#!/usr/bin/python
# Copyright: Ansible Project
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)

from __future__ import absolute_import, division, print_function
__metaclass__ = type


DOCUMENTATION = '''
---
module: ec2_vpc_subnet
version_added: 1.0.0
short_description: Manage subnets in AWS virtual private clouds
description:
    - Manage subnets in AWS virtual private clouds.
author:
- Robert Estelle (@erydo)
- Brad Davidson (@brandond)
requirements: [ boto3 ]
options:
  az:
    description:
      - "The availability zone for the subnet."
    type: str
  cidr:
    description:
      - "The CIDR block for the subnet. E.g. 192.0.2.0/24."
    type: str
    required: true
  ipv6_cidr:
    description:
      - "The IPv6 CIDR block for the subnet. The VPC must have a /56 block assigned and this value must be a valid IPv6 /64 that falls in the VPC range."
      - "Required if I(assign_instances_ipv6=true)"
    type: str
  tags:
    description:
      - "A dict of tags to apply to the subnet. Any tags currently applied to the subnet and not present here will be removed."
    aliases: [ 'resource_tags' ]
    type: dict
  state:
    description:
      - "Create or remove the subnet."
    default: present
    choices: [ 'present', 'absent' ]
    type: str
  vpc_id:
    description:
      - "VPC ID of the VPC in which to create or delete the subnet."
    required: true
    type: str
  map_public:
    description:
      - "Specify C(yes) to indicate that instances launched into the subnet should be assigned public IP address by default."
    type: bool
    default: 'no'
  assign_instances_ipv6:
    description:
      - "Specify C(yes) to indicate that instances launched into the subnet should be automatically assigned an IPv6 address."
    type: bool
    default: false
  wait:
    description:
      - "When I(wait=true) and I(state=present), module will wait for subnet to be in available state before continuing."
    type: bool
    default: true
  wait_timeout:
    description:
      - "Number of seconds to wait for subnet to become available I(wait=True)."
    default: 300
    type: int
  purge_tags:
    description:
      - Whether or not to remove tags that do not appear in the I(tags) list.
    type: bool
    default: true
extends_documentation_fragment:
- amazon.aws.aws
- amazon.aws.ec2

'''

EXAMPLES = '''
# Note: These examples do not set authentication details, see the AWS Guide for details.

- name: Create subnet for database servers
  amazon.aws.ec2_vpc_subnet:
    state: present
    vpc_id: vpc-123456
    cidr: 10.0.1.16/28
    tags:
      Name: Database Subnet
  register: database_subnet

- name: Remove subnet for database servers
  amazon.aws.ec2_vpc_subnet:
    state: absent
    vpc_id: vpc-123456
    cidr: 10.0.1.16/28

- name: Create subnet with IPv6 block assigned
  amazon.aws.ec2_vpc_subnet:
    state: present
    vpc_id: vpc-123456
    cidr: 10.1.100.0/24
    ipv6_cidr: 2001:db8:0:102::/64

- name: Remove IPv6 block assigned to subnet
  amazon.aws.ec2_vpc_subnet:
    state: present
    vpc_id: vpc-123456
    cidr: 10.1.100.0/24
    ipv6_cidr: ''
'''

