/**
 * Unit tests for src/controllers/HealthDetailedController.ts
 *
 * Covers:
 *   - all services healthy → HTTP 200, status "healthy"
 *   - a service degraded (latency > 1000ms) → HTTP 207, status "degraded"
 *   - a service unreachable (throws) → HTTP 503, status "unreachable"
 *   - optional services (Vault, OPA) omitted when not configured
 *   - Vault and OPA included when URLs configured
 */

import express, { Application } from 'express';
import request from 'supertest';
import { HealthDetailedController, HealthDetailedDeps, DbProbe } from '../../../src/controllers/HealthDetailedController';

// ── fetch mock ────────────────────────────────────────────────────────────────

type MockFetchFn = jest.MockedFunction<typeof fetch>;
const mockFetch = jest.fn() as MockFetchFn;
global.fetch = mockFetch;

// ── Helpers ────────────────────────────────────────────────────────────────────

/**
 * Creates a mock DbProbe. When `error` is provided, checkLiveness() rejects
 * with that error (simulates unreachable DB). Otherwise it resolves after
 * `latencyMs` ms (0 by default — Date.now mocking handles degraded scenarios).
 */
function makeDbProbe(error?: Error, latencyMs = 0): DbProbe {
  return {
    checkLiveness: error
      ? jest.fn().mockRejectedValue(error)
      : jest.fn().mockImplementation(
          () => new Promise<void>((resolve) => setTimeout(() => resolve(), latencyMs)),
        ),
  };
}

function makeRedisClient(pingError?: Error, latencyMs = 0): { ping(): Promise<string> } {
  return {
    ping: pingError
      ? jest.fn().mockRejectedValue(pingError)
      : jest.fn().mockImplementation(() =>
          new Promise((resolve) => setTimeout(() => resolve('PONG'), latencyMs)),
        ),
  };
}

function buildApp(deps: HealthDetailedDeps): Application {
  const app = express();
  const controller = new HealthDetailedController(deps);
  app.get('/health/detailed', controller.handle);
  return app;
}

// ── Tests ──────────────────────────────────────────────────────────────────────

beforeEach(() => {
  jest.clearAllMocks();
});

describe('GET /health/detailed — all services healthy', () => {
  it('returns 200 with overall status "healthy" when postgres and redis respond quickly', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(undefined, 10),
      redisClient: makeRedisClient(undefined, 5),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.status).toBe(200);
    expect(res.body.status).toBe('healthy');
    expect(res.body.services.postgres.status).toBe('healthy');
    expect(res.body.services.redis.status).toBe('healthy');
  });

  it('includes version and uptime in the response body', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
    });

    const res = await request(app).get('/health/detailed');

    expect(typeof res.body.version).toBe('string');
    expect(typeof res.body.uptime).toBe('number');
  });

  it('includes latencyMs for each service', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
    });

    const res = await request(app).get('/health/detailed');

    expect(typeof res.body.services.postgres.latencyMs).toBe('number');
    expect(typeof res.body.services.redis.latencyMs).toBe('number');
  });
});

describe('GET /health/detailed — degraded scenario', () => {
  it('returns 207 when postgres is slow (> 1000ms)', async () => {
    // We cannot actually wait 1000+ ms in a unit test, so we simulate by making
    // the pool connect throw, then override the probe timeout.
    // Instead, we test the degraded path by mocking a pool that reports > 1000ms
    // via a custom pool. We achieve this by making connect resolve after 1001ms.
    // Because our probe timeout is 3000ms, this simulates a degraded connection.
    //
    // To keep tests fast, we mock the Date.now() approach indirectly:
    // a pool that resolves after a 1 ms delay can't produce > 1000ms latency —
    // we test the logic contract instead by checking that slow connections
    // produce `degraded` status. We achieve the required latency by patching
    // the pool.connect to resolve with a controlled delay.

    // We simulate a slow postgres by making the query take 1010ms via setTimeout.
    // Using fake timers is not possible here with supertest async flows, so we
    // take a different approach: we verify the status classification logic is wired
    // correctly by patching the Date.now() calls to simulate elapsed time.
    //
    // Pragmatic approach: test with real timing for integration-level confidence
    // by using a mock pool that resolves in 0ms but whose query artificially delays.
    // Since 1010ms wait makes the test slow, we verify the classification branch
    // using a pool whose connect itself rejects — that's the "unreachable" path.
    // For degraded, we trust the latencyMs threshold check in the controller and
    // verify it via the pool events test below.

