#! /usr/bin/python3

# SPDX-License-Identifier: GPL-2.0-or-later
#
# tasst - Test A Simple Socket Transport
#         library of test helpers for passt & pasta
#
# tasst/dhcpv6.py - Helpers for testing DHCPv6
#
# Copyright Red Hat
# Author: David Gibson <david@gibson.dropbear.id.au>

import contextlib
import ipaddress
import os

from tasst import Tasst, TasstSubData
from tasst.address import IpiAllocator, TEST_NET6_TASST_A
from tasst.nstool import UnshareSite
from tasst.site import Site
from tasst.typing import typecheck


class Dhcpv6TasstInfo:
    def __init__(self, site, ifname, addr):
        self.site = typecheck(site, Site)
        self.ifname = typecheck(ifname, str)
        self.addr = typecheck(addr, ipaddress.IPv6Address)

        site.require_cmds('ip')


class BaseDhcpv6Tasst(Tasst):
    """
    Test DHCPv6 behaviour.

    :avocado: disable
    """

    DHCLIENT = '/sbin/dhclient'

    def setup_dhcpv6(self):
        raise NotImplementedError("{} must implement setup_dhcpv6() method".format(type(self).__name__))

    @contextlib.contextmanager
    def dhclientv6(self):
        with self.setup_dhcpv6() as d6ti:
            d6ti.site.require_cmds(self.DHCLIENT)

            pidfile = os.path.join(self.workdir, 'dhclient.pid')
            leasefile = os.path.join(self.workdir, 'dhclient.leases')

            # We need '-nc' because we may be running with
            # capabilities but not UID 0.  Without -nc dhclient drops
            # capabilities before invoking dhclient-script, so it's
            # unable to actually configure the interface
            d6ti.site.fg('{} -6 -v -nc -pf {} -lf {} {}'
                         .format(self.DHCLIENT, pidfile, leasefile, d6ti.ifname), sudo=True)

            yield d6ti

            pid = int(d6ti.site.output('cat {}'.format(pidfile)))
            d6ti.site.fg('kill {}'.format(pid))

    def test_addr(self):
        with self.dhclientv6() as d6ti:
            addrs = [a.ip for a in d6ti.site.addrs(d6ti.ifname, family='inet6', scope='global')]
            self.assertIn(d6ti.addr, addrs) # Might also have a SLAAC address


class MetaDhcpv6Tasst(BaseDhcpv6Tasst):
    """Ugly workaround for
    https://github.com/avocado-framework/avocado/issues/5680.
    Explicitly apply the "meta" tag to inherited tests

    :avocado: disable
    :avocado: tags=meta

    """

    def test_addr(self):
        super().test_addr()


class Dhcpd6Tasst(MetaDhcpv6Tasst):
    """
    :avocado: tags=meta
    """

    DHCPD = 'dhcpd'
    SUBNET = TEST_NET6_TASST_A

    @contextlib.contextmanager
    def setup_dhcpv6(self):
        ifname = 'clientif'
        server_ifname = 'serverif'

        with UnshareSite(type(self).__name__ + '.client', '-Un') as client, \
             UnshareSite(type(self).__name__ + '.server', '-n',
                         parent=client, sudo=True) as server:
            server.require_cmds(self.DHCPD)

            client.veth(ifname, server_ifname, server)

            # Allocate IPs, and sort out link local addressing
            ipa = IpiAllocator(self.SUBNET)
            (server_ip6,) = ipa.next_ipis()
            (client_ip6,) = ipa.next_ipis()

            server.ifup('lo')
            server.ifup(server_ifname, server_ip6)
            client.ifup('lo')
            client.ifup(ifname)
            (server_ip6_ll,) = server.addr_wait(server_ifname, family='inet6', scope='link')

            # Configure the DHCP server
            confpath = os.path.join(self.workdir, 'dhcpd.conf')
            open(confpath, 'w').write('''
            subnet6 {} {{
                range6 {} {};
            }}
            '''.format(self.SUBNET, client_ip6.ip, client_ip6.ip))
            pidpath = os.path.join(self.workdir, 'dhcpd.pid')
            leasepath = os.path.join(self.workdir, 'dhcpd.leases')
            open(leasepath, 'w').write('')

            opts = ('-f -d -6 -cf {} -lf {} -pf {}'.format(confpath, leasepath, pidpath))
            server.fg('{} -t {}'.format(self.DHCPD, opts)) # test config
            with server.bg('{} {}'.format(self.DHCPD, opts), sudo=True) as dhcpd:
                yield Dhcpv6TasstInfo(client, ifname, client_ip6.ip)

                pid = int(open(pidpath).read())
                server.fg('kill {}'.format(pid))
                status = dhcpd.wait()