#!/usr/bin/python
# -*- coding: utf-8 -*-

# Copyright: (c) 2016, Google Inc.
# 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

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

DOCUMENTATION = '''
---
module: gcpubsub
version_added: "2.3"
short_description: Create and Delete Topics/Subscriptions, Publish and pull messages on PubSub
description:
    - Create and Delete Topics/Subscriptions, Publish and pull messages on PubSub.
      See U(https://cloud.google.com/pubsub/docs) for an overview.
requirements:
  - google-auth >= 0.5.0
  - google-cloud-pubsub >= 0.22.0
notes:
  - Subscription pull happens before publish.  You cannot publish and pull in the same task.
author:
  - Tom Melendez (@supertom) <tom@supertom.com>
options:
  topic:
    description:
       - GCP pubsub topic name.
       - Only the name, not the full path, is required.
    required: yes
  subscription:
    description:
       - Dictionary containing a subscripton name associated with a topic (required), along with optional ack_deadline, push_endpoint and pull.
         For pulling from a subscription, message_ack (bool), max_messages (int) and return_immediate are available as subfields.
         See subfields name, push_endpoint and ack_deadline for more information.
  name:
    description: Subfield of subscription. Required if subscription is specified. See examples.
  ack_deadline:
    description: Subfield of subscription. Not required. Default deadline for subscriptions to ACK the message before it is resent. See examples.
  pull:
    description:
        - Subfield of subscription. Not required. If specified, messages will be retrieved from topic via the provided subscription name.
          max_messages (int; default None; max number of messages to pull), message_ack (bool; default False; acknowledge the message) and return_immediately
          (bool; default True, don't wait for messages to appear). If the messages are acknowledged, changed is set to True, otherwise, changed is False.
  push_endpoint:
    description:
        - Subfield of subscription.  Not required.  If specified, message will be sent to an endpoint.
          See U(https://cloud.google.com/pubsub/docs/advanced#push_endpoints) for more information.
  publish:
    description:
        - List of dictionaries describing messages and attributes to be published.  Dictionary is in message(str):attributes(dict) format.
          Only message is required.
  state:
    description:
        - State of the topic or queue.
        - Applies to the most granular resource.
        - If subscription isspecified we remove it.
        - If only topic is specified, that is what is removed.
        - NOTE - A topic can be removed without first removing the subscription.
    choices: [ absent, present ]
    default: present
'''

EXAMPLES = '''
# (Message will be pushed; there is no check to see if the message was pushed before
- name: Create a topic and publish a message to it
  gcpubsub:
    topic: ansible-topic-example
    state: present

# Subscriptions associated with topic are not deleted.
- name: Delete Topic
  gcpubsub:
    topic: ansible-topic-example
    state: absent

# Setting absent will keep the messages from being sent
- name: Publish multiple messages, with attributes (key:value available with the message)
  gcpubsub:
    topic: '{{ topic_name }}'
    state: present
    publish:
      - message: this is message 1
        attributes:
          mykey1: myvalue
          mykey2: myvalu2
          mykey3: myvalue3
      - message: this is message 2
        attributes:
          server: prod
          sla: "99.9999"
          owner: fred

- name: Create Subscription (pull)
  gcpubsub:
    topic: ansible-topic-example
    subscription:
    - name: mysub
    state: present

# pull is default, ack_deadline is not required
- name: Create Subscription with ack_deadline and push endpoint
  gcpubsub:
    topic: ansible-topic-example
    subscription:
    - name: mysub
      ack_deadline: "60"
      push_endpoint: http://pushendpoint.example.com
    state: present

# Setting push_endpoint to "None" converts subscription to pull.
- name: Subscription change from push to pull
  gcpubsub:
    topic: ansible-topic-example
    subscription:
      name: mysub
      push_endpoint: "None"

### Topic will not be deleted
- name: Delete subscription
  gcpubsub:
    topic: ansible-topic-example
    subscription:
    - name: mysub
    state: absent

# only pull keyword is required.
- name: Pull messages from subscription
  gcpubsub:
    topic: ansible-topic-example
    subscription:
      name: ansible-topic-example-sub
      pull:
        message_ack: yes
        max_messages: "100"
'''

RETURN = '''
publish:
    description: List of dictionaries describing messages and attributes to be published.  Dictionary is in message(str):attributes(dict) format.
                 Only message is required.
    returned: Only when specified
    type: list
    sample: "publish: ['message': 'my message', attributes: {'key1': 'value1'}]"

pulled_messages:
    description: list of dictionaries containing message info.  Fields are ack_id, attributes, data, message_id.
    returned: Only when subscription.pull is specified
    type: list
    sample: [{ "ack_id": "XkASTCcYREl...","attributes": {"key1": "val1",...}, "data": "this is message 1", "message_id": "49107464153705"},..]

state:
    description: The state of the topic or subscription. Value will be either 'absent' or 'present'.
    returned: Always
    type: str
    sample: "present"

subscription:
    description: Name of subscription.
    returned: When subscription fields are specified
    type: str
    sample: "mysubscription"

topic:
    description: Name of topic.
    returned: Always
    type: str
    sample: "mytopic"
'''

try:
    from ast import literal_eval
    HAS_PYTHON26 = True
except ImportError:
    HAS_PYTHON26 = False

try:
    from google.cloud import pubsub
    HAS_GOOGLE_CLOUD_PUBSUB = True
except ImportError as e:
    HAS_GOOGLE_CLOUD_PUBSUB = False

from ansible.module_utils.basic import AnsibleModule
from ansible.module_utils.gcp import check_min_pkg_version, get_google_cloud_credentials


