// services/api/src/request-id.middleware.spec.ts —— 请求 ID 解析单测：
// 透传上游值 / 缺省生成 UUID / 超长值拒收换新（Task 7 遗留项④）。
import type { ServerResponse } from 'node:http';
import {
  MAX_REQUEST_ID_LENGTH,
  resolveRequestId,
} from './request-id.middleware';

function fakeReq(header?: string): { headers: Record<string, string>; id?: string } {
  return header === undefined ? { headers: {} } : { headers: { 'x-request-id': header } };
}

function fakeRes(): ServerResponse & { captured?: string } {
  const res = { headers: {} } as unknown as ServerResponse & { captured?: string };
  Object.defineProperty(res, 'setHeader', {
    value: (name: string, value: string) => {
      res.captured = value;
      return res;
    },
  });
  return res;
}

describe('resolveRequestId', () => {
  it('echoes a reasonable upstream x-request-id', () => {
    const req = fakeReq('upstream-id-1');
    const res = fakeRes();
    expect(resolveRequestId(req as never, res)).toBe('upstream-id-1');
    expect(req.id).toBe('upstream-id-1');
    expect(res.captured).toBe('upstream-id-1');
  });

  it('generates a UUID v4 when the header is absent', () => {
    const req = fakeReq();
    const id = resolveRequestId(req as never, fakeRes());
    expect(id).toMatch(/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/);
    expect(req.id).toBe(id);
  });

  it('treats a blank header as absent', () => {
    const id = resolveRequestId(fakeReq('   ') as never, fakeRes());
    expect(id).not.toBe('   ');
  });

  it('replaces an over-long upstream id (>128 chars) with a fresh UUID', () => {
    const overlong = 'x'.repeat(MAX_REQUEST_ID_LENGTH + 1);
    const req = fakeReq(overlong);
    const res = fakeRes();
    const id = resolveRequestId(req as never, res);
    expect(id).not.toBe(overlong);
    expect(id.length).toBeLessThanOrEqual(MAX_REQUEST_ID_LENGTH);
    expect(req.id).toBe(id);
    expect(res.captured).toBe(id);
  });

  it('still echoes an id of exactly the cap (128 chars)', () => {
    const exact = 'y'.repeat(MAX_REQUEST_ID_LENGTH);
    const id = resolveRequestId(fakeReq(exact) as never, fakeRes());
    expect(id).toBe(exact);
  });

  it('reuses req.id when already resolved (pino-http genReqId runs first)', () => {
    const req = { ...fakeReq('ignored'), id: 'already-set' };
    expect(resolveRequestId(req as never, fakeRes())).toBe('already-set');
  });
});