RETURN = '''
subnet:
    description: Dictionary of subnet values
    returned: I(state=present)
    type: complex
    contains:
        id:
            description: Subnet resource id
            returned: I(state=present)
            type: str
            sample: subnet-b883b2c4
        cidr_block:
            description: The IPv4 CIDR of the Subnet
            returned: I(state=present)
            type: str
            sample: "10.0.0.0/16"
        ipv6_cidr_block:
            description: The IPv6 CIDR block actively associated with the Subnet
            returned: I(state=present)
            type: str
            sample: "2001:db8:0:102::/64"
        availability_zone:
            description: Availability zone of the Subnet
            returned: I(state=present)
            type: str
            sample: us-east-1a
        state:
            description: state of the Subnet
            returned: I(state=present)
            type: str
            sample: available
        tags:
            description: tags attached to the Subnet, includes name
            returned: I(state=present)
            type: dict
            sample: {"Name": "My Subnet", "env": "staging"}
        map_public_ip_on_launch:
            description: whether public IP is auto-assigned to new instances
            returned: I(state=present)
            type: bool
            sample: false
        assign_ipv6_address_on_creation:
            description: whether IPv6 address is auto-assigned to new instances
            returned: I(state=present)
            type: bool
            sample: false
        vpc_id:
            description: the id of the VPC where this Subnet exists
            returned: I(state=present)
            type: str
            sample: vpc-67236184
        available_ip_address_count:
            description: number of available IPv4 addresses
            returned: I(state=present)
            type: str
            sample: 251
        default_for_az:
            description: indicates whether this is the default Subnet for this Availability Zone
            returned: I(state=present)
            type: bool
            sample: false
        ipv6_association_id:
            description: The IPv6 association ID for the currently associated CIDR
            returned: I(state=present)
            type: str
            sample: subnet-cidr-assoc-b85c74d2
        ipv6_cidr_block_association_set:
            description: An array of IPv6 cidr block association set information.
            returned: I(state=present)
            type: complex
            contains:
                association_id:
                    description: The association ID
                    returned: always
                    type: str
                ipv6_cidr_block:
                    description: The IPv6 CIDR block that is associated with the subnet.
                    returned: always
                    type: str
                ipv6_cidr_block_state:
                    description: A hash/dict that contains a single item. The state of the cidr block association.
                    returned: always
                    type: dict
                    contains:
                        state:
                            description: The CIDR block association state.
                            returned: always
                            type: str
'''


import time

try:
    import botocore
except ImportError:
    pass  # caught by AnsibleAWSModule

from ansible.module_utils._text import to_text
from ansible.module_utils.common.dict_transformations import camel_dict_to_snake_dict

from ..module_utils.core import AnsibleAWSModule
from ..module_utils.ec2 import AWSRetry
from ..module_utils.ec2 import ansible_dict_to_boto3_filter_list
from ..module_utils.ec2 import ansible_dict_to_boto3_tag_list
from ..module_utils.ec2 import boto3_tag_list_to_ansible_dict
from ..module_utils.ec2 import compare_aws_tags
from ..module_utils.ec2 import describe_ec2_tags
from ..module_utils.ec2 import ensure_ec2_tags
from ..module_utils.waiters import get_waiter


def get_subnet_info(subnet):
    if 'Subnets' in subnet:
        return [get_subnet_info(s) for s in subnet['Subnets']]
    elif 'Subnet' in subnet:
        subnet = camel_dict_to_snake_dict(subnet['Subnet'])
    else:
        subnet = camel_dict_to_snake_dict(subnet)

    if 'tags' in subnet:
        subnet['tags'] = boto3_tag_list_to_ansible_dict(subnet['tags'])
    else:
        subnet['tags'] = dict()

    if 'subnet_id' in subnet:
        subnet['id'] = subnet['subnet_id']
        del subnet['subnet_id']

    subnet['ipv6_cidr_block'] = ''
    subnet['ipv6_association_id'] = ''
    ipv6set = subnet.get('ipv6_cidr_block_association_set')
    if ipv6set:
        for item in ipv6set:
            if item.get('ipv6_cidr_block_state', {}).get('state') in ('associated', 'associating'):
                subnet['ipv6_cidr_block'] = item['ipv6_cidr_block']
                subnet['ipv6_association_id'] = item['association_id']

    return subnet


def waiter_params(module, params, start_time):
    if not module.botocore_at_least("1.7.0"):
        remaining_wait_timeout = int(module.params['wait_timeout'] + start_time - time.time())
        params['WaiterConfig'] = {'Delay': 5, 'MaxAttempts': remaining_wait_timeout // 5}
    return params


def handle_waiter(conn, module, waiter_name, params, start_time):
    try:
        get_waiter(conn, waiter_name).wait(
            **waiter_params(module, params, start_time)
        )
    except botocore.exceptions.WaiterError as e:
        module.fail_json_aws(e, "Failed to wait for updates to complete")
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, "An exception happened while trying to wait for updates")


