#!/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/>.
#


ANSIBLE_METADATA = {'metadata_version': '1.1',
                    'status': ['preview'],
                    'supported_by': 'network'}

DOCUMENTATION = '''
---
module: nxos_hsrp
extends_documentation_fragment: nxos
version_added: "2.2"
short_description: Manages HSRP configuration on NX-OS switches.
description:
  - Manages HSRP configuration on NX-OS switches.
author:
  - Jason Edelman (@jedelman8)
  - Gabriele Gerbino (@GGabriele)
notes:
  - Tested against NXOSv 7.3.(0)D1(1) on VIRL
  - HSRP feature needs to be enabled first on the system.
  - SVIs must exist before using this module.
  - Interface must be a L3 port before using this module.
  - HSRP cannot be configured on loopback interfaces.
  - MD5 authentication is only possible with HSRPv2 while it is ignored if
    HSRPv1 is used instead, while it will not raise any error. Here we allow
    MD5 authentication only with HSRPv2 in order to enforce better practice.
options:
  group:
    description:
      - HSRP group number.
    required: true
  interface:
    description:
      - Full name of interface that is being managed for HSRP.
    required: true
  version:
    description:
      - HSRP version.
    required: false
    default: 2
    choices: ['1','2']
  priority:
    description:
      - HSRP priority.
    required: false
    default: null
  vip:
    description:
      - HSRP virtual IP address.
    required: false
    default: null
  auth_string:
    description:
      - Authentication string.
    required: false
    default: null
  auth_type:
    description:
      - Authentication type.
    required: false
    default: null
    choices: ['text','md5']
  state:
    description:
      - Specify desired state of the resource.
    required: false
    choices: ['present','absent']
    default: 'present'
'''

EXAMPLES = '''
- name: Ensure HSRP is configured with following params on a SVI
  nxos_hsrp:
    group: 10
    vip: 10.1.1.1
    priority: 150
    interface: vlan10
    preempt: enabled
    host: 68.170.147.165

- name: Ensure HSRP is configured with following params on a SVI
  nxos_hsrp:
    group: 10
    vip: 10.1.1.1
    priority: 150
    interface: vlan10
    preempt: enabled
    host: 68.170.147.165
    auth_type: text
    auth_string: CISCO

- name: Remove HSRP config for given interface, group, and VIP
  nxos_hsrp:
    group: 10
    interface: vlan10
    vip: 10.1.1.1
    host: 68.170.147.165
    state: absent
'''

RETURN = '''
commands:
    description: commands sent to the device
    returned: always
    type: list
    sample: ["interface vlan10", "hsrp version 2", "hsrp 30", "ip 10.30.1.1"]
'''

from ansible.module_utils.nxos import load_config, run_commands
from ansible.module_utils.nxos import nxos_argument_spec, check_args
from ansible.module_utils.basic import AnsibleModule


def execute_show_command(command, module):
    if module.params['transport'] == 'cli':
        command += ' | json'
        cmds = [command]
        body = run_commands(module, cmds)
    elif module.params['transport'] == 'nxapi':
        cmds = [command]
        body = run_commands(module, cmds)

    return body


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


def get_interface_type(interface):
    if interface.upper().startswith('ET'):
        return 'ethernet'
    elif interface.upper().startswith('VL'):
        return 'svi'
    elif interface.upper().startswith('LO'):
        return 'loopback'
    elif interface.upper().startswith('MG'):
        return 'management'
    elif interface.upper().startswith('MA'):
        return 'management'
    elif interface.upper().startswith('PO'):
        return 'portchannel'
    else:
        return 'unknown'


def get_interface_mode(interface, intf_type, module):
    command = 'show interface {0}'.format(interface)
    interface = {}
    mode = 'unknown'
    try:
        body = execute_show_command(command, module)[0]
    except IndexError:
        return None

    if intf_type in ['ethernet', 'portchannel']:
        interface_table = body['TABLE_interface']['ROW_interface']
        mode = str(interface_table.get('eth_mode', 'layer3'))
        if mode == 'access' or mode == 'trunk':
            mode = 'layer2'
    elif intf_type == 'svi':
        mode = 'layer3'
    return mode


def get_hsrp_groups_on_interfaces(device, module):
    command = 'show hsrp all'
    hsrp = {}

