"""A CLI util which generates a base64 string from a Snowflake private key."""

import argparse
import base64
import os

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


def generate_snowflake_private_key_string(passphrase, path_to_rsa_key_p8=None):
    """Generate a base64 encoded string.

    This string we need to place as SNOWFLAKE_PRIVATE_KEY_STRING
    to AWS Secrets Manager.

    Afterwards we can add it to SF_CONFIG as
    'private_key': base64.b64decode(
        bytes(os.environ.get('SNOWFLAKE_PRIVATE_KEY_STRING'),
              encoding='utf-8'))
    """
    snowflake_private_key_path = (
        path_to_rsa_key_p8 or '{}/.ssh/snowflake/rsa_key.p8'.format(
            os.environ['HOME']))
    with open(snowflake_private_key_path, 'rb') as key:
        p_key = serialization.load_pem_private_key(
            key.read(),
            password=passphrase.encode(),
            backend=default_backend()
        )

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

    private_key_string = str(base64.b64encode(private_key))[1:]

    with open(
        os.path.join(
            os.getcwd(),
            'snowflake_private_key_string.txt'), 'wt') as txt_file:
        txt_file.writelines(private_key_string)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(
        description='Generate base64 encoded string to place in '
                    'AWS Secrets Manager')
    parser.add_argument('passphrase', help='private key passphrase')
    parser.add_argument('path_to_rsa_key_p8', nargs='?', default=None,
                        help='full path to Snowflake private key rsa_key.p8')

    args = parser.parse_args()

    generate_snowflake_private_key_string(
        args.passphrase, args.path_to_rsa_key_p8)