def create_subnet(conn, module, vpc_id, cidr, ipv6_cidr=None, az=None, start_time=None):
    wait = module.params['wait']
    wait_timeout = module.params['wait_timeout']

    params = dict(VpcId=vpc_id,
                  CidrBlock=cidr)

    if ipv6_cidr:
        params['Ipv6CidrBlock'] = ipv6_cidr

    if az:
        params['AvailabilityZone'] = az

    try:
        subnet = get_subnet_info(conn.create_subnet(aws_retry=True, **params))
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't create subnet")

    # Sometimes AWS takes its time to create a subnet and so using
    # new subnets's id to do things like create tags results in
    # exception.
    if wait and subnet.get('state') != 'available':
        handle_waiter(conn, module, 'subnet_exists', {'SubnetIds': [subnet['id']]}, start_time)
        handle_waiter(conn, module, 'subnet_available', {'SubnetIds': [subnet['id']]}, start_time)
        subnet['state'] = 'available'

    return subnet


def ensure_tags(conn, module, subnet, tags, purge_tags, start_time):

    changed = ensure_ec2_tags(
        conn, module, subnet['id'],
        resource_type='subnet',
        purge_tags=purge_tags,
        tags=tags,
        retry_codes=['InvalidSubnetID.NotFound'])

    if module.params['wait'] and not module.check_mode:
        # Wait for tags to be updated
        filters = [{'Name': 'tag:{0}'.format(k), 'Values': [v]} for k, v in tags.items()]
        handle_waiter(conn, module, 'subnet_exists',
                      {'SubnetIds': [subnet['id']], 'Filters': filters}, start_time)

    return changed


def ensure_map_public(conn, module, subnet, map_public, check_mode, start_time):
    if check_mode:
        return
    try:
        conn.modify_subnet_attribute(aws_retry=True, SubnetId=subnet['id'],
                                     MapPublicIpOnLaunch={'Value': map_public})
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't modify subnet attribute")


def ensure_assign_ipv6_on_create(conn, module, subnet, assign_instances_ipv6, check_mode, start_time):
    if check_mode:
        return
    try:
        conn.modify_subnet_attribute(aws_retry=True, SubnetId=subnet['id'],
                                     AssignIpv6AddressOnCreation={'Value': assign_instances_ipv6})
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't modify subnet attribute")


def disassociate_ipv6_cidr(conn, module, subnet, start_time):
    if subnet.get('assign_ipv6_address_on_creation'):
        ensure_assign_ipv6_on_create(conn, module, subnet, False, False, start_time)

    try:
        conn.disassociate_subnet_cidr_block(aws_retry=True, AssociationId=subnet['ipv6_association_id'])
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't disassociate ipv6 cidr block id {0} from subnet {1}"
                             .format(subnet['ipv6_association_id'], subnet['id']))

    # Wait for cidr block to be disassociated
    if module.params['wait']:
        filters = ansible_dict_to_boto3_filter_list(
            {'ipv6-cidr-block-association.state': ['disassociated'],
             'vpc-id': subnet['vpc_id']}
        )
        handle_waiter(conn, module, 'subnet_exists',
                      {'SubnetIds': [subnet['id']], 'Filters': filters}, start_time)


def ensure_ipv6_cidr_block(conn, module, subnet, ipv6_cidr, check_mode, start_time):
    wait = module.params['wait']
    changed = False

    if subnet['ipv6_association_id'] and not ipv6_cidr:
        if not check_mode:
            disassociate_ipv6_cidr(conn, module, subnet, start_time)
        changed = True

    if ipv6_cidr:
        filters = ansible_dict_to_boto3_filter_list({'ipv6-cidr-block-association.ipv6-cidr-block': ipv6_cidr,
                                                     'vpc-id': subnet['vpc_id']})

