/*
 * 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.beam.fn.harness.control;

import static org.apache.beam.vendor.guava.v20_0.com.google.common.base.Throwables.getStackTraceAsString;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.not;
import static org.hamcrest.Matchers.nullValue;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.fail;

import java.util.EnumMap;
import java.util.UUID;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.beam.model.fnexecution.v1.BeamFnApi;
import org.apache.beam.model.fnexecution.v1.BeamFnApi.InstructionRequest;
import org.apache.beam.model.fnexecution.v1.BeamFnApi.RegisterRequest;
import org.apache.beam.model.fnexecution.v1.BeamFnControlGrpc;
import org.apache.beam.model.pipeline.v1.Endpoints;
import org.apache.beam.sdk.fn.function.ThrowingFunction;
import org.apache.beam.sdk.fn.stream.OutboundObserverFactory;
import org.apache.beam.sdk.fn.test.InProcessManagedChannelFactory;
import org.apache.beam.sdk.fn.test.TestStreams;
import org.apache.beam.vendor.grpc.v1p13p1.io.grpc.Server;
import org.apache.beam.vendor.grpc.v1p13p1.io.grpc.inprocess.InProcessServerBuilder;
import org.apache.beam.vendor.grpc.v1p13p1.io.grpc.stub.CallStreamObserver;
import org.apache.beam.vendor.grpc.v1p13p1.io.grpc.stub.StreamObserver;
import org.apache.beam.vendor.guava.v20_0.com.google.common.util.concurrent.Uninterruptibles;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link BeamFnControlClient}. */
@RunWith(JUnit4.class)
public class BeamFnControlClientTest {
  private static final BeamFnApi.InstructionRequest SUCCESSFUL_REQUEST =
      BeamFnApi.InstructionRequest.newBuilder()
          .setInstructionId("1L")
          .setProcessBundle(BeamFnApi.ProcessBundleRequest.getDefaultInstance())
          .build();
  private static final BeamFnApi.InstructionResponse SUCCESSFUL_RESPONSE =
      BeamFnApi.InstructionResponse.newBuilder()
          .setInstructionId("1L")
          .setProcessBundle(BeamFnApi.ProcessBundleResponse.getDefaultInstance())
          .build();
  private static final BeamFnApi.InstructionRequest UNKNOWN_HANDLER_REQUEST =
      BeamFnApi.InstructionRequest.newBuilder().setInstructionId("2L").build();
  private static final BeamFnApi.InstructionResponse UNKNOWN_HANDLER_RESPONSE =
      BeamFnApi.InstructionResponse.newBuilder()
          .setInstructionId("2L")
          .setError(
              "Unknown InstructionRequest type "
                  + BeamFnApi.InstructionRequest.RequestCase.REQUEST_NOT_SET)
          .build();
  private static final RuntimeException FAILURE = new RuntimeException("TestFailure");
  private static final BeamFnApi.InstructionRequest FAILURE_REQUEST =
      BeamFnApi.InstructionRequest.newBuilder()
          .setInstructionId("3L")
          .setRegister(BeamFnApi.RegisterRequest.getDefaultInstance())
          .build();
  private static final BeamFnApi.InstructionResponse FAILURE_RESPONSE =
      BeamFnApi.InstructionResponse.newBuilder()
          .setInstructionId("3L")
          .setError(getStackTraceAsString(FAILURE))
          .build();

  @Test
  public void testDelegation() throws Exception {
    AtomicBoolean clientClosedStream = new AtomicBoolean();
    BlockingQueue<BeamFnApi.InstructionResponse> values = new LinkedBlockingQueue<>();
    BlockingQueue<StreamObserver<BeamFnApi.InstructionRequest>> outboundServerObservers =
        new LinkedBlockingQueue<>();
    CallStreamObserver<BeamFnApi.InstructionResponse> inboundServerObserver =
        TestStreams.withOnNext(values::add)
            .withOnCompleted(() -> clientClosedStream.set(true))
            .build();

    Endpoints.ApiServiceDescriptor apiServiceDescriptor =
        Endpoints.ApiServiceDescriptor.newBuilder()
            .setUrl(this.getClass().getName() + "-" + UUID.randomUUID().toString())
            .build();
    Server server =
        InProcessServerBuilder.forName(apiServiceDescriptor.getUrl())
            .addService(
                new BeamFnControlGrpc.BeamFnControlImplBase() {
                  @Override
                  public StreamObserver<BeamFnApi.InstructionResponse> control(
                      StreamObserver<BeamFnApi.InstructionRequest> outboundObserver) {
                    Uninterruptibles.putUninterruptibly(outboundServerObservers, outboundObserver);
                    return inboundServerObserver;
                  }
                })
            .build();
    server.start();
    try {
      EnumMap<
              BeamFnApi.InstructionRequest.RequestCase,
              ThrowingFunction<BeamFnApi.InstructionRequest, BeamFnApi.InstructionResponse.Builder>>
          handlers = new EnumMap<>(BeamFnApi.InstructionRequest.RequestCase.class);
      handlers.put(
          BeamFnApi.InstructionRequest.RequestCase.PROCESS_BUNDLE,
          value ->
              BeamFnApi.InstructionResponse.newBuilder()
                  .setProcessBundle(BeamFnApi.ProcessBundleResponse.getDefaultInstance()));
      handlers.put(
          BeamFnApi.InstructionRequest.RequestCase.REGISTER,
          value -> {
            throw FAILURE;
          });

