'use strict';

const express            = require('express');
const Database           = require('better-sqlite3');
const path               = require('path');
const { timingSafeEqual } = require('crypto');

const app  = express();
const PORT = Number(process.env.PORT) || 3000;
const DB   = new Database(process.env.DB_PATH || '/data/honeypot.db');

// ── Database setup ────────────────────────────────────────────────────────────

DB.pragma('journal_mode = WAL');
DB.pragma('synchronous  = NORMAL');
DB.pragma('cache_size   = -8000');

DB.exec(`
  CREATE TABLE IF NOT EXISTS blocks (
    id          INTEGER PRIMARY KEY AUTOINCREMENT,
    received_at INTEGER NOT NULL DEFAULT (unixepoch()),
    site_id     TEXT    NOT NULL DEFAULT '',
    ip_masked   TEXT    NOT NULL DEFAULT '',
    form_type   TEXT    NOT NULL DEFAULT '',
    reason      TEXT    NOT NULL DEFAULT '',
    ua_family   TEXT    NOT NULL DEFAULT ''
  );
  CREATE TABLE IF NOT EXISTS sites (
    site_id     TEXT    PRIMARY KEY,
    first_seen  INTEGER NOT NULL DEFAULT (unixepoch()),
    last_seen   INTEGER NOT NULL DEFAULT (unixepoch()),
    block_count INTEGER NOT NULL DEFAULT 0
  );
  CREATE INDEX IF NOT EXISTS idx_recv ON blocks(received_at DESC);
  CREATE INDEX IF NOT EXISTS idx_ip   ON blocks(ip_masked);
  CREATE INDEX IF NOT EXISTS idx_site ON blocks(site_id);
`);

// ── Auth token ────────────────────────────────────────────────────────────────

const API_TOKEN = (process.env.API_TOKEN || '').trim();

function requireToken(req, res, next) {
  if (!API_TOKEN) return next(); // dev: no token set = open

  const auth  = req.headers['authorization'] || '';
  const token = auth.startsWith('Bearer ') ? auth.slice(7) : '';

  // Constant-time comparison — pad both to 128 bytes to avoid length leaks
  const a = Buffer.alloc(128); Buffer.from(token).copy(a, 0, 0, 128);
  const b = Buffer.alloc(128); Buffer.from(API_TOKEN).copy(b, 0, 0, 128);

  if (!timingSafeEqual(a, b) || token !== API_TOKEN) {
    return res.status(403).json({ error: 'Forbidden' });
  }
  next();
}

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

function sanitizeIP(ip = '') {
  return String(ip).trim().slice(0, 45) || '?';
}

const UA_MAP = [
  [/curl\//i,                       'curl'],
  [/python-requests|python\//i,     'Python'],
  [/go-http-client/i,               'Go'],
  [/wget\//i,                       'Wget'],
  [/java\//i,                       'Java'],
  [/ruby/i,                         'Ruby'],
  [/perl\//i,                       'Perl'],
  [/php\//i,                        'PHP'],
  [/scrapy/i,                       'Scrapy'],
  [/postman/i,                      'Postman'],
  [/axios/i,                        'Axios'],
  [/node-fetch|node\.js/i,          'Node.js'],
  [/headlesschrome|phantomjs/i,     'Headless Browser'],
  [/(bot|crawler|spider|slurp)/i,   'Bot/Crawler'],
  [/chrome/i,                       'Chrome'],
  [/firefox/i,                      'Firefox'],
  [/safari/i,                       'Safari'],
  [/edge|edg\//i,                   'Edge'],
  [/opera|opr\//i,                  'Opera'],
  [/msie|trident/i,                 'IE'],
];

function parseUA(ua = '') {
  for (const [re, label] of UA_MAP) if (re.test(ua)) return label;
  return ua.length ? 'Other' : 'No UA';
}

// ── In-memory rate limiter ────────────────────────────────────────────────────

const rl = new Map();
setInterval(() => { const n = Date.now(); for (const [k, v] of rl) if (n > v.r) rl.delete(k); }, 30_000);

function allowed(ip, max = 30, win = 60_000) {
  const n = Date.now();
  let e = rl.get(ip);
  if (!e || n > e.r) { e = { c: 0, r: n + win }; rl.set(ip, e); }
  return ++e.c <= max;
}

// ── Stats cache (30s TTL) ─────────────────────────────────────────────────────

let _cache = null, _cacheTs = 0;

function getStats() {
  if (_cache && Date.now() - _cacheTs < 30_000) return _cache;
  const now = Math.floor(Date.now() / 1000);

