#!/usr/bin/python
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.
#
from __future__ import absolute_import, division, print_function

__metaclass__ = type


DOCUMENTATION = """
module: nxos_bgp
extends_documentation_fragment:
- cisco.nxos.nxos
short_description: Manages BGP configuration.
description:
- Manages BGP configurations on NX-OS switches.
version_added: 1.0.0
author:
- Jason Edelman (@jedelman8)
- Gabriele Gerbino (@GGabriele)
notes:
- Tested against NXOSv 7.3.(0)D1(1) on VIRL
- C(state=absent) removes the whole BGP ASN configuration when C(vrf=default) or the
  whole VRF instance within the BGP process when using a different VRF.
- Default when supported restores params default value.
- Configuring global params is only permitted if C(vrf=default).
options:
  asn:
    description:
    - BGP autonomous system number. Valid values are String, Integer in ASPLAIN or
      ASDOT notation.
    required: true
  vrf:
    description:
    - Name of the VRF. The name 'default' is a valid VRF representing the global BGP.
  bestpath_always_compare_med:
    description:
    - Enable/Disable MED comparison on paths from different autonomous systems.
    type: bool
  bestpath_aspath_multipath_relax:
    description:
    - Enable/Disable load sharing across the providers with different (but equal-length)
      AS paths.
    type: bool
  bestpath_compare_routerid:
    description:
    - Enable/Disable comparison of router IDs for identical eBGP paths.
    type: bool
  bestpath_compare_neighborid:
    description:
    - Enable/Disable neighborid. Use this when more paths available than max path
      config.
    type: bool
  bestpath_cost_community_ignore:
    description:
    - Enable/Disable Ignores the cost community for BGP best-path calculations.
    type: bool
  bestpath_med_confed:
    description:
    - Enable/Disable enforcement of bestpath to do a MED comparison only between paths
      originated within a confederation.
    type: bool
  bestpath_med_missing_as_worst:
    description:
    - Enable/Disable assigns the value of infinity to received routes that do not
      carry the MED attribute, making these routes the least desirable.
    type: bool
  bestpath_med_non_deterministic:
    description:
    - Enable/Disable deterministic selection of the best MED pat from among the paths
      from the same autonomous system.
    type: bool
  cluster_id:
    description:
    - Route Reflector Cluster-ID.
  confederation_id:
    description:
    - Routing domain confederation AS.
  confederation_peers:
    description:
    - AS confederation parameters.
  disable_policy_batching:
    description:
    - Enable/Disable the batching evaluation of prefix advertisement to all peers.
    type: bool
  disable_policy_batching_ipv4_prefix_list:
    description:
    - Enable/Disable the batching evaluation of prefix advertisements to all peers
      with prefix list.
  disable_policy_batching_ipv6_prefix_list:
    description:
    - Enable/Disable the batching evaluation of prefix advertisements to all peers
      with prefix list.
  enforce_first_as:
    description:
    - Enable/Disable enforces the neighbor autonomous system to be the first AS number
      listed in the AS path attribute for eBGP. On NX-OS, this property is only supported
      in the global BGP context.
    type: bool
  event_history_cli:
    description:
    - Enable/Disable cli event history buffer.
    choices:
    - size_small
    - size_medium
    - size_large
    - size_disable
    - default
  event_history_detail:
    description:
    - Enable/Disable detail event history buffer.
    choices:
    - size_small
    - size_medium
    - size_large
    - size_disable
    - default
  event_history_events:
    description:
    - Enable/Disable event history buffer.
    choices:
    - size_small
    - size_medium
    - size_large
    - size_disable
    - default
  event_history_periodic:
    description:
    - Enable/Disable periodic event history buffer.
    choices:
    - size_small
    - size_medium
    - size_large
    - size_disable
    - default
  fast_external_fallover:
    description:
    - Enable/Disable immediately reset the session if the link to a directly connected
      BGP peer goes down.  Only supported in the global BGP context.
    type: bool
  flush_routes:
    description:
    - Enable/Disable flush routes in RIB upon controlled restart. On NX-OS, this property
      is only supported in the global BGP context.
    type: bool
  graceful_restart:
    description:
    - Enable/Disable graceful restart.
    type: bool
  graceful_restart_helper:
    description:
    - Enable/Disable graceful restart helper mode.
    type: bool
  graceful_restart_timers_restart:
    description:
    - Set maximum time for a restart sent to the BGP peer.
  graceful_restart_timers_stalepath_time:
    description:
    - Set maximum time that BGP keeps the stale routes from the restarting BGP peer.
  isolate:
    description:
    - Enable/Disable isolate this router from BGP perspective.
    type: bool
  local_as:
    description:
    - Local AS number to be used within a VRF instance.
  log_neighbor_changes:
    description:
    - Enable/Disable message logging for neighbor up/down event.
    type: bool
  maxas_limit:
    description:
    - Specify Maximum number of AS numbers allowed in the AS-path attribute. Valid
      values are between 1 and 512.
  neighbor_down_fib_accelerate:
    description:
    - Enable/Disable handle BGP neighbor down event, due to various reasons.
    type: bool
  reconnect_interval:
    description:
    - The BGP reconnection interval for dropped sessions. Valid values are between
      1 and 60.
  router_id:
    description:
    - Router Identifier (ID) of the BGP router VRF instance.
  shutdown:
    description:
    - Administratively shutdown the BGP protocol.
    type: bool
  suppress_fib_pending:
    description:
    - Enable/Disable advertise only routes programmed in hardware to peers.
    type: bool
  timer_bestpath_limit:
    description:
    - Specify timeout for the first best path after a restart, in seconds.
  timer_bgp_hold:
    description:
    - Set BGP hold timer.
  timer_bgp_keepalive:
    description:
    - Set BGP keepalive timer.
  state:
    description:
    - Determines whether the config should be present or not on the device.
    default: present
    choices:
    - present
    - absent
"""