    try:
        body = execute_show_command(command, module)[0]
        get_data = body['TABLE_grp_detail']['ROW_grp_detail']
    except (IndexError, KeyError, AttributeError):
        return {}

    for entry in get_data:
        interface = str(entry['sh_if_index'].lower())
        value = hsrp.get(interface, 'new')
        if value == 'new':
            hsrp[interface] = []
        group = str(entry['sh_group_num'])
        hsrp[interface].append(group)

    return hsrp


def get_hsrp_group(group, interface, module):
    command = 'show hsrp group {0}'.format(group)
    hsrp = {}

    hsrp_key = {
        'sh_if_index': 'interface',
        'sh_group_num': 'group',
        'sh_group_version': 'version',
        'sh_cfg_prio': 'priority',
        'sh_preempt': 'preempt',
        'sh_vip': 'vip',
        'sh_authentication_type': 'auth_type',
        'sh_authentication_data': 'auth_string'
    }

    try:
        body = execute_show_command(command, module)[0]
        hsrp_table = body['TABLE_grp_detail']['ROW_grp_detail']
    except (AttributeError, IndexError, TypeError):
        return {}

    if isinstance(hsrp_table, dict):
        hsrp_table = [hsrp_table]

    for hsrp_group in hsrp_table:
        parsed_hsrp = apply_key_map(hsrp_key, hsrp_group)

        parsed_hsrp['interface'] = parsed_hsrp['interface'].lower()

        if parsed_hsrp['version'] == 'v1':
            parsed_hsrp['version'] = '1'
        elif parsed_hsrp['version'] == 'v2':
            parsed_hsrp['version'] = '2'

        if parsed_hsrp['interface'] == interface:
            return parsed_hsrp

    return hsrp


def get_commands_remove_hsrp(group, interface):
    commands = ['interface {0}'.format(interface), 'no hsrp {0}'.format(group)]
    return commands


def get_commands_config_hsrp(delta, interface, args):
    commands = []

    config_args = {
        'group': 'hsrp {group}',
        'priority': 'priority {priority}',
        'preempt': '{preempt}',
        'vip': 'ip {vip}'
    }

    preempt = delta.get('preempt', None)
    group = delta.get('group', None)
    if preempt:
        if preempt == 'enabled':
            delta['preempt'] = 'preempt'
        elif preempt == 'disabled':
            delta['preempt'] = 'no preempt'

    for key in delta:
        command = config_args.get(key, 'DNE').format(**delta)
        if command and command != 'DNE':
            if key == 'group':
                commands.insert(0, command)
            else:
                commands.append(command)
        command = None

    auth_type = delta.get('auth_type', None)
    auth_string = delta.get('auth_string', None)
    if auth_type or auth_string:
        if not auth_type:
            auth_type = args['auth_type']
        elif not auth_string:
            auth_string = args['auth_string']
        if auth_type == 'md5':
            command = 'authentication md5 key-string {0}'.format(auth_string)
            commands.append(command)
        elif auth_type == 'text':
            command = 'authentication text {0}'.format(auth_string)
            commands.append(command)

    if commands and not group:
        commands.insert(0, 'hsrp {0}'.format(args['group']))

    version = delta.get('version', None)
    if version:
        if version == '2':
            command = 'hsrp version 2'
        elif version == '1':
            command = 'hsrp version 1'
        commands.insert(0, command)
        commands.insert(0, 'interface {0}'.format(interface))

    if commands:
        if not commands[0].startswith('interface'):
            commands.insert(0, 'interface {0}'.format(interface))

    return commands


def is_default(interface, module):
    command = 'show run interface {0}'.format(interface)

    try:
        body = execute_show_command(command, module)[0]
        if 'invalid' in body.lower():
            return 'DNE'
        else:
            raw_list = body.split('\n')
            if raw_list[-1].startswith('interface'):
                return True
            else:
                return False
    except (KeyError):
        return 'DNE'


def validate_config(body, vip, module):
    new_body = ''.join(body)
    if "invalid ip address" in new_body.lower():
        module.fail_json(msg="Invalid VIP. Possible duplicate IP address.",
                         vip=vip)


def validate_params(param, module):
    value = module.params[param]
    version = module.params['version']

