postgres.js

const { createClient, createPool } = require('@vercel/postgres');

let dbPromise = null;

async function getDb() {
  if (!dbPromise) {
    dbPromise = initializeDb();
  }
  return dbPromise;
}

async function initializeDb() {
  const connectionString = process.env.POSTGRES_URL;

  if (!connectionString) {
    throw new Error('POSTGRES_URL is not configured');
  }

  try {
    return createPool({ connectionString });
  } catch (error) {
    if (error.code !== 'invalid_connection_string') {
      throw error;
    }

    const client = createClient({ connectionString });
    await client.connect();
    return client;
  }
}

async function sql(strings, ...values) {
  const db = await getDb();
  return db.sql(strings, ...values);
}

module.exports = { sql };