XXX: bash completion (for interfaces names)
        if ifname:
            filtered = [next((itf for itf in self.interface_list if itf.name == ifname), None)]
        filtered = [elem for elem in filtered if elem is not None]
        if ifname and filtered == []:
            logging.error('Could not find interface {}'.format(ifname))
            sys.exit(1)

        # Global state
        self.state = {
            'netplan-global-state': {
                'online': online_state,
                'nameservers': self.resolvconf_json()
            }
        }
        # Per interface
        itf_iter = self.interface_list if all else filtered
        for itf in itf_iter:
            ifname, obj = itf.json()
            self.state[ifname] = obj

    @classmethod
    def resolvconf_json(cls) -> dict:
        res = {
            'addresses': [],
            'search': [],
            'mode': None,
            }
        try:
            with open('/etc/resolv.conf') as f:
                # check first line for systemd-resolved stub or compat modes
                firstline = f.readline()
                if '# This is /run/systemd/resolve/stub-resolv.conf' in firstline:
                    res['mode'] = 'stub'
                elif '# This is /run/systemd/resolve/resolv.conf' in firstline:
                    res['mode'] = 'compat'
                for line in [firstline] + f.readlines():
                    if line.startswith('nameserver'):
                        res['addresses'] += line.split()[1:]  # append
                    if line.startswith('search'):
                        res['search'] = line.split()[1:]  # override
        except Exception as e:
            logging.warning('Cannot parse /etc/resolv.conf: {}'.format(str(e)))
        return res

    @classmethod
    def query_online_state(cls, interfaces: list) -> bool:
        # TODO: fully implement network-online.target specification (FO020):
        # https://discourse.ubuntu.com/t/spec-definition-of-an-online-system/27838
        for itf in interfaces:
            if itf.up and itf.addresses and itf.routes and itf.dns_addresses:
                non_local_ips = []
                for addr in itf.addresses:
                    ip, extra = list(addr.items())[0]
                    if 'flags' not in extra or 'link' not in extra['flags']:
                        non_local_ips.append(ip)
                default_routes = [x for x in itf.routes if x.get('to', None) == 'default']
                if non_local_ips and default_routes and itf.dns_addresses:
                    return True
        return False

    @classmethod
    def process_generic(cls, cmd_output: str) -> JSON:
        return json.loads(cmd_output)

    @classmethod
    def query_iproute2(cls) -> JSON:
        data: JSON = None
        try:
            output: str = subprocess.check_output(['ip', '-d', '-j', 'addr'],
                                                  text=True)
            data = cls.process_generic(output)
        except Exception as e:
            logging.critical('Cannot query iproute2 interface data: {}'.format(str(e)))
        return data

    @classmethod
    def process_networkd(cls, cmd_output) -> JSON:
        return json.loads(cmd_output)['Interfaces']

    @classmethod
    def query_networkd(cls) -> JSON:
        data: JSON = None
        try:
            output: str = subprocess.check_output(['networkctl', '--json=short'],
                                                  text=True)
            data = cls.process_networkd(output)
        except Exception as e:
            logging.critical('Cannot query networkd interface data: {}'.format(str(e)))
        return data

    @classmethod
    def process_nm(cls, cmd_output) -> JSON:
        data: JSON = []
        for line in cmd_output.splitlines():
            split = line.split(':')
            dev = split[0] if split[0] else None
            if dev:  # ignore inactive connection profiles
                data.append({
                    'device': dev,
                    'name': split[1],
                    'uuid': split[2],
                    'filename': split[3],
                    'type': split[4],
                    'autoconnect': split[5],
                    })
        return data

    @classmethod
    def query_nm(cls) -> JSON:
        data: JSON = None
        try:
            output: str = utils.nmcli_out(['-t', '-f',
                                           'DEVICE,NAME,UUID,FILENAME,TYPE,AUTOCONNECT',
                                           'con', 'show'])
            data = cls.process_nm(output)
        except Exception as e:
            logging.debug('Cannot query NetworkManager interface data: {}'.format(str(e)))
        return data

    @classmethod
    def query_routes(cls) -> tuple:
        data4 = None
        data6 = None
        try:
            output4: str = subprocess.check_output(['ip', '-d', '-j', '-4', 'route', 'show', 'table', 'all'],
                                                   text=True)
            data4: JSON = cls.process_generic(output4)
            output6: str = subprocess.check_output(['ip', '-d', '-j', '-6', 'route', 'show', 'table', 'all'],
                                                   text=True)
            data6: JSON = cls.process_generic(output6)
        except Exception as e:
            logging.debug('Cannot query iproute2 route data: {}'.format(str(e)))

