#!/usr/bin/env python
# SPDX-License-Identifier: ISC

# Copyright (c) 2023 by
# Donatas Abraitis <donatas@opensourcerouting.org>
#

"""
Test if BGP graceful restart / long-lived graceful restart capabilities
(restart time, stale time and notification flag) are exchanged dynamically
via BGP dynamic capability.
"""

import os
import sys
import json
import pytest
import functools

pytestmark = [pytest.mark.bgpd]

CWD = os.path.dirname(os.path.realpath(__file__))
sys.path.append(os.path.join(CWD, "../"))

# pylint: disable=C0413
from lib import topotest
from lib.topogen import Topogen, get_topogen
from lib.common_config import step


def setup_module(mod):
    topodef = {"s1": ("r1", "r2")}
    tgen = Topogen(topodef, mod.__name__)
    tgen.start_topology()

    router_list = tgen.routers()

    for _, (rname, router) in enumerate(router_list.items(), 1):
        router.load_frr_config(os.path.join(CWD, "{}/frr.conf".format(rname)))

    tgen.start_router()


def teardown_module(mod):
    tgen = get_topogen()
    tgen.stop_topology()


def test_bgp_dynamic_capability_graceful_restart():
    tgen = get_topogen()

    if tgen.routers_have_failure():
        pytest.skip(tgen.errors)

    r1 = tgen.gears["r1"]
    r2 = tgen.gears["r2"]

    def _bgp_converge():
        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
        expected = {
            "192.168.1.2": {
                "bgpState": "Established",
                "neighborCapabilities": {
                    "dynamic": "advertisedAndReceived",
                    "gracefulRestart": "advertisedAndReceived",
                    "longLivedGracefulRestart": "advertisedAndReceived",
                },
                "addressFamilyInfo": {
                    "ipv4Unicast": {
                        "acceptedPrefixCounter": 3,
                    }
                },
                "gracefulRestartInfo": {
                    "nBit": True,
                    "timers": {
                        "receivedRestartTimer": 120,
                        "configuredLlgrStaleTime": 10,
                    },
                    "ipv4Unicast": {
                        "timers": {
                            "llgrStaleTime": 10,
                        }
                    },
                },
            }
        }
        return topotest.json_cmp(output, expected)

    test_func = functools.partial(
        _bgp_converge,
    )
    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
    assert result is None, "Can't converge"

    step(
        "Change Graceful-Restart restart-time, LLGR stale-time and check if they changed dynamically"
    )

    # Clear message stats to check if we receive a notification or not after we
    # change the settings fo LLGR.
    r1.vtysh_cmd("clear bgp 192.168.1.2 message-stats")
    r2.vtysh_cmd(
        """
    configure terminal
    router bgp
     bgp graceful-restart restart-time 123
     bgp long-lived-graceful-restart stale-time 5
    """
    )

    def _bgp_check_if_session_not_reset_after_changing_gr_settings():
        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
        expected = {
            "192.168.1.2": {
                "bgpState": "Established",
                "neighborCapabilities": {
                    "dynamic": "advertisedAndReceived",
                    "gracefulRestart": "advertisedAndReceived",
                    "longLivedGracefulRestart": "advertisedAndReceived",
                },
                "addressFamilyInfo": {
                    "ipv4Unicast": {
                        "acceptedPrefixCounter": 3,
                    }
                },
                "gracefulRestartInfo": {
                    "nBit": True,
                    "timers": {
                        "receivedRestartTimer": 123,
                        "configuredLlgrStaleTime": 10,
                    },
                    "ipv4Unicast": {
                        "timers": {
                            "llgrStaleTime": 5,
                        }
                    },
                },
                "messageStats": {
                    "notificationsRecv": 0,
                    "capabilityRecv": 2,
                },
            }
        }
        return topotest.json_cmp(output, expected)

    test_func = functools.partial(
        _bgp_check_if_session_not_reset_after_changing_gr_settings,
    )
    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
    assert (
        result is None
    ), "Session was reset after changing Graceful-Restart restart-time"

    step(
        "Disable Graceful-Restart notification support, and check if it's changed dynamically"
    )

    # Clear message stats to check if we receive a notification or not after we
    # disable graceful-restart notification support.
    r1.vtysh_cmd("clear bgp 192.168.1.2 message-stats")
    r2.vtysh_cmd(
        """
    configure terminal
    router bgp
     no bgp graceful-restart notification
    """
    )

    def _bgp_check_if_session_not_reset_after_changing_notification():
        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
        expected = {
            "192.168.1.2": {
                "bgpState": "Established",
                "neighborCapabilities": {
                    "dynamic": "advertisedAndReceived",
                    "gracefulRestart": "advertisedAndReceived",
                    "longLivedGracefulRestart": "advertisedAndReceived",
                },
                "gracefulRestartInfo": {
                    "nBit": False,
                    "timers": {
                        "receivedRestartTimer": 123,
                        "configuredLlgrStaleTime": 10,
                    },
                    "ipv4Unicast": {
                        "timers": {
                            "llgrStaleTime": 5,
                        }
                    },
                },
                "messageStats": {
                    "notificationsRecv": 0,
                    "capabilityRecv": 1,
                },
            }
        }
        return topotest.json_cmp(output, expected)

    test_func = functools.partial(
        _bgp_check_if_session_not_reset_after_changing_notification,
    )
    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
    assert (
        result is None
    ), "Session was reset after changing Graceful-Restart notification support"

    # Clear message stats to check if we receive a notification or not after we
    # disable GR.
    r1.vtysh_cmd("clear bgp 192.168.1.2 message-stats")
    r1.vtysh_cmd(
        """
    configure terminal
    router bgp
     bgp graceful-restart-disable
    """
    )

    def _bgp_check_if_gr_llgr_capability_is_absent():
        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
        expected = {
            "192.168.1.2": {
                "bgpState": "Established",
                "neighborCapabilities": {
                    "dynamic": "advertisedAndReceived",
                    "gracefulRestartCapability": "received",
                    "longLivedGracefulRestart": "received",
                },
                "messageStats": {
                    "notificationsRecv": 0,
                },
            }
        }
        return topotest.json_cmp(output, expected)

    test_func = functools.partial(
        _bgp_check_if_gr_llgr_capability_is_absent,
    )
    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
    assert result is None, "Failed to disable GR/LLGR capabilities"


if __name__ == "__main__":
    args = ["-s"] + sys.argv[1:]
    sys.exit(pytest.main(args))