  _cache = {
    total:        DB.prepare('SELECT COUNT(*) n FROM blocks').get().n,
    today:        DB.prepare('SELECT COUNT(*) n FROM blocks WHERE received_at > ?').get(now - 86400).n,
    last_7d:      DB.prepare('SELECT COUNT(*) n FROM blocks WHERE received_at > ?').get(now - 604800).n,
    last_30d:     DB.prepare('SELECT COUNT(*) n FROM blocks WHERE received_at > ?').get(now - 2592000).n,
    total_sites:  DB.prepare('SELECT COUNT(*) n FROM sites').get().n,
    top_ips:      DB.prepare(`
      SELECT ip_masked ip, COUNT(*) hits
      FROM blocks WHERE received_at > ?
      GROUP BY ip_masked ORDER BY hits DESC LIMIT 10
    `).all(now - 2592000),
    top_forms:    DB.prepare(`
      SELECT form_type, COUNT(*) hits
      FROM blocks WHERE received_at > ?
      GROUP BY form_type ORDER BY hits DESC LIMIT 8
    `).all(now - 2592000),
    top_reasons:  DB.prepare(`
      SELECT reason, COUNT(*) hits
      FROM blocks WHERE received_at > ?
      GROUP BY reason ORDER BY hits DESC LIMIT 8
    `).all(now - 2592000),
    top_ua:       DB.prepare(`
      SELECT ua_family, COUNT(*) hits
      FROM blocks WHERE received_at > ?
      GROUP BY ua_family ORDER BY hits DESC LIMIT 8
    `).all(now - 2592000),
    recent:       DB.prepare(`
      SELECT received_at, ip_masked ip, form_type, reason, ua_family
      FROM blocks ORDER BY id DESC LIMIT 40
    `).all(),
    hourly:       DB.prepare(`
      SELECT (received_at / 3600) * 3600 h, COUNT(*) n
      FROM blocks WHERE received_at > ?
      GROUP BY h ORDER BY h ASC
    `).all(now - 86400),
  };
  _cacheTs = Date.now();
  return _cache;
}

// ── SSE live stream ───────────────────────────────────────────────────────────

const sseClients = new Set();
let lastId = DB.prepare('SELECT MAX(id) id FROM blocks').get().id || 0;

setInterval(() => {
  if (!sseClients.size) return;
  const rows = DB.prepare('SELECT * FROM blocks WHERE id > ? ORDER BY id ASC LIMIT 20').all(lastId);
  if (!rows.length) return;
  lastId = rows.at(-1).id;
  const msg = `data: ${JSON.stringify(rows)}\n\n`;
  for (const r of sseClients) { try { r.write(msg); } catch { sseClients.delete(r); } }
}, 2000);

// ── Prepared statements ───────────────────────────────────────────────────────

const stmtIns = DB.prepare(
  'INSERT INTO blocks (received_at, site_id, ip_masked, form_type, reason, ua_family) VALUES (?,?,?,?,?,?)'
);
const stmtSite = DB.prepare(`
  INSERT INTO sites (site_id, first_seen, last_seen, block_count) VALUES (?,?,?,?)
  ON CONFLICT(site_id) DO UPDATE SET
    last_seen   = excluded.last_seen,
    block_count = block_count + excluded.block_count
`);

const insertBatch = DB.transaction((siteId, blocks) => {
  const now = Math.floor(Date.now() / 1000);
  for (const b of blocks) {
    const ts = b.blocked_at ? Math.floor(new Date(b.blocked_at) / 1000) : now;
    stmtIns.run(
      ts, siteId,
      sanitizeIP(b.ip),
      String(b.form_type   || '').slice(0, 100),
      String(b.reason      || '').slice(0, 255),
      parseUA(b.user_agent || '')
    );
  }
  stmtSite.run(siteId, now, now, blocks.length);
});

// ── Express routes ────────────────────────────────────────────────────────────

app.use(express.json({ limit: '128kb' }));
app.use(express.static(path.join(__dirname, 'public')));

// Submit blocks from a WordPress site (token-protected)
app.post('/api/v1/submit', requireToken, (req, res) => {
  const clientIP = (req.headers['x-forwarded-for'] || '').split(',')[0].trim()
    || req.socket.remoteAddress || '';

  if (!allowed(clientIP)) {
    return res.status(429).json({ error: 'Rate limit exceeded' });
  }

  const { site_hash, blocks } = req.body || {};

  if (!site_hash || typeof site_hash !== 'string' || site_hash.length < 8) {
    return res.status(400).json({ error: 'Invalid site_hash' });
  }
  if (!Array.isArray(blocks) || !blocks.length || blocks.length > 50) {
    return res.status(400).json({ error: 'blocks must be array of 1–50 items' });
  }

  try {
    insertBatch(site_hash.slice(0, 20), blocks);
    _cache = null; // invalidate stats cache
    res.json({ ok: true, received: blocks.length });
  } catch (e) {
    console.error('[submit]', e.message);
    res.status(500).json({ error: 'Internal error' });
  }
});

// Public aggregated stats
app.get('/api/v1/stats', (_, res) => res.json(getStats()));

// SSE live feed
app.get('/api/v1/stream', (req, res) => {
  res.writeHead(200, {
    'Content-Type':      'text/event-stream',
    'Cache-Control':     'no-cache',
    'Connection':        'keep-alive',
    'X-Accel-Buffering': 'no',
  });
  res.write(':\n\n'); // flush headers
  sseClients.add(res);
  req.on('close', () => sseClients.delete(res));
});

// Health check
app.get('/api/v1/health', (_, res) =>
  res.json({ ok: true, uptime: process.uptime(), sse_clients: sseClients.size })
);

app.listen(PORT, '0.0.0.0', () => {
  console.log(`[honeypot-api] listening on :${PORT}`);
  console.log(`[honeypot-api] db: ${process.env.DB_PATH || '/data/honeypot.db'}`);
});