"""Utility functions to support database interactions in tests."""

from functools import wraps
import sys

from backend import config
from backend.connectors import mysql
from backend.models.vendor import Vendor

from tests.testutils.seed.vendor_seed import vendor_seed_data


def create_tables():
    """Create the vendor and related tables."""
    with mysql.db_session() as session:
        exit_if_not_test_environment(session)
        mysql.BaseModel.metadata.create_all(mysql.db_engine)


def seed_tables():
    """Seed the vendor and related tables."""
    with mysql.db_session() as session:
        exit_if_not_test_environment(session)
        session.bulk_insert_mappings(Vendor, vendor_seed_data)


def drop_tables():
    """Drop vendor and related tables."""
    with mysql.db_session() as session:
        exit_if_not_test_environment(session)
        mysql.BaseModel.metadata.drop_all(mysql.db_engine)


def test_schema(function):
    """Create and tear down the test DB schema around a function call.

    Args:
        Function (func): the function to be called after creating the test
        schema.

    Returns:
        Function: The decorated function.
    """
    @wraps(function)
    def call_function_within_db_context(*args, **kwargs):
        create_tables()
        seed_tables()

        try:
            function_return = function(*args, **kwargs)
        finally:
            drop_tables()

        return function_return

    return call_function_within_db_context


def exit_if_not_test_environment(session):
    """For safety, only run tests in test environment pointed to sqlite.

    Exit immediately if not in test environment or not pointed to sqlite.
    """
    if config.ENVIRONMENT != config.TEST_ENVIRONMENT:
        sys.exit('Environment must be set to {}.'.format(
            config.TEST_ENVIRONMENT))

    if 'sqlite' not in session.bind.url.drivername:
        sys.exit('Tests must point to sqlite database.')