CLOUD_CLIENT = 'google-cloud-pubsub'
CLOUD_CLIENT_MINIMUM_VERSION = '0.22.0'
CLOUD_CLIENT_USER_AGENT = 'ansible-pubsub-0.1'


def publish_messages(message_list, topic):
    with topic.batch() as batch:
        for message in message_list:
            msg = message['message']
            attrs = {}
            if 'attributes' in message:
                attrs = message['attributes']
            batch.publish(bytes(msg), **attrs)
    return True


def pull_messages(pull_params, sub):
    """
    :rtype: tuple (output, changed)
    """
    changed = False
    max_messages = pull_params.get('max_messages', None)
    message_ack = pull_params.get('message_ack', 'no')
    return_immediately = pull_params.get('return_immediately', False)

    output = []
    pulled = sub.pull(return_immediately=return_immediately, max_messages=max_messages)

    for ack_id, msg in pulled:
        msg_dict = {'message_id': msg.message_id,
                    'attributes': msg.attributes,
                    'data': msg.data,
                    'ack_id': ack_id}
        output.append(msg_dict)

    if message_ack:
        ack_ids = [m['ack_id'] for m in output]
        if ack_ids:
            sub.acknowledge(ack_ids)
            changed = True
    return (output, changed)


def main():

    module = AnsibleModule(
        argument_spec=dict(
            topic=dict(type='str', required=True),
            state=dict(type='str', default='present', choices=['absent', 'present']),
            publish=dict(type='list'),
            subscription=dict(type='dict'),
            service_account_email=dict(type='str'),
            credentials_file=dict(type='str'),
            project_id=dict(type='str'),
        ),
    )

    if not HAS_PYTHON26:
        module.fail_json(
            msg="GCE module requires python's 'ast' module, python v2.6+")

    if not HAS_GOOGLE_CLOUD_PUBSUB:
        module.fail_json(msg="Please install google-cloud-pubsub library.")

    if not check_min_pkg_version(CLOUD_CLIENT, CLOUD_CLIENT_MINIMUM_VERSION):
        module.fail_json(msg="Please install %s client version %s" % (CLOUD_CLIENT, CLOUD_CLIENT_MINIMUM_VERSION))

    mod_params = {}
    mod_params['publish'] = module.params.get('publish')
    mod_params['state'] = module.params.get('state')
    mod_params['topic'] = module.params.get('topic')
    mod_params['subscription'] = module.params.get('subscription')

    creds, params = get_google_cloud_credentials(module)
    pubsub_client = pubsub.Client(project=params['project_id'], credentials=creds, use_gax=False)
    pubsub_client.user_agent = CLOUD_CLIENT_USER_AGENT

    changed = False
    json_output = {}

    t = None
    if mod_params['topic']:
        t = pubsub_client.topic(mod_params['topic'])
    s = None
    if mod_params['subscription']:
        # Note: default ack deadline cannot be changed without deleting/recreating subscription
        s = t.subscription(mod_params['subscription']['name'],
                           ack_deadline=mod_params['subscription'].get('ack_deadline', None),
                           push_endpoint=mod_params['subscription'].get('push_endpoint', None))

    if mod_params['state'] == 'absent':
        # Remove the most granular resource.  If subcription is specified
        # we remove it.  If only topic is specified, that is what is removed.
        # Note that a topic can be removed without first removing the subscription.
        # TODO(supertom): Enhancement: Provide an option to only delete a topic
        # if there are no subscriptions associated with it (which the API does not support).
        if s is not None:
            if s.exists():
                s.delete()
                changed = True
        else:
            if t.exists():
                t.delete()
                changed = True
    elif mod_params['state'] == 'present':
        if not t.exists():
            t.create()
            changed = True
        if s:
            if not s.exists():
                s.create()
                s.reload()
                changed = True
            else:
                # Subscription operations
                # TODO(supertom): if more 'update' operations arise, turn this into a function.
                s.reload()
                push_endpoint = mod_params['subscription'].get('push_endpoint', None)
                if push_endpoint is not None:
                    if push_endpoint != s.push_endpoint:
                        if push_endpoint == 'None':
                            push_endpoint = None
                        s.modify_push_configuration(push_endpoint=push_endpoint)
                        s.reload()
                        changed = push_endpoint == s.push_endpoint

                if 'pull' in mod_params['subscription']:
                    if s.push_endpoint is not None:
                        module.fail_json(msg="Cannot pull messages, push_endpoint is configured.")
                    (json_output['pulled_messages'], changed) = pull_messages(
                        mod_params['subscription']['pull'], s)

        # publish messages to the topic
        if mod_params['publish'] and len(mod_params['publish']) > 0:
            changed = publish_messages(mod_params['publish'], t)

    json_output['changed'] = changed
    json_output.update(mod_params)
    module.exit_json(**json_output)


if __name__ == '__main__':
    main()