#

# Copyright (c) 2019-2020 Red Hat, Inc.

#

# This file is part of nmstate

#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU Lesser General Public License as published by

# the Free Software Foundation, either version 2.1 of the License, or

# (at your option) any later version.

#

# 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 Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public License

# along with this program. If not, see <https://www.gnu.org/licenses/>.

#

from itertools import chain

from operator import itemgetter

from libnmstate import iplib

from libnmstate.dns import DnsState

from libnmstate.error import NmstateInternalError

from libnmstate.nm import active_connection as nm_ac

from libnmstate.schema import DNS

DNS_DEFAULT_PRIORITY_VPN = 50

DNS_DEFAULT_PRIORITY_OTHER = 100

DEFAULT_DNS_PRIORITY = 0

# The 40 is chose as default DHCP DNS priority is 100, and VPN DNS priority is

# 50, the static DNS configuration should be list before them.

DNS_PRIORITY_STATIC_BASE = 40

IPV6_ADDRESS_LENGTH = 128

def get_running(context):

    dns_state = {DNS.SERVER: [], DNS.SEARCH: []}

    for dns_conf in context.get_dns_configuration():

        iface_name = dns_conf.get_interface()

        for ns in dns_conf.get_nameservers():

            if iplib.is_ipv6_link_local_addr(ns, IPV6_ADDRESS_LENGTH):

                if not iface_name:

                    # For IPv6 link local address, the interface name should be

                    # appended also.

                    raise NmstateInternalError(

                        "Missing interface for IPv6 link-local DNS server "

                        "entry {}".format(ns)

                    )

                ns_addr = "{}%{}".format(ns, iface_name)

            else:

                ns_addr = ns

            if ns_addr not in dns_state[DNS.SERVER]:

                dns_state[DNS.SERVER].append(ns_addr)

        dns_domains = [

            dns_domain

            for dns_domain in dns_conf.get_domains()

            if dns_domain not in dns_state[DNS.SEARCH]

        ]

        dns_state[DNS.SEARCH].extend(dns_domains)

    if not dns_state[DNS.SERVER] and not dns_state[DNS.SEARCH]:

        dns_state = {}

    return dns_state

def get_config(acs_and_ipv4_profiles, acs_and_ipv6_profiles):

    dns_conf = {DNS.SERVER: [], DNS.SEARCH: []}

    tmp_dns_confs = []

    for ac, ip_profile in chain(acs_and_ipv6_profiles, acs_and_ipv4_profiles):

        if not ip_profile.props.dns and not ip_profile.props.dns_search:

            continue

        priority = ip_profile.props.dns_priority

        if priority == DEFAULT_DNS_PRIORITY:

            # ^ The dns_priority in 'NetworkManager.conf' is been ignored

            #   due to the lacking of query function in libnm API.

            if ac.get_vpn():

                priority = DNS_DEFAULT_PRIORITY_VPN

            else:

                priority = DNS_DEFAULT_PRIORITY_OTHER

        tmp_dns_confs.append(

            {

                "server": ip_profile.props.dns,

                "priority": priority,

                "search": ip_profile.props.dns_search,

            }

        )

    # NetworkManager sorts the DNS entries based on various criteria including

    # which profile was activated first when profiles are activated. Therefore

    # the configuration does not completely define the order. To define the

    # order in a declarative way, Nmstate only uses the priority to order the

    # entries. Reference:

    # https://developer.gnome.org/NetworkManager/stable/nm-settings.html#nm-settings.property.ipv4.dns-priority

    tmp_dns_confs.sort(key=itemgetter("priority"))

    for e in tmp_dns_confs:

        dns_conf[DNS.SERVER].extend(e["server"])

        dns_conf[DNS.SEARCH].extend(e["search"])

    if not dns_conf[DNS.SERVER] and dns_conf[DNS.SEARCH]:

        return {}

    return dns_conf

def add_dns(setting_ip, dns_state):

    priority = dns_state.get(DnsState.PRIORITY_METADATA)

    if priority is not None:

        setting_ip.props.dns_priority = priority + DNS_PRIORITY_STATIC_BASE

    for server in dns_state.get(DNS.SERVER, []):

        setting_ip.add_dns(server)

    for search in dns_state.get(DNS.SEARCH, []):

        setting_ip.add_dns_search(search)

def get_dns_config_iface_names(acs_and_ipv4_profiles, acs_and_ipv6_profiles):

    """

    Return a list of interface names which hold static DNS configuration.

    """

    iface_names = []

    for ac, ip_profile in chain(acs_and_ipv6_profiles, acs_and_ipv4_profiles):

        if ip_profile.props.dns or ip_profile.props.dns_search:

            iface_names.append(nm_ac.ActiveConnection(nm_ac_con=ac).devname)

    return iface_names