Add user stats endpoint with JWT authentication and data size calculation

src/controllers/userController.js

@@ -0,0 +1,74 @@
+const jwt = require('jsonwebtoken');
+const Note = require('../models/Note');
+const Category = require('../models/Category');
+
+const JWT_SECRET = process.env.JWT_SECRET;
+
+const getStats = async (req, res) => {
+  try {
+    // 1. Verificamos el token (igual que en syncController)
+    const authorizationHeader = req.headers.authorization || '';
+    if (!authorizationHeader.startsWith('Bearer ')) {
+      return res.status(401).json({ error: 'Authorization header missing' });
+    }
+
+    const token = authorizationHeader.slice(7).trim();
+    const payload = jwt.verify(token, JWT_SECRET);
+    const userId = payload && payload.id;
+    if (!userId) return res.status(401).json({ error: 'Usuario inválido' });
+
+    // 2. Traemos solo los campos pesados para no saturar la RAM del servidor
+    const notes = await Note.findAll({
+      where: { userId },
+      attributes: ['title', 'body', 'permanentDelete']
+    });
+
+    const categories = await Category.findAll({
+      where: { userId },
+      attributes: ['encrypted_name']
+    });
+
+    // 3. Calculamos el tamaño exacto en Bytes usando Buffer
+    let totalBytes = 0;
+
+    notes.forEach(note => {
+      // Si está borrada permanentemente no ocupa texto real
+      if (note.permanentDelete) return; 
+      
+      if (note.title) totalBytes += Buffer.byteLength(note.title, 'utf8');
+      if (note.body) totalBytes += Buffer.byteLength(note.body, 'utf8');
+      // Sumamos ~150 bytes por nota para representar el peso de los UUIDs (id), fechas y booleanos
+      totalBytes += 150; 
+    });
+
+    categories.forEach(cat => {
+      if (cat.encrypted_name) totalBytes += Buffer.byteLength(cat.encrypted_name, 'utf8');
+      totalBytes += 100; // Margen para UUIDs, colores e iconos
+    });
+
+    // 4. Formateamos el resultado
+    let formattedSize = '0 KB';
+    if (totalBytes > 0) {
+      if (totalBytes < 1024 * 1024) {
+        formattedSize = `${(totalBytes / 1024).toFixed(2)} KB`;
+      } else {
+        formattedSize = `${(totalBytes / (1024 * 1024)).toFixed(2)} MB`;
+      }
+    }
+
+    res.json({
+      totalNotes: notes.length,
+      totalCategories: categories.length,
+      sizeBytes: totalBytes,
+      formattedSize: formattedSize
+    });
+
+  } catch (error) {
+    if (error.name === 'JsonWebTokenError' || error.name === 'TokenExpiredError') {
+      return res.status(401).json({ error: 'Token inválido o expirado' });
+    }
+    res.status(500).json({ error: error.message });
+  }
+};
+
+module.exports = { getStats };

src/routes/userRoutes.js

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+const express = require('express');
+const router = express.Router();
+const userController = require('../controllers/userController');
+
+// Ruta GET protegida por token
+router.get('/user/stats', userController.getStats);
+
+module.exports = router;