EXAMPLES = """
- name: Configure a simple ASN
  cisco.nxos.nxos_bgp:
    asn: 65535
    vrf: test
    router_id: 192.0.2.1
    state: present
"""

RETURN = """
commands:
    description: commands sent to the device
    returned: always
    type: list
    sample: ["router bgp 65535", "vrf test", "router-id 192.0.2.1"]
"""

import re

from ansible_collections.cisco.nxos.plugins.module_utils.network.nxos.nxos import (
    get_config,
    load_config,
)
from ansible_collections.cisco.nxos.plugins.module_utils.network.nxos.nxos import (
    nxos_argument_spec,
)
from ansible.module_utils.basic import AnsibleModule
from ansible_collections.ansible.netcommon.plugins.module_utils.network.common.config import (
    CustomNetworkConfig,
)


BOOL_PARAMS = [
    "bestpath_always_compare_med",
    "bestpath_aspath_multipath_relax",
    "bestpath_compare_neighborid",
    "bestpath_compare_routerid",
    "bestpath_cost_community_ignore",
    "bestpath_med_confed",
    "bestpath_med_missing_as_worst",
    "bestpath_med_non_deterministic",
    "disable_policy_batching",
    "enforce_first_as",
    "fast_external_fallover",
    "flush_routes",
    "graceful_restart",
    "graceful_restart_helper",
    "isolate",
    "log_neighbor_changes",
    "neighbor_down_fib_accelerate",
    "shutdown",
    "suppress_fib_pending",
]
GLOBAL_PARAMS = [
    "disable_policy_batching",
    "disable_policy_batching_ipv4_prefix_list",
    "disable_policy_batching_ipv6_prefix_list",
    "enforce_first_as",
    "event_history_cli",
    "event_history_detail",
    "event_history_events",
    "event_history_periodic",
    "fast_external_fallover",
    "flush_routes",
    "isolate",
    "suppress_fib_pending",
    "shutdown",
]
PARAM_TO_DEFAULT_KEYMAP = {
    "timer_bgp_keepalive": "60",
    "timer_bgp_hold": "180",
    "timer_bestpath_limit": "300",
    "graceful_restart": True,
    "graceful_restart_timers_restart": "120",
    "graceful_restart_timers_stalepath_time": "300",
    "reconnect_interval": "60",
    "suppress_fib_pending": True,
    "fast_external_fallover": True,
    "enforce_first_as": True,
    "event_history_cli": True,
    "event_history_detail": False,
    "event_history_events": True,
    "event_history_periodic": True,
    "maxas_limit": "",
    "router_id": "",
    "cluster_id": "",
    "disable_policy_batching_ipv4_prefix_list": "",
    "disable_policy_batching_ipv6_prefix_list": "",
    "local_as": "",
    "confederation_id": "",
}
PARAM_TO_COMMAND_KEYMAP = {
    "asn": "router bgp",
    "bestpath_always_compare_med": "bestpath always-compare-med",
    "bestpath_aspath_multipath_relax": "bestpath as-path multipath-relax",
    "bestpath_compare_neighborid": "bestpath compare-neighborid",
    "bestpath_compare_routerid": "bestpath compare-routerid",
    "bestpath_cost_community_ignore": "bestpath cost-community ignore",
    "bestpath_med_confed": "bestpath med confed",
    "bestpath_med_missing_as_worst": "bestpath med missing-as-worst",
    "bestpath_med_non_deterministic": "bestpath med non-deterministic",
    "cluster_id": "cluster-id",
    "confederation_id": "confederation identifier",
    "confederation_peers": "confederation peers",
    "disable_policy_batching": "disable-policy-batching",
    "disable_policy_batching_ipv4_prefix_list": "disable-policy-batching ipv4 prefix-list",
    "disable_policy_batching_ipv6_prefix_list": "disable-policy-batching ipv6 prefix-list",
    "enforce_first_as": "enforce-first-as",
    "event_history_cli": "event-history cli",
    "event_history_detail": "event-history detail",
    "event_history_events": "event-history events",
    "event_history_periodic": "event-history periodic",
    "fast_external_fallover": "fast-external-fallover",
    "flush_routes": "flush-routes",
    "graceful_restart": "graceful-restart",
    "graceful_restart_helper": "graceful-restart-helper",
    "graceful_restart_timers_restart": "graceful-restart restart-time",
    "graceful_restart_timers_stalepath_time": "graceful-restart stalepath-time",
    "isolate": "isolate",
    "local_as": "local-as",
    "log_neighbor_changes": "log-neighbor-changes",
    "maxas_limit": "maxas-limit",
    "neighbor_down_fib_accelerate": "neighbor-down fib-accelerate",
    "reconnect_interval": "reconnect-interval",
    "router_id": "router-id",
    "shutdown": "shutdown",
    "suppress_fib_pending": "suppress-fib-pending",
    "timer_bestpath_limit": "timers bestpath-limit",
    "timer_bgp_hold": "timers bgp",
    "timer_bgp_keepalive": "timers bgp",
    "vrf": "vrf",
}


