#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
"""Objects relating to sourcing secrets from AWS Secrets Manager"""

from typing import Optional

import boto3

try:
    from functools import cached_property
except ImportError:
    from cached_property import cached_property

from airflow.secrets import BaseSecretsBackend
from airflow.utils.log.logging_mixin import LoggingMixin


class SecretsManagerBackend(BaseSecretsBackend, LoggingMixin):
    """
    Retrieves Connection or Variables from AWS Secrets Manager

    Configurable via ``airflow.cfg`` like so:

    .. code-block:: ini

        [secrets]
        backend = airflow.providers.amazon.aws.secrets.secrets_manager.SecretsManagerBackend
        backend_kwargs = {"connections_prefix": "airflow/connections"}

    For example, if secrets prefix is ``airflow/connections/smtp_default``, this would be accessible
    if you provide ``{"connections_prefix": "airflow/connections"}`` and request conn_id ``smtp_default``.
    If variables prefix is ``airflow/variables/hello``, this would be accessible
    if you provide ``{"variables_prefix": "airflow/variables"}`` and request variable key ``hello``.
    And if config_prefix is ``airflow/config/sql_alchemy_conn``, this would be accessible
    if you provide ``{"config_prefix": "airflow/config"}`` and request config
    key ``sql_alchemy_conn``.

    You can also pass additional keyword arguments like ``aws_secret_access_key``, ``aws_access_key_id``
    or ``region_name`` to this class and they would be passed on to Boto3 client.

    :param connections_prefix: Specifies the prefix of the secret to read to get Connections.
        If set to None (null), requests for connections will not be sent to AWS Secrets Manager
    :type connections_prefix: str
    :param variables_prefix: Specifies the prefix of the secret to read to get Variables.
        If set to None (null), requests for variables will not be sent to AWS Secrets Manager
    :type variables_prefix: str
    :param config_prefix: Specifies the prefix of the secret to read to get Configurations.
        If set to None (null), requests for configurations will not be sent to AWS Secrets Manager
    :type config_prefix: str
    :param profile_name: The name of a profile to use. If not given, then the default profile is used.
    :type profile_name: str
    :param sep: separator used to concatenate secret_prefix and secret_id. Default: "/"
    :type sep: str
    """

    def __init__(
        self,
        connections_prefix: str = "airflow/connections",
        variables_prefix: str = "airflow/variables",
        config_prefix: str = "airflow/config",
        profile_name: Optional[str] = None,
        sep: str = "/",
        **kwargs,
    ):
        super().__init__()
        if connections_prefix is not None:
            self.connections_prefix = connections_prefix.rstrip("/")
        else:
            self.connections_prefix = connections_prefix
        if variables_prefix is not None:
            self.variables_prefix = variables_prefix.rstrip("/")
        else:
            self.variables_prefix = variables_prefix
        if config_prefix is not None:
            self.config_prefix = config_prefix.rstrip("/")
        else:
            self.config_prefix = config_prefix
        self.profile_name = profile_name
        self.sep = sep
        self.kwargs = kwargs

    @cached_property
    def client(self):
        """Create a Secrets Manager client"""
        session = boto3.session.Session(
            profile_name=self.profile_name,
        )
        return session.client(service_name="secretsmanager", **self.kwargs)

    def get_conn_uri(self, conn_id: str) -> Optional[str]:
        """
        Get Connection Value

        :param conn_id: connection id
        :type conn_id: str
        """
        if self.connections_prefix is None:
            return None

        return self._get_secret(self.connections_prefix, conn_id)

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

        :param key: Variable Key
        :return: Variable Value
        """
        if self.variables_prefix is None:
            return None

        return self._get_secret(self.variables_prefix, key)

    def get_config(self, key: str) -> Optional[str]:
        """
        Get Airflow Configuration

        :param key: Configuration Option Key
        :return: Configuration Option Value
        """
        if self.config_prefix is None:
            return None

        return self._get_secret(self.config_prefix, key)

    def _get_secret(self, path_prefix: str, secret_id: str) -> Optional[str]:
        """
        Get secret value from Secrets Manager

        :param path_prefix: Prefix for the Path to get Secret
        :type path_prefix: str
        :param secret_id: Secret Key
        :type secret_id: str
        """
        secrets_path = self.build_path(path_prefix, secret_id, self.sep)
        try:
            response = self.client.get_secret_value(
                SecretId=secrets_path,
            )
            return response.get("SecretString")
        except self.client.exceptions.ResourceNotFoundException:
            self.log.debug(
                "An error occurred (ResourceNotFoundException) when calling the "
                "get_secret_value operation: "
                "Secret %s not found.",
                secrets_path,
            )
            return None