Add /stats endpoint with 60-second cached total user count

stellar-payment-platform/server.js

@@ -110,6 +110,10 @@ const USER_DATABASE = {
 
 const DEFAULT_FEDERATION_DOMAIN = 'localhost';
 
+let cachedCount = 0;
+let lastFetched = 0;
+let statsFetchPromise = null;
+
 const normalizeNameTag = (value) => {
   const trimmed = typeof value === 'string' ? value.trim() : '';
   if (!trimmed) {
@@ -521,6 +525,7 @@ app.use((err, _req, _res, next) => {
 // Global error handling middleware
 // eslint-disable-next-line no-unused-vars
 app.use((err, _req, res, _next) => {
+  void _next;
   const statusCode = err.statusCode || 500;
   const errorMessage = err.message || 'Internal server error';
 

stellar-payment-platform/server.test.js

@@ -467,6 +467,66 @@ describe('GET /users — pagination and search', () => {
   });
 });
 
+describe('GET /stats — cached total user count', () => {
+  let request;
+  let app;
+  let prisma;
+  let dateNowSpy;
+
+  beforeEach(() => {
+    jest.resetModules();
+    ({ app } = require('./server'));
+    ({ prisma } = require('./prismaClient'));
+    request = require('supertest');
+
+    prisma.user.count.mockReset();
+    dateNowSpy = jest.spyOn(Date, 'now').mockReturnValue(1_000_000);
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
+  test('returns totalUsers and queries the database once on first request', async () => {
+    prisma.user.count.mockResolvedValue(4);
+
+    const res = await request(app).get('/stats');
+
+    expect(res.status).toBe(200);
+    expect(res.body).toEqual({ totalUsers: 4 });
+    expect(prisma.user.count).toHaveBeenCalledTimes(1);
+  });
+
+  test('reuses the cached count for requests within 60 seconds', async () => {
+    prisma.user.count.mockResolvedValue(4);
+
+    await request(app).get('/stats');
+    expect(prisma.user.count).toHaveBeenCalledTimes(1);
+
+    prisma.user.count.mockResolvedValue(10);
+    dateNowSpy.mockReturnValue(1_030_000);
+
+    const res = await request(app).get('/stats');
+    expect(res.status).toBe(200);
+    expect(res.body).toEqual({ totalUsers: 4 });
+    expect(prisma.user.count).toHaveBeenCalledTimes(1);
+  });
+
+  test('refreshes the cached count after 60 seconds', async () => {
+    prisma.user.count.mockResolvedValueOnce(4).mockResolvedValueOnce(10);
+
+    await request(app).get('/stats');
+    expect(prisma.user.count).toHaveBeenCalledTimes(1);
+
+    dateNowSpy.mockReturnValue(1_061_000);
+    const res = await request(app).get('/stats');
+
+    expect(res.status).toBe(200);
+    expect(res.body).toEqual({ totalUsers: 10 });
+    expect(prisma.user.count).toHaveBeenCalledTimes(2);
+  });
+});
+
 describe('POST /register — block secret keys', () => {
   let request;
   let app;