#!/usr/bin/env python3
#
# Copyright (C) 2018-2020 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import os

from sys import exit
from ipaddress import ip_address
from ipaddress import ip_interface
from ipaddress import IPv4Interface
from ipaddress import IPv6Interface
from ipaddress import IPv4Address
from ipaddress import IPv6Address
from json import dumps
from pathlib import Path

import vyos.config

from vyos import ConfigError
from vyos.util import call
from vyos.util import makedir
from vyos.template import render

from vyos.ifconfig.vrrp import VRRP

from vyos import airbag
airbag.enable()

def get_config(config=None):
    vrrp_groups = []
    sync_groups = []

    if config:
        config = config
    else:
        config = vyos.config.Config()

    # Get the VRRP groups
    for group_name in config.list_nodes("high-availability vrrp group"):
        config.set_level("high-availability vrrp group {0}".format(group_name))

        # Retrieve the values
        group = {"preempt": True, "use_vmac": False, "disable": False}

        if config.exists("disable"):
            group["disable"] = True

        group["name"] = group_name
        group["vrid"] = config.return_value("vrid")
        group["interface"] = config.return_value("interface")
        group["description"] = config.return_value("description")
        group["advertise_interval"] = config.return_value("advertise-interval")
        group["priority"] = config.return_value("priority")
        group["hello_source"] = config.return_value("hello-source-address")
        group["peer_address"] = config.return_value("peer-address")
        group["sync_group"] = config.return_value("sync-group")
        group["preempt_delay"] = config.return_value("preempt-delay")
        group["virtual_addresses"] = config.return_values("virtual-address")
        group["virtual_addresses_excluded"] = config.return_values("virtual-address-excluded")

        group["auth_password"] = config.return_value("authentication password")
        group["auth_type"] = config.return_value("authentication type")

        group["health_check_script"] = config.return_value("health-check script")
        group["health_check_interval"] = config.return_value("health-check interval")
        group["health_check_count"] = config.return_value("health-check failure-count")

        group["master_script"] = config.return_value("transition-script master")
        group["backup_script"] = config.return_value("transition-script backup")
        group["fault_script"] = config.return_value("transition-script fault")
        group["stop_script"] = config.return_value("transition-script stop")
        group["script_mode_force"] = config.exists("transition-script mode-force")

        if config.exists("no-preempt"):
            group["preempt"] = False
        if config.exists("rfc3768-compatibility"):
            group["use_vmac"] = True

        # Substitute defaults where applicable
        if not group["advertise_interval"]:
            group["advertise_interval"] = 1
        if not group["priority"]:
            group["priority"] = 100
        if not group["preempt_delay"]:
            group["preempt_delay"] = 0
        if not group["health_check_interval"]:
            group["health_check_interval"] = 60
        if not group["health_check_count"]:
            group["health_check_count"] = 3

        # FIXUP: translate our option for auth type to keepalived's syntax
        # for simplicity
        if group["auth_type"]:
            if group["auth_type"] == "plaintext-password":
                group["auth_type"] = "PASS"
            else:
                group["auth_type"] = "AH"

        vrrp_groups.append(group)

    config.set_level("")

    # Get the sync group used for conntrack-sync
    conntrack_sync_group = None
    if config.exists("service conntrack-sync failover-mechanism vrrp"):
        conntrack_sync_group = config.return_value("service conntrack-sync failover-mechanism vrrp sync-group")

    # Get the sync groups
    for sync_group_name in config.list_nodes("high-availability vrrp sync-group"):
        config.set_level("high-availability vrrp sync-group {0}".format(sync_group_name))

        sync_group = {"conntrack_sync": False}
        sync_group["name"] = sync_group_name
        sync_group["members"] = config.return_values("member")
        if conntrack_sync_group:
            if conntrack_sync_group == sync_group_name:
                sync_group["conntrack_sync"] = True

        # add transition script configuration
        sync_group["master_script"] = config.return_value("transition-script master")
        sync_group["backup_script"] = config.return_value("transition-script backup")
        sync_group["fault_script"] = config.return_value("transition-script fault")
        sync_group["stop_script"] = config.return_value("transition-script stop")

        sync_groups.append(sync_group)

    # create a file with dict with proposed configuration
    dirname = os.path.dirname(VRRP.location['vyos'])
    makedir(dirname)
    with open(VRRP.location['vyos'] + ".temp", 'w') as dict_file:
        dict_file.write(dumps({'vrrp_groups': vrrp_groups, 'sync_groups': sync_groups}))

    return (vrrp_groups, sync_groups)


def verify(data):
    vrrp_groups, sync_groups = data

    for group in vrrp_groups:
        # Check required fields
        if not group["vrid"]:
            raise ConfigError("vrid is required but not set in VRRP group {0}".format(group["name"]))
        if not group["interface"]:
            raise ConfigError("interface is required but not set in VRRP group {0}".format(group["name"]))
        if not group["virtual_addresses"]:
            raise ConfigError("virtual-address is required but not set in VRRP group {0}".format(group["name"]))

        if group["auth_password"] and (not group["auth_type"]):
            raise ConfigError("authentication type is required but not set in VRRP group {0}".format(group["name"]))

