# Copyright 2022 Google LLC
#
# Licensed 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.

"""Utility functions for Auth server."""

import google_crc32c
from google.cloud import secretmanager

CORRUPTION_ERR_MSG = "Data corruption detected"


def access_secret_version(project_id, secret_id, version_id):
    """
    Access the payload for the given secret version if one exists. The version
    can be a version number as a string (e.g. "5") or an alias (e.g. "latest").
    """

    # Create the Secret Manager client.
    client = secretmanager.SecretManagerServiceClient()

    # Build the resource name of the secret version.
    name = f"projects/{project_id}/secrets/{secret_id}/versions/{version_id}"

    # Access the secret version.
    response = client.access_secret_version(request={"name": name})
    # Verify payload checksum.
    crc32c = google_crc32c.Checksum()
    crc32c.update(response.payload.data)
    if response.payload.data_crc32c != int(crc32c.hexdigest(), 16):
        return {"response": response, "error": CORRUPTION_ERR_MSG}

    # Return payload.
    return {"response": response.payload.data.decode("UTF-8"), "error": None}