#!/usr/bin/env python3

import unittest
import ipaddress
from framework import VppTestCase, VppTestRunner

from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6DestUnreach
from scapy.layers.l2 import Ether
from scapy.packet import Raw


class TestNPT66(VppTestCase):
    """NPTv6 Test Case"""

    extra_vpp_plugin_config = [
        "plugin npt66_plugin.so {enable}",
    ]

    def setUp(self):
        super(TestNPT66, self).setUp()

        # create 2 pg interfaces
        self.create_pg_interfaces(range(2))

        for i in self.pg_interfaces:
            i.admin_up()
            i.config_ip6()
            i.resolve_ndp()

    def tearDown(self):
        for i in self.pg_interfaces:
            i.unconfig_ip6()
            i.admin_down()
        super(TestNPT66, self).tearDown()

    def send_and_verify(self, internal, reply_icmp_error=False):
        sendif = self.pg0
        recvif = self.pg1
        local_mac = self.pg0.local_mac
        remote_mac = self.pg0.remote_mac
        src = ipaddress.ip_interface(internal).ip + 1
        dst = self.pg1.remote_ip6

        p = (
            Ether(dst=local_mac, src=remote_mac)
            / IPv6(src=src, dst=dst)
            / ICMPv6EchoRequest()
            / Raw(b"Request")
        )
        # print('Sending packet')
        # p.show2()
        rxs = self.send_and_expect(sendif, p, recvif)
        for rx in rxs:
            # print('Received packet')
            # rx.show2()
            original_cksum = rx[ICMPv6EchoRequest].cksum
            del rx[ICMPv6EchoRequest].cksum
            rx = rx.__class__(bytes(rx))
            self.assertEqual(original_cksum, rx[ICMPv6EchoRequest].cksum)

            # Generate a replies
            if reply_icmp_error:
                # print('Generating an ICMP error message')
                reply = (
                    Ether(dst=rx[Ether].src, src=local_mac)
                    / IPv6(src=rx[IPv6].dst, dst=rx[IPv6].src)
                    / ICMPv6DestUnreach()
                    / rx[IPv6]
                )
                # print('Sending ICMP error message reply')
                # reply.show2()
                replies = self.send_and_expect(recvif, reply, sendif)
                for r in replies:
                    # print('Received ICMP error message reply on the other side')
                    # r.show2()
                    self.assertEqual(str(p[IPv6].src), r[IPv6].dst)
                    original_cksum = r[ICMPv6EchoRequest].cksum
                    del r[ICMPv6EchoRequest].cksum
                    r = r.__class__(bytes(r))
                    self.assertEqual(original_cksum, r[ICMPv6EchoRequest].cksum)

            else:
                reply = (
                    Ether(dst=rx[Ether].src, src=local_mac)
                    / IPv6(src=rx[IPv6].dst, dst=rx[IPv6].src)
                    / ICMPv6EchoRequest()
                    / Raw(b"Reply")
                )

                replies = self.send_and_expect(recvif, reply, sendif)
                for r in replies:
                    r.show2()
                    self.assertEqual(str(p[IPv6].src), r[IPv6].dst)
                    original_cksum = r[ICMPv6EchoRequest].cksum
                    del r[ICMPv6EchoRequest].cksum
                    r = r.__class__(bytes(r))
                    self.assertEqual(original_cksum, r[ICMPv6EchoRequest].cksum)

    def do_test(self, internal, external, reply_icmp_error=False):
        """Add NPT66 binding and send packet"""
        self.vapi.npt66_binding_add_del(
            sw_if_index=self.pg1.sw_if_index,
            internal=internal,
            external=external,
            is_add=True,
        )
        ## TODO use route api
        self.vapi.cli(f"ip route add {internal} via {self.pg0.remote_ip6}")

        self.send_and_verify(internal, reply_icmp_error=reply_icmp_error)

        self.vapi.npt66_binding_add_del(
            sw_if_index=self.pg1.sw_if_index,
            internal=internal,
            external=external,
            is_add=False,
        )

    def test_npt66_simple(self):
        """Send and receive a packet through NPT66"""

        self.do_test("fd00:0000:0000::/48", "2001:4650:c3ed::/48")
        self.do_test("fc00:1::/48", "2001:db8:1::/48")
        self.do_test("fc00:1234::/32", "2001:db8:1::/32")
        self.do_test("fc00:1234::/63", "2001:db8:1::/56")

    def test_npt66_icmp6(self):
        """Send and receive a packet through NPT66"""

        # Test ICMP6 error packets
        self.do_test(
            "fd00:0000:0000::/48", "2001:4650:c3ed::/48", reply_icmp_error=True
        )
        self.do_test("fc00:1::/48", "2001:db8:1::/48", reply_icmp_error=True)
        self.do_test("fc00:1234::/32", "2001:db8:1::/32", reply_icmp_error=True)
        self.do_test("fc00:1234::/63", "2001:db8:1::/56", reply_icmp_error=True)


if __name__ == "__main__":
    unittest.main(testRunner=VppTestRunner)