        try:
            _subnets = conn.describe_subnets(aws_retry=True, Filters=filters)
            check_subnets = get_subnet_info(_subnets)
        except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
            module.fail_json_aws(e, msg="Couldn't get subnet info")

        if check_subnets and check_subnets[0]['ipv6_cidr_block']:
            module.fail_json(msg="The IPv6 CIDR '{0}' conflicts with another subnet".format(ipv6_cidr))

        if subnet['ipv6_association_id']:
            if not check_mode:
                disassociate_ipv6_cidr(conn, module, subnet, start_time)
            changed = True

        try:
            if not check_mode:
                associate_resp = conn.associate_subnet_cidr_block(aws_retry=True, SubnetId=subnet['id'],
                                                                  Ipv6CidrBlock=ipv6_cidr)
            changed = True
        except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
            module.fail_json_aws(e, msg="Couldn't associate ipv6 cidr {0} to {1}".format(ipv6_cidr, subnet['id']))
        else:
            if not check_mode and wait:
                filters = ansible_dict_to_boto3_filter_list(
                    {'ipv6-cidr-block-association.state': ['associated'],
                     'vpc-id': subnet['vpc_id']}
                )
                handle_waiter(conn, module, 'subnet_exists',
                              {'SubnetIds': [subnet['id']], 'Filters': filters}, start_time)

        if associate_resp.get('Ipv6CidrBlockAssociation', {}).get('AssociationId'):
            subnet['ipv6_association_id'] = associate_resp['Ipv6CidrBlockAssociation']['AssociationId']
            subnet['ipv6_cidr_block'] = associate_resp['Ipv6CidrBlockAssociation']['Ipv6CidrBlock']
            if subnet['ipv6_cidr_block_association_set']:
                subnet['ipv6_cidr_block_association_set'][0] = camel_dict_to_snake_dict(associate_resp['Ipv6CidrBlockAssociation'])
            else:
                subnet['ipv6_cidr_block_association_set'].append(camel_dict_to_snake_dict(associate_resp['Ipv6CidrBlockAssociation']))

    return changed


def get_matching_subnet(conn, module, vpc_id, cidr):
    filters = ansible_dict_to_boto3_filter_list({'vpc-id': vpc_id, 'cidr-block': cidr})
    try:
        _subnets = conn.describe_subnets(aws_retry=True, Filters=filters)
        subnets = get_subnet_info(_subnets)
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't get matching subnet")

    if subnets:
        return subnets[0]

    return None


def ensure_subnet_present(conn, module):
    subnet = get_matching_subnet(conn, module, module.params['vpc_id'], module.params['cidr'])
    changed = False

    # Initialize start so max time does not exceed the specified wait_timeout for multiple operations
    start_time = time.time()

    if subnet is None:
        if not module.check_mode:
            subnet = create_subnet(conn, module, module.params['vpc_id'], module.params['cidr'],
                                   ipv6_cidr=module.params['ipv6_cidr'], az=module.params['az'], start_time=start_time)
        changed = True
        # Subnet will be None when check_mode is true
        if subnet is None:
            return {
                'changed': changed,
                'subnet': {}
            }
    if module.params['wait']:
        handle_waiter(conn, module, 'subnet_exists', {'SubnetIds': [subnet['id']]}, start_time)

    if module.params['ipv6_cidr'] != subnet.get('ipv6_cidr_block'):
        if ensure_ipv6_cidr_block(conn, module, subnet, module.params['ipv6_cidr'], module.check_mode, start_time):
            changed = True

    if module.params['map_public'] != subnet['map_public_ip_on_launch']:
        ensure_map_public(conn, module, subnet, module.params['map_public'], module.check_mode, start_time)
        changed = True

    if module.params['assign_instances_ipv6'] != subnet.get('assign_ipv6_address_on_creation'):
        ensure_assign_ipv6_on_create(conn, module, subnet, module.params['assign_instances_ipv6'], module.check_mode, start_time)
        changed = True

    if module.params['tags'] != subnet['tags']:
        stringified_tags_dict = dict((to_text(k), to_text(v)) for k, v in module.params['tags'].items())
        if ensure_tags(conn, module, subnet, stringified_tags_dict, module.params['purge_tags'], start_time):
            changed = True

