#!/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/>.
#


DOCUMENTATION = '''
---
module: nxos_hsrp
version_added: "2.2"
short_description: Manages HSRP configuration on NX-OS switches
description:
    - Manages HSRP configuration on NX-OS switches
extends_documentation_fragment: nxos
author:
    - Jason Edelman (@jedelman8)
    - Gabriele Gerbino (@GGabriele)
notes:
    - 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 = '''
# 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
# 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
# removing 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 = '''
proposed:
    description: k/v pairs of parameters passed into module
    returned: always
    type: dict
    sample: {"group": "30", "version": "2", "vip": "10.30.1.1"}
existing:
    description: k/v pairs of existing hsrp info on the interface
    type: dict
    sample: {}
end_state:
    description: k/v pairs of hsrp after module execution
    returned: always
    type: dict
    sample: {"auth_string": "cisco", "auth_type": "text",
            "group": "30", "interface": "vlan10", "preempt": "disabled",
            "priority": "100", "version": "2", "vip": "10.30.1.1"}
updates:
    description: commands sent to the device
    returned: always
    type: list
    sample: ["interface vlan10", "hsrp version 2", "hsrp 30", "ip 10.30.1.1"]
changed:
    description: check to see if a change was made on the device
    returned: always
    type: boolean
    sample: true
'''

# COMMON CODE FOR MIGRATION

import re
import time
import collections
import itertools
import shlex
import json

from ansible.module_utils.basic import AnsibleModule, env_fallback, get_exception
from ansible.module_utils.basic import BOOLEANS_TRUE, BOOLEANS_FALSE
from ansible.module_utils.shell import Shell, ShellError, HAS_PARAMIKO
from ansible.module_utils.netcfg import parse
from ansible.module_utils.urls import fetch_url


DEFAULT_COMMENT_TOKENS = ['#', '!']

class ConfigLine(object):

    def __init__(self, text):
        self.text = text
        self.children = list()
        self.parents = list()
        self.raw = None

    @property
    def line(self):
        line = ['set']
        line.extend([p.text for p in self.parents])
        line.append(self.text)
        return ' '.join(line)

    def __str__(self):
        return self.raw

    def __eq__(self, other):
        if self.text == other.text:
            return self.parents == other.parents

    def __ne__(self, other):
        return not self.__eq__(other)

def ignore_line(text, tokens=None):
    for item in (tokens or DEFAULT_COMMENT_TOKENS):
        if text.startswith(item):
            return True

def get_next(iterable):
    item, next_item = itertools.tee(iterable, 2)
    next_item = itertools.islice(next_item, 1, None)
    return itertools.izip_longest(item, next_item)

def parse(lines, indent, comment_tokens=None):
    toplevel = re.compile(r'\S')
    childline = re.compile(r'^\s*(.+)$')

    ancestors = list()
    config = list()

    for line in str(lines).split('\n'):
        text = str(re.sub(r'([{};])', '', line)).strip()

        cfg = ConfigLine(text)
        cfg.raw = line

        if not text or ignore_line(text, comment_tokens):
            continue

        # handle top level commands
        if toplevel.match(line):
            ancestors = [cfg]

        # handle sub level commands
        else:
            match = childline.match(line)
            line_indent = match.start(1)
            level = int(line_indent / indent)
            parent_level = level - 1

            cfg.parents = ancestors[:level]

            if level > len(ancestors):
                config.append(cfg)
                continue

            for i in range(level, len(ancestors)):
                ancestors.pop()

            ancestors.append(cfg)
            ancestors[parent_level].children.append(cfg)

        config.append(cfg)

    return config


class CustomNetworkConfig(object):

    def __init__(self, indent=None, contents=None, device_os=None):
        self.indent = indent or 1
        self._config = list()
        self._device_os = device_os

        if contents:
            self.load(contents)

