# Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file 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.
"""Helper utilities for use by integration tests."""
import base64
import json
import os
from collections import namedtuple
from typing import Any, Callable, Iterable, Optional, Text

import aws_encryption_sdk
import pytest
from aws_encryption_sdk.identifiers import CommitmentPolicy
from aws_encryption_sdk.key_providers.kms import StrictAwsKmsMasterKeyProvider

HERE = os.path.abspath(os.path.dirname(__file__))
DEPLOYMENT_REGION = "AWS_ENCRYPTION_SDK_PYTHON_DECRYPT_ORACLE_REGION"
DEPLOYMENT_ID = "AWS_ENCRYPTION_SDK_PYTHON_DECRYPT_ORACLE_API_DEPLOYMENT_ID"
AWS_KMS_KEY_ID = "AWS_ENCRYPTION_SDK_PYTHON_INTEGRATION_TEST_AWS_KMS_KEY_ID"
_KMS_MKP = None
_ENDPOINT = None

CLIENT = aws_encryption_sdk.EncryptionSDKClient(commitment_policy=CommitmentPolicy.FORBID_ENCRYPT_ALLOW_DECRYPT)


def decrypt_endpoint() -> Text:
    """Build the API endpoint based on environment variables."""
    global _ENDPOINT  # pylint: disable=global-statement

    if _ENDPOINT is not None:
        return _ENDPOINT

    try:
        deployment_id = os.environ[DEPLOYMENT_ID]
        region = os.environ[DEPLOYMENT_REGION]
    except KeyError as error:
        raise ValueError(
            (
                'Environment variables "{region}" and "{deployment}" '
                "must be set to the correct values for the deployed decrypt oracle."
            ).format(region=DEPLOYMENT_REGION, deployment=DEPLOYMENT_ID)
        ) from error

    _ENDPOINT = "https://{deployment_id}.execute-api.{region}.amazonaws.com/api/v0/decrypt".format(
        deployment_id=deployment_id, region=region
    )
    return _ENDPOINT


def get_cmk_arn() -> Text:
    """Retrieve the target CMK ARN from environment variable."""
    try:
        arn = os.environ[AWS_KMS_KEY_ID]
    except KeyError as error:
        raise ValueError(
            'Environment variable "{}" must be set to a valid KMS CMK ARN for integration tests to run'.format(
                AWS_KMS_KEY_ID
            )
        ) from error

    if arn.startswith("arn:") and ":alias/" not in arn:
        return arn

    raise ValueError("KMS CMK ARN provided for integration tests must be a key not an alias")


def kms_master_key_provider(cache: Optional[bool] = True):
    """Build the expected KMS Master Key Provider based on environment variables."""
    global _KMS_MKP  # pylint: disable=global-statement

    if cache and _KMS_MKP is not None:
        return _KMS_MKP

    cmk_arn = get_cmk_arn()
    _kms_master_key_provider = StrictAwsKmsMasterKeyProvider(key_ids=[cmk_arn])

    if cache:
        _KMS_MKP = _kms_master_key_provider

    return _kms_master_key_provider


def test_vectors_filename() -> Text:
    """Provide the absolute path to the test vectors file."""
    return os.path.join(HERE, "..", "vectors", "decrypt_vectors.json")


TestVector = namedtuple("TestVector", ["plaintext", "ciphertext", "key_type", "algorithm_suite"])


def all_test_vectors() -> Iterable[Any]:
    """Collect and iterate through all test vectors."""

    with open(test_vectors_filename(), "r", encoding="utf-8") as vectors_file:
        raw_vectors = json.load(vectors_file)

    for vector in raw_vectors:
        vector_name = "::".join([vector["key-type"], vector["algorithm-suite"]])
        plaintext = base64.b64decode(vector["plaintext"].encode("utf-8"))
        ciphertext = base64.b64decode(vector["ciphertext"].encode("utf-8"))
        yield pytest.param(
            TestVector(
                plaintext=plaintext,
                ciphertext=ciphertext,
                key_type=vector["key-type"],
                algorithm_suite=vector["algorithm-suite"],
            ),
            id=vector_name,
        )


def filtered_test_vectors(filter_function: Callable) -> Iterable[Any]:
    """Collect and iterate through all test vectors that pass the filter function."""
    for vector_param in all_test_vectors():
        if filter_function(vector_param.values[0]):
            yield vector_param