def get_value(arg, config):
    command = PARAM_TO_COMMAND_KEYMAP.get(arg)

    if command.split()[0] == "event-history":
        has_size = re.search(
            r"^\s+{0} size\s(?P<value>.*)$".format(command), config, re.M
        )

        if command == "event-history detail":
            value = False
        else:
            value = "size_small"

        if has_size:
            value = "size_%s" % has_size.group("value")

    elif arg in ["enforce_first_as", "fast_external_fallover"]:
        no_command_re = re.compile(r"no\s+{0}\s*".format(command), re.M)
        value = True

        if no_command_re.search(config):
            value = False

    elif arg in BOOL_PARAMS:
        has_command = re.search(r"^\s+{0}\s*$".format(command), config, re.M)
        value = False

        if has_command:
            value = True
    else:
        command_val_re = re.compile(
            r"(?:{0}\s)(?P<value>.*)".format(command), re.M
        )
        value = ""

        has_command = command_val_re.search(config)
        if has_command:
            found_value = has_command.group("value")

            if arg == "confederation_peers":
                value = found_value.split()
            elif arg == "timer_bgp_keepalive":
                value = found_value.split()[0]
            elif arg == "timer_bgp_hold":
                split_values = found_value.split()
                if len(split_values) == 2:
                    value = split_values[1]
            elif found_value:
                value = found_value

    return value


def get_existing(module, args, warnings):
    existing = {}
    netcfg = CustomNetworkConfig(
        indent=2, contents=get_config(module, flags=["bgp all"])
    )

    asn_re = re.compile(
        r".*router\sbgp\s(?P<existing_asn>\d+(\.\d+)?).*", re.S
    )
    asn_match = asn_re.match(str(netcfg))

    if asn_match:
        existing_asn = asn_match.group("existing_asn")
        bgp_parent = "router bgp {0}".format(existing_asn)

        if module.params["vrf"] != "default":
            parents = [bgp_parent, "vrf {0}".format(module.params["vrf"])]
        else:
            parents = [bgp_parent]

        config = netcfg.get_section(parents)
        if config:
            for arg in args:
                if arg != "asn" and (
                    module.params["vrf"] == "default"
                    or arg not in GLOBAL_PARAMS
                ):
                    existing[arg] = get_value(arg, config)

            existing["asn"] = existing_asn
            if module.params["vrf"] == "default":
                existing["vrf"] = "default"

    if (
        not existing
        and module.params["vrf"] != "default"
        and module.params["state"] == "present"
    ):
        msg = "VRF {0} doesn't exist.".format(module.params["vrf"])
        warnings.append(msg)

    return existing


def apply_key_map(key_map, table):
    new_dict = {}
    for key in table:
        new_key = key_map.get(key)
        if new_key:
            new_dict[new_key] = table.get(key)

