Session 7h: Stripe products, tier config, scan limits, response gating, free tier

src/middleware/scanLimit.js

@@ -0,0 +1,99 @@
+/**
+ * Per-tier daily scan limit middleware.
+ *
+ * Reads `req.user.tier` (set by requireAuth) and counts scans in a
+ * rolling 24h window. Anonymous callers fall through to a 'free'
+ * bucket keyed by IP so the open demo can't be DOS'd via shell.
+ *
+ * The middleware is separate from the IP rate limiter (SEC-1, Session
+ * 7d) on /api/analyze: that one caps RAW request rate (10/min) per IP
+ * regardless of who's authenticated. This one caps PAID-OPERATION
+ * counts per user per day per tier.
+ *
+ * Counts live in-memory (Map<userOrIpKey, Array<timestamp>>) — same
+ * trade-off as rateLimit.js. Survives a Coolify redeploy by resetting
+ * to zero, which is the user-friendly fallback.
+ */
+
+const { getScanLimit } = require('../config/tiers');
+
+const WINDOW_MS = 24 * 60 * 60 * 1000;
+const MAX_TRACKED = 50_000;
+
+const hits = new Map();
+
+function clientKey(req) {
+  if (req.user?.id) return `u:${req.user.id}`;
+  return `ip:${req.ip || req.socket?.remoteAddress || 'unknown'}`;
+}
+
+function evictIfFull() {
+  if (hits.size <= MAX_TRACKED) return;
+  const oldest = hits.keys().next().value;
+  if (oldest !== undefined) hits.delete(oldest);
+}
+
+function pruneOlderThan(arr, cutoff) {
+  let w = 0;
+  for (let i = 0; i < arr.length; i += 1) {
+    if (arr[i] > cutoff) {
+      arr[w] = arr[i];
+      w += 1;
+    }
+  }
+  arr.length = w;
+  return w;
+}
+
+function scanLimit() {
+  return function scanLimitMiddleware(req, res, next) {
+    const tier = req.user?.tier || 'free';
+    const limit = getScanLimit(tier);
+    // Infinity → never block; skip the bookkeeping entirely so the
+    // hot Desk path doesn't allocate Map entries it'll never read.
+    if (limit === Infinity) return next();
+
+    const key = clientKey(req);
+    const now = Date.now();
+    const cutoff = now - WINDOW_MS;
+
+    let ts = hits.get(key);
+    if (!ts) {
+      ts = [];
+      hits.set(key, ts);
+      evictIfFull();
+    }
+
+    const used = pruneOlderThan(ts, cutoff);
+    if (used >= limit) {
+      const oldest = ts[0];
+      const retryAfterSec = Math.max(1, Math.ceil((oldest + WINDOW_MS - now) / 1000));
+      res.set('Retry-After', String(retryAfterSec));
+      res.set('X-Scans-Used', String(used));
+      res.set('X-Scans-Limit', String(limit));
+      return res.status(429).json({
+        error: 'Daily scan limit reached. Upgrade for more scans.',
+        scans_used: used,
+        scans_limit: limit,
+        retry_after_seconds: retryAfterSec,
+        tier,
+      });
+    }
+
+    ts.push(now);
+    res.set('X-Scans-Used', String(used + 1));
+    res.set('X-Scans-Limit', String(limit));
+    return next();
+  };
+}
+
+// Test helper — drop all tracked counts. Not exported in module.exports
+// to keep prod surface clean; reachable via the __internals bag.
+function resetForTests() {
+  hits.clear();
+}
+
+module.exports = {
+  scanLimit,
+  __internals: { hits, clientKey, resetForTests, WINDOW_MS, MAX_TRACKED },
+};