        # Add the address family to the data
        # IPv4: 2, IPv6: 10
        if data4:
            for route in data4:
                route.update({'family': AF_INET.value})
        if data6:
            for route in data6:
                route.update({'family': AF_INET6.value})
        return (data4, data6)

    @classmethod
    def query_resolved(cls) -> tuple:
        addresses = None
        search = None
        try:
            busctl = shutil.which('busctl')
            if busctl is None:
                raise RuntimeError('missing busctl utility')
            json_out = subprocess.check_output(
                [busctl, '--json=short', 'call', '--system',
                 'org.freedesktop.resolve1',  # the service
                 '/org/freedesktop/resolve1',  # the object
                 'org.freedesktop.DBus.Properties',  # the interface
                 'GetAll', 's',  # the method and signature
                 'org.freedesktop.resolve1.Manager',  # the parameter
                 ], text=True)
            res = json.loads(json_out)
            data = res.get('data', [{}])[0]
            # make sure the type doesn't change. We expect an array of two
            # intergers and an array of bytes (IP address)
            assert data.get('DNS', {}).get('type') == 'a(iiay)', 'DNS address type doesn\'t match'
            addresses = data.get('DNS', {}).get('data')
            # make sure the type dosn't change. We expect an array of an integer
            # a string (DNS search domain) and a boolean
            assert data.get('Domains', {}).get('type') == 'a(isb)', 'DNS search type doesn\'t match'
            search = data.get('Domains', {}).get('data')
        except Exception as err:
            logging.debug('Cannot query resolved DNS data: %s', str(err))
        return (addresses, search)

    @classmethod
    def query_members(cls, ifname: str) -> List[str]:
        ''' Return a list containing the interfaces that are members of a bond/bridge/vrf '''
        members = []
        output: str = None
        try:
            output = subprocess.check_output(
                ['ip', '-d', '-j', 'link', 'show', 'master', ifname], text=True)   # wokeignore:rule=master
        except Exception as e:
            logging.warning('Cannot query bridge: {}'.format(str(e)))
            return []

        output_json = json.loads(output)
        for member in output_json:
            members.append(member.get('ifname'))

        return members

    @classmethod
    def correlate_members_and_uplink(cls, interfaces: List[Interface]) -> None:
        '''
        Associate interfaces with their members and parent interfaces.
        If an interface is a member of a bond/bridge/vrf, identify which interface
        if a member of. If an interface has members, identify what are the members.
        '''
        uplink_types = ['bond', 'bridge', 'vrf']
        members_to_uplink = {}
        uplink_to_members = defaultdict(list)
        for interface in filter(lambda i: i.type in uplink_types, interfaces):
            members = cls.query_members(interface.name)
            for member in members:
                member_tuple = namedtuple('Member', ['name', 'type'])
                members_to_uplink[member] = member_tuple(interface.name, interface.type)
            uplink_to_members[interface.name] = members

        for interface in interfaces:
            if uplink := members_to_uplink.get(interface.name):
                if uplink.type == 'bridge':
                    interface.bridge = uplink.name
                if uplink.type == 'bond':
                    interface.bond = uplink.name
                if uplink.type == 'vrf':
                    interface.vrf = uplink.name

            if interface.type in uplink_types:
                if members := uplink_to_members.get(interface.name):
                    interface.members = members

    @property
    def number_of_interfaces(self) -> int:
        return len(self.interface_list)

    def get_data(self) -> dict:
        return self.state


class NetplanConfigState():
    ''' Collects the Netplan's network configuration '''

    def __init__(self, subtree='all', rootdir='/'):

        parser = netplan.Parser()
        parser.load_yaml_hierarchy(rootdir)

        np_state = netplan.State()
        np_state.import_parser_results(parser)
        self.netdefs = np_state.netdefs

        self.state = StringIO()

        if subtree == 'all':
            np_state._dump_yaml(output_file=self.state)
        else:
            if not subtree.startswith('network'):
                subtree = '.'.join(('network', subtree))
            # Split at '.' but not at '\.' via negative lookbehind expression
            subtree = re.split(r'(?<!\\)\.', subtree)
            # Replace remaining '\.' by plain '.'
            subtree = [elem.replace(r'\.', '.') for elem in subtree]

            tmp_in = StringIO()
            np_state._dump_yaml(output_file=tmp_in)
            netplan._dump_yaml_subtree(subtree, tmp_in, self.state)

    def __str__(self) -> str:
        return self.state.getvalue()

    def get_data(self) -> dict:
        return yaml.safe_load(self.state.getvalue())
