index.js

const express = require('express');
const bodyParser = require('body-parser');
const { poolPrimary, poolReplica, poolReplica2 } = require('./db');

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

function chooseReplica(){
  const replicaPool = [poolReplica, poolReplica2];
  const replicaId = parseInt(Math.random()*100);
  return replicaPool[replicaId];
}

app.post('/orders', async (req, res) => {
  const { userId, product, quantity, address } = req.body;

  if (!userId || !product || !quantity || !address) {
    return res.status(400).json({ error: 'All fields are required' });
  }

  try {
    const result = await poolPrimary.query(
      `INSERT INTO orders (user_id, product, quantity, address, status)
       VALUES ($1, $2, $3, $4, $5)
       RETURNING id`,
      [userId, product, quantity, address, 'Pending']
    );

    const orderId = result.rows[0].id;
    res.status(201).json({ orderId });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to create order' });
  }
});

app.put('/orders/:orderId', async (req, res) => {
  const { orderId } = req.params;
  const { userId, status } = req.body;

  if (!['Approved', 'Rejected'].includes(status)) {
    return res
      .status(400)
      .json({ error: 'Invalid status. Use "Approved" or "Rejected"' });
  }

  try {
    const adminCheck = await poolPrimary.query(
      `SELECT is_admin FROM users WHERE id = $1`,
      [userId]
    );

    if (!adminCheck.rows[0] || !adminCheck.rows[0].is_admin) {
      return res.status(403).json({ error: 'Admin access required' });
    }

    const result = await poolPrimary.query(
      `UPDATE orders SET status = $1 WHERE id = $2 RETURNING id`,
      [status, orderId]
    );

    if (result.rowCount === 0) {
      return res.status(404).json({ error: 'Order not found' });
    }

    res.status(200).json({ message: `Order ${orderId} has been ${status}` });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to update order status' });
  }
});

app.get('/orders/:orderId/status', async (req, res) => {
  const { orderId } = req.params;

  try {
    const pool = chooseReplica();
    const result = await pool.query(
      `SELECT status FROM orders WHERE id = $1`,
      [orderId]
    );

    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Order not found' });
    }

    res.status(200).json({ status: result.rows[0].status });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: 'Failed to fetch order status' });
  }
});

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});