/**
 * DC-118 regression pins — generic-UA self-noise conjunction filter.
 *
 * Live census (2026-08-23, /var/log/caddy/access.log): the DNS2 watchdog
 * and on-host cron jobs hit Caddy with a stock curl/8.5.0 UA from
 * 127.0.0.1 (339/5000 lines) and the host's own tailscale IP (20/5000) —
 * ~300 GET /api/health 401 warn-events/day burying real perimeter
 * signal. External curl traffic (zgrab/ scanners using curl, real
 * attackers) MUST stay visible.
 *
 * Design: DashCaddy-* probe UA prefixes are dropped unconditionally
 * (they are our own binaries). GENERIC tool UAs (curl/) are dropped ONLY
 * when the source remote_ip is one of this host's own addresses
 * (DASHCADDY_SELF_IPS env, default loopback). remote_ip (the TCP peer)
 * is the input — never client_ip/X-Forwarded-For, which is spoofable.
 *
 * All tests use the REAL worker: temp access log, real tail, real event
 * store, hermetic sinks. No mocks of the module under test.
 */

const path = require('path');
const fs = require('fs');
const os = require('os');

// Hermetic sinks (same pattern as caddy-worker-pipeline-dc113.test.js)
const TMP_DIR = fs.mkdtempSync(path.join(os.tmpdir(), 'dc118-caddy-'));
process.env.SECURITY_EVENT_LOG_FILE = path.join(TMP_DIR, 'security-events.jsonl');
process.env.CADDY_ACCESS_LOG = path.join(TMP_DIR, 'access.log');
process.env.DATA_DIR = TMP_DIR;
// Self-IP set for these tests: loopback defaults + a fake tailscale IP.
process.env.DASHCADDY_SELF_IPS = '127.0.0.1,::1,100.121.150.22';

const { startCaddyWorker } = require('../src/security/event-workers');
const { getStore } = require('../src/security/event-store');

let capturedWarns = [];
let capturedInfos = [];
const fakeLogger = {
  warn: (ctx, msg, extra) => capturedWarns.push({ ctx, msg, extra }),
  info: (ctx, msg, extra) => capturedInfos.push({ ctx, msg, extra }),
  error: () => {},
};

const ACCESS_LOG = process.env.CADDY_ACCESS_LOG;
const STORE_FILE = process.env.SECURITY_EVENT_LOG_FILE;

function mkLine({ ip, ua, uri = '/api/health', status = 401 }) {
  return JSON.stringify({
    ts: Date.now() / 1000,
    request: {
      remote_ip: ip, method: 'GET', uri, host: 'status.sami', proto: 'HTTP/2.0',
      headers: ua === null ? {} : { 'User-Agent': [ua] },
    },
    status,
    duration: 0.004,
  }) + '\n';
}

function readStored() {
  try {
    return fs.readFileSync(STORE_FILE, 'utf8').trim().split('\n')
      .filter(Boolean).map(l => JSON.parse(l));
  } catch { return []; }
}

async function waitForEvents(n, { timeoutMs = 5000 } = {}) {
  const deadline = Date.now() + timeoutMs;
  while (Date.now() < deadline) {
    const events = readStored().filter(e => e.source_type === 'caddy');
    if (events.length >= n) return events;
    await new Promise(r => setTimeout(r, 50));
  }
  throw new Error(`timed out waiting for ${n} caddy events (got ${readStored().filter(e => e.source_type === 'caddy').length})`);
}

async function waitForQuiet({ settleMs = 1200 } = {}) {
  // Inverse of waitForEvents: give the tail a window to (wrongly) emit,
  // then assert it did not.
  await new Promise(r => setTimeout(r, settleMs));
  return readStored().filter(e => e.source_type === 'caddy');
}

beforeEach(() => {
  fs.writeFileSync(STORE_FILE, '', 'utf8');
  fs.writeFileSync(ACCESS_LOG, '', 'utf8');
  // Reset the tail's persisted offset (same flake lesson as DC-112/113).
  fs.writeFileSync(path.join(TMP_DIR, '.caddy-tail-offset'), '0', 'utf8');
  capturedWarns = [];
  capturedInfos = [];
  getStore({ log: fakeLogger }); // fresh singleton pointed at the temp store file
});

