#!/usr/bin/python
DOCUMENTATION = '''
---
module: ec2_eip
short_description: associate an EC2 elastic IP with an instance.
description:
    - This module associates AWS EC2 elastic IP addresses with instances
version_added: 1.4
options:
  instance_id:
    description:
      - The EC2 instance id
    required: false
  public_ip:
    description:
      - The elastic IP address to associate with the instance.
      - If absent, allocate a new address
    required: false
  state:
    description:
      - If present, associate the IP with the instance.
      - If absent, disassociate the IP with the instance.
    required: false
    choices: ['present', 'absent']
    default: present
  region:
    description:
      - the EC2 region to use
    required: false
    default: null
    aliases: [ ec2_region ]
  in_vpc:
    description:
      - allocate an EIP inside a VPC or not
    required: false
    default: false
    version_added: "1.4"
  reuse_existing_ip_allowed:
    description:
      - Reuse an EIP that is not associated to an instance (when available),'''
''' instead of allocating a new one.
    required: false
    default: false
    version_added: "1.6"

extends_documentation_fragment: aws
author: "Lorin Hochstein (@lorin) <lorin@nimbisservices.com>"
notes:
   - This module will return C(public_ip) on success, which will contain the
     public IP address associated with the instance.
   - There may be a delay between the time the Elastic IP is assigned and when
     the cloud instance is reachable via the new address. Use wait_for and
     pause to delay further playbook execution until the instance is reachable,
     if necessary.
'''

EXAMPLES = '''
- name: associate an elastic IP with an instance
  ec2_eip: instance_id=i-1212f003 ip=93.184.216.119

- name: disassociate an elastic IP from an instance
  ec2_eip: instance_id=i-1212f003 ip=93.184.216.119 state=absent

- name: allocate a new elastic IP and associate it with an instance
  ec2_eip: instance_id=i-1212f003

- name: allocate a new elastic IP without associating it to anything
  action: ec2_eip
  register: eip
- name: output the IP
  debug: msg="Allocated IP is {{ eip.public_ip }}"

- name: another way of allocating an elastic IP without associating it to anything
  ec2_eip: state='present'

- name: provision new instances with ec2
  ec2: keypair=mykey instance_type=c1.medium image=emi-40603AD1 wait=yes'''
''' group=webserver count=3
  register: ec2
- name: associate new elastic IPs with each of the instances
  ec2_eip: "instance_id={{ item }}"
  with_items: ec2.instance_ids

- name: allocate a new elastic IP inside a VPC in us-west-2
  ec2_eip: region=us-west-2 in_vpc=yes
  register: eip
- name: output the IP
  debug: msg="Allocated IP inside a VPC is {{ eip.public_ip }}"
'''

try:
    import boto.ec2
    HAS_BOTO = True
except ImportError:
    HAS_BOTO = False


class EIPException(Exception):
    pass


def associate_ip_and_instance(ec2, address, instance_id, check_mode):
    if address_is_associated_with_instance(ec2, address, instance_id):
        return {'changed': False}

    # If we're in check mode, nothing else to do
    if not check_mode:
        if address.domain == 'vpc':
            res = ec2.associate_address(instance_id,
                                        allocation_id=address.allocation_id)
        else:
            res = ec2.associate_address(instance_id,
                                        public_ip=address.public_ip)
        if not res:
            raise EIPException('association failed')

    return {'changed': True}


def disassociate_ip_and_instance(ec2, address, instance_id, check_mode):
    if not address_is_associated_with_instance(ec2, address, instance_id):
        return {'changed': False}

    # If we're in check mode, nothing else to do
    if not check_mode:
        if address.domain == 'vpc':
            res = ec2.disassociate_address(
                association_id=address.association_id)
        else:
            res = ec2.disassociate_address(public_ip=address.public_ip)

        if not res:
            raise EIPException('disassociation failed')

    return {'changed': True}


def _find_address_by_ip(ec2, public_ip):
    try:
        return ec2.get_all_addresses([public_ip])[0]
    except boto.exception.EC2ResponseError as e:
        if "Address '{}' not found.".format(public_ip) not in e.message:
            raise


