text: /**
   * Copyright 2016, Google, Inc.
   * 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.
   */
  
  // [START app]
  'use strict';
  
  const express = require('express');
  const bodyParser = require('body-parser');
  const Buffer = require('safe-buffer').Buffer;
  
  // By default, the client will authenticate using the service account file
  // specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
  // the project specified by the GCLOUD_PROJECT environment variable. See
  // https://googlecloudplatform.github.io/gcloud-node/#/docs/google-cloud/latest/guides/authentication
  // These environment variables are set automatically on Google App Engine
  const PubSub = require('@google-cloud/pubsub');
  
  // Instantiate a pubsub client
  const pubsub = PubSub();
  
  const app = express();
  app.set('view engine', 'pug');
  
  const formBodyParser = bodyParser.urlencoded({ extended: false });
  const jsonBodyParser = bodyParser.json();
  
  // List of all messages received by this instance
  const messages = [];
  
  // The following environment variables are set by app.yaml when running on GAE,
  // but will need to be manually set when running locally.
  const PUBSUB_VERIFICATION_TOKEN = process.env.PUBSUB_VERIFICATION_TOKEN;
  
  const topic = pubsub.topic(process.env.PUBSUB_TOPIC);
  
  // [START index]
  app.get('/', (req, res) => {
    res.render('index', { messages: messages });
  });
  
  app.post('/', formBodyParser, (req, res, next) => {
    if (!req.body.payload) {
      res.status(400).send('Missing payload');
      return;
    }
  
    topic.publish({
      data: req.body.payload
    }, (err) => {
      if (err) {
        next(err);
        return;
      }
      res.status(200).send('Message sent');
    });
  });
  // [END index]
  
  // [START push]
  app.post('/pubsub/push', jsonBodyParser, (req, res) => {
    if (req.query.token !== PUBSUB_VERIFICATION_TOKEN) {
      res.status(400).send();
      return;
    }
  
    // The message is a unicode string encoded in base64.
    const message = Buffer.from(req.body.message.data, 'base64').toString('utf-8');
  
    messages.push(message);
  
    res.status(200).send();
  });
  // [END push]
  
  // Start the server
  const PORT = process.env.PORT || 8080;
  app.listen(PORT, () => {
    console.log(`App listening on port ${PORT}`);
    console.log('Press Ctrl+C to quit.');
  });
  // [END app]
  