# -*- coding: utf-8 -*-
'''
Read tops data from a mongodb collection

This module will load tops data from a mongo collection. It uses the node's id
for lookups.

Salt Master Mongo Configuration
===============================

The module shares the same base mongo connection variables as
:py:mod:`salt.returners.mongo_return`. These variables go in your master
config file.

   * ``mongo.db`` - The mongo database to connect to. Defaults to ``'salt'``.
   * ``mongo.host`` - The mongo host to connect to. Supports replica sets by
     specifying all hosts in the set, comma-delimited. Defaults to ``'salt'``.
   * ``mongo.port`` - The port that the mongo database is running on. Defaults
     to ``27017``.
   * ``mongo.user`` - The username for connecting to mongo. Only required if
     you are using mongo authentication. Defaults to ``''``.
   * ``mongo.password`` - The password for connecting to mongo. Only required
     if you are using mongo authentication. Defaults to ``''``.


Configuring the Mongo Tops Subsystem
====================================

.. code-block:: yaml

  master_tops:
    mongo:
      collection: tops
      id_field: _id
      re_replace: ""
      re_pattern: \\.example\\.com
      states_field: states
      environment_field: environment


Module Documentation
====================
'''
from __future__ import absolute_import

# Import python libs
import logging
import re

# Import third party libs
try:
    import pymongo
    HAS_PYMONGO = True
except ImportError:
    HAS_PYMONGO = False


__opts__ = {'mongo.db': 'salt',
            'mongo.host': 'salt',
            'mongo.password': '',
            'mongo.port': 27017,
            'mongo.user': ''}


def __virtual__():
    if not HAS_PYMONGO:
        return False
    return 'mongo'

# Set up logging
log = logging.getLogger(__name__)


def top(**kwargs):
    '''
    Connect to a mongo database and read per-node tops data.

    Parameters:
        * `collection`: The mongodb collection to read data from. Defaults to
          ``'tops'``.
        * `id_field`: The field in the collection that represents an individual
          minion id. Defaults to ``'_id'``.
        * `re_pattern`: If your naming convention in the collection is shorter
          than the minion id, you can use this to trim the name.
          `re_pattern` will be used to match the name, and `re_replace` will
          be used to replace it. Backrefs are supported as they are in the
          Python standard library. If ``None``, no mangling of the name will
          be performed - the collection will be searched with the entire
          minion id. Defaults to ``None``.
        * `re_replace`: Use as the replacement value in node ids matched with
          `re_pattern`. Defaults to ''. Feel free to use backreferences here.
        * `states_field`: The name of the field providing a list of states.
        * `environment_field`: The name of the field providing the environment.
          Defaults to ``environment``.
    '''
    host = __opts__['mongo.host']
    port = __opts__['mongo.port']
    collection = __opts__['master_tops']['mongo'].get('collection', 'tops')
    id_field = __opts__['master_tops']['mongo'].get('id_field', '_id')
    re_pattern = __opts__['master_tops']['mongo'].get('re_pattern', '')
    re_replace = __opts__['master_tops']['mongo'].get('re_replace', '')
    states_field = __opts__['master_tops']['mongo'].get('states_field', 'states')
    environment_field = __opts__['master_tops']['mongo'].get('environment_field', 'environment')

    log.info('connecting to {0}:{1} for mongo ext_tops'.format(host, port))
    conn = pymongo.MongoClient(host, port)

    log.debug('using database \'{0}\''.format(__opts__['mongo.db']))
    mdb = conn[__opts__['mongo.db']]

    user = __opts__.get('mongo.user')
    password = __opts__.get('mongo.password')

    if user and password:
        log.debug('authenticating as \'{0}\''.format(user))
        mdb.authenticate(user, password)

    # Do the regex string replacement on the minion id
    minion_id = kwargs['opts']['id']
    if re_pattern:
        minion_id = re.sub(re_pattern, re_replace, minion_id)

    log.info(
        'ext_tops.mongo: looking up tops def for {{\'{0}\': \'{1}\'}} '
        'in mongo'.format(
            id_field, minion_id
        )
    )

    result = mdb[collection].find_one({id_field: minion_id}, projection=[states_field, environment_field])
    if result and states_field in result:
        if environment_field in result:
            environment = result[environment_field]
        else:
            environment = 'base'
        log.debug('ext_tops.mongo: found document, returning states')
        return {environment: result[states_field]}
    else:
        # If we can't find the minion the database it's not necessarily an
        # error.
        log.debug(
            'ext_tops.mongo: no document found in collection {0}'.format(
                collection
            )
        )
        return {}
