Notary Express App

const express = require('express');
const app = express();
const port = 3000;
const { Mintblue, sha256 } = require('mintblue');

let project = '[YOUR_PROJECT_ID]';

Mintblue.create({
  token: '[YOUR_SDK_KEY]',
}).then((client) => {
  console.log('mintBlue client instantiated, setting up express...');
  app.use(express.urlencoded());

  app.post('/', async (req, res) => {
    // calculate data hash
    const hash = await sha256(req.body.data);

    // look up hash in notary
    let result = await findNotaryRecord(hash);
    if (result) {
      // notary record found, show result
      res.send(
        `Found notary record:<br />Transaction ID: ${result.txid}<br />SHA256: ${result.hash}<br />Timestamp: ${result.timestamp}`
      );
    } else {
      // no notary record found, create new record and show
      const { txid } = await client.createTransaction({
        project_id: project,
        outputs: [
          {
            type: 'data',
            value: hash,
          },
        ],
      });
      const result = await findNotaryRecord(hash);
      res.send(
        `Created notary record:<br />Transaction ID: ${result.txid}<br />SHA256: ${result.hash}<br />Timestamp: ${result.timestamp}`
      );
    }
  });

  app.get('/', (req, res, next) => {
    // present simple form allowing the user to input a string
    res.send(`
    <form method="POST" action="/">
        <input type="text" name="data" placeholder="data">
        <input type="submit">
    </form>
  `);
  });

  const getNotary = async () => {
    // get notary transactions
    const txs = await client.listTransactions(project);
    const notary = [];
    for (tx of txs) {
      // fetch notary record payload
      const payload = await client.getTransaction(tx.txid);
      notary.push({
        txid: tx.txid,
        hash: payload[0].value,
        timestamp: tx.published_at,
      });
    }
    return notary;
  };

  // find hash in notary records
  const findNotaryRecord = async (hash) => {
    const hashes = await getNotary();

    const result = hashes.find((el) => {
      return el.hash === hash;
    });
    return result;
  };

  // set up express listener
  app.listen(port, () => {
    console.log(`Notary app listening on port ${port}`);
  });
});