service.ts

import { connect, JSONCodec, ServiceError } from "./natslib.ts";
import { generateBadge } from "./generator.ts";

type Badge = {
  name: string;
  company?: string;
};

const jc = JSONCodec<Badge>();
const nc = await connect({ servers: "demo.nats.io" });

const service = await nc.services.add({
  name: "badge_generator",
  version: "0.0.1",
  description: "Generates a RethinkConn badge",
});

service.addEndpoint("generate", {
  subject: "generate.badge",
  metadata: {
    "request": "{ name: string, company?: string }",
    "response": "Uint8Array",
  },
  handler: (err, msg) => {
    if (err) {
      // stop will stop the service, and close it with the specified error
      service.stop(err).then();
      return;
    }
    const req = jc.decode(msg.data);
    if (typeof req.name !== "string" || req.name.length === 0) {
      console.log(
        `${service.info().name} is rejecting a request without a name`,
      );
      // you can report an error to the client
      msg.respondError(400, "name is required");
      return;
    }
    return generateBadge(req)
      .then((d) => {
        msg.respond(d);
      })
      .catch((err) => {
        const sr = ServiceError.toServiceError(err);
        msg.respondError(sr?.code, sr?.message);
      });
  },
});

const si = service.info();
// you can monitor if your service closes by awaiting done - it resolves
// to null or an error
service.stopped.then((err: Error | null) => {
  if (err) {
    console.log(`${si.name} stopped with error: ${err.message}`);
  } else {
    console.log(`${si.name} stopped.`);
  }
});

console.log(
  `${si.name} ${si.version} started with ID: ${si.id}`,
);