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.camel.component.grpc;
  
  import com.google.auth.Credentials;
  import com.google.auth.oauth2.GoogleCredentials;
  import io.grpc.CallCredentials;
  import io.grpc.ManagedChannel;
  import io.grpc.auth.MoreCallCredentials;
  import io.grpc.netty.GrpcSslContexts;
  import io.grpc.netty.NegotiationType;
  import io.grpc.netty.NettyChannelBuilder;
  import io.grpc.stub.StreamObserver;
  import io.netty.handler.ssl.SslContextBuilder;
  import org.apache.camel.AsyncCallback;
  import org.apache.camel.Exchange;
  import org.apache.camel.component.grpc.auth.jwt.JwtCallCredentials;
  import org.apache.camel.component.grpc.auth.jwt.JwtHelper;
  import org.apache.camel.component.grpc.client.*;
  import org.apache.camel.support.DefaultAsyncProducer;
  import org.apache.camel.support.ResourceHelper;
  import org.apache.camel.support.service.ServiceHelper;
  import org.apache.camel.util.ObjectHelper;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Represents asynchronous and synchronous gRPC producer implementations.
   */
  public class GrpcProducer extends DefaultAsyncProducer {
  
      private static final Logger LOG = LoggerFactory.getLogger(GrpcProducer.class);
  
      protected final GrpcConfiguration configuration;
      protected final GrpcEndpoint endpoint;
      private ManagedChannel channel;
      private Object grpcStub;
      private GrpcExchangeForwarder forwarder;
      private GrpcStreamObserverFactory streamObserverFactory;
  
      public GrpcProducer(GrpcEndpoint endpoint, GrpcConfiguration configuration) {
          super(endpoint);
          this.endpoint = endpoint;
          this.configuration = configuration;
  
          if (configuration.getProducerStrategy() == GrpcProducerStrategy.STREAMING) {
              if (configuration.isSynchronous()) {
                  throw new IllegalStateException("Cannot use synchronous processing in streaming mode");
              } else if (configuration.getStreamRepliesTo() == null) {
                  throw new IllegalStateException("The streamReplyTo property is mandatory when using the STREAMING mode");
              }
          }
  
          if (configuration.getAuthenticationType() == GrpcAuthType.GOOGLE
                  && configuration.getNegotiationType() != NegotiationType.TLS) {
              throw new IllegalStateException("Google token-based authentication requires SSL/TLS negotiation mode");
          }
      }
  
      @Override
      public boolean process(Exchange exchange, AsyncCallback callback) {
          StreamObserver<Object> streamObserver = streamObserverFactory.getStreamObserver(exchange, callback);
          return forwarder.forward(exchange, streamObserver, callback);
      }
  
      @Override
      public void process(Exchange exchange) throws Exception {
          forwarder.forward(exchange);
      }
  
      @Override
      protected void doStart() throws Exception {
          super.doStart();
          if (channel == null) {
              CallCredentials callCreds = null;
              initializeChannel();
  
              if (configuration.getAuthenticationType() == GrpcAuthType.GOOGLE) {
                  ObjectHelper.notNull(configuration.getKeyCertChainResource(), "serviceAccountResource");
  
                  Credentials creds = GoogleCredentials.fromStream(
                          ResourceHelper.resolveResourceAsInputStream(endpoint.getCamelContext(),
                                  configuration.getServiceAccountResource()));
                  callCreds = MoreCallCredentials.from(creds);
              } else if (configuration.getAuthenticationType() == GrpcAuthType.JWT) {
                  ObjectHelper.notNull(configuration.getJwtSecret(), "jwtSecret");
  
                  String jwtToken = JwtHelper.createJwtToken(configuration.getJwtAlgorithm(), configuration.getJwtSecret(),
                          configuration.getJwtIssuer(), configuration.getJwtSubject());
                  callCreds = new JwtCallCredentials(jwtToken);
              }
  
              if (configuration.isSynchronous()) {
                  LOG.debug("Getting synchronous method stub from channel");
                  grpcStub = GrpcUtils.constructGrpcBlockingStub(endpoint.getServicePackage(), endpoint.getServiceName(), channel,
                          callCreds, endpoint.getCamelContext());
              } else {
                  LOG.debug("Getting asynchronous method stub from channel");
                  grpcStub = GrpcUtils.constructGrpcAsyncStub(endpoint.getServicePackage(), endpoint.getServiceName(), channel,
                          callCreds, endpoint.getCamelContext());
              }
              forwarder = GrpcExchangeForwarderFactory.createExchangeForwarder(configuration, grpcStub);
  
              streamObserverFactory = new GrpcStreamObserverFactory(getEndpoint(), configuration);
              ServiceHelper.startService(streamObserverFactory);
          }
      }
  
      @Override
      protected void doStop() throws Exception {
          ServiceHelper.stopService(streamObserverFactory);
          if (channel != null) {
              forwarder.shutdown();
              forwarder = null;
  
              LOG.debug("Terminating channel to the remote gRPC server");
              channel.shutdown().shutdownNow();
              channel = null;
              grpcStub = null;
              streamObserverFactory = null;
          }
          super.doStop();
      }
  
      protected void initializeChannel() throws Exception {
          NettyChannelBuilder channelBuilder;
  
          if (ObjectHelper.isNotEmpty(configuration.getHost()) && configuration.getPort() > 0) {
              LOG.info("Creating channel to the remote gRPC server {}:{}", configuration.getHost(), configuration.getPort());
              channelBuilder = NettyChannelBuilder.forAddress(configuration.getHost(), configuration.getPort());
          } else {
              throw new IllegalArgumentException("No connection properties (host or port) specified");
          }
          if (configuration.getNegotiationType() == NegotiationType.TLS) {
              ObjectHelper.notNull(configuration.getKeyCertChainResource(), "keyCertChainResource");
              ObjectHelper.notNull(configuration.getKeyResource(), "keyResource");
  
              SslContextBuilder sslContextBuilder = GrpcSslContexts.forClient()
                      .keyManager(
                              ResourceHelper.resolveResourceAsInputStream(endpoint.getCamelContext(),
                                      configuration.getKeyCertChainResource()),
                              ResourceHelper.resolveResourceAsInputStream(endpoint.getCamelContext(),
                                      configuration.getKeyResource()),
                              configuration.getKeyPassword());
  
              if (ObjectHelper.isNotEmpty(configuration.getTrustCertCollectionResource())) {
                  sslContextBuilder
                          = sslContextBuilder.trustManager(ResourceHelper.resolveResourceAsInputStream(endpoint.getCamelContext(),
                                  configuration.getTrustCertCollectionResource()));
              }
  
              channelBuilder = channelBuilder.sslContext(GrpcSslContexts.configure(sslContextBuilder).build());
          }
  
          channel = channelBuilder.negotiationType(configuration.getNegotiationType())
                  .flowControlWindow(configuration.getFlowControlWindow())
                  .userAgent(configuration.getUserAgent())
                  .maxInboundMessageSize(configuration.getMaxMessageSize())
                  .intercept(configuration.getClientInterceptors())
                  .build();
      }
  }
  