content: /*
   * 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.
   */
  
  package org.apache.cassandra.sidecar.client.retry;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.CompletionException;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.stream.IntStream;
  import java.util.stream.Stream;
  
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.Arguments;
  import org.junit.jupiter.params.provider.MethodSource;
  import org.junit.jupiter.params.provider.ValueSource;
  
  import org.apache.cassandra.sidecar.client.HttpResponse;
  import org.apache.cassandra.sidecar.client.exception.ResourceNotFoundException;
  import org.apache.cassandra.sidecar.client.exception.RetriesExhaustedException;
  import org.apache.cassandra.sidecar.client.exception.UnexpectedStatusCodeException;
  import org.apache.cassandra.sidecar.common.request.Request;
  
  import static io.netty.handler.codec.http.HttpResponseStatus.ACCEPTED;
  import static io.netty.handler.codec.http.HttpResponseStatus.INTERNAL_SERVER_ERROR;
  import static io.netty.handler.codec.http.HttpResponseStatus.NOT_ACCEPTABLE;
  import static io.netty.handler.codec.http.HttpResponseStatus.NOT_FOUND;
  import static io.netty.handler.codec.http.HttpResponseStatus.NOT_IMPLEMENTED;
  import static io.netty.handler.codec.http.HttpResponseStatus.OK;
  import static io.netty.handler.codec.http.HttpResponseStatus.SERVICE_UNAVAILABLE;
  import static org.apache.cassandra.sidecar.common.http.SidecarHttpResponseStatus.CHECKSUM_MISMATCH;
  import static org.assertj.core.api.Assertions.assertThat;
  import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  import static org.assertj.core.api.Fail.fail;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.when;
  
  /**
   * Unit tests for the {@link BasicRetryPolicy}
   */
  class BasicRetryPolicyTest
  {
      HttpResponse mockResponse;
      Request mockRequest;
      RetryPolicy defaultBasicRetryPolicy;
      Map<String, List<String>> headersMap;
  
      @BeforeEach
      void setup()
      {
          defaultBasicRetryPolicy = new BasicRetryPolicy();
          headersMap = new HashMap<>();
          mockResponse = mock(HttpResponse.class);
          mockRequest = mock(Request.class);
          when(mockResponse.headers()).thenReturn(headersMap);
          when(mockRequest.requestURI()).thenReturn("/api/uri");
      }
  
      @ParameterizedTest(name = "{index} => canRetryOnADifferentHost={0}")
      @ValueSource(booleans = { true, false })
      void testRetriesWhenThrowableIsProvided(boolean canRetryOnADifferentHost)
      {
          IllegalArgumentException throwable = new IllegalArgumentException("Connection Refused");
          testWithRetries(mockRequest, null, throwable, 3, 100, canRetryOnADifferentHost);
      }
  
      @Test
      void testRetriesOnInternalServerErrorStatusCode()
      {
          when(mockResponse.statusCode()).thenReturn(INTERNAL_SERVER_ERROR.code());
          testWithRetries(mockRequest, mockResponse, null, 5, 200, false);
          testWithRetries(mockRequest, mockResponse, null, 5, 200, true);
      }
  
      @Test
      void testCompletesWithOKStatusCode() throws ExecutionException, InterruptedException
      {
          when(mockResponse.statusCode()).thenReturn(OK.code());
  
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          defaultBasicRetryPolicy.onResponse(future, mockRequest, mockResponse, null, 1, false,
                                             (attempts, retryDelayMillis) -> fail("Should never retry"));
          future.join();
          assertThat(future.isDone()).isTrue();
          assertThat(future.get()).isSameAs(mockResponse);
      }
  
      @ParameterizedTest(name = "{index} => canRetryOnADifferentHost={0}")
      @ValueSource(booleans = { true, false })
      void testCompletesWithNotFoundStatusCode(boolean canRetryOnADifferentHost)
      throws ExecutionException, InterruptedException
      {
          when(mockResponse.statusCode()).thenReturn(NOT_FOUND.code());
  
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          if (canRetryOnADifferentHost)
          {
              testWithRetries(mockRequest, mockResponse, null, 3, 50, true);
          }
          else
          {
              defaultBasicRetryPolicy.onResponse(future, mockRequest, mockResponse, null, 1, canRetryOnADifferentHost,
                                                 (attempts, retryDelayMillis) -> fail("Should never retry"));
              assertThatExceptionOfType(CompletionException.class)
              .isThrownBy(future::join)
              .withCauseInstanceOf(ResourceNotFoundException.class);
          }
      }
  
