Get started as a seller

import 'dotenv/config';
import express from 'express';
import { paymentMiddlewareFromConfig } from '@x402/express';
import {
  createInflowFacilitator,
  createInflowSellerClient,
  inflowAccepts,
  inflowSchemeRegistrations,
} from '@inflowpayai/x402-seller';

const environment = process.env.INFLOW_ENVIRONMENT as 'sandbox' | 'production';
const apiKey = process.env.INFLOW_API_KEY;
if (!environment || !apiKey) {
  console.error('Set INFLOW_ENVIRONMENT and INFLOW_API_KEY (see .env).');
  process.exit(1);
}

// Verifies and settles payments through InFlow.
const inflow = createInflowFacilitator({ environment, apiKey });

// Async. It primes its caches before it resolves.
const seller = await createInflowSellerClient({ environment, apiKey });

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

app.use(
  paymentMiddlewareFromConfig(
    {
      'GET /api/widgets': {
        accepts: await inflowAccepts(seller, { price: '$0.01' }),
      },
    },
    [inflow],
    // Required third argument. The middleware refuses to boot without it.
    await inflowSchemeRegistrations(seller),
  ),
);

app.get('/api/widgets', (_req, res) => res.json({ widgets: [1, 2, 3] }));
app.get('/free', (_req, res) => res.json({ ok: true }));

app.listen(Number(process.env.PORT ?? 3000));