Webhooks

const express = require('express');
const crypto = require('crypto');
const app = express();

// Capture the raw body so the HMAC is computed over the exact bytes Fluz sent.
app.use('/webhooks/fluz', express.raw({ type: 'application/json' }));

function verifyFluzWebhook(rawBody, signature, apiKey) {
  const expected = crypto.createHmac('sha256', apiKey).update(rawBody).digest('hex');
  const received = Buffer.from(signature || '', 'hex');
  const computed = Buffer.from(expected, 'hex');
  return received.length === computed.length &&
         crypto.timingSafeEqual(received, computed);
}

app.post('/webhooks/fluz', (req, res) => {
  const signature = req.headers['x-hmac-signature'];
  const eventId = req.headers['x-event-id'];

  // req.body is a Buffer because of express.raw above
  if (!verifyFluzWebhook(req.body, signature, process.env.FLUZ_API_KEY)) {
    return res.status(401).send('Invalid signature');
  }

  // Acknowledge immediately, then process asynchronously
  res.status(200).send('OK');

  const event = JSON.parse(req.body.toString('utf8'));
  handleEvent(eventId, event).catch(err =>
    console.error('Webhook processing error:', err)
  );
});

import hmac, hashlib
from flask import Flask, request

app = Flask(__name__)

def verify_fluz_webhook(raw_body: bytes, signature: str, api_key: str) -> bool:
    expected = hmac.new(api_key.encode("utf-8"), raw_body, hashlib.sha256).hexdigest()
    return hmac.compare_digest(expected, signature or "")

@app.post("/webhooks/fluz")
def fluz_webhook():
    signature = request.headers.get("X-HMAC-Signature")
    event_id = request.headers.get("X-Event-ID")

    # request.get_data() returns the raw bytes — do NOT use request.json for verification
    if not verify_fluz_webhook(request.get_data(), signature, FLUZ_API_KEY):
        return "Invalid signature", 401

    enqueue(event_id, request.get_json())  # process asynchronously
    return "OK", 200

const seen = new Set(); // use Redis or a database in production

async function handleEvent(eventId, event) {
  if (seen.has(eventId)) return;  // already processed — skip
  seen.add(eventId);

  switch (event.eventType) {
    case 'TRANSACTION_CREATE':    await onTransactionCreated(event); break;
    case 'TRANSACTION_UPDATE':    await onTransactionUpdated(event); break;
    case 'TRANSACTION_DECLINE':   await onTransactionDeclined(event); break;
    case 'DEPOSIT_COMPLETE':      await onDepositComplete(event); break;
    case 'WIDGET_KYC_INITIATION': await onKycInitiated(event); break;
    // ...handle remaining widget events
  }
}

{
  "eventType": "TRANSACTION_CREATE",
  "recordId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "transactionId": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "transactionType": "PURCHASE",
  "amount": 42.99,
  "destination": "Coffee Shop",
  "source": "Virtual Card",
  "status": "COMPLETED",
  "channel": "VIRTUAL_CARD",
  "connectedAppId": "your-app-id",
  "connectedAppName": "Your App",
  "createdAt": "2025-01-15T10:30:00.000Z",
  "merchantName": "Coffee Shop",
  "merchantCity": "New York",
  "merchantState": "NY",
  "merchantCountry": "US",
  "cardLastFour": "1234",
  "virtualCardId": "vc-uuid-here",
  "cashbackRate": 0.05
}

{
  "eventType": "TRANSACTION_UPDATE",
  "recordId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "transactionId": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "transactionType": "PURCHASE",
  "amount": 42.99,
  "status": "SETTLED",
  "createdAt": "2025-01-15T10:30:00.000Z",
  "updatedAt": "2025-01-16T08:00:00.000Z"
}

{
  "eventType": "TRANSACTION_DECLINE",
  "transactionId": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "transactionType": "PURCHASE",
  "amount": 500.00,
  "fluzAmount": 500.00,
  "externalFundingAmount": 0,
  "currency": "USD",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "status": "DECLINED",
  "merchantName": "Electronics Store",
  "cardLastFour": "1234",
  "virtualCardId": "vc-uuid-here",
  "isCashBalanceUsed": true,
  "isPrepaymentBalanceUsed": false,
  "isRewardsBalanceUsed": false,
  "isReserveBalanceUsed": false,
  "transactionDateTime": "2025-01-15T10:30:00.000Z",
  "declineTitle": "Transaction Declined",
  "declineReason": "Insufficient funds",
  "declineDescription": "Your account balance was not sufficient for this transaction.",
  "declineCategory": "BALANCE"
}

{
  "eventType": "DEPOSIT_COMPLETE",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "externalReferenceId": "your-reference-123",
  "amount": 50.00
}

{
  "eventType": "WIDGET_KYC_INITIATION",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "externalReferenceId": "your-reference-123"
}

{
  "eventType": "WIDGET_DEPOSIT_COMPLETE",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "externalReferenceId": "your-reference-123",
  "amount": 25.50
}

{
  "eventType": "WIDGET_WITHDRAW_COMPLETE",
  "userId": "550e8400-e29b-41d4-a716-446655440000",
  "accountId": "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
  "externalReferenceId": "your-reference-123",
  "amount": 15.00
}