      BeamFnControlClient client =
          new BeamFnControlClient(
              "",
              apiServiceDescriptor,
              InProcessManagedChannelFactory.create(),
              OutboundObserverFactory.trivial(),
              handlers);

      // Get the connected client and attempt to send and receive an instruction
      StreamObserver<BeamFnApi.InstructionRequest> outboundServerObserver =
          outboundServerObservers.take();

      ExecutorService executor = Executors.newCachedThreadPool();
      Future<Void> future =
          executor.submit(
              () -> {
                client.processInstructionRequests(executor);
                return null;
              });

      outboundServerObserver.onNext(SUCCESSFUL_REQUEST);
      assertEquals(SUCCESSFUL_RESPONSE, values.take());

      // Ensure that conversion of an unknown request type is properly converted to a
      // failure response.
      outboundServerObserver.onNext(UNKNOWN_HANDLER_REQUEST);
      assertEquals(UNKNOWN_HANDLER_RESPONSE, values.take());

      // Ensure that all exceptions are caught and translated to failures
      outboundServerObserver.onNext(FAILURE_REQUEST);
      assertEquals(FAILURE_RESPONSE, values.take());

      // Ensure that the server completing the stream translates to the completable future
      // being completed allowing for a successful shutdown of the client.
      outboundServerObserver.onCompleted();
      future.get();
    } finally {
      server.shutdownNow();
    }
  }

  @Test
  public void testJavaErrorResponse() throws Exception {
    BlockingQueue<StreamObserver<BeamFnApi.InstructionRequest>> outboundServerObservers =
        new LinkedBlockingQueue<>();
    BlockingQueue<Throwable> error = new LinkedBlockingQueue<>();
    CallStreamObserver<BeamFnApi.InstructionResponse> inboundServerObserver =
        TestStreams.<BeamFnApi.InstructionResponse>withOnNext(
                response -> fail(String.format("Unexpected Response %s", response)))
            .withOnError(error::add)
            .build();

    Endpoints.ApiServiceDescriptor apiServiceDescriptor =
        Endpoints.ApiServiceDescriptor.newBuilder()
            .setUrl(this.getClass().getName() + "-" + UUID.randomUUID().toString())
            .build();
    Server server =
        InProcessServerBuilder.forName(apiServiceDescriptor.getUrl())
            .addService(
                new BeamFnControlGrpc.BeamFnControlImplBase() {
                  @Override
                  public StreamObserver<BeamFnApi.InstructionResponse> control(
                      StreamObserver<BeamFnApi.InstructionRequest> outboundObserver) {
                    Uninterruptibles.putUninterruptibly(outboundServerObservers, outboundObserver);
                    return inboundServerObserver;
                  }
                })
            .build();
    server.start();
    try {
      EnumMap<
              BeamFnApi.InstructionRequest.RequestCase,
              ThrowingFunction<BeamFnApi.InstructionRequest, BeamFnApi.InstructionResponse.Builder>>
          handlers = new EnumMap<>(BeamFnApi.InstructionRequest.RequestCase.class);
      handlers.put(
          BeamFnApi.InstructionRequest.RequestCase.REGISTER,
          value -> {
            throw new Error("Test Error");
          });

      BeamFnControlClient client =
          new BeamFnControlClient(
              "",
              apiServiceDescriptor,
              InProcessManagedChannelFactory.create(),
              OutboundObserverFactory.trivial(),
              handlers);

      // Get the connected client and attempt to send and receive an instruction
      StreamObserver<BeamFnApi.InstructionRequest> outboundServerObserver =
          outboundServerObservers.take();

      ExecutorService executor = Executors.newCachedThreadPool();
      Future<Void> future =
          executor.submit(
              () -> {
                client.processInstructionRequests(executor);
                return null;
              });

      // Ensure that all exceptions are caught and translated to failures
      outboundServerObserver.onNext(
          InstructionRequest.newBuilder()
              .setInstructionId("0")
              .setRegister(RegisterRequest.getDefaultInstance())
              .build());
      // There should be an error reported to the StreamObserver.
      assertThat(error.take(), not(nullValue()));

      // Ensure that the client shuts down when an Error is thrown from the harness
      try {
        future.get();
        throw new IllegalStateException("The future should have terminated with an error");
      } catch (ExecutionException errorWrapper) {
        assertThat(errorWrapper.getCause().getMessage(), containsString("Test Error"));
      }
    } finally {
      server.shutdownNow();
    }
  }
}
