#!/usr/bin/env python3
# vi: ts=4 expandtab
#
# Copyright (C) 2021 VMware Inc.
#
# Author: Shreenidhi Shedi <yesshedi@gmail.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

import os


from . import renderer
from cloudinit import util
from cloudinit import subp
from cloudinit import log as logging
from collections import OrderedDict

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 get_final_conf(self):
        contents = ''
        for k, v in self.conf_dict.items():
            if not v:
                continue
            contents += '['+k+']\n'
            for e in v:
                contents += e + '\n'
            contents += '\n'

        return contents

    def dump_data(self, target_fn):
        if not target_fn:
            LOG.warning('Target file not given')
            return

        contents = self.get_final_conf()
        LOG.debug('Final content: %s', contents)
        util.write_file(target_fn, 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.resolved_conf = config.get('resolved_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):
        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):
        sec = 'Link'

        if not iface:
            return

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

    def parse_routes(self, conf, cfg):
        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_section(sec, route_cfg_map[k], v)

    def parse_subnets(self, iface, cfg):
        dhcp = 'no'
        sec = 'Network'
        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']:
                    self.parse_routes(i, cfg)
            if 'address' in e:
                subnet_cfg_map = {
                    'address': 'Address',
                    'gateway': 'Gateway',
                    'dns_nameservers': 'DNS',
                    'dns_search': 'Domains',
                }
                for k, v in e.items():
                    if k == 'address':
                        if 'prefix' in e:
                            v += '/' + str(e['prefix'])
                        cfg.update_section('Address', subnet_cfg_map[k], v)
                    elif k == 'gateway':
                        cfg.update_section('Route', subnet_cfg_map[k], v)
                    elif k == 'dns_nameservers' or k == 'dns_search':
                        cfg.update_section(sec, subnet_cfg_map[k], ' '.join(v))

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

    # This is to accommodate extra keys present in VMware config
    def dhcp_domain(self, d, cfg):
        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, ns):
        sec = 'Network'

        dns_cfg_map = {
            'search': 'Domains',
            'nameservers': 'DNS',
            'addresses': 'DNS',
        }

        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

        for k, v in dns_cfg_map.items():
            if k in dns and dns[k]:
                cfg.update_section(sec, v, ' '.join(dns[k]))

    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, templates=None, target=None):
        fp_nwkd = self.network_conf_dir
        if target:
            fp_nwkd = subp.target_path(target) + fp_nwkd

        util.ensure_dir(os.path.dirname(fp_nwkd))

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

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

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

            for route in ns.iter_routes():
                self.parse_routes(route, cfg)

            if ns.version == 2:
                name = iface['name']
                # network state doesn't give dhcp domain info
                # using ns.config as a workaround here
                self.dhcp_domain(ns.config['ethernets'][name], cfg)

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

        return ret_dict


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


def network_state_to_networkd(ns):
    renderer = Renderer({})
    return renderer._render_content(ns)