server.ts

/**
 * Runnable example: a small Koa app that uses both the @unirate/koa
 * middleware and the ready-made router.
 *
 * Run it (needs koa, @koa/router, and a TS runner such as tsx):
 *
 *   UNIRATE_API_KEY=your-key npx tsx examples/server.ts
 *
 * Then try:
 *   curl "http://localhost:3000/eur"
 *   curl "http://localhost:3000/summary"
 *   curl "http://localhost:3000/api/unirate/rate?from=USD&to=GBP"
 *   curl "http://localhost:3000/api/unirate/convert?from=USD&to=EUR&amount=100"
 *   curl "http://localhost:3000/api/unirate/currencies"
 *   curl "http://localhost:3000/api/unirate/vat?country=DE"
 */
import Koa from "koa";
import { unirate, unirateRouter } from "@unirate/koa";

const apiKey = process.env.UNIRATE_API_KEY;
if (!apiKey) {
  console.error("Set UNIRATE_API_KEY (get a free key at https://unirateapi.com)");
  process.exit(1);
}

const app = new Koa();

// 1. Middleware — a typed client is attached to ctx.state.unirate.
app.use(unirate({ apiKey }));

// 2. Router — mount the ready-made JSON endpoints under /api/unirate.
const router = unirateRouter({ apiKey });
router.prefix("/api/unirate");
app.use(router.routes()).use(router.allowedMethods());

// 3. Custom handlers using the client from ctx.state.
app.use(async (ctx) => {
  if (ctx.path === "/eur") {
    const rate = await ctx.state.unirate.getRate("USD", "EUR");
    ctx.body = { pair: "USD/EUR", rate };
    return;
  }
  if (ctx.path === "/summary") {
    const client = ctx.state.unirate;
    const [rate, converted, currencies] = await Promise.all([
      client.getRate("USD", "GBP"),
      client.convert("EUR", 100, "USD"),
      client.getSupportedCurrencies(),
    ]);
    ctx.body = {
      usdGbp: rate,
      hundredUsdInEur: converted,
      supportedCount: currencies.length,
    };
    return;
  }
});

const port = Number(process.env.PORT ?? 3000);
app.listen(port, () => {
  console.log(`Listening on http://localhost:${port}`);
});