Dynamic Pricing

import express from 'express';
import { createDynamicPricing, createX402Server } from '@dexterai/x402/server';
 
const app = express();
const server = createX402Server({
  payTo: 'YourSolanaAddress...',
  network: 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp',
  facilitatorUrl: 'https://x402.dexter.cash',
});
 
const pricing = createDynamicPricing({
  unitSize: 1000,
  ratePerUnit: 0.01,
  minUsd: 0.01,
  maxUsd: 10.0,
});
 
app.use(express.json());
 
app.post('/api/process', async (req, res) => {
  const { text } = req.body;
  const paymentSig = req.headers['payment-signature'];
 
  if (!paymentSig) {
    const quote = pricing.calculate(text);
    const requirements = await server.buildRequirements({
      amountAtomic: quote.amountAtomic,
      resourceUrl: req.originalUrl,
    });
 
    res.setHeader('PAYMENT-REQUIRED', server.encodeRequirements(requirements));
    res.setHeader('X-Quote-Hash', quote.quoteHash);
    return res.status(402).json({ usdAmount: quote.usdAmount });
  }
 
  const quoteHash = req.headers['x-quote-hash'];
  if (!pricing.validateQuote(text, quoteHash)) {
    return res.status(400).json({ error: 'Input changed, re-quote required' });
  }
 
  const result = await server.settlePayment(paymentSig);
  if (!result.success) {
    return res.status(402).json({ error: result.errorReason });
  }
 
  res.json({ processed: text.length });
});