# -*- coding: utf-8 -*-
'''
Retrieve Pillar data by doing a postgres query

.. versionadded:: 2017.7.0

:maturity: new
:depends: psycopg2
:platform: all

Complete Example
================

.. code-block:: yaml

    postgres:
      user: 'salt'
      pass: 'super_secret_password'
      db: 'salt_db'

    ext_pillar:
      - postgres:
          fromdb:
            query: 'SELECT col1,col2,col3,col4,col5,col6,col7
                      FROM some_random_table
                     WHERE minion_pattern LIKE %s'
            depth: 5
            as_list: True
            with_lists: [1,3]
'''
from __future__ import absolute_import, print_function, unicode_literals

# Import python libs
from contextlib import contextmanager
import logging

# Import Salt libs
from salt.pillar.sql_base import SqlBaseExtPillar

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

# Import third party libs
try:
    import psycopg2
    HAS_POSTGRES = True
except ImportError:
    HAS_POSTGRES = False


def __virtual__():
    if not HAS_POSTGRES:
        return False
    return True


class POSTGRESExtPillar(SqlBaseExtPillar):
    '''
    This class receives and processes the database rows from POSTGRES.
    '''
    @classmethod
    def _db_name(cls):
        return 'POSTGRES'

    def _get_options(self):
        '''
        Returns options used for the POSTGRES connection.
        '''
        defaults = {'host': 'localhost',
                    'user': 'salt',
                    'pass': 'salt',
                    'db': 'salt',
                    'port': 5432}
        _options = {}
        _opts = __opts__.get('postgres', {})
        for attr in defaults:
            if attr not in _opts:
                log.debug('Using default for POSTGRES %s', attr)
                _options[attr] = defaults[attr]
                continue
            _options[attr] = _opts[attr]
        return _options

    @contextmanager
    def _get_cursor(self):
        '''
        Yield a POSTGRES cursor
        '''
        _options = self._get_options()
        conn = psycopg2.connect(host=_options['host'],
                                user=_options['user'],
                                password=_options['pass'],
                                dbname=_options['db'],
                                port=_options['port'])
        cursor = conn.cursor()
        try:
            yield cursor
            log.debug('Connected to POSTGRES DB')
        except psycopg2.DatabaseError as err:
            log.exception('Error in ext_pillar POSTGRES: %s', err.args)
        finally:
            conn.close()

    def extract_queries(self, args, kwargs):  # pylint: disable=useless-super-delegation
        '''
            This function normalizes the config block into a set of queries we
            can use.  The return is a list of consistently laid out dicts.
        '''
        return super(POSTGRESExtPillar, self).extract_queries(args, kwargs)


def ext_pillar(minion_id,
               pillar,
               *args,
               **kwargs):
    '''
    Execute queries against POSTGRES, merge and return as a dict
    '''
    return POSTGRESExtPillar().fetch(minion_id, pillar, *args, **kwargs)