    if param == 'group':
        try:
            if (int(value) < 0 or int(value) > 255) and version == '1':
                raise ValueError
            elif int(value) < 0 or int(value) > 4095:
                raise ValueError
        except ValueError:
            module.fail_json(msg="Warning! 'group' must be an integer between"
                                 " 0 and 255 when version 1 and up to 4095 "
                                 "when version 2.", group=value,
                                 version=version)
    elif param == 'priority':
        try:
            if (int(value) < 0 or int(value) > 255):
                raise ValueError
        except ValueError:
            module.fail_json(msg="Warning! 'priority' must be an integer "
                                 "between 0 and 255", priority=value)


def main():
    argument_spec = dict(
        group=dict(required=True, type='str'),
        interface=dict(required=True),
        version=dict(choices=['1', '2'], default='2', required=False),
        priority=dict(type='str', required=False),
        preempt=dict(type='str', choices=['disabled', 'enabled'], required=False),
        vip=dict(type='str', required=False),
        auth_type=dict(choices=['text', 'md5'], required=False),
        auth_string=dict(type='str', required=False),
        state=dict(choices=['absent', 'present'], required=False, default='present')
    )

    argument_spec.update(nxos_argument_spec)

    module = AnsibleModule(argument_spec=argument_spec, supports_check_mode=True)

    warnings = list()
    check_args(module, warnings)
    results = dict(changed=False, warnings=warnings)

    interface = module.params['interface'].lower()
    group = module.params['group']
    version = module.params['version']
    state = module.params['state']
    priority = module.params['priority']
    preempt = module.params['preempt']
    vip = module.params['vip']
    auth_type = module.params['auth_type']
    auth_string = module.params['auth_string']

    transport = module.params['transport']

    if state == 'present' and not vip:
        module.fail_json(msg='the "vip" param is required when state=present')

    for param in ['group', 'priority']:
        if module.params[param] is not None:
            validate_params(param, module)

    intf_type = get_interface_type(interface)
    if (intf_type != 'ethernet' and transport == 'cli'):
        if is_default(interface, module) == 'DNE':
            module.fail_json(msg='That interface does not exist yet. Create '
                                 'it first.', interface=interface)
        if intf_type == 'loopback':
            module.fail_json(msg="Loopback interfaces don't support HSRP.",
                             interface=interface)

    mode = get_interface_mode(interface, intf_type, module)
    if mode == 'layer2':
        module.fail_json(msg='That interface is a layer2 port.\nMake it '
                             'a layer 3 port first.', interface=interface)

    if auth_type or auth_string:
        if not (auth_type and auth_string):
            module.fail_json(msg='When using auth parameters, you need BOTH '
                                 'auth_type AND auth_string.')

    args = dict(group=group, version=version, priority=priority,
                preempt=preempt, vip=vip, auth_type=auth_type,
                auth_string=auth_string)

    proposed = dict((k, v) for k, v in args.items() if v is not None)

    existing = get_hsrp_group(group, interface, module)

    # This will enforce better practice with md5 and hsrp version.
    if proposed.get('auth_type', None) == 'md5':
        if proposed['version'] == '1':
            module.fail_json(msg="It's recommended to use HSRP v2 "
                                 "when auth_type=md5")

    elif not proposed.get('auth_type', None) and existing:
        if (proposed['version'] == '1' and
                existing['auth_type'] == 'md5'):
            module.fail_json(msg="Existing auth_type is md5. It's recommended "
                                 "to use HSRP v2 when using md5")

    commands = []
    if state == 'present':
        delta = dict(
            set(proposed.items()).difference(existing.items()))
        if delta:
            command = get_commands_config_hsrp(delta, interface, args)
            commands.extend(command)

    elif state == 'absent':
        if existing:
            command = get_commands_remove_hsrp(group, interface)
            commands.extend(command)

    if commands:
        if module.check_mode:
            module.exit_json(**results)
        else:
            load_config(module, commands)

            # validate IP
            if transport == 'cli' and state == 'present':
                commands.insert(0, 'config t')
                body = run_commands(module, commands)
                validate_config(body, vip, module)

            results['changed'] = True

            if 'configure' in commands:
                commands.pop(0)

    results['commands'] = commands
    module.exit_json(**results)


if __name__ == '__main__':
    main()
