# Copyright 2017 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.
import contextlib
import datetime
import json

import botocore.endpoint
from botocore.config import Config
from botocore.exceptions import ClientError
from tests import BaseSessionTest, ClientHTTPStubber, mock

RETRY_MODES = ('legacy', 'standard', 'adaptive')


class BaseRetryTest(BaseSessionTest):
    def setUp(self):
        super().setUp()
        self.region = 'us-west-2'
        self.sleep_patch = mock.patch('time.sleep')
        self.sleep_patch.start()

    def tearDown(self):
        super().tearDown()
        self.sleep_patch.stop()

    @contextlib.contextmanager
    def assert_will_retry_n_times(
        self, client, num_retries, status=500, body=b'{}'
    ):
        num_responses = num_retries + 1
        if not isinstance(body, bytes):
            body = json.dumps(body).encode()
        with ClientHTTPStubber(client) as http_stubber:
            for _ in range(num_responses):
                http_stubber.add_response(status=status, body=body)
            with self.assertRaisesRegex(
                ClientError, f'reached max retries: {num_retries}'
            ):
                yield
            self.assertEqual(len(http_stubber.requests), num_responses)


class TestRetryHeader(BaseRetryTest):
    def _retry_headers_test_cases(self):
        responses = [
            [
                (500, {'Date': 'Sat, 01 Jun 2019 00:00:00 GMT'}),
                (500, {'Date': 'Sat, 01 Jun 2019 00:00:01 GMT'}),
                (200, {'Date': 'Sat, 01 Jun 2019 00:00:02 GMT'}),
            ],
            [
                (500, {'Date': 'Sat, 01 Jun 2019 00:10:03 GMT'}),
                (500, {'Date': 'Sat, 01 Jun 2019 00:10:09 GMT'}),
                (200, {'Date': 'Sat, 01 Jun 2019 00:10:15 GMT'}),
            ],
        ]

        # The first, third and seventh datetime values of each
        # utcnow_side_effects list are side_effect values for when
        # utcnow is called in SigV4 signing.
        utcnow_side_effects = [
            [
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 1, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 1, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 2, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
            ],
            [
                datetime.datetime(2020, 6, 1, 0, 0, 0, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 5, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 6, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 11, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 12, 0),
                datetime.datetime(2019, 6, 1, 0, 0, 0, 0),
            ],
        ]
        expected_headers = [
            [
                b'attempt=1',
                b'ttl=20190601T000011Z; attempt=2; max=3',
                b'ttl=20190601T000012Z; attempt=3; max=3',
            ],
            [
                b'attempt=1',
                b'ttl=20190601T001014Z; attempt=2; max=3',
                b'ttl=20190601T001020Z; attempt=3; max=3',
            ],
        ]
        test_cases = list(
            zip(responses, utcnow_side_effects, expected_headers)
        )
        return test_cases

    def _test_amz_sdk_request_header_with_test_case(
        self, responses, utcnow_side_effects, expected_headers, client_config
    ):
        datetime_patcher = mock.patch.object(
            botocore.endpoint.datetime,
            'datetime',
            mock.Mock(wraps=datetime.datetime),
        )
        mocked_datetime = datetime_patcher.start()
        mocked_datetime.utcnow.side_effect = utcnow_side_effects

        client = self.session.create_client(
            'dynamodb', self.region, config=client_config
        )
        with ClientHTTPStubber(client) as http_stubber:
            for response in responses:
                http_stubber.add_response(
                    headers=response[1], status=response[0], body=b'{}'
                )
            client.list_tables()
            amz_sdk_request_headers = [
                request.headers['amz-sdk-request']
                for request in http_stubber.requests
            ]
            self.assertListEqual(amz_sdk_request_headers, expected_headers)
        datetime_patcher.stop()

    def test_amz_sdk_request_header(self):
        test_cases = self._retry_headers_test_cases()
        for retry_mode in RETRY_MODES:
            retries_config = {'mode': retry_mode, 'total_max_attempts': 3}
            client_config = Config(read_timeout=10, retries=retries_config)
            for test_case in test_cases:
                self._test_amz_sdk_request_header_with_test_case(
                    *test_case, client_config=client_config
                )

    def test_amz_sdk_invocation_id_header_persists(self):
        for retry_mode in RETRY_MODES:
            client_config = Config(retries={'mode': retry_mode})
            client = self.session.create_client(
                'dynamodb', self.region, config=client_config
            )
            num_retries = 2
            with ClientHTTPStubber(client) as http_stubber:
                for _ in range(num_retries):
                    http_stubber.add_response(status=500)
                http_stubber.add_response(status=200)
                client.list_tables()
                amz_sdk_invocation_id_headers = [
                    request.headers['amz-sdk-invocation-id']
                    for request in http_stubber.requests
                ]
                self.assertEqual(
                    amz_sdk_invocation_id_headers[0],
                    amz_sdk_invocation_id_headers[1],
                )
                self.assertEqual(
                    amz_sdk_invocation_id_headers[1],
                    amz_sdk_invocation_id_headers[2],
                )

