/**
 * GET /api/agents/registry — proxies ml/serving's manifest list with a short
 * in-process cache. Tests stub global fetch and verify caching + 502 fallback.
 */
import { describe, it, expect, vi, beforeAll, afterEach, beforeEach } from 'vitest';
import express from 'express';
import * as http from 'http';

vi.mock('../../middleware/session.js', () => ({
  sessionMiddleware: (_req: express.Request, _res: express.Response, next: express.NextFunction) => next(),
  requireAuth: (req: express.Request, _res: express.Response, next: express.NextFunction) => {
    (req as any).userId = 'user-1';
    next();
  },
}));

const REGISTRY_PAYLOAD = {
  agents: [
    { id: 'overdue-task', version: '1.0.0', pref_schema: { type: 'object' } },
    { id: 'momentum', version: '1.0.0', pref_schema: { type: 'object' } },
  ],
};

function get(url: string): Promise<{ status: number; body: any }> {
  return new Promise((resolve, reject) => {
    const u = new URL(url);
    http.get({ hostname: u.hostname, port: Number(u.port), path: u.pathname }, (res) => {
      let data = '';
      res.on('data', (c) => { data += c; });
      res.on('end', () => {
        try { resolve({ status: res.statusCode ?? 0, body: data ? JSON.parse(data) : null }); }
        catch { resolve({ status: res.statusCode ?? 0, body: data }); }
      });
    }).on('error', reject);
  });
}

describe('GET /api/agents/registry', () => {
  let server: http.Server;
  let baseUrl: string;
  let savedFetch: typeof globalThis.fetch;
  let resetCache: () => void;

  beforeAll(async () => {
    const mod = await import('../agent-registry.js');
    const router = mod.default;
    resetCache = mod._resetRegistryCache;
    const app = express();
    app.use('/api/agents', router);
    server = await new Promise<http.Server>((resolve) => {
      const s = app.listen(0, () => resolve(s));
    });
    const addr = server.address() as { port: number };
    baseUrl = `http://localhost:${addr.port}`;
    savedFetch = globalThis.fetch;
  });

  beforeEach(() => {
    resetCache();
  });

  afterEach(() => {
    globalThis.fetch = savedFetch;
  });

  it('proxies ml/serving manifests', async () => {
    const fetchMock = vi.fn(async () =>
      new Response(JSON.stringify(REGISTRY_PAYLOAD), { status: 200 }),
    );
    globalThis.fetch = fetchMock as unknown as typeof fetch;

    const r = await get(`${baseUrl}/api/agents/registry`);
    expect(r.status).toBe(200);
    expect(r.body).toEqual(REGISTRY_PAYLOAD);
    expect(fetchMock).toHaveBeenCalledTimes(1);
  });

  it('caches across calls within the TTL', async () => {
    const fetchMock = vi.fn(async () =>
      new Response(JSON.stringify(REGISTRY_PAYLOAD), { status: 200 }),
    );
    globalThis.fetch = fetchMock as unknown as typeof fetch;

    await get(`${baseUrl}/api/agents/registry`);
    await get(`${baseUrl}/api/agents/registry`);
    expect(fetchMock).toHaveBeenCalledTimes(1);
  });

  it('returns 502 when ml/serving fails', async () => {
    globalThis.fetch = vi.fn(async () => new Response('boom', { status: 500 })) as unknown as typeof fetch;
    const r = await get(`${baseUrl}/api/agents/registry`);
    expect(r.status).toBe(502);
    expect(r.body.error).toBe('ml/serving unavailable');
  });

  it('does not cache failures', async () => {
    const fetchMock = vi.fn()
      .mockResolvedValueOnce(new Response('boom', { status: 500 }))
      .mockResolvedValueOnce(new Response(JSON.stringify(REGISTRY_PAYLOAD), { status: 200 }));
    globalThis.fetch = fetchMock as unknown as typeof fetch;

    const first = await get(`${baseUrl}/api/agents/registry`);
    expect(first.status).toBe(502);
    const second = await get(`${baseUrl}/api/agents/registry`);
    expect(second.status).toBe(200);
    expect(fetchMock).toHaveBeenCalledTimes(2);
  });
});