from psycopg2 import connect
from psycopg2.extensions import AsIs


def create_db(
    hostname="localhost", username=None, password=None, dbname=None, port=None
):
    """Create test database.

    :param hostname: string
    :param username: string
    :param password: string
    :param dbname: string
    :param port: int
    :return:

    """
    cn = create_cn(hostname, password, username, "postgres", port)

    # ISOLATION_LEVEL_AUTOCOMMIT = 0
    # Needed for DB creation.
    cn.set_isolation_level(0)

    with cn.cursor() as cr:
        cr.execute("drop database if exists %s", (AsIs(dbname),))
        cr.execute("create database %s", (AsIs(dbname),))

    cn.close()

    cn = create_cn(hostname, password, username, dbname, port)
    return cn


def create_cn(hostname, password, username, dbname, port):
    """
    Open connection to database.
    :param hostname:
    :param password:
    :param username:
    :param dbname: string
    :return: psycopg2.connection
    """
    cn = connect(
        host=hostname, user=username, database=dbname, password=password, port=port
    )

    print(f"Created connection: {cn.dsn}.")
    return cn


def drop_db(hostname="localhost", username=None, password=None, dbname=None, port=None):
    """
    Drop database.
    :param hostname: string
    :param username: string
    :param password: string
    :param dbname: string
    """
    cn = create_cn(hostname, password, username, "postgres", port)

    # ISOLATION_LEVEL_AUTOCOMMIT = 0
    # Needed for DB drop.
    cn.set_isolation_level(0)

    with cn.cursor() as cr:
        cr.execute("drop database if exists %s", (AsIs(dbname),))

    close_cn(cn)


def close_cn(cn=None):
    """
    Close connection.
    :param connection: psycopg2.connection
    """
    if cn:
        cn.close()
        print(f"Closed connection: {cn.dsn}.")