#!/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/>.

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=""),
            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"]
    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"
    }
    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()