    @property
    def items(self):
        return self._config

    @property
    def lines(self):
        lines = list()
        for item, next_item in get_next(self.items):
            if next_item is None:
                lines.append(item.line)
            elif not next_item.line.startswith(item.line):
                lines.append(item.line)
        return lines

    def __str__(self):
        text = ''
        for item in self.items:
            if not item.parents:
                expand = self.get_section(item.text)
                text += '%s\n' % self.get_section(item.text)
        return str(text).strip()

    def load(self, contents):
        self._config = parse(contents, indent=self.indent)

    def load_from_file(self, filename):
        self.load(open(filename).read())

    def get(self, path):
        if isinstance(path, basestring):
            path = [path]
        for item in self._config:
            if item.text == path[-1]:
                parents = [p.text for p in item.parents]
                if parents == path[:-1]:
                    return item

    def search(self, regexp, path=None):
        regex = re.compile(r'^%s' % regexp, re.M)

        if path:
            parent = self.get(path)
            if not parent or not parent.children:
                return
            children = [c.text for c in parent.children]
            data = '\n'.join(children)
        else:
            data = str(self)

        match = regex.search(data)
        if match:
            if match.groups():
                values = match.groupdict().values()
                groups = list(set(match.groups()).difference(values))
                return (groups, match.groupdict())
            else:
                return match.group()

    def findall(self, regexp):
        regexp = r'%s' % regexp
        return re.findall(regexp, str(self))

    def expand(self, obj, items):
        block = [item.raw for item in obj.parents]
        block.append(obj.raw)

        current_level = items
        for b in block:
            if b not in current_level:
                current_level[b] = collections.OrderedDict()
            current_level = current_level[b]
        for c in obj.children:
            if c.raw not in current_level:
                current_level[c.raw] = collections.OrderedDict()

    def to_lines(self, section):
        lines = list()
        for entry in section[1:]:
            line = ['set']
            line.extend([p.text for p in entry.parents])
            line.append(entry.text)
            lines.append(' '.join(line))
        return lines

    def to_block(self, section):
        return '\n'.join([item.raw for item in section])

    def get_section(self, path):
        try:
            section = self.get_section_objects(path)
            if self._device_os == 'junos':
                return self.to_lines(section)
            return self.to_block(section)
        except ValueError:
            return list()

    def get_section_objects(self, path):
        if not isinstance(path, list):
            path = [path]
        obj = self.get_object(path)
        if not obj:
            raise ValueError('path does not exist in config')
        return self.expand_section(obj)

    def expand_section(self, configobj, S=None):
        if S is None:
            S = list()
        S.append(configobj)
        for child in configobj.children:
            if child in S:
                continue
            self.expand_section(child, S)
        return S

    def flatten(self, data, obj=None):
        if obj is None:
            obj = list()
        for k, v in data.items():
            obj.append(k)
            self.flatten(v, obj)
        return obj

    def get_object(self, path):
        for item in self.items:
            if item.text == path[-1]:
                parents = [p.text for p in item.parents]
                if parents == path[:-1]:
                    return item

    def get_children(self, path):
        obj = self.get_object(path)
        if obj:
            return obj.children

    def difference(self, other, path=None, match='line', replace='line'):
        updates = list()

        config = self.items
        if path:
            config = self.get_children(path) or list()

        if match == 'line':
            for item in config:
                if item not in other.items:
                    updates.append(item)

        elif match == 'strict':
            if path:
                current = other.get_children(path) or list()
            else:
                current = other.items

            for index, item in enumerate(config):
                try:
                    if item != current[index]:
                        updates.append(item)
                except IndexError:
                    updates.append(item)

        elif match == 'exact':
            if path:
                current = other.get_children(path) or list()
            else:
                current = other.items

            if len(current) != len(config):
                updates.extend(config)
            else:
                for ours, theirs in itertools.izip(config, current):
                    if ours != theirs:
                        updates.extend(config)
                        break

        if self._device_os == 'junos':
            return updates

        diffs = collections.OrderedDict()
        for update in updates:
            if replace == 'block' and update.parents:
                update = update.parents[-1]
            self.expand(update, diffs)

        return self.flatten(diffs)

    def replace(self, replace, text=None, regex=None, parents=None,
            add_if_missing=False, ignore_whitespace=False):
        match = None

        parents = parents or list()
        if text is None and regex is None:
            raise ValueError('missing required arguments')

        if not regex:
            regex = ['^%s$' % text]

        patterns = [re.compile(r, re.I) for r in to_list(regex)]

        for item in self.items:
            for regexp in patterns:
                if ignore_whitespace is True:
                    string = item.text
                else:
                    string = item.raw
                if regexp.search(item.text):
                    if item.text != replace:
                        if parents == [p.text for p in item.parents]:
                            match = item
                            break