    return new_dict


def state_present(module, existing, proposed, candidate):
    commands = list()
    proposed_commands = apply_key_map(PARAM_TO_COMMAND_KEYMAP, proposed)
    existing_commands = apply_key_map(PARAM_TO_COMMAND_KEYMAP, existing)

    for key, value in proposed_commands.items():
        if value is True:
            commands.append(key)
        elif value is False:
            commands.append("no {0}".format(key))
        elif value == "default":
            default_value = PARAM_TO_DEFAULT_KEYMAP.get(key)
            existing_value = existing_commands.get(key)

            if default_value:
                commands.append("{0} {1}".format(key, default_value))
            elif existing_value:
                if key == "confederation peers":
                    existing_value = " ".join(existing_value)
                commands.append("no {0} {1}".format(key, existing_value))
        elif not value:
            existing_value = existing_commands.get(key)
            if existing_value:
                commands.append("no {0} {1}".format(key, existing_value))
        elif key == "confederation peers":
            commands.append("{0} {1}".format(key, value))
        elif key.startswith("timers bgp"):
            command = "timers bgp {0} {1}".format(
                proposed["timer_bgp_keepalive"], proposed["timer_bgp_hold"]
            )
            if command not in commands:
                commands.append(command)
        else:
            if value.startswith("size"):
                value = value.replace("_", " ")
            command = "{0} {1}".format(key, value)
            commands.append(command)

    parents = []
    if commands:
        commands = fix_commands(commands)
        parents = ["router bgp {0}".format(module.params["asn"])]
        if module.params["vrf"] != "default":
            parents.append("vrf {0}".format(module.params["vrf"]))
    elif proposed:
        if module.params["vrf"] != "default":
            commands.append("vrf {0}".format(module.params["vrf"]))
            parents = ["router bgp {0}".format(module.params["asn"])]
        else:
            commands.append("router bgp {0}".format(module.params["asn"]))

    candidate.add(commands, parents=parents)


def state_absent(module, existing, candidate):
    commands = []
    parents = []
    if module.params["vrf"] == "default":
        commands.append("no router bgp {0}".format(module.params["asn"]))
    elif existing.get("vrf") == module.params["vrf"]:
        commands.append("no vrf {0}".format(module.params["vrf"]))
        parents = ["router bgp {0}".format(module.params["asn"])]

    candidate.add(commands, parents=parents)


def fix_commands(commands):
    local_as_command = ""
    confederation_id_command = ""
    confederation_peers_command = ""

    for command in commands:
        if "local-as" in command:
            local_as_command = command
        elif "confederation identifier" in command:
            confederation_id_command = command
        elif "confederation peers" in command:
            confederation_peers_command = command

    if local_as_command and confederation_id_command:
        if "no" in confederation_id_command:
            commands.pop(commands.index(local_as_command))
            commands.pop(commands.index(confederation_id_command))
            commands.append(confederation_id_command)
            commands.append(local_as_command)
        else:
            commands.pop(commands.index(local_as_command))
            commands.pop(commands.index(confederation_id_command))
            commands.append(local_as_command)
            commands.append(confederation_id_command)

    if confederation_peers_command and confederation_id_command:
        if local_as_command:
            if "no" in local_as_command:
                commands.pop(commands.index(local_as_command))
                commands.pop(commands.index(confederation_id_command))
                commands.pop(commands.index(confederation_peers_command))
                commands.append(confederation_id_command)
                commands.append(confederation_peers_command)
                commands.append(local_as_command)
            else:
                commands.pop(commands.index(local_as_command))
                commands.pop(commands.index(confederation_id_command))
                commands.pop(commands.index(confederation_peers_command))
                commands.append(local_as_command)
                commands.append(confederation_id_command)
                commands.append(confederation_peers_command)
        else:
            commands.pop(commands.index(confederation_peers_command))
            commands.pop(commands.index(confederation_id_command))
            commands.append(confederation_id_command)
            commands.append(confederation_peers_command)

