/*
 *
 * Copyright 2023 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.
 *
 */

const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');
const parseArgs = require('minimist');

const PROTO_PATH = __dirname + '/../protos/echo.proto';

const packageDefinition = protoLoader.loadSync(
  PROTO_PATH,
  {keepCase: true,
   longs: String,
   enums: String,
   defaults: true,
   oneofs: true
  });
const echoProto = grpc.loadPackageDefinition(packageDefinition).grpc.examples.echo;

const PROPAGATE_PREFIX = '[propagate me]';

let client;

function unaryEcho(call, callback) {
  const message = call.request.message;
  if (message.startsWith(PROPAGATE_PREFIX)) {
    setTimeout(() => {
      client.unaryEcho({message: message.slice(PROPAGATE_PREFIX.length)}, {parent: call}, callback);
    }, 800);
    return;
  } else if (message === 'delay') {
    setTimeout(() => {
      callback(null, call.request);
    }, 1500);
  } else {
    callback(null, call.request);
  }
}

function bidirectionalStreamingEcho(call) {
  let lastMessage = null;
  call.on('data', value => {
    const message = value.message;
    lastMessage = message;
    call.pause();
    if (message.startsWith(PROPAGATE_PREFIX)) {
      setTimeout(() => {
        client.unaryEcho({message: message.slice(PROPAGATE_PREFIX.length)}, {parent: call}, (error, response) => {
          call.resume();
          if (error) {
            call.emit(error);
            return;
          }
          call.write(response);
        });
      }, 800);
      return;
    } else if (message === 'delay') {
      setTimeout(() => {
        call.write(value);
        call.resume();
      }, 1500);
    } else {
      call.write(value);
      call.resume();
    }
  });
  call.on('end', () => {
    if (lastMessage === null) {
      call.emit('error', {code: grpc.status.INVALID_ARGUMENT, details: 'request message not received'});
    }
    call.end();
  });
}

const serviceImplementation = {
  unaryEcho,
  bidirectionalStreamingEcho
}

function main() {
  const argv = parseArgs(process.argv.slice(2), {
    string: 'port',
    default: {port: '50052'}
  });
  const server = new grpc.Server();
  server.addService(echoProto.Echo.service, serviceImplementation);
  server.bindAsync(`0.0.0.0:${argv.port}`, grpc.ServerCredentials.createInsecure(), (err, port) => {
    if (err != null) {
      return console.error(err);
    }
    console.log(`gRPC listening on ${port}`)
  });
  client = new echoProto.Echo(`localhost:${argv.port}`, grpc.credentials.createInsecure());
}

main();