/*
 * 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.runners.dataflow.worker.fn.logging;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.containsInAnyOrder;

import java.net.InetAddress;
import java.net.ServerSocket;
import java.util.ArrayList;
import java.util.Collection;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import org.apache.beam.model.fnexecution.v1.BeamFnApi;
import org.apache.beam.model.fnexecution.v1.BeamFnLoggingGrpc;
import org.apache.beam.model.pipeline.v1.Endpoints;
import org.apache.beam.runners.dataflow.harness.test.TestStreams;
import org.apache.beam.runners.dataflow.worker.fn.stream.ServerStreamObserverFactory;
import org.apache.beam.runners.fnexecution.GrpcContextHeaderAccessorProvider;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.BindableService;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.ManagedChannel;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.Server;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.inprocess.InProcessChannelBuilder;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.inprocess.InProcessServerBuilder;
import org.apache.beam.vendor.grpc.v1p26p0.io.grpc.stub.StreamObserver;
import org.apache.beam.vendor.guava.v26_0_jre.com.google.common.net.HostAndPort;
import org.junit.After;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for {@link BeamFnLoggingService}. */
@RunWith(JUnit4.class)
public class BeamFnLoggingServiceTest {
  private Server server;

  private Endpoints.ApiServiceDescriptor findOpenPort() throws Exception {
    InetAddress address = InetAddress.getLoopbackAddress();
    try (ServerSocket socket = new ServerSocket(0, -1, address)) {
      return Endpoints.ApiServiceDescriptor.newBuilder()
          .setUrl(HostAndPort.fromParts(address.getHostAddress(), socket.getLocalPort()).toString())
          .build();
    }
  }

  @After
  public void tearDown() {
    server.shutdownNow();
  }

  @Test
  public void testMultipleClientsSuccessfullyProcessed() throws Exception {
    ConcurrentLinkedQueue<BeamFnApi.LogEntry> logs = new ConcurrentLinkedQueue<>();
    try (BeamFnLoggingService service =
        new BeamFnLoggingService(
            findOpenPort(),
            logs::add,
            ServerStreamObserverFactory.fromOptions(PipelineOptionsFactory.create())::from,
            GrpcContextHeaderAccessorProvider.getHeaderAccessor())) {
      server = createServer(service, service.getApiServiceDescriptor());

      Collection<Callable<Void>> tasks = new ArrayList<>();
      for (int i = 1; i <= 3; ++i) {
        int instructionId = i;
        tasks.add(
            () -> {
              CountDownLatch waitForServerHangup = new CountDownLatch(1);
              ManagedChannel channel =
                  InProcessChannelBuilder.forName(service.getApiServiceDescriptor().getUrl())
                      .build();
              StreamObserver<BeamFnApi.LogEntry.List> outboundObserver =
                  BeamFnLoggingGrpc.newStub(channel)
                      .logging(
                          TestStreams.withOnNext(BeamFnLoggingServiceTest::discardMessage)
                              .withOnCompleted(waitForServerHangup::countDown)
                              .build());
              outboundObserver.onNext(createLogsWithIds(instructionId, -instructionId));
              outboundObserver.onCompleted();
              waitForServerHangup.await();
              return null;
            });
      }
      ExecutorService executorService = Executors.newCachedThreadPool();
      executorService.invokeAll(tasks);
      assertThat(
          logs,
          containsInAnyOrder(
              createLogWithId(1L),
              createLogWithId(2L),
              createLogWithId(3L),
              createLogWithId(-1L),
              createLogWithId(-2L),
              createLogWithId(-3L)));
    }
  }

