Add user activity logging system

- Create services/activityLogger.js with configurable log levels (all, navigation, none)
- Create routes/activity.js with endpoints for logging and admin statistics
- Integrate login/logout activity logging into auth routes
- Add TTL index for automatic 90-day cleanup of activity records
- Mount activity routes at /activity

routes/activity.js

@@ -0,0 +1,179 @@
+const express = require('express');
+const { ObjectId } = require('mongodb');
+const { requireAuth, requireAdmin } = require('../middleware/auth');
+const { logActivity, ACTIONS, ACTIVITY_COLLECTION } = require('../services/activityLogger');
+
+const router = express.Router();
+
+/**
+ * POST /log - Log frontend activity
+ * Protected with requireAuth
+ */
+router.post('/log', requireAuth, async (req, res) => {
+  try {
+    const { action, metadata } = req.body;
+
+    // Validate action is in ACTIONS object
+    if (!action || !Object.values(ACTIONS).includes(action)) {
+      return res.status(400).json({ error: 'Invalid action type' });
+    }
+
+    const db = req.app.locals.db;
+
+    // Log the activity with merged metadata
+    await logActivity(
+      db,
+      req.user._id,
+      action,
+      { ...metadata, page: metadata?.page },
+      req
+    );
+
+    res.json({ success: true });
+  } catch (error) {
+    console.error('Error logging activity:', error);
+    res.status(500).json({ error: 'Failed to log activity' });
+  }
+});
+
+/**
+ * GET /user/:userId - Get activity for specific user
+ * Protected with requireAuth and requireAdmin
+ */
+router.get('/user/:userId', requireAuth, requireAdmin, async (req, res) => {
+  try {
+    const { userId } = req.params;
+    const limit = parseInt(req.query.limit) || 50;
+    const skip = parseInt(req.query.skip) || 0;
+
+    const db = req.app.locals.db;
+
+    // Convert userId to ObjectId
+    let userObjectId;
+    try {
+      userObjectId = new ObjectId(userId);
+    } catch (error) {
+      return res.status(400).json({ error: 'Invalid user ID format' });
+    }
+
+    // Find activities for the user
+    const activities = await db
+      .collection(ACTIVITY_COLLECTION)
+      .find({ userId: userObjectId })
+      .sort({ timestamp: -1 })
+      .skip(skip)
+      .limit(limit)
+      .toArray();
+
+    // Get total count
+    const total = await db
+      .collection(ACTIVITY_COLLECTION)
+      .countDocuments({ userId: userObjectId });
+
+    res.json({ activities, total });
+  } catch (error) {
+    console.error('Error fetching user activity:', error);
+    res.status(500).json({ error: 'Failed to fetch user activity' });
+  }
+});
+
+/**
+ * GET /recent - Get recent activity across all users
+ * Protected with requireAuth and requireAdmin
+ */
+router.get('/recent', requireAuth, requireAdmin, async (req, res) => {
+  try {
+    const limit = parseInt(req.query.limit) || 50;
+    const skip = parseInt(req.query.skip) || 0;
+
+    const db = req.app.locals.db;
+
+    // Find all activities sorted by timestamp
+    const activities = await db
+      .collection(ACTIVITY_COLLECTION)
+      .find({})
+      .sort({ timestamp: -1 })
+      .skip(skip)
+      .limit(limit)
+      .toArray();
+
+    // Get total count
+    const total = await db.collection(ACTIVITY_COLLECTION).countDocuments({});
+
+    res.json({ activities, total });
+  } catch (error) {
+    console.error('Error fetching recent activity:', error);
+    res.status(500).json({ error: 'Failed to fetch recent activity' });
+  }
+});
+
+/**
+ * GET /stats - Get activity statistics
+ * Protected with requireAuth and requireAdmin
+ */
+router.get('/stats', requireAuth, requireAdmin, async (req, res) => {
+  try {
+    const db = req.app.locals.db;
+
+    // Calculate date 7 days ago
+    const sevenDaysAgo = new Date();
+    sevenDaysAgo.setDate(sevenDaysAgo.getDate() - 7);
+
+    // Aggregate activity counts by action type in last 7 days
+    const actionCountsResult = await db
+      .collection(ACTIVITY_COLLECTION)
+      .aggregate([
+        {
+          $match: {
+            timestamp: { $gte: sevenDaysAgo }
+          }
+        },
+        {
+          $group: {
+            _id: '$action',
+            count: { $sum: 1 }
+          }
+        }
+      ])
+      .toArray();
+
+    // Convert array to object
+    const actionCounts = {};
+    actionCountsResult.forEach(item => {
+      actionCounts[item._id] = item.count;
+    });
+
+    // Count unique active users in last 7 days
+    const activeUsersResult = await db
+      .collection(ACTIVITY_COLLECTION)
+      .aggregate([
+        {
+          $match: {
+            timestamp: { $gte: sevenDaysAgo }
+          }
+        },
+        {
+          $group: {
+            _id: '$userId'
+          }
+        },
+        {
+          $count: 'total'
+        }
+      ])
+      .toArray();
+
+    const activeUsers = activeUsersResult.length > 0 ? activeUsersResult[0].total : 0;
+
+    res.json({
+      actionCounts,
+      activeUsers,
+      period: '7d'
+    });
+  } catch (error) {
+    console.error('Error fetching activity stats:', error);
+    res.status(500).json({ error: 'Failed to fetch activity statistics' });
+  }
+});
+
+module.exports = router;

routes/auth.js

@@ -3,6 +3,7 @@ const passport = require('passport');
 const jwt = require('jsonwebtoken');
 const authConfig = require('../config/auth');
 const { requireAuth, generateToken } = require('../middleware/auth');
+const { logActivity, ACTIONS } = require('../services/activityLogger');
 
 const router = express.Router();
 
@@ -49,6 +50,10 @@ router.get('/google/callback',
       // Set auth cookie
       res.cookie(authConfig.cookie.name, token, authConfig.cookie.options);
 
+      // Log login activity
+      const db = req.app.locals.db;
+      await logActivity(db, user._id, ACTIONS.LOGIN, { method: 'google' }, req);
+
       // Redirect to frontend
       res.redirect(process.env.FRONTEND_URL);
     } catch (err) {
@@ -80,7 +85,11 @@ router.get('/me', requireAuth, (req, res) => {
  * Clears authentication cookie
  * Protected route - requires valid JWT
  */
-router.post('/logout', requireAuth, (req, res) => {
+router.post('/logout', requireAuth, async (req, res) => {
+  // Log logout activity before clearing cookie
+  const db = req.app.locals.db;
+  await logActivity(db, req.user._id, ACTIONS.LOGOUT, {}, req);
+
   // Clear the auth cookie
   res.clearCookie(authConfig.cookie.name, {
     ...authConfig.cookie.options,