    subnet = get_matching_subnet(conn, module, module.params['vpc_id'], module.params['cidr'])
    if not module.check_mode and module.params['wait']:
        # GET calls are not monotonic for map_public_ip_on_launch and assign_ipv6_address_on_creation
        # so we only wait for those if necessary just before returning the subnet
        subnet = ensure_final_subnet(conn, module, subnet, start_time)

    return {
        'changed': changed,
        'subnet': subnet
    }


def ensure_final_subnet(conn, module, subnet, start_time):
    for rewait in range(0, 30):
        map_public_correct = False
        assign_ipv6_correct = False

        if module.params['map_public'] == subnet['map_public_ip_on_launch']:
            map_public_correct = True
        else:
            if module.params['map_public']:
                handle_waiter(conn, module, 'subnet_has_map_public', {'SubnetIds': [subnet['id']]}, start_time)
            else:
                handle_waiter(conn, module, 'subnet_no_map_public', {'SubnetIds': [subnet['id']]}, start_time)

        if module.params['assign_instances_ipv6'] == subnet.get('assign_ipv6_address_on_creation'):
            assign_ipv6_correct = True
        else:
            if module.params['assign_instances_ipv6']:
                handle_waiter(conn, module, 'subnet_has_assign_ipv6', {'SubnetIds': [subnet['id']]}, start_time)
            else:
                handle_waiter(conn, module, 'subnet_no_assign_ipv6', {'SubnetIds': [subnet['id']]}, start_time)

        if map_public_correct and assign_ipv6_correct:
            break

        time.sleep(5)
        subnet = get_matching_subnet(conn, module, module.params['vpc_id'], module.params['cidr'])

    return subnet


def ensure_subnet_absent(conn, module):
    subnet = get_matching_subnet(conn, module, module.params['vpc_id'], module.params['cidr'])
    if subnet is None:
        return {'changed': False}

    try:
        if not module.check_mode:
            conn.delete_subnet(aws_retry=True, SubnetId=subnet['id'])
            if module.params['wait']:
                handle_waiter(conn, module, 'subnet_deleted', {'SubnetIds': [subnet['id']]}, time.time())
        return {'changed': True}
    except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
        module.fail_json_aws(e, msg="Couldn't delete subnet")


def main():
    argument_spec = dict(
        az=dict(default=None, required=False),
        cidr=dict(required=True),
        ipv6_cidr=dict(default='', required=False),
        state=dict(default='present', choices=['present', 'absent']),
        tags=dict(default={}, required=False, type='dict', aliases=['resource_tags']),
        vpc_id=dict(required=True),
        map_public=dict(default=False, required=False, type='bool'),
        assign_instances_ipv6=dict(default=False, required=False, type='bool'),
        wait=dict(type='bool', default=True),
        wait_timeout=dict(type='int', default=300, required=False),
        purge_tags=dict(default=True, type='bool')
    )

    required_if = [('assign_instances_ipv6', True, ['ipv6_cidr'])]

    module = AnsibleAWSModule(argument_spec=argument_spec, supports_check_mode=True, required_if=required_if)

    if module.params.get('assign_instances_ipv6') and not module.params.get('ipv6_cidr'):
        module.fail_json(msg="assign_instances_ipv6 is True but ipv6_cidr is None or an empty string")

    if not module.botocore_at_least("1.7.0"):
        module.warn("botocore >= 1.7.0 is required to use wait_timeout for custom wait times")

    retry_decorator = AWSRetry.jittered_backoff(retries=10)
    connection = module.client('ec2', retry_decorator=retry_decorator)

    state = module.params.get('state')

    try:
        if state == 'present':
            result = ensure_subnet_present(connection, module)
        elif state == 'absent':
            result = ensure_subnet_absent(connection, module)
    except botocore.exceptions.ClientError as e:
        module.fail_json_aws(e)

    module.exit_json(**result)


if __name__ == '__main__':
    main()
