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

# Copyright: (c) 2018, Andrew Klychkov (@Andersson007) <aaklychkov@mail.ru>
# 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 = r'''
---
module: postgresql_ping
short_description: Check remote PostgreSQL server availability
description:
- Simple module to check remote PostgreSQL server availability.
version_added: '2.8'
options:
  db:
    description:
    - Name of database to connect.
    type: str
    aliases:
    - login_db
notes:
- The default authentication assumes that you are either logging in as or
  sudo'ing to the postgres account on the host.
- This module uses psycopg2, a Python PostgreSQL database adapter. You must
  ensure that psycopg2 is installed on the host before using this module. If
  the remote host is the PostgreSQL server (which is the default case), then
  PostgreSQL must also be installed on the remote host. For Ubuntu-based
  systems, install the postgresql, libpq-dev, and python-psycopg2 packages
  on the remote host before using this module.
requirements: [ psycopg2 ]
author:
- Andrew Klychkov (@Andersson007)
extends_documentation_fragment: postgres
'''

EXAMPLES = r'''
# PostgreSQL ping dbsrv server from the shell:
# ansible dbsrv -m postgresql_ping

# In the example below you need to generate certificates previously.
# See https://www.postgresql.org/docs/current/libpq-ssl.html for more information.
- name: PostgreSQL ping dbsrv server using not default credentials and ssl
  postgresql_ping:
    db: protected_db
    login_host: dbsrv
    login_user: secret
    login_password: secret_pass
    ca_cert: /root/root.crt
    ssl_mode: verify-full
'''

RETURN = r'''
is_available:
  description: PostgreSQL server availability.
  returned: always
  type: bool
  sample: true
server_version:
  description: PostgreSQL server version.
  returned: always
  type: dict
  sample: { major: 10, minor: 1 }
'''

try:
    from psycopg2.extras import DictCursor
except ImportError:
    # psycopg2 is checked by connect_to_db()
    # from ansible.module_utils.postgres
    pass

from ansible.module_utils.basic import AnsibleModule, missing_required_lib
from ansible.module_utils.database import SQLParseError
from ansible.module_utils.postgres import connect_to_db, postgres_common_argument_spec
from ansible.module_utils._text import to_native
from ansible.module_utils.six import iteritems


# ===========================================
# PostgreSQL module specific support methods.
#


class PgPing(object):
    def __init__(self, module, cursor):
        self.module = module
        self.cursor = cursor
        self.is_available = False
        self.version = {}

    def do(self):
        self.get_pg_version()
        return (self.is_available, self.version)

    def get_pg_version(self):
        query = "SELECT version()"
        raw = self.__exec_sql(query)[0][0]
        if raw:
            self.is_available = True
            raw = raw.split()[1].split('.')
            self.version = dict(
                major=int(raw[0]),
                minor=int(raw[1]),
            )

    def __exec_sql(self, query):
        try:
            self.cursor.execute(query)
            res = self.cursor.fetchall()
            if res:
                return res
        except Exception as e:
            self.module.fail_json("Unable to execute '%s': %s" % (query, to_native(e)))

        return False

# ===========================================
# Module execution.
#


def main():
    argument_spec = postgres_common_argument_spec()
    argument_spec.update(
        db=dict(type='str', aliases=['login_db']),
    )
    module = AnsibleModule(
        argument_spec=argument_spec,
        supports_check_mode=True,
    )

    # Set some default values:
    cursor = False
    db_connection = False
    result = dict(
        changed=False,
        is_available=False,
        server_version=dict(),
    )

    db_connection = connect_to_db(module, fail_on_conn=False)

    if db_connection is not None:
        cursor = db_connection.cursor(cursor_factory=DictCursor)

    # Do job:
    pg_ping = PgPing(module, cursor)
    if cursor:
        # If connection established:
        result["is_available"], result["server_version"] = pg_ping.do()
        db_connection.rollback()

    module.exit_json(**result)


if __name__ == '__main__':
    main()