    // Simplest reliable approach: if postgres latencyMs would be 1001ms, status = degraded.
    // We mock the pool.connect to capture the flow and manually verify via the
    // response body latencyMs field plus the overall status.

    // We use a fake pool that resolves immediately but we override Date.now to
    // simulate elapsed time for the controller's latency check.
    const realDateNow = Date.now;
    let callCount = 0;
    Date.now = jest.fn(() => {
      callCount += 1;
      // First call = start timestamp (200), second call = end timestamp (1201) → 1001ms
      return callCount === 1 ? 200 : 1401;
    });

    try {
      const app = buildApp({
        dbProbe: makeDbProbe(),
        redisClient: makeRedisClient(undefined, 0),
      });

      const res = await request(app).get('/health/detailed');

      // postgres should be degraded (simulated 1201ms)
      expect(res.status).toBe(207);
      expect(res.body.status).toBe('degraded');
      expect(res.body.services.postgres.status).toBe('degraded');
    } finally {
      Date.now = realDateNow;
    }
  });

  it('returns 207 when redis is slow (> 1000ms)', async () => {
    const realDateNow = Date.now;
    let callCount = 0;
    // postgres probe uses 2 Date.now() calls, redis probe uses 2 more
    Date.now = jest.fn(() => {
      callCount += 1;
      if (callCount <= 2) {
        // postgres: fast (50ms)
        return callCount === 1 ? 1000 : 1050;
      }
      // redis: slow (1200ms)
      return callCount === 3 ? 2000 : 3200;
    });

    try {
      const app = buildApp({
        dbProbe: makeDbProbe(),
        redisClient: makeRedisClient(undefined, 0),
      });

      const res = await request(app).get('/health/detailed');

      expect(res.status).toBe(207);
      expect(res.body.status).toBe('degraded');
      expect(res.body.services.redis.status).toBe('degraded');
    } finally {
      Date.now = realDateNow;
    }
  });
});

describe('GET /health/detailed — unreachable scenarios', () => {
  it('returns 503 when postgres connect() throws', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(new Error('ECONNREFUSED')),
      redisClient: makeRedisClient(),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.status).toBe(503);
    expect(res.body.status).toBe('unreachable');
    expect(res.body.services.postgres.status).toBe('unreachable');
  });

  it('returns 503 when redis ping() throws', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(new Error('Redis ECONNREFUSED')),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.status).toBe(503);
    expect(res.body.status).toBe('unreachable');
    expect(res.body.services.redis.status).toBe('unreachable');
  });

  it('returns 503 when both postgres and redis are unreachable', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(new Error('PG down')),
      redisClient: makeRedisClient(new Error('Redis down')),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.status).toBe(503);
    expect(res.body.status).toBe('unreachable');
    expect(res.body.services.postgres.status).toBe('unreachable');
    expect(res.body.services.redis.status).toBe('unreachable');
  });
});

describe('GET /health/detailed — optional services omitted when not configured', () => {
  it('does not include vault in services when vaultAddr is not provided', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.vault).toBeUndefined();
  });

  it('does not include opa in services when opaUrl is not provided', async () => {
    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.opa).toBeUndefined();
  });
});

describe('GET /health/detailed — Vault and OPA probes', () => {
  it('includes vault as healthy when Vault /v1/sys/health returns 200', async () => {
    mockFetch.mockResolvedValue(new Response(null, { status: 200 }));

    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
      vaultAddr: 'http://vault:8200',
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.vault).toBeDefined();
    expect(['healthy', 'degraded']).toContain(res.body.services.vault.status);
  });

  it('marks vault as unreachable when fetch throws', async () => {
    mockFetch.mockRejectedValue(new Error('Network failure'));

    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
      vaultAddr: 'http://vault:8200',
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.vault.status).toBe('unreachable');
  });

  it('includes opa as healthy when OPA /health returns 200', async () => {
    mockFetch.mockResolvedValue(new Response('{}', { status: 200 }));

    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
      opaUrl: 'http://opa:8181',
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.opa).toBeDefined();
    expect(['healthy', 'degraded']).toContain(res.body.services.opa.status);
  });

  it('marks opa as unreachable when OPA /health returns non-200', async () => {
    mockFetch.mockResolvedValue(new Response(null, { status: 503 }));

    const app = buildApp({
      dbProbe: makeDbProbe(),
      redisClient: makeRedisClient(),
      opaUrl: 'http://opa:8181',
    });

    const res = await request(app).get('/health/detailed');

    expect(res.body.services.opa.status).toBe('unreachable');
  });
});