        if match:
            match.text = replace
            indent = len(match.raw) - len(match.raw.lstrip())
            match.raw = replace.rjust(len(replace) + indent)

        elif add_if_missing:
            self.add(replace, parents=parents)


    def add(self, lines, parents=None):
        """Adds one or lines of configuration
        """

        ancestors = list()
        offset = 0
        obj = None

        ## global config command
        if not parents:
            for line in to_list(lines):
                item = ConfigLine(line)
                item.raw = line
                if item not in self.items:
                    self.items.append(item)

        else:
            for index, p in enumerate(parents):
                try:
                    i = index + 1
                    obj = self.get_section_objects(parents[:i])[0]
                    ancestors.append(obj)

                except ValueError:
                    # add parent to config
                    offset = index * self.indent
                    obj = ConfigLine(p)
                    obj.raw = p.rjust(len(p) + offset)
                    if ancestors:
                        obj.parents = list(ancestors)
                        ancestors[-1].children.append(obj)
                    self.items.append(obj)
                    ancestors.append(obj)

            # add child objects
            for line in to_list(lines):
                # check if child already exists
                for child in ancestors[-1].children:
                    if child.text == line:
                        break
                else:
                    offset = len(parents) * self.indent
                    item = ConfigLine(line)
                    item.raw = line.rjust(len(line) + offset)
                    item.parents = ancestors
                    ancestors[-1].children.append(item)
                    self.items.append(item)


def argument_spec():
    return dict(
        # config options
        running_config=dict(aliases=['config']),
        save_config=dict(type='bool', default=False, aliases=['save'])
    )
nxos_argument_spec = argument_spec()


NET_PASSWD_RE = re.compile(r"[\r\n]?password: $", re.I)

NET_COMMON_ARGS = dict(
    host=dict(required=True),
    port=dict(type='int'),
    username=dict(fallback=(env_fallback, ['ANSIBLE_NET_USERNAME'])),
    password=dict(no_log=True, fallback=(env_fallback, ['ANSIBLE_NET_PASSWORD'])),
    ssh_keyfile=dict(fallback=(env_fallback, ['ANSIBLE_NET_SSH_KEYFILE']), type='path'),
    transport=dict(default='cli', choices=['cli', 'nxapi']),
    use_ssl=dict(default=False, type='bool'),
    validate_certs=dict(default=True, type='bool'),
    provider=dict(type='dict'),
    timeout=dict(default=10, type='int')
)

NXAPI_COMMAND_TYPES = ['cli_show', 'cli_show_ascii', 'cli_conf', 'bash']

NXAPI_ENCODINGS = ['json', 'xml']

CLI_PROMPTS_RE = [
    re.compile(r'[\r\n]?[a-zA-Z]{1}[a-zA-Z0-9-]*[>|#|%](?:\s*)$'),
    re.compile(r'[\r\n]?[a-zA-Z]{1}[a-zA-Z0-9-]*\(.+\)#(?:\s*)$')
]

CLI_ERRORS_RE = [
    re.compile(r"% ?Error"),
    re.compile(r"^% \w+", re.M),
    re.compile(r"% ?Bad secret"),
    re.compile(r"invalid input", re.I),
    re.compile(r"(?:incomplete|ambiguous) command", re.I),
    re.compile(r"connection timed out", re.I),
    re.compile(r"[^\r\n]+ not found", re.I),
    re.compile(r"'[^']' +returned error code: ?\d+"),
    re.compile(r"syntax error"),
    re.compile(r"unknown command")
]


def to_list(val):
    if isinstance(val, (list, tuple)):
        return list(val)
    elif val is not None:
        return [val]
    else:
        return list()


class Nxapi(object):

    def __init__(self, module):
        self.module = module

        # sets the module_utils/urls.py req parameters
        self.module.params['url_username'] = module.params['username']
        self.module.params['url_password'] = module.params['password']

        self.url = None
        self._nxapi_auth = None

    def _get_body(self, commands, command_type, encoding, version='1.0', chunk='0', sid=None):
        """Encodes a NXAPI JSON request message
        """
        if isinstance(commands, (list, set, tuple)):
            commands = ' ;'.join(commands)

