import express, { Request } from "express";
import bodyParser from "body-parser";
import { createProxyMiddleware } from "http-proxy-middleware";
import { v4 as uuidv4 } from "uuid";
import { Hex } from "viem";
import { paymentMiddleware } from "x402-express";
import { config } from "dotenv";
config();
// --- Configuration ---
const PORT = 5000;
const publicKey = process.env.PUBLIC_KEY as Hex;
console.log("🚀 ~ publicKey:", publicKey);
// --- Express App ---
const app = express();
app.use(bodyParser.json());
// 🛡️ x402 MIDDLEWARE
app.use(
paymentMiddleware(
publicKey,
{
"POST /weather": {
price: "$0.001",
network: "base-sepolia",
},
"POST /exchange": {
price: "$0.002",
network: "base-sepolia",
},
},
{
url: "https://x402.org/facilitator",
}
)
);
// ✅ Custom route (demo purpose)
// app.get("/weather", (req, res) => {
// console.log("🚀 ~ api call to /weather");
// res.send({
// report: {
// weather: "sunny",
// temperature: 70,
// },
// });
// });
// ✅ Proxy /a2a/message to Python Hello World Agent
app.use(
"/weather",
createProxyMiddleware({
target: "http://localhost:9999", // Python agent runs here
changeOrigin: true,
pathRewrite: { "^/weather": "/" }, // Optional: forward as root path
selfHandleResponse: true,
on: {
proxyReq: (proxyReq, req, res) => {
// console.log("🚀 ~ req:", req);
if (req.method === "POST") {
const userMessage = "how much is 10 USD in INR?";
const payload = {
jsonrpc: "2.0",
id: uuidv4(),
method: "message/send",
params: {
message: {
role: "user",
parts: [
{
kind: "text",
text: userMessage,
},
],
messageId: uuidv4(),
},
},
};
const bodyString = JSON.stringify(payload);
// Set proper headers
proxyReq.setHeader("Content-Type", "application/json");
proxyReq.setHeader("Content-Length", Buffer.byteLength(bodyString));
// Overwrite the request stream with new body
proxyReq.write(bodyString);
}
},
proxyRes: (proxyRes, req, res) => {
let body = Buffer.from("");
proxyRes.on("data", (chunk) => {
body = Buffer.concat([body, chunk]);
});
proxyRes.on("end", () => {
try {
const json = JSON.parse(body.toString("utf-8"));
console.log("🚀 ~ proxyRes.on ~ json:", json);
const text = json?.result?.parts?.[0]?.text;
console.log("🚀 ~ proxyRes.on ~ text:", text);
res.end(
JSON.stringify({ text: json?.result?.parts[0]?.text || "" })
);
// if (typeof text === "string") {
// res.end(JSON.stringify(text));
// } else {
// res.statusCode = 500;
// res.end(
// JSON.stringify({ error: "Invalid agent response format" })
// );
// }
} catch (err) {
console.error("❌ Failed to parse agent response", err);
res.statusCode = 500;
res.end(JSON.stringify({ error: "Failed to parse response" }));
}
});
},
},
})
);
app.use(
"/exchange",
createProxyMiddleware({
target: "http://localhost:10000",
changeOrigin: true,
pathRewrite: { "^/exchange": "/" },
selfHandleResponse: true,
on: {
proxyReq: (proxyReq, req: Request, res) => {
console.log("🚀 ~ req:", req);
if (req.method === "POST") {
console.log("🚀 ~ req.body?.message:", req.body?.message);
const userMessage = req.body?.message || "how much is 10 USD in INR?";
const payload = {
jsonrpc: "2.0",
id: uuidv4(),
method: "message/send",
params: {
message: {
role: "user",
parts: [
{
kind: "text",
text: userMessage,
},
],
messageId: uuidv4(),
},
},
};
const bodyString = JSON.stringify(payload);
// Set proper headers
proxyReq.setHeader("Content-Type", "application/json");
proxyReq.setHeader("Content-Length", Buffer.byteLength(bodyString));
// Overwrite the request stream with new body
proxyReq.write(bodyString);
}
},
proxyRes: (proxyRes, req, res) => {
let body = Buffer.from("");
proxyRes.on("data", (chunk) => {
body = Buffer.concat([body, chunk]);
});
proxyRes.on("end", () => {
try {
const json = JSON.parse(body.toString("utf-8"));
console.log("🚀 ~ proxyRes.on ~ json:", json);
const text = json?.result?.status.message.parts?.[0]?.text;
console.log("🚀 ~ proxyRes.on ~ text:", text);
res.end(
JSON.stringify({
text: json?.result?.status.message.parts?.[0]?.text || "",
})
);
// if (typeof text === "string") {
// res.end(JSON.stringify(text));
// } else {
// res.statusCode = 500;
// res.end(
// JSON.stringify({ error: "Invalid agent response format" })
// );
// }
} catch (err) {
console.error("❌ Failed to parse agent response", err);
res.statusCode = 500;
res.end(JSON.stringify({ error: "Failed to parse response" }));
}
});
},
},
})
);
// Start the server
app.listen(PORT, () => {
console.log(`x402 middleware listening at http://localhost:${PORT}`);
});
