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.server;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  
  import io.grpc.BindableService;
  import io.grpc.stub.StreamObserver;
  import javassist.util.proxy.MethodHandler;
  import javassist.util.proxy.ProxyFactory;
  import org.apache.camel.component.grpc.GrpcConsumer;
  import org.apache.camel.component.grpc.GrpcEndpoint;
  import org.apache.camel.component.grpc.GrpcUtils;
  
  /**
   * BindableServiceFactory implementation that uses Javassist to generate & proxy gRPC service classes
   */
  public class DefaultBindableServiceFactory implements BindableServiceFactory {
  
      @Override
      public BindableService createBindableService(GrpcConsumer consumer) {
          GrpcEndpoint endpoint = (GrpcEndpoint) consumer.getEndpoint();
          ProxyFactory serviceProxy = new ProxyFactory();
          MethodHandler methodHandler = new MethodHandler() {
              private final GrpcMethodHandler grpcMethodHandler = new GrpcMethodHandler(consumer);
  
              @Override
              public Object invoke(Object self, Method thisMethod, Method proceed, Object[] args) throws Throwable {
                  // Determines that the incoming parameters are transmitted in synchronous mode
                  // Two incoming parameters and second is instance of the io.grpc.stub.StreamObserver
                  if (args.length == 2 && args[1] instanceof StreamObserver) {
                      grpcMethodHandler.handle(args[0], (StreamObserver<Object>) args[1], thisMethod.getName());
                  } else if (args.length == 1 && args[0] instanceof StreamObserver) {
                      // Single incoming parameter is instance of the io.grpc.stub.StreamObserver
                      return grpcMethodHandler.handleForConsumerStrategy((StreamObserver<Object>) args[0], thisMethod.getName());
                  } else {
                      throw new IllegalArgumentException("Invalid to process gRPC method: " + thisMethod.getName());
                  }
                  return null;
              }
          };
          serviceProxy.setSuperclass(GrpcUtils.constructGrpcImplBaseClass(endpoint.getServicePackage(), endpoint.getServiceName(),
                  endpoint.getCamelContext()));
          try {
              return (BindableService) serviceProxy.create(new Class<?>[0], new Object[0], methodHandler);
          } catch (NoSuchMethodException | IllegalArgumentException | InstantiationException | IllegalAccessException
                   | InvocationTargetException e) {
              throw new IllegalArgumentException(
                      "Unable to create bindable proxy service for " + endpoint.getConfiguration().getService());
          }
      }
  }
  