/*
 * Copyright 2019 The gRPC Authors
 *
 * Licensed 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 io.grpc.examples.jwtauth;

import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import io.grpc.stub.StreamObserver;
import java.io.IOException;
import java.util.logging.Logger;

/**
 * Server that manages startup/shutdown of a {@code Greeter} server. This also uses a {@link
 * JwtServerInterceptor} to intercept the JWT token passed
 */
public class AuthServer {

  private static final Logger logger = Logger.getLogger(AuthServer.class.getName());

  private Server server;
  private int port;

  public AuthServer(int port) {
    this.port = port;
  }

  private void start() throws IOException {
    server = ServerBuilder.forPort(port)
        .addService(new GreeterImpl())
        .intercept(new JwtServerInterceptor())  // add the JwtServerInterceptor
        .build()
        .start();
    logger.info("Server started, listening on " + port);
    Runtime.getRuntime().addShutdownHook(new Thread() {
      @Override
      public void run() {
        // Use stderr here since the logger may have been reset by its JVM shutdown hook.
        System.err.println("*** shutting down gRPC server since JVM is shutting down");
        AuthServer.this.stop();
        System.err.println("*** server shut down");
      }
    });
  }

  private void stop() {
    if (server != null) {
      server.shutdown();
    }
  }

  /**
   * Await termination on the main thread since the grpc library uses daemon threads.
   */
  private void blockUntilShutdown() throws InterruptedException {
    if (server != null) {
      server.awaitTermination();
    }
  }

  /**
   * Main launches the server from the command line.
   */
  public static void main(String[] args) throws IOException, InterruptedException {

    // The port on which the server should run
    int port = 50051; // default
    if (args.length > 0) {
      port = Integer.parseInt(args[0]);
    }

    final AuthServer server = new AuthServer(port);
    server.start();
    server.blockUntilShutdown();
  }

  static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
    @Override
    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
      // get client id added to context by interceptor
      String clientId = Constant.CLIENT_ID_CONTEXT_KEY.get();
      logger.info("Processing request from " + clientId);
      HelloReply reply = HelloReply.newBuilder().setMessage("Hello, " + req.getName()).build();
      responseObserver.onNext(reply);
      responseObserver.onCompleted();
    }
  }
}
