import json
import os.path
from typing import Dict

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


def get_connection_parameters(account: str) -> Dict[str, bytes]:
    """
    Function to return parameters for Snowflake connection
    :param account: name of the connection defined in the connections.json file
    :return: dictionary containing connection parameter with values
    """
    f = os.path.dirname(__file__) + "/connections.json"
    with open(f, "r") as file:
        connection_params = json.load(file)[account]
        private_key_file = connection_params["private_file"]
    with open(private_key_file, "rb") as key:
        p_key = serialization.load_pem_private_key(
            key.read(), password=connection_params["password"].encode(), backend=default_backend()
        )

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

    connection_parameters = {
        "account": connection_params["account"],
        "user": connection_params["user"],
        "role": connection_params["role"],
        "private_key": pkb,
        "warehouse": connection_params["warehouse"],
        "database": connection_params["database"],
        "schema": connection_params["schema"],
    }

    return connection_parameters