Express (x402 v1)

// An x402 v1 service (x402-express 1.x) wrapped by the Forge feedback SDK.
// v1 carries the 402 challenge in the JSON body, so Forge adds the rating sentence to each accepts[].description.
// The only Forge-specific lines are marked with (forge).
import express from "express";
import { paymentMiddleware } from "x402-express";
import { createForge } from "@forgeintel/sdk"; // (forge)

const required = (name: string) => {
  const value = process.env[name];
  if (!value) throw new Error(`Set ${name}`);
  return value;
};

const PAY_TO = required("PAY_TO") as `0x${string}`;
const NETWORK = (process.env.NETWORK ?? "base-sepolia") as "base" | "base-sepolia"; // v1 network names
const FACILITATOR_URL = (process.env.FACILITATOR_URL ?? "https://x402.org/facilitator") as `${string}://${string}`;

// (forge) PUBLIC_URL is this service's public origin; it's used in the rating URLs agents see.
const forge = createForge({
  apiKey: required("FORGE_API_KEY"),
  backendUrl: required("FORGE_BACKEND_URL"),
  publicUrl: required("PUBLIC_URL"),
});

const app = express();
app.use(forge.middleware()); // (forge) before payment middleware

app.use(
  paymentMiddleware(
    PAY_TO,
    {
      "POST /api/text-stats": {
        price: "$0.001",
        network: NETWORK,
        config: {
          description: "Count characters, words and sentences in a text and estimate reading time.",
          mimeType: "application/json",
        },
      },
    },
    { url: FACILITATOR_URL },
  ),
);

app.get("/health", (_req, res) => void res.json({ status: "ok" }));

app.post("/api/text-stats", express.json({ limit: "100kb" }), (req, res) => {
  const text = typeof req.body?.text === "string" ? req.body.text : "";
  if (!text) return void res.status(400).json({ error: "text is required" });
  const words = text.split(/\s+/).filter(Boolean).length;
  res.json({
    characters: text.length,
    words,
    sentences: text.split(/[.!?]+/).filter((s: string) => s.trim()).length,
    reading_time_seconds: Math.ceil((words / 238) * 60),
  });
});

const port = Number(process.env.PORT ?? 4021);
const server = app.listen(port, () => console.log(`x402 v1 example on http://localhost:${port}`));

process.on("SIGTERM", () => server.close(() => void forge.shutdown())); // (forge) flush pending events