      @ParameterizedTest(name = "{index} => canRetryOnADifferentHost={0}")
      @ValueSource(booleans = { true, false })
      void testRetriesWithNotImplementedStatusCode(boolean canRetryOnADifferentHost)
      {
          when(mockResponse.statusCode()).thenReturn(NOT_IMPLEMENTED.code());
  
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          defaultBasicRetryPolicy.onResponse(future, mockRequest, mockResponse, null, 1, canRetryOnADifferentHost,
                                             (attempts, retryDelayMillis) -> fail("Should never retry"));
  
          assertThatExceptionOfType(CompletionException.class)
          .isThrownBy(future::join)
          .withCauseInstanceOf(UnsupportedOperationException.class);
          assertThat(future.isCompletedExceptionally()).isTrue();
      }
  
      @Test
      void testRetriesWithNotAcceptableStatusCode()
      {
          when(mockResponse.statusCode()).thenReturn(NOT_ACCEPTABLE.code());
          testWithRetries(mockRequest, mockResponse, null, 8, 50, true);
      }
  
      @ParameterizedTest(name = "{index} => canRetryOnADifferentHost={0}")
      @ValueSource(booleans = { true, false })
      void testRetriesWithServiceUnavailableStatusCode(boolean canRetryOnADifferentHost)
      {
          when(mockResponse.statusCode()).thenReturn(SERVICE_UNAVAILABLE.code());
          testWithRetries(mockRequest, mockResponse, null, 5, 300, canRetryOnADifferentHost);
      }
  
      @ParameterizedTest(name = "{index} => canRetryOnADifferentHost={0}")
      @ValueSource(booleans = { true, false })
      void testRetriesWithChecksumMismatchStatusCode(boolean canRetryOnADifferentHost)
      {
          when(mockResponse.statusCode()).thenReturn(CHECKSUM_MISMATCH.code());
          testWithRetries(mockRequest, mockResponse, null, 5, 300, canRetryOnADifferentHost);
      }
  
      @Test
      void testRetriesWithServiceUnavailableStatusCodeWithRetryAfterHeader()
      {
          when(mockResponse.statusCode()).thenReturn(SERVICE_UNAVAILABLE.code());
          headersMap.put("Retry-After", Collections.singletonList("5")); // 5 seconds -> 5,000 millis
          testWithRetries(mockRequest, mockResponse, null, 5, 1000, 5000, false);
          testWithRetries(mockRequest, mockResponse, null, 5, 1000, 0, true);
      }
  
      @Test
      void testRetriesWithServiceUnavailableStatusCodeWithInvalidRetryAfterHeader()
      {
          when(mockResponse.statusCode()).thenReturn(SERVICE_UNAVAILABLE.code());
          headersMap.put("Retry-After", Collections.singletonList("one-thousand-seconds"));
          testWithRetries(mockRequest, mockResponse, null, 5, 200, 200, false);
          testWithRetries(mockRequest, mockResponse, null, 5, 200, 0, true);
      }
  
      @Test
      void testRetriesWithAcceptedStatusCode() throws ExecutionException, InterruptedException
      {
          when(mockResponse.statusCode()).thenReturn(ACCEPTED.code());
          RetryPolicy retryPolicy = new BasicRetryPolicy(1);
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          AtomicInteger retryActionCalls = new AtomicInteger(0);
          int maxRetries = 50;
          for (int currentAttempt = 1; currentAttempt <= maxRetries; currentAttempt++)
          {
              retryPolicy.onResponse(future, mockRequest, mockResponse, null, currentAttempt, true,
                                     (attempts, retryDelayMillis) -> {
                                         retryActionCalls.incrementAndGet();
                                         assertThat(attempts).isEqualTo(1);
                                         assertThat(retryDelayMillis).isEqualTo(0);
                                     });
          }
  
          when(mockResponse.statusCode()).thenReturn(OK.code());
  
          retryPolicy.onResponse(future, mockRequest, mockResponse, null, 1, false,
                                 (attempts, retryDelayMillis) -> fail("Should not retry"));
          future.join();
          assertThat(future.isDone()).isTrue();
          assertThat(future.get()).isSameAs(mockResponse);
          assertThat(retryActionCalls.get()).isEqualTo(maxRetries);
      }
  
      private static Stream<Arguments> clientStatusCodeArguments()
      {
          return IntStream.range(400, 500)
                          .filter(statusCode -> statusCode != NOT_FOUND.code()
                                                && statusCode != CHECKSUM_MISMATCH.code())
                          .boxed()
                          .map(Arguments::of);
      }
  
