canvasServer.js

const express = require("express"),
  dotenv = require("dotenv"),
  jsforce = require("jsforce"),
  bodyParser = require("body-parser"),
  session = require("express-session"),
  decode = require("salesforce-signed-request");

dotenv.config();

const app = express();
app.set("view engine", "ejs");

app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))

app.use(express.static("public"));
app.use(session({ secret: "S3CRE7", resave: true, saveUninitialized: true }));

const oauth2 = new jsforce.OAuth2({
  clientId: process.env.CLIENT_ID,
  redirectUri: process.env.REDIRECT_URI,
  clientSecret: process.env.CONSUMER_SECRET,
  loginUrl: process.env.SALESFORCE_LOGIN_URL,
  version: process.env.SALESFORCE_API_VERSION
});

const sfClient = new jsforce.Connection({ oauth2: oauth2 });

app.get("/", (req, res) => {
  res.redirect("/oauth2/login");
});


app.get("/oauth2/login", (req, res) => {
  const authUrl = oauth2.getAuthorizationUrl({ scope: "api id web refresh_token" });
  res.redirect(authUrl);
});


app.get("/oauth2/callback", (req, res) => {
  const tenMinutes = 1000 * 60 * 10;
  req.connection.setTimeout(tenMinutes);

  sfClient.authorize(req.query.code, (err, userInfo) => {

    if (err) {
      handleError(err, res);
    } else {
      req.session.accessToken = sfClient.accessToken;
      req.session.instanceUrl = sfClient.instanceUrl;
      req.session.refreshToken = sfClient.refreshToken;

      sfClient.streaming.topic("/event/EncowayCPQ__e")
        .subscribe((message) => {
          console.log({ "RECEIVED EVENT": message });
        });

      res.redirect("/param1/param2/param3");
    }
  });
});


app.get("/:p1/:p2/:p3", (req, res) => {
  if (!req.session.accessToken || !req.session.instanceUrl) {
    return res.redirect("/");
  }

  let signedRequest = {
    user: {
      firstName: "Anmol",
      fullName: "Anmol Kumar"
    }
  }

  const query = "SELECT Id, Name, Account.Name, Opportunity.Name, BillingStreet, BillingCity FROM Quote";

  sfClient.query(query, (err, result) => {
    if (err) {
      return handleError(err, res);
    }

    res.render("index", {
      quoteId: result.records[0].Id,
      context: JSON.stringify(signedRequest, null, 2),
      quote: JSON.stringify(result, null, 2),
      params: JSON.stringify(req.params, null, 2),
      query: JSON.stringify(req.query, null, 2)
    });
  });
});


app.post("/:p1/:p2/:p3", (req, res) => {

  if (!req.session.accessToken || !req.session.instanceUrl) {
    return res.redirect("/oauth2/login");
  }

  const signedRequest = decode(req.body.signed_request, process.env.CONSUMER_SECRET);
  const quoteId = signedRequest.context.environment.parameters.recordId;

  const query = `SELECT Id, Name, Account.Name, Opportunity.Name, BillingStreet, BillingCity FROM Quote WHERE Id = '${quoteId}'`;

  sfClient.query(query, (err, result) => {
    if (err) {
      return handleError(err, res);
    }

    res.render("index", {
      quoteId: quoteId,
      context: JSON.stringify(signedRequest, null, 2),
      quote: JSON.stringify(result, null, 2),
      params: JSON.stringify(req.params, null, 2),
      query: JSON.stringify(req.query, null, 2)
    });
  });
});

app.get("/createQuote/:recordId", (req, response) => {

  const recordId = req.params.recordId;
  const payload = { Name: "Anmol", Price: 10000 };
  setTimeout(() => {
    publish(recordId, 'Quote created', payload);
  }, 50);

  response.send("We are working on it, will notify you through platform event in a while");
});

app.set("port", process.env.PORT || 5000);

app.listen(app.get("port"), function () {
  console.log("Express server listening on port " + app.get("port"));
});

function publish(recordId, type, payload) {
  sfClient.sobject("EncowayCPQ__e").create({
    RecordId__c: recordId,
    Type__c: type,
    txt_PayLoad__c: JSON.stringify(payload)
  }).then((result) => {
    console.dir(result);
  }).catch(function (err) {
    console.log("Error: " + err);
  });
}


function handleError(err, res) {
  console.error(err);
  res.status(403).send(err);
}