# Copyright (C) 2021-2022 VMware Inc.
#
# Author: Shreenidhi Shedi <yesshedi@gmail.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import logging
from collections import OrderedDict
from typing import Optional

from cloudinit import subp, util
from cloudinit.net import renderer, should_add_gateway_onlink_flag
from cloudinit.net.network_state import NetworkState

LOG = logging.getLogger(__name__)


class CfgParser:
    def __init__(self):
        self.conf_dict = OrderedDict(
            {
                "Match": [],
                "Link": [],
                "Network": [],
                "DHCPv4": [],
                "DHCPv6": [],
                "Address": [],
                "Route": {},
            }
        )

    def update_section(self, sec, key, val):
        for k in self.conf_dict.keys():
            if k == sec:
                self.conf_dict[k].append(key + "=" + str(val))
                # remove duplicates from list
                self.conf_dict[k] = list(dict.fromkeys(self.conf_dict[k]))
                self.conf_dict[k].sort()

    def update_route_section(self, sec, rid, key, val):
        """
        For each route section we use rid as a key, this allows us to isolate
        this route from others on subsequent calls.
        """
        for k in self.conf_dict.keys():
            if k == sec:
                if rid not in self.conf_dict[k]:
                    self.conf_dict[k][rid] = []
                self.conf_dict[k][rid].append(key + "=" + str(val))
                # remove duplicates from list
                self.conf_dict[k][rid] = list(
                    dict.fromkeys(self.conf_dict[k][rid])
                )
                self.conf_dict[k][rid].sort()

    def get_final_conf(self):
        contents = ""
        for k, v in sorted(self.conf_dict.items()):
            if not v:
                continue
            if k == "Address":
                for e in sorted(v):
                    contents += "[" + k + "]\n"
                    contents += e + "\n"
                    contents += "\n"
            elif k == "Route":
                for n in sorted(v):
                    contents += "[" + k + "]\n"
                    for e in sorted(v[n]):
                        contents += e + "\n"
                    contents += "\n"
            else:
                contents += "[" + k + "]\n"
                for e in sorted(v):
                    contents += e + "\n"
                contents += "\n"

        return contents


class Renderer(renderer.Renderer):
    """
    Renders network information in /etc/systemd/network

    This Renderer is currently experimental and doesn't support all the
    use cases supported by the other renderers yet.
    """

    def __init__(self, config=None):
        if not config:
            config = {}
        self.resolve_conf_fn = config.get(
            "resolve_conf_fn", "/etc/systemd/resolved.conf"
        )
        self.network_conf_dir = config.get(
            "network_conf_dir", "/etc/systemd/network/"
        )

    def generate_match_section(self, iface, cfg: CfgParser):
        sec = "Match"
        match_dict = {
            "name": "Name",
            "driver": "Driver",
            "mac_address": "MACAddress",
        }

        if not iface:
            return

        for k, v in match_dict.items():
            if k in iface and iface[k]:
                cfg.update_section(sec, v, iface[k])

        return iface["name"]

    def generate_link_section(self, iface, cfg: CfgParser):
        sec = "Link"

        if not iface:
            return

        if "mtu" in iface and iface["mtu"]:
            cfg.update_section(sec, "MTUBytes", iface["mtu"])

        if "optional" in iface and iface["optional"]:
            cfg.update_section(sec, "RequiredForOnline", "no")

    def parse_routes(self, rid, conf, cfg: CfgParser):
        """
        Parse a route and use rid as a key in order to isolate the route from
        others in the route dict.
        """
        sec = "Route"
        route_cfg_map = {
            "gateway": "Gateway",
            "network": "Destination",
            "metric": "Metric",
        }

        # prefix is derived using netmask by network_state
        prefix = ""
        if "prefix" in conf:
            prefix = "/" + str(conf["prefix"])

        for k, v in conf.items():
            if k not in route_cfg_map:
                continue
            if k == "network":
                v += prefix
            cfg.update_route_section(sec, rid, route_cfg_map[k], v)

    def parse_subnets(self, iface, cfg: CfgParser):
        dhcp = "no"
        sec = "Network"
        rid = 0
        for e in iface.get("subnets", []):
            t = e["type"]
            if t == "dhcp4" or t == "dhcp":
                if dhcp == "no":
                    dhcp = "ipv4"
                elif dhcp == "ipv6":
                    dhcp = "yes"
            elif t == "dhcp6":
                if dhcp == "no":
                    dhcp = "ipv6"
                elif dhcp == "ipv4":
                    dhcp = "yes"
            if "routes" in e and e["routes"]:
                for i in e["routes"]:
                    # Use "r" as a dict key prefix for this route to isolate
                    # it from other sources of routes
                    self.parse_routes(f"r{rid}", i, cfg)
                    rid = rid + 1
            if "address" in e:
                addr = e["address"]
                if "prefix" in e:
                    addr += "/" + str(e["prefix"])
                subnet_cfg_map = {
                    "address": "Address",
                    "gateway": "Gateway",
                    "dns_nameservers": "DNS",
                    "dns_search": "Domains",
                }
                for k, v in e.items():
                    if k == "address":
                        cfg.update_section("Address", subnet_cfg_map[k], addr)
                    elif k == "gateway":
                        # Use "a" as a dict key prefix for this route to
                        # isolate it from other sources of routes
                        cfg.update_route_section(
                            "Route", f"a{rid}", subnet_cfg_map[k], v
                        )
                        if should_add_gateway_onlink_flag(v, addr):
                            LOG.debug(
                                "Gateway %s is not contained within subnet %s,"
                                " adding GatewayOnLink flag",
                                v,
                                addr,
                            )
                            cfg.update_route_section(
                                "Route", f"a{rid}", "GatewayOnLink", "yes"
                            )
                        rid = rid + 1
                    elif k == "dns_nameservers" or k == "dns_search":
                        cfg.update_section(sec, subnet_cfg_map[k], " ".join(v))

