server.js

const express = require('express');
const OpenTok = require('opentok');
const bodyParser = require('body-parser');
const config = require('./config');

const app = express();

app.use(express.static(`${__dirname}/public`));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

const OT = new OpenTok(config.apiKey, config.apiSecret);

/**
   * generateToken is used to create a token for a user
   * @param {String} sessionId
   * @param {String} sipTokenData
*/

const generateToken = (sessionId, sipTokenData = '') => OT.generateToken(sessionId, {
  role: 'publisher',
  data: sipTokenData,
});

/**
   * generatePin is used to create a 4 digit pin
*/

const generatePin = () => {
  const pin = Math.floor(Math.random() * 9000) + 1000;
  if (app.get(pin)) {
    return generatePin();
  }
  return pin;
};

/**
   * renderRoom is used to render the ejs template
   * @param {Object} res
   * @param {String} sessionId
   * @param {String} token
   * @param {String} roomId
   * @param {Number} pinCode

*/

const renderRoom = (res, sessionId, token, roomId, pinCode) => {
  const { apiKey, conferenceNumber } = config;
  res.render('index.ejs', {
    apiKey,
    sessionId,
    token,
    roomId,
    pinCode,
    conferenceNumber,
  });
};


/**
   * setSipOptions is used to set properties for the OT.dial API call
   * @returns {Object}
*/

const setSipOptions = () => ({
  auth: {
    username: config.sip.username,
    password: config.sip.password,
  },
  secure: false,
});

/**
   * When the room/:roomId request is made, either a template is rendered is served with the 
   * sessionid, token, pinCode, roomId, and apiKey.
*/

app.get('/room/:roomId', (req, res) => {
  const { roomId } = req.params;
  let pinCode;
  if (app.get(roomId)) {
    const sessionId = app.get(roomId);
    const token = generateToken(sessionId);
    pinCode = app.get(sessionId);
    renderRoom(res, sessionId, token, roomId, pinCode);
  } else {
    pinCode = generatePin();
    OT.createSession({
      mediaMode: 'routed',
    }, (error, session) => {
      if (error) {
        return res.send('There was an error').status(500);
      }
      const { sessionId } = session;
      const token = generateToken(sessionId);
      app.set(roomId, sessionId);
      app.set(pinCode, sessionId);
      renderRoom(res, sessionId, token, roomId, pinCode);
    });
  }
});

/**
   * When the dial-out get request is made, the dial method of the OpenTok Dial API is invoked
*/

app.get('/dial-out', (req, res) => {
  const { roomId } = req.query;
  const { conferenceNumber } = config;
  const sipTokenData = `{"sip":true, "role":"client", "name":"'${conferenceNumber}'"}`;
  const sessionId = app.get(roomId);
  const token = generateToken(sessionId, sipTokenData);
  const options = setSipOptions();
  const sipUri = `sip:${conferenceNumber}@sip.nexmo.com;transport=tls`;
  OT.dial(sessionId, token, sipUri, options, (error, sipCall) => {
    if (error) {
      res.status(500).send('There was an error dialing out');
    } else {
      app.set(conferenceNumber + roomId, sipCall.connectionId);
      res.json(sipCall);
    }
  });
});

/**
   * When the hang-up get request is made, the forceDisconnect method of the OpenTok API is invoked
*/
app.get('/hang-up', (req, res) => {
  const { roomId } = req.query;
  const { conferenceNumber } = config;
  if (app.get(roomId) + app.get(conferenceNumber + roomId)) {
    const sessionId = app.get(roomId);
    const connectionId = app.get(conferenceNumber + roomId); 
    OT.forceDisconnect(sessionId, connectionId, (error) => {
      if (error) {
        res.status(500).send('There was an error hanging up');
      } else {
        res.status(200).send('Ok');
      }
    });
  } else {
    res.status(400).send('There was an error hanging up');
  }
});

app.get('/nexmo-answer', (req, res) => {
  const { serverUrl } = config;
  const ncco = [];
  if (req.query['SipHeader_X-OpenTok-SessionId']) {
    ncco.push({
      action: 'conversation',
      name: req.query['SipHeader_X-OpenTok-SessionId'],
    });
  } else {
    ncco.push(
      {
        action: 'talk',
        text: 'Please enter a a pin code to join the session'
      },
      {
        action: 'input',
        eventUrl: [`${serverUrl}/nexmo-dtmf`]
      }
    )
  }

  res.json(ncco);
});

app.post('/nexmo-dtmf', (req, res) => {
  const { dtmf } = req.body;
  let sessionId;

  if (app.get(dtmf)) {
    sessionId = app.get(dtmf);
  }

  const ncco = [
  {
    action: 'conversation',
    name: sessionId,
  }];

  res.json(ncco)
})

app.get('/nexmo-events', (req, res) => {
  res.status(200).send();
});


const port = process.env.PORT || '3000';
app.listen(port, () => console.log(`listening on port ${port}`));