billing-service/index.js

const express = require('express');
const bodyParser = require('body-parser');
const { Pool } = require('pg');
const Redis = require('ioredis');
const fetch = require('node-fetch');

const pool = new Pool({ connectionString: process.env.DATABASE_URL || 'postgresql://localhost/integral' });
const redis = new Redis(process.env.REDIS_URL || 'redis://localhost:6379');

const app = express();
app.use(bodyParser.json());

redis.subscribe('payouts:created', () => console.log('listening for payouts'));

redis.on('message', async (channel, msg) => {
  if (channel !== 'payouts:created') return;
  const { payoutId } = JSON.parse(msg);
  console.log('handle payout', payoutId);
  // naive: call settle endpoint
  try {
    await settlePayout(payoutId);
  } catch (err) {
    console.error(err);
  }
});


async function settlePayout(payoutId) {
  // fetch payout
  const r = await pool.query('SELECT * FROM payouts WHERE id=$1 FOR UPDATE', [payoutId]);
  if (r.rowCount === 0) throw new Error('payout not found');
  const payout = r.rows[0];
  if (payout.status !== 'created') return;

  // mark queued
  await pool.query('UPDATE payouts SET status=$1 WHERE id=$2', ['processing', payoutId]);

  // Example: call external TMS / Accounting system / Payment Gateway
  // This is a stub — replace with real API call (e.g. TMS settlement API, or bank transfer).
  const remote = await fakePaymentGateway(payout);

  if (remote.success) {
    const txRef = remote.txRef;
    await pool.query('UPDATE payouts SET status=$1, tx_ref=$2, settled_at=now() WHERE id=$3',
                     ['settled', txRef, payoutId]);
    await redis.publish('payouts:settled', JSON.stringify({ payoutId, txRef }));
  } else {
    await pool.query('UPDATE payouts SET status=$1 WHERE id=$2', ['failed', payoutId]);
    await redis.publish('payouts:failed', JSON.stringify({ payoutId }));
  }
}

async function fakePaymentGateway(payout) {
  // fake delay
  await new Promise(r => setTimeout(r, 600));
  return { success: true, txRef: `TX-${Date.now()}-${Math.floor(Math.random()*1000)}` };
}

app.post('/settle/:payoutId', async (req, res) => {
  try {
    const { payoutId } = req.params;
    await settlePayout(payoutId);
    res.json({ success: true });
  } catch (err) {
    console.error(err);
    res.status(500).json({ success: false, error: err.message });
  }
});

app.listen(process.env.PORT || 3010, () => console.log('billing-service listening 3010'));