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"""Objects relating to sourcing connections from environment variables"""

import os
import warnings
from typing import Optional

from airflow.secrets import BaseSecretsBackend

CONN_ENV_PREFIX = "AIRFLOW_CONN_"
VAR_ENV_PREFIX = "AIRFLOW_VAR_"


class EnvironmentVariablesBackend(BaseSecretsBackend):
    """Retrieves Connection object and Variable from environment variable."""

    def get_conn_uri(self, conn_id: str) -> Optional[str]:
        """
        Return URI representation of Connection conn_id
        :param conn_id: the connection id
        :return: deserialized Connection
        """
        warnings.warn(
            "This method is deprecated. Please use "
            "`airflow.secrets.environment_variables.EnvironmentVariablesBackend.get_conn_value`.",
            PendingDeprecationWarning,
            stacklevel=2,
        )
        return self.get_conn_value(conn_id)

    def get_conn_value(self, conn_id: str) -> Optional[str]:
        return os.environ.get(CONN_ENV_PREFIX + conn_id.upper())

    def get_variable(self, key: str) -> Optional[str]:
        """
        Get Airflow Variable from Environment Variable

        :param key: Variable Key
        :return: Variable Value
        """
        return os.environ.get(VAR_ENV_PREFIX + key.upper())
