import Fastify from 'fastify';
import { registerRoutes } from './routes.js';
import { resolveAdvertiseUrl, startDiscoveryBroadcaster } from '../discovery.js';

export function buildApp(cwd: string) {
  const app = Fastify({ logger: false });
  registerRoutes(app, cwd);
  return app;
}

export async function startServer(cwd: string, options: { port?: number; host?: string } = {}): Promise<{ app: Fastify.FastifyInstance; url: string }> {
  const app = buildApp(cwd);
  const port = options.port ?? 3377;
  const host = options.host ?? '127.0.0.1';

  let broadcaster: ReturnType<typeof startDiscoveryBroadcaster> | undefined;
  app.addHook('onClose', async () => {
    broadcaster?.stop();
  });

  try {
    await app.listen({ port, host });
    const address = app.server.address();
    const actualPort = typeof address === 'string' ? port : (address?.port ?? port);
    const url = `http://${host === '0.0.0.0' ? '127.0.0.1' : host}:${actualPort}`;
    console.log(`AgentHub server listening on ${url}`);

    const advertiseUrl = resolveAdvertiseUrl(host, actualPort);
    broadcaster = startDiscoveryBroadcaster(advertiseUrl);

    return { app, url };
  } catch (err) {
    const e = err as NodeJS.ErrnoException;
    if (e.code === 'EADDRINUSE') {
      console.error(
        `Port ${port} is already in use by another process that is not AgentHub. ` +
          `Stop it, or start with a different --port.`,
      );
    } else {
      console.error(err);
    }
    process.exit(1);
  }
}