    return commands


def main():
    argument_spec = dict(
        asn=dict(required=True, type="str"),
        vrf=dict(required=False, type="str", default="default"),
        bestpath_always_compare_med=dict(required=False, type="bool"),
        bestpath_aspath_multipath_relax=dict(required=False, type="bool"),
        bestpath_compare_neighborid=dict(required=False, type="bool"),
        bestpath_compare_routerid=dict(required=False, type="bool"),
        bestpath_cost_community_ignore=dict(required=False, type="bool"),
        bestpath_med_confed=dict(required=False, type="bool"),
        bestpath_med_missing_as_worst=dict(required=False, type="bool"),
        bestpath_med_non_deterministic=dict(required=False, type="bool"),
        cluster_id=dict(required=False, type="str"),
        confederation_id=dict(required=False, type="str"),
        confederation_peers=dict(required=False, type="list"),
        disable_policy_batching=dict(required=False, type="bool"),
        disable_policy_batching_ipv4_prefix_list=dict(
            required=False, type="str"
        ),
        disable_policy_batching_ipv6_prefix_list=dict(
            required=False, type="str"
        ),
        enforce_first_as=dict(required=False, type="bool"),
        event_history_cli=dict(
            required=False,
            choices=[
                "true",
                "false",
                "default",
                "size_small",
                "size_medium",
                "size_large",
                "size_disable",
            ],
        ),
        event_history_detail=dict(
            required=False,
            choices=[
                "true",
                "false",
                "default",
                "size_small",
                "size_medium",
                "size_large",
                "size_disable",
            ],
        ),
        event_history_events=dict(
            required=False,
            choices=[
                "true",
                "false",
                "default",
                "size_small",
                "size_medium",
                "size_large",
                "size_disable",
            ],
        ),
        event_history_periodic=dict(
            required=False,
            choices=[
                "true",
                "false",
                "default",
                "size_small",
                "size_medium",
                "size_large",
                "size_disable",
            ],
        ),
        fast_external_fallover=dict(required=False, type="bool"),
        flush_routes=dict(required=False, type="bool"),
        graceful_restart=dict(required=False, type="bool"),
        graceful_restart_helper=dict(required=False, type="bool"),
        graceful_restart_timers_restart=dict(required=False, type="str"),
        graceful_restart_timers_stalepath_time=dict(
            required=False, type="str"
        ),
        isolate=dict(required=False, type="bool"),
        local_as=dict(required=False, type="str"),
        log_neighbor_changes=dict(required=False, type="bool"),
        maxas_limit=dict(required=False, type="str"),
        neighbor_down_fib_accelerate=dict(required=False, type="bool"),
        reconnect_interval=dict(required=False, type="str"),
        router_id=dict(required=False, type="str"),
        shutdown=dict(required=False, type="bool"),
        suppress_fib_pending=dict(required=False, type="bool"),
        timer_bestpath_limit=dict(required=False, type="str"),
        timer_bgp_hold=dict(required=False, type="str"),
        timer_bgp_keepalive=dict(required=False, type="str"),
        state=dict(
            choices=["present", "absent"], default="present", required=False
        ),
    )
    argument_spec.update(nxos_argument_spec)

    module = AnsibleModule(
        argument_spec=argument_spec,
        required_together=[["timer_bgp_hold", "timer_bgp_keepalive"]],
        supports_check_mode=True,
    )

    warnings = list()
    result = dict(changed=False, warnings=warnings)

    state = module.params["state"]

    if module.params["vrf"] != "default":
        for param in GLOBAL_PARAMS:
            if module.params[param]:
                module.fail_json(
                    msg='Global params can be modified only under "default" VRF.',
                    vrf=module.params["vrf"],
                    global_param=param,
                )

    args = PARAM_TO_COMMAND_KEYMAP.keys()
    existing = get_existing(module, args, warnings)

    if existing.get("asn") and state == "present":
        if existing.get("asn") != module.params["asn"]:
            module.fail_json(
                msg="Another BGP ASN already exists.",
                proposed_asn=module.params["asn"],
                existing_asn=existing.get("asn"),
            )

    proposed_args = dict(
        (k, v) for k, v in module.params.items() if v is not None and k in args
    )
    proposed = {}
    for key, value in proposed_args.items():
        if key not in ["asn", "vrf"]:
            if str(value).lower() == "default":
                value = PARAM_TO_DEFAULT_KEYMAP.get(key, "default")
            if key == "confederation_peers":
                if value[0] == "default":
                    if existing.get(key):
                        proposed[key] = "default"
                else:
                    v = set([int(i) for i in value])
                    ex = set([int(i) for i in existing.get(key)])
                    if v != ex:
                        proposed[key] = " ".join(str(s) for s in v)
            else:
                if existing.get(key) != value:
                    proposed[key] = value

    candidate = CustomNetworkConfig(indent=3)
    if state == "present":
        state_present(module, existing, proposed, candidate)
    elif existing.get("asn") == module.params["asn"]:
        state_absent(module, existing, candidate)

    if candidate:
        candidate = candidate.items_text()
        if not module.check_mode:
            load_config(module, candidate)
        result["changed"] = True
        result["commands"] = candidate
    else:
        result["commands"] = []

    module.exit_json(**result)


if __name__ == "__main__":
    main()