  @Test
  public void testMultipleClientsFailingIsHandledGracefullyByServer() throws Exception {
    Collection<Callable<Void>> tasks = new ArrayList<>();
    ConcurrentLinkedQueue<BeamFnApi.LogEntry> logs = new ConcurrentLinkedQueue<>();
    try (BeamFnLoggingService service =
        new BeamFnLoggingService(
            findOpenPort(),
            logs::add,
            ServerStreamObserverFactory.fromOptions(PipelineOptionsFactory.create())::from,
            GrpcContextHeaderAccessorProvider.getHeaderAccessor())) {
      server = createServer(service, service.getApiServiceDescriptor());
      for (int i = 1; i <= 3; ++i) {
        int instructionId = i;
        tasks.add(
            () -> {
              CountDownLatch waitForTermination = new CountDownLatch(1);
              ManagedChannel channel =
                  InProcessChannelBuilder.forName(service.getApiServiceDescriptor().getUrl())
                      .build();
              StreamObserver<BeamFnApi.LogEntry.List> outboundObserver =
                  BeamFnLoggingGrpc.newStub(channel)
                      .logging(
                          TestStreams.withOnNext(BeamFnLoggingServiceTest::discardMessage)
                              .withOnError(waitForTermination::countDown)
                              .build());
              outboundObserver.onNext(createLogsWithIds(instructionId, -instructionId));
              outboundObserver.onError(new RuntimeException("Client " + instructionId));
              waitForTermination.await();
              return null;
            });
      }
      ExecutorService executorService = Executors.newCachedThreadPool();
      executorService.invokeAll(tasks);
    }
  }

  @Test
  public void testServerCloseHangsUpClients() throws Exception {
    LinkedBlockingQueue<BeamFnApi.LogEntry> logs = new LinkedBlockingQueue<>();
    ExecutorService executorService = Executors.newCachedThreadPool();
    Collection<Future<Void>> futures = new ArrayList<>();
    try (BeamFnLoggingService service =
        new BeamFnLoggingService(
            findOpenPort(),
            logs::add,
            ServerStreamObserverFactory.fromOptions(PipelineOptionsFactory.create())::from,
            GrpcContextHeaderAccessorProvider.getHeaderAccessor())) {
      server = createServer(service, service.getApiServiceDescriptor());

      for (int i = 1; i <= 3; ++i) {
        long instructionId = i;
        futures.add(
            executorService.submit(
                () -> {
                  CountDownLatch waitForServerHangup = new CountDownLatch(1);
                  ManagedChannel channel =
                      InProcessChannelBuilder.forName(service.getApiServiceDescriptor().getUrl())
                          .build();
                  StreamObserver<BeamFnApi.LogEntry.List> outboundObserver =
                      BeamFnLoggingGrpc.newStub(channel)
                          .logging(
                              TestStreams.withOnNext(BeamFnLoggingServiceTest::discardMessage)
                                  .withOnCompleted(waitForServerHangup::countDown)
                                  .build());
                  outboundObserver.onNext(createLogsWithIds(instructionId));
                  waitForServerHangup.await();
                  return null;
                }));
      }
      // Wait till each client has sent their message showing that they have connected.
      for (int i = 1; i <= 3; ++i) {
        logs.take();
      }
      service.close();
      server.shutdownNow();
    }

    for (Future<Void> future : futures) {
      future.get();
    }
  }

  private static void discardMessage(BeamFnApi.LogControl ignored) {}

  private BeamFnApi.LogEntry.List createLogsWithIds(long... ids) {
    BeamFnApi.LogEntry.List.Builder builder = BeamFnApi.LogEntry.List.newBuilder();
    for (long id : ids) {
      builder.addLogEntries(createLogWithId(id));
    }
    return builder.build();
  }

  private BeamFnApi.LogEntry createLogWithId(long id) {
    return BeamFnApi.LogEntry.newBuilder().setInstructionId(Long.toString(id)).build();
  }

  private Server createServer(
      BindableService service, Endpoints.ApiServiceDescriptor serviceDescriptor) throws Exception {
    Server server =
        InProcessServerBuilder.forName(serviceDescriptor.getUrl()).addService(service).build();
    server.start();
    return server;
  }
}