    def test_amz_sdk_invocation_id_header_unique_per_invocation(self):
        client = self.session.create_client('dynamodb', self.region)
        num_of_invocations = 2
        with ClientHTTPStubber(client) as http_stubber:
            for _ in range(num_of_invocations):
                http_stubber.add_response(status=500)
                http_stubber.add_response(status=200)
                client.list_tables()
            amz_sdk_invocation_id_headers = [
                request.headers['amz-sdk-invocation-id']
                for request in http_stubber.requests
            ]
            self.assertEqual(
                amz_sdk_invocation_id_headers[0],
                amz_sdk_invocation_id_headers[1],
            )
            self.assertEqual(
                amz_sdk_invocation_id_headers[2],
                amz_sdk_invocation_id_headers[3],
            )
            self.assertNotEqual(
                amz_sdk_invocation_id_headers[0],
                amz_sdk_invocation_id_headers[2],
            )


class TestLegacyRetry(BaseRetryTest):
    def test_can_override_max_attempts(self):
        client = self.session.create_client(
            'dynamodb', self.region, config=Config(retries={'max_attempts': 1})
        )
        with self.assert_will_retry_n_times(client, 1):
            client.list_tables()

    def test_do_not_attempt_retries(self):
        client = self.session.create_client(
            'dynamodb', self.region, config=Config(retries={'max_attempts': 0})
        )
        with self.assert_will_retry_n_times(client, 0):
            client.list_tables()

    def test_setting_max_attempts_does_not_set_for_other_clients(self):
        # Make one client with max attempts configured.
        self.session.create_client(
            'codecommit',
            self.region,
            config=Config(retries={'max_attempts': 1}),
        )

        # Make another client that has no custom retry configured.
        client = self.session.create_client('codecommit', self.region)
        # It should use the default max retries, which should be four retries
        # for this service.
        with self.assert_will_retry_n_times(client, 4):
            client.list_repositories()

    def test_service_specific_defaults_do_not_mutate_general_defaults(self):
        # This tests for a bug where if you created a client for a service
        # with specific retry configurations and then created a client for
        # a service whose retry configurations fallback to the general
        # defaults, the second client would actually use the defaults of
        # the first client.

        # Make a dynamodb client. It's a special case client that is
        # configured to a make a maximum of 10 requests (9 retries).
        client = self.session.create_client('dynamodb', self.region)
        with self.assert_will_retry_n_times(client, 9):
            client.list_tables()

        # A codecommit client is not a special case for retries. It will at
        # most make 5 requests (4 retries) for its default.
        client = self.session.create_client('codecommit', self.region)
        with self.assert_will_retry_n_times(client, 4):
            client.list_repositories()

    def test_set_max_attempts_on_session(self):
        self.session.set_default_client_config(
            Config(retries={'max_attempts': 1})
        )
        # Max attempts should be inherited from the session.
        client = self.session.create_client('codecommit', self.region)
        with self.assert_will_retry_n_times(client, 1):
            client.list_repositories()

    def test_can_clobber_max_attempts_on_session(self):
        self.session.set_default_client_config(
            Config(retries={'max_attempts': 1})
        )
        # Max attempts should override the session's configured max attempts.
        client = self.session.create_client(
            'codecommit',
            self.region,
            config=Config(retries={'max_attempts': 0}),
        )
        with self.assert_will_retry_n_times(client, 0):
            client.list_repositories()


class TestRetriesV2(BaseRetryTest):
    def create_client_with_retry_mode(
        self, service, retry_mode, max_attempts=None
    ):
        retries = {'mode': retry_mode}
        if max_attempts is not None:
            retries['total_max_attempts'] = max_attempts
        client = self.session.create_client(
            service, self.region, config=Config(retries=retries)
        )
        return client

    def test_standard_mode_has_default_3_retries(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard'
        )
        with self.assert_will_retry_n_times(client, 2):
            client.list_tables()

    def test_standard_mode_can_configure_max_attempts(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard', max_attempts=5
        )
        with self.assert_will_retry_n_times(client, 4):
            client.list_tables()

    def test_no_retry_needed_standard_mode(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard'
        )
        with ClientHTTPStubber(client) as http_stubber:
            http_stubber.add_response(status=200, body=b'{}')
            client.list_tables()

    def test_standard_mode_retry_throttling_error(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard'
        )
        error_body = {"__type": "ThrottlingException", "message": "Error"}
        with self.assert_will_retry_n_times(
            client, 2, status=400, body=error_body
        ):
            client.list_tables()

    def test_standard_mode_retry_transient_error(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard'
        )
        with self.assert_will_retry_n_times(client, 2, status=502):
            client.list_tables()

    def test_adaptive_mode_still_retries_errors(self):
        # Verify that adaptive mode is just adding on to standard mode.
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='adaptive'
        )
        with self.assert_will_retry_n_times(client, 2):
            client.list_tables()

    def test_adaptive_mode_retry_transient_error(self):
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='adaptive'
        )
        with self.assert_will_retry_n_times(client, 2, status=502):
            client.list_tables()

    def test_can_exhaust_default_retry_quota(self):
        # Quota of 500 / 5 retry costs == 100 retry attempts
        # 100 retry attempts / 2 retries per API call == 50 client calls
        client = self.create_client_with_retry_mode(
            'dynamodb', retry_mode='standard'
        )
        for i in range(50):
            with self.assert_will_retry_n_times(client, 2, status=502):
                client.list_tables()
        # Now on the 51th attempt we should see quota errors, which we can
        # verify by looking at the request metadata.
        with ClientHTTPStubber(client) as http_stubber:
            http_stubber.add_response(status=502, body=b'{}')
            with self.assertRaises(ClientError) as e:
                client.list_tables()
        self.assertTrue(
            e.exception.response['ResponseMetadata'].get('RetryQuotaReached')
        )