        # Keepalived doesn't allow mixing IPv4 and IPv6 in one group, so we mirror that restriction

        # XXX: filter on map object is destructive, so we force it to list.
        # Additionally, filter objects always evaluate to True, empty or not,
        # so we force them to lists as well.
        vaddrs = list(map(lambda i: ip_interface(i), group["virtual_addresses"]))
        vaddrs4 = list(filter(lambda x: isinstance(x, IPv4Interface), vaddrs))
        vaddrs6 = list(filter(lambda x: isinstance(x, IPv6Interface), vaddrs))

        if vaddrs4 and vaddrs6:
            raise ConfigError("VRRP group {0} mixes IPv4 and IPv6 virtual addresses, this is not allowed. Create separate groups for IPv4 and IPv6".format(group["name"]))

        if vaddrs4:
            if group["hello_source"]:
                hsa = ip_address(group["hello_source"])
                if isinstance(hsa, IPv6Address):
                    raise ConfigError("VRRP group {0} uses IPv4 but its hello-source-address is IPv6".format(group["name"]))
            if group["peer_address"]:
                pa = ip_address(group["peer_address"])
                if isinstance(pa, IPv6Address):
                    raise ConfigError("VRRP group {0} uses IPv4 but its peer-address is IPv6".format(group["name"]))

        if vaddrs6:
            if group["hello_source"]:
                hsa = ip_address(group["hello_source"])
                if isinstance(hsa, IPv4Address):
                    raise ConfigError("VRRP group {0} uses IPv6 but its hello-source-address is IPv4".format(group["name"]))
            if group["peer_address"]:
                pa = ip_address(group["peer_address"])
                if isinstance(pa, IPv4Address):
                    raise ConfigError("VRRP group {0} uses IPv6 but its peer-address is IPv4".format(group["name"]))

        # Warn the user about the deprecated mode-force option
        if group["script_mode_force"]:
            print("""Warning: "transition-script mode-force" VRRP option is deprecated and will be removed in VyOS 1.4.""")
            print("""It's no longer necessary, so you can safely remove it from your config now.""")

    # Disallow same VRID on multiple interfaces
    _groups = sorted(vrrp_groups, key=(lambda x: x["interface"]))
    count = len(_groups) - 1
    index = 0
    while (index < count):
        if (_groups[index]["vrid"] == _groups[index + 1]["vrid"]) and (_groups[index]["interface"] == _groups[index + 1]["interface"]):
            raise ConfigError("VRID {0} is used in groups {1} and {2} that both use interface {3}. Groups on the same interface must use different VRIDs".format(
              _groups[index]["vrid"], _groups[index]["name"], _groups[index + 1]["name"], _groups[index]["interface"]))
        else:
            index += 1

    # Check sync groups
    vrrp_group_names = list(map(lambda x: x["name"], vrrp_groups))

    for sync_group in sync_groups:
        for m in sync_group["members"]:
            if not (m in vrrp_group_names):
                raise ConfigError("VRRP sync-group {0} refers to VRRP group {1}, but group {1} does not exist".format(sync_group["name"], m))


def generate(data):
    vrrp_groups, sync_groups = data

    # Remove disabled groups from the sync group member lists
    for sync_group in sync_groups:
        for member in sync_group["members"]:
            g = list(filter(lambda x: x["name"] == member, vrrp_groups))[0]
            if g["disable"]:
                print("Warning: ignoring disabled VRRP group {0} in sync-group {1}".format(g["name"], sync_group["name"]))
    # Filter out disabled groups
    vrrp_groups = list(filter(lambda x: x["disable"] is not True, vrrp_groups))

    render(VRRP.location['config'], 'vrrp/keepalived.conf.tmpl',
            {"groups": vrrp_groups, "sync_groups": sync_groups})
    render(VRRP.location['daemon'], 'vrrp/daemon.tmpl', {})
    return None


def apply(data):
    vrrp_groups, sync_groups = data
    if vrrp_groups:
        # safely rename a temporary file with configuration dict
        try:
            dict_file = Path("{}.temp".format(VRRP.location['vyos']))
            dict_file.rename(Path(VRRP.location['vyos']))
        except Exception as err:
            print("Unable to rename the file with keepalived config for FIFO pipe: {}".format(err))

        if not VRRP.is_running():
            print("Starting the VRRP process")
            ret = call("systemctl restart keepalived.service")
        else:
            print("Reloading the VRRP process")
            ret = call("systemctl reload keepalived.service")

        if ret != 0:
            raise ConfigError("keepalived failed to start")
    else:
        # VRRP is removed in the commit
        print("Stopping the VRRP process")
        call("systemctl stop keepalived.service")
        os.unlink(VRRP.location['daemon'])

    return None


if __name__ == '__main__':
    try:
        c = get_config()
        verify(c)
        generate(c)
        apply(c)
    except ConfigError as e:
        print("VRRP error: {0}".format(str(e)))
        exit(1)