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

# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

DOCUMENTATION = '''
---
module: postgresql_db
short_description: Add or remove PostgreSQL databases from a remote host.
description:
   - Add or remove PostgreSQL databases from a remote host.
version_added: "0.6"
options:
  name:
    description:
      - name of the database to add or remove
    required: true
    default: null
  login_user:
    description:
      - The username used to authenticate with
    required: false
    default: null
  login_password:
    description:
      - The password used to authenticate with
    required: false
    default: null
  login_host:
    description:
      - Host running the database
    required: false
    default: localhost
  owner:
    description:
      - Name of the role to set as owner of the database
    required: false
    default: null
  state:
    description:
      - The database state
    required: false
    default: present
    choices: [ "present", "absent" ]
examples:
   - code: "postgresql_db: db=acme"
     description: Create a new database with name 'acme'
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: Lorin Hochstein
'''

try:
    import psycopg2
except ImportError:
    postgresqldb_found = False
else:
    postgresqldb_found = True

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

def set_owner(cursor, db, owner):
    query = "ALTER DATABASE %s OWNER TO %s" % (db, owner)
    cursor.execute(query)
    return True

def db_owned_by(cursor, db, user):
    query = """SELECT * FROM pg_database JOIN pg_user ON datdba = usesysid
    WHERE usename = %(user)s and datname = %(db)s"""
    cursor.execute(query, {'db':db, 'user':user})
    return cursor.rowcount == 1

def db_exists(cursor, db):
    query = "SELECT * FROM pg_database WHERE datname=%(db)s"
    cursor.execute(query, {'db': db})
    return cursor.rowcount == 1

def db_delete(cursor, db):
    if db_exists(cursor, db):
        query = "DROP DATABASE %s" % db
        cursor.execute(query)
        return True
    else:
        return False

def db_create(cursor, db, owner, template, encoding):
    if not db_exists(cursor, db):
        if owner:
            owner = " OWNER %s" % owner
        if template:
            template = " TEMPLATE %s" % template
        if encoding:
            encoding = " ENCODING '%s'" % encoding
        query = "CREATE DATABASE %s%s%s%s" % (db, owner, template, encoding)
        cursor.execute(query)
        return True
    elif owner and not db_owned_by(cursor, db, owner):
        return set_owner(cursor, db, owner)
    else:
        return False

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

def main():
    module = AnsibleModule(
        argument_spec=dict(
            login_user=dict(default="postgres"),
            login_password=dict(default=""),
            login_host=dict(default=""),
            port=dict(default="5432"),
            db=dict(required=True, aliases=['name']),
            owner=dict(default=""),
            template=dict(default=""),
            encoding=dict(default=""),
            state=dict(default="present", choices=["absent", "present"]),
        )
    )

    if not postgresqldb_found:
        module.fail_json(msg="the python psycopg2 module is required")

    db = module.params["db"]
    port = module.params["port"]
    owner = module.params["owner"]
    template = module.params["template"]
    encoding = module.params["encoding"]
    state = module.params["state"]
    changed = False

    # To use defaults values, keyword arguments must be absent, so 
    # check which values are empty and don't include in the **kw
    # dictionary
    params_map =  {
        "login_host":"host",
        "login_user":"user",
        "login_password":"password",
        "port":"port"
    }
    kw = dict( (params_map[k], v) for (k, v) in module.params.iteritems() 
              if k in params_map and v != '' )
    try:
        db_connection = psycopg2.connect(database="template1", **kw)
        # Enable autocommit so we can create databases
        if psycopg2.__version__ >= '2.4.2':
            db_connection.autocommit = True
        else:
            db_connection.set_isolation_level(psycopg2
                                              .extensions
                                              .ISOLATION_LEVEL_AUTOCOMMIT)
        cursor = db_connection.cursor()
    except Exception, e:
        module.fail_json(msg="unable to connect to database: %s" % e)

    try:
        if state == "absent":
            changed = db_delete(cursor, db)
        elif state == "present":
            changed = db_create(cursor, db, owner, template, encoding)
    except Exception, e:
        module.fail_json(msg="Database query failed: %s" % e)

    module.exit_json(changed=changed, db=db)

# this is magic, see lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()