        if encoding not in NXAPI_ENCODINGS:
            msg = 'invalid encoding, received %s, exceped one of %s' % \
                    (encoding, ','.join(NXAPI_ENCODINGS))
            self.module_fail_json(msg=msg)

        msg = {
            'version': version,
            'type': command_type,
            'chunk': chunk,
            'sid': sid,
            'input': commands,
            'output_format': encoding
        }
        return dict(ins_api=msg)

    def connect(self):
        host = self.module.params['host']
        port = self.module.params['port']

        if self.module.params['use_ssl']:
            proto = 'https'
            if not port:
                port = 443
        else:
            proto = 'http'
            if not port:
                port = 80

        self.url = '%s://%s:%s/ins' % (proto, host, port)

    def send(self, commands, command_type='cli_show_ascii', encoding='json'):
        """Send commands to the device.
        """
        clist = to_list(commands)

        if command_type not in NXAPI_COMMAND_TYPES:
            msg = 'invalid command_type, received %s, exceped one of %s' % \
                    (command_type, ','.join(NXAPI_COMMAND_TYPES))
            self.module_fail_json(msg=msg)

        data = self._get_body(clist, command_type, encoding)
        data = self.module.jsonify(data)

        headers = {'Content-Type': 'application/json'}
        if self._nxapi_auth:
            headers['Cookie'] = self._nxapi_auth

        response, headers = fetch_url(self.module, self.url, data=data,
                headers=headers, method='POST')

        self._nxapi_auth = headers.get('set-cookie')

        if headers['status'] != 200:
            self.module.fail_json(**headers)

        response = self.module.from_json(response.read())
        result = list()

        output = response['ins_api']['outputs']['output']
        for item in to_list(output):
            if item['code'] != '200':
                self.module.fail_json(**item)
            else:
                result.append(item['body'])

        return result


class Cli(object):

    def __init__(self, module):
        self.module = module
        self.shell = None

    def connect(self, **kwargs):
        host = self.module.params['host']
        port = self.module.params['port'] or 22

        username = self.module.params['username']
        password = self.module.params['password']
        timeout = self.module.params['timeout']
        key_filename = self.module.params['ssh_keyfile']

        allow_agent = (key_filename is not None) or (key_filename is None and password is None)

        try:
            self.shell = Shell(kickstart=False, prompts_re=CLI_PROMPTS_RE,
                    errors_re=CLI_ERRORS_RE)
            self.shell.open(host, port=port, username=username,
                    password=password, key_filename=key_filename,
                    allow_agent=allow_agent, timeout=timeout)
        except ShellError:
            e = get_exception()
            msg = 'failed to connect to %s:%s - %s' % (host, port, str(e))
            self.module.fail_json(msg=msg)

    def send(self, commands, encoding='text'):
        try:
            return self.shell.send(commands)
        except ShellError:
            e = get_exception()
            self.module.fail_json(msg=e.message, commands=commands)


class NetworkModule(AnsibleModule):

    def __init__(self, *args, **kwargs):
        super(NetworkModule, self).__init__(*args, **kwargs)
        self.connection = None
        self._config = None
        self._connected = False

    @property
    def connected(self):
        return self._connected

    @property
    def config(self):
        if not self._config:
            self._config = self.get_config()
        return self._config

    def _load_params(self):
        super(NetworkModule, self)._load_params()
        provider = self.params.get('provider') or dict()
        for key, value in provider.items():
            if key in NET_COMMON_ARGS:
                if self.params.get(key) is None and value is not None:
                    self.params[key] = value

    def connect(self):
        cls = globals().get(str(self.params['transport']).capitalize())
        try:
            self.connection = cls(self)
        except TypeError:
            e = get_exception()
            self.fail_json(msg=e.message)

        self.connection.connect()

        if self.params['transport'] == 'cli':
            self.connection.send('terminal length 0')

        self._connected = True

    def configure(self, commands):
        commands = to_list(commands)
        if self.params['transport'] == 'cli':
            return self.configure_cli(commands)
        else:
            return self.execute(commands, command_type='cli_conf')

    def configure_cli(self, commands):
        commands = to_list(commands)
        commands.insert(0, 'configure')
        responses = self.execute(commands)
        responses.pop(0)
        return responses

    def execute(self, commands, **kwargs):
        if not self.connected:
            self.connect()
        return self.connection.send(commands, **kwargs)

