#!/usr/bin/env python
# Copyright 2015, Rackspace US, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import os
import re
import subprocess
from ansible.module_utils.basic import *

DOCUMENTATION = """
---
module: neutron_migrations_facts
short_description:
    - A module for gathering neutron migrations facts.
description:
    - This module creates a fact called 'neutron_migrations', which is a dict
      containing keys that represent each alembic migration branch.  The value
      for each key is another dict, containing a key value for the current
      neutron revision for that branch (revision), and whether or not the
      branch is currently at the latest revision (head).  The
      'neutron_migrations' fact can then be used to determine if migrations
      for either branch are required, and allows us to only apply migrations
      if necessary.
options:
    release:
        description:
            - This is the OpenStack release you're running, used when
              searching for migration revisions in the neutron code.
        default: liberty
author: Rcbops
"""

EXAMPLES = """
- name: Gather neutron migration facts
  neutron_migrations_facts:
    release: mitaka
"""

MIGRATIONS = {'expand': {'revision': None, 'head': None},
              'contract': {'revision': None, 'head': None}}


def get_branch(release, revision):
    migrations_dir = '/usr/local/lib/python2.7/dist-packages/neutron/db/' \
                     'migration/alembic_migrations/versions/%s/' % release
    for branch in MIGRATIONS.keys():
        for file in os.listdir('%s/%s' % (migrations_dir, branch)):
            if file.endswith('.py') and file.split('_')[0] == revision:
                return branch


def main():
    module = AnsibleModule(
        argument_spec=dict(
            release=dict(
                type='str',
                default='liberty'
            )
        ),
        supports_check_mode=False
    )
    state_change = False

    try:
        current = subprocess.check_output(['neutron-db-manage', 'current'])
    except subprocess.CalledProcessError as e:
        message = 'neutron fact collection failed: "%s".' % e
        module.fail_json(msg=message)

    for line in current.splitlines():
        head = False
        match = re.search("^([0-9a-z]{4,12})(\s\(head\))?$", line)
        if match:
            revision = match.group(1)
            if match.group(2):
                head = True
            branch = get_branch(module.params['release'], revision)
            if branch is None:
                message = 'neutron fact collection failed: unable to find ' \
                          'migration with revision %s' % revision
                module.fail_json(msg=message)

            MIGRATIONS[branch]['revision'] = revision
            MIGRATIONS[branch]['head'] = head

    module.exit_json(changed=state_change,
                     ansible_facts={'neutron_migrations': MIGRATIONS})

if __name__ == '__main__':
    main()