"""Snoflake helper functions."""
from typing import Dict
from typing import Optional
from typing import Union

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization

from dbdeploy.base import config
from dbdeploy.base import constants


def get_sf_config(snowflake_account: str) -> Dict[str, Optional[Union[str, bytes]]]:
    """Return Snowflake config with credentials.

    Returns:
        dict: SF credentials
    """
    snowflake_private_key = constants.PRIVATE_KEY_TEMPLATE.format(config.SNOWFLAKE_ACCOUNTS[snowflake_account].SNOWFLAKE_PRIVATE_KEY_STRING)  # noqa: E501

    p_key = serialization.load_pem_private_key(
        snowflake_private_key.encode(),
        password=str(config.SNOWFLAKE_ACCOUNTS[snowflake_account].SNOWFLAKE_KEY_PASSPHRASE).encode(),  # noqa: E501
        backend=default_backend(),
    )

    private_key = p_key.private_bytes(
        encoding=serialization.Encoding.DER,
        format=serialization.PrivateFormat.PKCS8,
        encryption_algorithm=serialization.NoEncryption())

    # Return Snowflake connection parameters including credentials
    return {
        'role': config.SNOWFLAKE_ROLE,
        'warehouse': config.SNOWFLAKE_WAREHOUSE,
        'db': config.SNOWFLAKE_DATABASE,
        'schema': config.SNOWFLAKE_SCHEMA,
        'user': config.SNOWFLAKE_ACCOUNTS[snowflake_account].SNOWFLAKE_USER,
        'account': config.SNOWFLAKE_ACCOUNTS[snowflake_account].SNOWFLAKE_ACCOUNT,
        'private_key': private_key
    }