    def disconnect(self):
        self.connection.close()
        self._connected = False

    def parse_config(self, cfg):
        return parse(cfg, indent=2)

    def get_config(self):
        cmd = 'show running-config'
        if self.params.get('include_defaults'):
            cmd += ' all'
        response = self.execute(cmd)
        return response[0]


def get_module(**kwargs):
    """Return instance of NetworkModule
    """
    argument_spec = NET_COMMON_ARGS.copy()
    if kwargs.get('argument_spec'):
        argument_spec.update(kwargs['argument_spec'])
    kwargs['argument_spec'] = argument_spec

    module = NetworkModule(**kwargs)

    if module.params['transport'] == 'cli' and not HAS_PARAMIKO:
        module.fail_json(msg='paramiko is required but does not appear to be installed')

    return module


def custom_get_config(module, include_defaults=False):
    config = module.params['running_config']
    if not config:
        cmd = 'show running-config'
        if module.params['include_defaults']:
            cmd += ' all'
        if module.params['transport'] == 'nxapi':
            config = module.execute([cmd], command_type='cli_show_ascii')[0]
        else:
            config = module.execute([cmd])[0]

    return CustomNetworkConfig(indent=2, contents=config)

def load_config(module, candidate):
    config = custom_get_config(module)

    commands = candidate.difference(config)
    commands = [str(c).strip() for c in commands]

    save_config = module.params['save_config']

    result = dict(changed=False)

    if commands:
        if not module.check_mode:
            module.configure(commands)
            if save_config:
                module.config.save_config()

        result['changed'] = True
        result['updates'] = commands

    return result
# END OF COMMON CODE

def execute_config_command(commands, module):
    try:
        body = module.configure(commands)
    except ShellError:
        clie = get_exception()
        module.fail_json(msg='Error sending CLI commands',
                         error=str(clie), commands=commands)
    return body


def get_cli_body_ssh(command, response, module):
    """Get response for when transport=cli.  This is kind of a hack and mainly
    needed because these modules were originally written for NX-API.  And
    not every command supports "| json" when using cli/ssh.  As such, we assume
    if | json returns an XML string, it is a valid command, but that the
    resource doesn't exist yet. Instead, the output will be a raw string
    when issuing commands containing 'show run'.
    """
    if 'xml' in response[0]:
        body = []
    elif 'show run' in command:
        body = response
    else:
        try:
            response = response[0].replace(command + '\n\n', '').strip()
            body = [json.loads(response)]
        except ValueError:
            module.fail_json(msg='Command does not support JSON output',
                             command=command)
    return body


def execute_show(cmds, module, command_type=None):
    try:
        if command_type:
            response = module.execute(cmds, command_type=command_type)
        else:
            response = module.execute(cmds)
    except ShellError:
        clie = get_exception()
        module.fail_json(msg='Error sending {0}'.format(command),
                         error=str(clie))
    return response


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

    return body


def apply_key_map(key_map, table):
    new_dict = {}
    for key, value in table.items():
        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'

    if intf_type in ['ethernet', 'portchannel']:
        body = execute_show_command(command, module)[0]
        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):
    command = 'show hsrp all'
    body = execute_show_command(command, module)
    hsrp = {}

    try:
        get_data = body[0]['TABLE_grp_detail']['ROW_grp_detail']
    except (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)
    body = execute_show_command(command, module)
    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:
        hsrp_table = body[0]['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 = []
    commands.append('interface {0}'.format(interface))
    commands.append('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, value in delta.iteritems():
        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'),
    )
    module = get_module(argument_spec=argument_spec,
                        supports_check_mode=True)

    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.iteritems() 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")

    changed = False
    end_state = existing
    commands = []
    if state == 'present':
        delta = dict(
                    set(proposed.iteritems()).difference(existing.iteritems()))
        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(changed=True, commands=commands)
        else:
            body = execute_config_command(commands, module)
            if transport == 'cli':
                validate_config(body, vip, module)
            changed = True
            end_state = get_hsrp_group(group, interface, module)

    results = {}
    results['proposed'] = proposed
    results['existing'] = existing
    results['end_state'] = end_state
    results['updates'] = commands
    results['changed'] = changed

    module.exit_json(**results)


if __name__ == '__main__':
    main()