afterAll(() => {
  try { fs.rmSync(TMP_DIR, { recursive: true, force: true }); } catch {}
});

describe('DC-118: generic-UA self-noise conjunction filter', () => {
  let worker;
  afterEach(() => { if (worker) { worker.stop(); worker = null; } });

  test('matrix cell 1 — self IP + generic curl UA → DROPPED (loopback watchdog)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '127.0.0.1', ua: 'curl/8.5.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const events = await waitForQuiet();
    expect(events.length).toBe(0);
  });

  test('matrix cell 1b — self tailscale IP + curl UA → DROPPED (on-host cron)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '100.121.150.22', ua: 'curl/8.5.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const events = await waitForQuiet();
    expect(events.length).toBe(0);
  });

  test('matrix cell 2 — EXTERNAL IP + curl UA → KEPT (real attacker visibility)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '198.51.100.7', ua: 'curl/8.5.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const [ev] = await waitForEvents(1);
    expect(ev.actor).toBe('198.51.100.7');
    expect(ev.metadata.user_agent).toBe('curl/8.5.0');
    expect(ev.action).toBe('http.401');
    expect(ev.severity).toBe('warn'); // /api/health 401 stays a warn-event
  });

  test('matrix cell 3 — self IP + NON-generic UA (browser/attacker tool) → KEPT', async () => {
    // Even from our own IP, a browser or attack tool UA must not be
    // silently discarded — an attacker landing on the host itself is
    // exactly the event the store exists to keep.
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '127.0.0.1', ua: 'Mozilla/5.0 zgrab/0.x' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const [ev] = await waitForEvents(1);
    expect(ev.actor).toBe('127.0.0.1');
    expect(ev.metadata.user_agent).toBe('Mozilla/5.0 zgrab/0.x');
  });

  test('matrix cell 4 — self IP + no UA at all → KEPT (missing UA is not noise)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '127.0.0.1', ua: null }));
    worker = startCaddyWorker({ log: fakeLogger });
    const [ev] = await waitForEvents(1);
    expect(ev.actor).toBe('127.0.0.1');
    expect(ev.metadata.user_agent).toBeNull();
  });

  test('spoofed X-Forwarded-For (client_ip) cannot opt an attacker out — filter reads remote_ip only', async () => {
    fs.appendFileSync(ACCESS_LOG, JSON.stringify({
      ts: Date.now() / 1000,
      request: {
        remote_ip: '198.51.100.9', client_ip: '127.0.0.1', // claims to be us
        method: 'GET', uri: '/api/health', host: 'status.sami', proto: 'HTTP/2.0',
        headers: { 'User-Agent': ['curl/8.5.0'] },
      },
      status: 401,
      duration: 0.004,
    }) + '\n');
    worker = startCaddyWorker({ log: fakeLogger });
    const [ev] = await waitForEvents(1);
    expect(ev.actor).toBe('198.51.100.9'); // TCP peer, not the spoofable header
  });

  test('IPv6 loopback ::1 with curl UA → DROPPED (env-listed self IP)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '::1', ua: 'curl/8.5.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const events = await waitForQuiet();
    expect(events.length).toBe(0);
  });

  test('DashCaddy-* probe UA from a NON-self IP is still dropped (own binaries, unconditional)', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '172.17.0.4', ua: 'DashCaddy-HealthCheck/1.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    const events = await waitForQuiet();
    expect(events.length).toBe(0);
  });

  test('prefix future-proofing: curl/10.0 from self IP → DROPPED; curl-impersonate NOT dropped', async () => {
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '127.0.0.1', ua: 'curl/10.0' }));
    fs.appendFileSync(ACCESS_LOG, mkLine({ ip: '198.51.100.10', ua: 'curl-impersonate-chrome/1.0' }));
    worker = startCaddyWorker({ log: fakeLogger });
    // curl-impersonate does not match the 'curl/' prefix; kept from any IP.
    const events = await waitForEvents(1);
    expect(events.length).toBe(1);
    expect(events[0].metadata.user_agent).toBe('curl-impersonate-chrome/1.0');
  });
});