def _find_address_by_instance_id(ec2, instance_id):
    addresses = ec2.get_all_addresses(None, {'instance-id': instance_id})
    if addresses:
        return addresses[0]


def find_address(ec2, public_ip, instance_id):
    """ Find an existing Elastic IP address """
    if public_ip:
        return _find_address_by_ip(ec2, public_ip)
    elif instance_id:
        return _find_address_by_instance_id(ec2, instance_id)


def address_is_associated_with_instance(ec2, address, instance_id):
    """ Check if the elastic IP is currently associated with the instance """
    if address:
        return address and address.instance_id == instance_id
    return False


def allocate_address(ec2, domain, reuse_existing_ip_allowed):
    """ Allocate a new elastic IP address (when needed) and return it """
    if reuse_existing_ip_allowed:
        domain_filter = {'domain': domain or 'standard'}
        all_addresses = ec2.get_all_addresses(filters=domain_filter)

        unassociated_addresses = [a for a in all_addresses
                                  if not a.instance_id]
        if unassociated_addresses:
            return unassociated_addresses[0]

    return ec2.allocate_address(domain=domain)


def release_address(ec2, address, check_mode):
    """ Release a previously allocated elastic IP address """

    # If we're in check mode, nothing else to do
    if not check_mode:
        if not address.release():
            EIPException('release failed')

    return {'changed': True}


def find_instance(ec2, instance_id):
    """ Attempt to find the EC2 instance and return it """

    reservations = ec2.get_all_reservations(instance_ids=[instance_id])

    if len(reservations) == 1:
        instances = reservations[0].instances
        if len(instances) == 1:
            return instances[0]

    raise EIPException("could not find instance" + instance_id)


def ensure_present(ec2, domain, address, instance_id,
                   reuse_existing_ip_allowed, check_mode):
    changed = False

    # Return the EIP object since we've been given a public IP
    if not address:
        if check_mode:
            return {'changed': True}

        address = allocate_address(ec2, domain, reuse_existing_ip_allowed)
        changed = True

    if instance_id:
        # Allocate an IP for instance since no public_ip was provided
        instance = find_instance(ec2, instance_id)
        if instance.vpc_id:
            domain = 'vpc'

        # Associate address object (provided or allocated) with instance
        assoc_result = associate_ip_and_instance(ec2, address, instance_id,
                                                 check_mode)
        changed = changed or assoc_result['changed']

    return {'changed': changed, 'public_ip': address.public_ip}


def ensure_absent(ec2, domain, address, instance_id, check_mode):
    if not address:
        return {'changed': False}

    # disassociating address from instance
    if instance_id:
        return disassociate_ip_and_instance(ec2, address, instance_id,
                                            check_mode)
    # releasing address
    else:
        return release_address(ec2, address, check_mode)


def main():
    argument_spec = ec2_argument_spec()
    argument_spec.update(dict(
        instance_id=dict(required=False),
        public_ip=dict(required=False, aliases=['ip']),
        state=dict(required=False, default='present',
                   choices=['present', 'absent']),
        in_vpc=dict(required=False, type='bool', default=False),
        reuse_existing_ip_allowed=dict(required=False, type='bool',
                                       default=False),
        wait_timeout=dict(default=300),
    ))

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

    if not HAS_BOTO:
        module.fail_json(msg='boto required for this module')

    ec2 = ec2_connect(module)

    instance_id = module.params.get('instance_id')
    public_ip = module.params.get('public_ip')
    state = module.params.get('state')
    in_vpc = module.params.get('in_vpc')
    domain = 'vpc' if in_vpc else None
    reuse_existing_ip_allowed = module.params.get('reuse_existing_ip_allowed')

    try:
        address = find_address(ec2, public_ip, instance_id)

        if state == 'present':
            result = ensure_present(ec2, domain, address, instance_id,
                                    reuse_existing_ip_allowed,
                                    module.check_mode)
        else:
            result = ensure_absent(ec2, domain, address, instance_id, module.check_mode)
    except (boto.exception.EC2ResponseError, EIPException) as e:
        module.fail_json(msg=str(e))

    module.exit_json(**result)


# import module snippets
from ansible.module_utils.basic import *  # noqa
from ansible.module_utils.ec2 import *  # noqa

if __name__ == '__main__':
    main()