        cfg.update_section(sec, "DHCP", dhcp)

        if isinstance(iface.get("accept-ra", ""), bool):
            cfg.update_section(sec, "IPv6AcceptRA", iface["accept-ra"])

        return dhcp

    # This is to accommodate extra keys present in VMware config
    def dhcp_domain(self, d, cfg: CfgParser):
        for item in ["dhcp4domain", "dhcp6domain"]:
            if item not in d:
                continue
            ret = str(d[item]).casefold()
            try:
                ret = util.translate_bool(ret)
                ret = "yes" if ret else "no"
            except ValueError:
                if ret != "route":
                    LOG.warning("Invalid dhcp4domain value - %s", ret)
                    ret = "no"
            if item == "dhcp4domain":
                section = "DHCPv4"
            else:
                section = "DHCPv6"
            cfg.update_section(section, "UseDomains", ret)

    def parse_dns(self, iface, cfg: CfgParser, ns: NetworkState):
        sec = "Network"

        dns = iface.get("dns")
        if not dns and ns.version == 1:
            dns = {
                "search": ns.dns_searchdomains,
                "nameservers": ns.dns_nameservers,
            }
        elif not dns and ns.version == 2:
            return

        if dns.get("search"):
            cfg.update_section(sec, "Domains", " ".join(dns["search"]))
        if dns.get("nameservers"):
            cfg.update_section(sec, "DNS", " ".join(dns["nameservers"]))

    def parse_dhcp_overrides(self, cfg: CfgParser, device, dhcp, version):
        dhcp_config_maps = {
            "UseDNS": "use-dns",
            "UseDomains": "use-domains",
            "UseHostname": "use-hostname",
            "UseNTP": "use-ntp",
        }

        if version == "4":
            dhcp_config_maps.update(
                {
                    "SendHostname": "send-hostname",
                    "Hostname": "hostname",
                    "RouteMetric": "route-metric",
                    "UseMTU": "use-mtu",
                    "UseRoutes": "use-routes",
                }
            )

        if f"dhcp{version}-overrides" in device and dhcp in [
            "yes",
            f"ipv{version}",
        ]:
            dhcp_overrides = device[f"dhcp{version}-overrides"]
            for k, v in dhcp_config_maps.items():
                if v in dhcp_overrides:
                    cfg.update_section(f"DHCPv{version}", k, dhcp_overrides[v])

    def create_network_file(self, link, conf, nwk_dir):
        net_fn_owner = "systemd-network"

        LOG.debug("Setting Networking Config for %s", link)

        net_fn = nwk_dir + "10-cloud-init-" + link + ".network"
        util.write_file(net_fn, conf)
        util.chownbyname(net_fn, net_fn_owner, net_fn_owner)

    def render_network_state(
        self,
        network_state: NetworkState,
        templates: Optional[dict] = None,
        target=None,
    ) -> None:
        network_dir = self.network_conf_dir
        if target:
            network_dir = subp.target_path(target) + network_dir

        util.ensure_dir(network_dir)

        ret_dict = self._render_content(network_state)
        for k, v in ret_dict.items():
            self.create_network_file(k, v, network_dir)

    def _render_content(self, ns: NetworkState) -> dict:
        ret_dict = {}
        for iface in ns.iter_interfaces():
            cfg = CfgParser()

            link = self.generate_match_section(iface, cfg)
            self.generate_link_section(iface, cfg)
            dhcp = self.parse_subnets(iface, cfg)
            self.parse_dns(iface, cfg, ns)

            rid = 0
            for route in ns.iter_routes():
                # Use "c" as a dict key prefix for this route to isolate it
                # from other sources of routes
                self.parse_routes(f"c{rid}", route, cfg)
                rid = rid + 1

            if ns.version == 2:
                name: Optional[str] = iface["name"]
                # network state doesn't give dhcp domain info
                # using ns.config as a workaround here

                # Check to see if this interface matches against an interface
                # from the network state that specified a set-name directive.
                # If there is a device with a set-name directive and it has
                # set-name value that matches the current name, then update the
                # current name to the device's name. That will be the value in
                # the ns.config['ethernets'] dict below.
                for dev_name, dev_cfg in ns.config["ethernets"].items():
                    if "set-name" in dev_cfg:
                        if dev_cfg.get("set-name") == name:
                            name = dev_name
                            break
                if name in ns.config["ethernets"]:
                    device = ns.config["ethernets"][name]

                    # dhcp{version}domain are extra keys only present in
                    # VMware config
                    self.dhcp_domain(device, cfg)
                    for version in ["4", "6"]:
                        if (
                            f"dhcp{version}domain" in device
                            and "use-domains"
                            in device.get(f"dhcp{version}-overrides", {})
                        ):
                            exception = (
                                f"{name} has both dhcp{version}domain"
                                f" and dhcp{version}-overrides.use-domains"
                                f" configured. Use one"
                            )
                            raise RuntimeError(exception)

                        self.parse_dhcp_overrides(cfg, device, dhcp, version)

            ret_dict.update({link: cfg.get_final_conf()})

        return ret_dict


def available(target=None):
    expected = ["ip", "systemctl"]
    search = ["/usr/sbin", "/bin"]
    for p in expected:
        if not subp.which(p, search=search, target=target):
            return False
    return True
