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.bookkeeper.common.grpc.proxy;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import io.grpc.CallOptions;
  import io.grpc.HandlerRegistry;
  import io.grpc.MethodDescriptor;
  import io.grpc.ServerCallHandler;
  import io.grpc.ServerMethodDefinition;
  import io.grpc.ServerServiceDefinition;
  import java.io.InputStream;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import javax.annotation.Nullable;
  import org.apache.bookkeeper.common.grpc.netty.IdentityInputStreamMarshaller;
  
  /**
   * Registry for proxying grpc services.
   */
  public class ProxyHandlerRegistry extends HandlerRegistry {
  
      private final Map<String, ServerMethodDefinition<?, ?>> methods;
  
      private ProxyHandlerRegistry(Map<String, ServerMethodDefinition<?, ?>> methods) {
          this.methods = methods;
      }
  
      @Nullable
      @Override
      public ServerMethodDefinition<?, ?> lookupMethod(String methodName,
                                                       @Nullable String authority) {
          return methods.get(methodName);
      }
  
      private static ServerMethodDefinition<?, ?> createProxyServerMethodDefinition(
              MethodDescriptor<?, ?> methodDesc,
              ServerCallHandler<InputStream, InputStream> handler) {
          MethodDescriptor<InputStream, InputStream> methodDescriptor = MethodDescriptor.newBuilder(
              IdentityInputStreamMarshaller.of(), IdentityInputStreamMarshaller.of())
              .setFullMethodName(methodDesc.getFullMethodName())
              .setType(methodDesc.getType())
              .setIdempotent(methodDesc.isIdempotent())
              .setSafe(methodDesc.isSafe())
              .build();
          return ServerMethodDefinition.create(methodDescriptor, handler);
      }
  
      public static Builder newBuilder() {
          return new Builder();
      }
  
      /**
       * Builder to build the handler registry.
       */
      public static class Builder {
  
          // store per-service first, to make sure services are added/replaced atomically.
          private final HashMap<String, ServerServiceDefinition> services =
              new LinkedHashMap<>();
          private ChannelFinder finder;
  
          /**
           * Add the service to this grpc handler registry.
           *
           * @param service grpc service definition
           * @return registry builder
           */
          public Builder addService(ServerServiceDefinition service) {
              services.put(
                  service.getServiceDescriptor().getName(),
                  service);
              return this;
          }
  
          /**
           * Registered a channel finder for proxying server calls.
           *
           * @param finder channel finder
           * @return registry builder
           */
          public Builder setChannelFinder(ChannelFinder finder) {
              this.finder = finder;
              return this;
          }
  
          /**
           * Build the proxy handler registry.
           *
           * @return registry builder
           */
          public ProxyHandlerRegistry build() {
              checkNotNull(finder, "No channel finder defined");
  
              ProxyServerCallHandler<InputStream, InputStream> proxyHandler =
                  new ProxyServerCallHandler<>(finder, CallOptions.DEFAULT);
  
              Map<String, ServerMethodDefinition<?, ?>> methods = new HashMap<>();
              for (ServerServiceDefinition service : services.values()) {
                  for (ServerMethodDefinition<?, ?> method : service.getMethods()) {
                      String methodName = method.getMethodDescriptor().getFullMethodName();
                      methods.put(
                          methodName,
                          createProxyServerMethodDefinition(
                              method.getMethodDescriptor(),
                              proxyHandler)
                      );
                  }
              }
              return new ProxyHandlerRegistry(
                  Collections.unmodifiableMap(methods));
          }
  
      }
  
  }
  