Build a Slack and Microsoft Teams Contract Approval Flow (2026)

const express = require('express');
const fetch = require('node-fetch');
const app = express();
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

app.post('/slack/interactive', async (req, res) => {
  const payload = JSON.parse(req.body.payload);
  const { actions, response_url, user, channel } = payload;
  const actionValue = actions[0].value; // e.g., "approve_nda_req_99"

  // 1. Instantly respond to Slack to prevent timeouts (3s limit)
  res.status(200).send();

  // 2. Perform the async work (calling Signbee API)
  try {
    const signbeeDoc = await createSignbeeDocument(user, actionValue, response_url);
    
    // 3. Post signing URL back to Slack channel
    await updateSlackMessage(response_url, {
      text: `⚡ *NDA Prepared:* <${signbeeDoc.signing_url}|Click here to sign the document>`
    });
  } catch (err) {
    console.error('Failed to process flow:', err);
    await updateSlackMessage(response_url, {
      text: '❌ Error: Failed to generate document. Please try again.'
    });
  }
});

async function createSignbeeDocument(user, recordId, responseUrl) {
  const response = await fetch('https://signb.ee/api/v1/documents', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${process.env.SIGNBEE_API_KEY}`
    },
    body: JSON.stringify({
      title: 'Mutual Non-Disclosure Agreement',
      markdown: `# Mutual Non-Disclosure Agreement\n\nThis NDA is executed between the undersigned parties in 2026...\n\n* Recipient Name: ${user.name}\n* Record Reference: ${recordId}`,
      signers: [
        {
          name: user.name,
          email: `${user.name.toLowerCase().replace(/\s+/g, '')}@company.com`,
          role: 'signer'
        }
      ],
      metadata: {
        slack_response_url: responseUrl,
        record_id: recordId
      }
    })
  });

  if (!response.ok) {
    throw new Error(`Signbee API returned status ${response.status}`);
  }

  return response.json();
}

app.post('/webhooks/signbee', async (req, res) => {
  const { event, data } = req.body;

  if (event === 'document.signed') {
    const responseUrl = data.metadata.slack_response_url;
    const recordId = data.metadata.record_id;

    if (responseUrl) {
      await updateSlackMessage(responseUrl, {
        text: `🎉 *Contract Executed:* The NDA (Ref: ${recordId}) has been successfully signed by ${data.signers[0].name}.`,
        replace_original: false
      });
    }
  }

  res.status(200).json({ received: true });
});

async function updateSlackMessage(responseUrl, payload) {
  await fetch(responseUrl, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload)
  });
}