      @ParameterizedTest(name = "{index} => statusCode={0}")
      @MethodSource("clientStatusCodeArguments")
      void testRetriesWithClientError(int statusCode)
      {
          when(mockResponse.statusCode()).thenReturn(statusCode);
          testWithRetries(mockRequest, mockResponse, null, 2, 200, 200, false, false);
          testWithRetries(mockRequest, mockResponse, null, 2, 200, 0, true, false);
      }
  
      private static Stream<Arguments> serverStatusCodeArguments()
      {
          return IntStream.range(500, 600)
                          .filter(statusCode -> statusCode != INTERNAL_SERVER_ERROR.code()
                                                && statusCode != NOT_IMPLEMENTED.code()
                                                && statusCode != SERVICE_UNAVAILABLE.code())
                          .boxed()
                          .map(Arguments::of);
      }
  
      @ParameterizedTest(name = "{index} => statusCode={0}")
      @MethodSource("serverStatusCodeArguments")
      void testRetriesWithServerError(int statusCode)
      {
          when(mockResponse.statusCode()).thenReturn(statusCode);
          testWithRetries(mockRequest, mockResponse, null, 3, 200, 200, false, false);
          testWithRetries(mockRequest, mockResponse, null, 3, 200, 0, true, false);
      }
  
      @Test
      void testFailsWithUnexpectedStatusCode()
      {
          when(mockResponse.statusCode()).thenReturn(700); // 700 is an invalid status code
  
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          defaultBasicRetryPolicy.onResponse(future, mockRequest, mockResponse, null, 1, false,
                                             (attempts, retryDelayMillis) -> fail("Should never retry"));
          assertThatExceptionOfType(CompletionException.class)
          .isThrownBy(future::join)
          .withCauseInstanceOf(UnexpectedStatusCodeException.class)
          .withMessageContaining("Unexpected HTTP status code 700");
          assertThat(future.isCompletedExceptionally()).isTrue();
      }
  
      private static void testWithRetries(Request request, HttpResponse response, Throwable throwable,
                                          int configuredMaxRetries, int configuredRetryDelayMillis,
                                          boolean canRetryOnADifferentHost)
      {
          testWithRetries(request, response, throwable, configuredMaxRetries, configuredRetryDelayMillis,
                          canRetryOnADifferentHost ? 0 : configuredRetryDelayMillis, canRetryOnADifferentHost);
      }
  
      private static void testWithRetries(Request request, HttpResponse response, Throwable throwable,
                                          int configuredMaxRetries, int configuredRetryDelayMillis,
                                          int expectedRetryDelayMillis, boolean canRetryOnADifferentHost)
      {
          testWithRetries(request, response, throwable, configuredMaxRetries, configuredRetryDelayMillis,
                          expectedRetryDelayMillis, canRetryOnADifferentHost, true);
      }
  
      private static void testWithRetries(Request request, HttpResponse response, Throwable throwable,
                                          int configuredMaxRetries, int configuredRetryDelayMillis,
                                          int expectedRetryDelayMillis, boolean canRetryOnADifferentHost,
                                          boolean expectedToRetryOnSameHost)
      {
          RetryPolicy retryPolicy = new BasicRetryPolicy(configuredMaxRetries, configuredRetryDelayMillis);
          CompletableFuture<HttpResponse> future = new CompletableFuture<>();
          for (int currentAttempt = 1; currentAttempt <= configuredMaxRetries; currentAttempt++)
          {
              // retries on error
              int expectedNextAttempt = currentAttempt + 1;
              retryPolicy.onResponse(future, request, response, throwable, currentAttempt, canRetryOnADifferentHost,
                                     (attempts, retryDelayMillis) -> {
                                         if (expectedNextAttempt > configuredMaxRetries)
                                         {
                                             fail("Should never retry");
                                         }
                                         else
                                         {
                                             assertThat(attempts).isEqualTo(expectedNextAttempt);
                                             assertThat(retryDelayMillis).isEqualTo(expectedRetryDelayMillis);
                                         }
                                     });
  
              if (!canRetryOnADifferentHost && !expectedToRetryOnSameHost)
              {
                  break;
              }
          }
  
          String description;
          if (expectedToRetryOnSameHost || canRetryOnADifferentHost)
          {
              description = "Unable to complete request '/api/uri' after " + configuredMaxRetries + " attempts";
          }
          else
          {
              description = "Unable to complete request '/api/uri' after 1 attempt";
          }
  
          assertThatExceptionOfType(CompletionException.class)
          .isThrownBy(future::join)
          .withCauseInstanceOf(RetriesExhaustedException.class)
          .withMessageContaining(description);
          assertThat(future.isCompletedExceptionally()).isTrue();
      }
  }
  