added NAS configuration file; updated MediaViewer to support thumbnail carousel; improved error handling in NASAPI and NASAUTH; refactored various comments for clarity

src/services/CredentialEncryption.js

@@ -1,24 +1,19 @@
 import * as Crypto from 'expo-crypto';
 
 /**
- * Credential Encryption Service
- *
- * Uses expo-crypto for password hashing (SHA-256)
- * Uses base64 encoding for storing account data objects in the database
+ * Handles password hashing (SHA-256) and base64 encoding of account data objects
  */
 class CredentialEncryption {
   /**
-   * Hash a password using SHA-256 via expo-crypto
-   * Returns a hex digest string
+   * Hash a password with SHA-256 and return a hex digest
    */
   async hashPassword(password) {
     try {
       if (!password) throw new Error('Password is required');
-      const digest = await Crypto.digestStringAsync(
+      return await Crypto.digestStringAsync(
         Crypto.CryptoDigestAlgorithm.SHA256,
         password
       );
-      return digest;
     } catch (error) {
       console.error('Password hashing error:', error);
       throw new Error('Failed to hash password: ' + error.message);
@@ -26,7 +21,7 @@ class CredentialEncryption {
   }
 
   /**
-   * Verify a password against a stored hash
+   * Compare a plaintext password against a stored hash
    */
   async verifyPassword(password, storedHash) {
     try {
@@ -39,15 +34,13 @@ class CredentialEncryption {
   }
 
   /**
-   * Encrypt an object for database storage (base64-encoded JSON)
+   * Encode an object as a base64 JSON string for database storage
    */
   encrypt(data) {
     try {
       if (!data) throw new Error('No data provided to encrypt');
       const jsonString = JSON.stringify(data);
-      // btoa is available in React Native / Hermes
-      const encoded = btoa(unescape(encodeURIComponent(jsonString)));
-      return encoded;
+      return btoa(unescape(encodeURIComponent(jsonString)));
     } catch (error) {
       console.error('Encryption error:', error);
       throw new Error('Failed to encrypt data: ' + error.message);
@@ -55,7 +48,7 @@ class CredentialEncryption {
   }
 
   /**
-   * Decrypt a base64-encoded JSON string back to an object
+   * Decode a base64 JSON string back to an object
    */
   decrypt(encryptedData) {
     try {
@@ -70,4 +63,3 @@ class CredentialEncryption {
 }
 
 export default new CredentialEncryption();
-

src/services/DatabaseService.js

@@ -5,9 +5,7 @@ let db = null;
 let initPromise = null;
 
 const DatabaseService = {
-  /**
-   * Initialize the database and create tables
-   */
+  // Open the database and create all tables
   initDatabase: async () => {
     if (initPromise) return initPromise;
 
@@ -63,13 +61,9 @@ const DatabaseService = {
           )
         `);
 
-        // Migration: add columns if they don't exist
-        try {
-          await db.execAsync(`ALTER TABLE users ADD COLUMN auto_backup_services TEXT DEFAULT '[]'`);
-        } catch (e) { /* column already exists */ }
-        try {
-          await db.execAsync(`ALTER TABLE users ADD COLUMN theme_preference TEXT DEFAULT 'light'`);
-        } catch (e) { /* column already exists */ }
+        // Add optional columns (safe migration — errors ignored if columns already exist)
+        try { await db.execAsync(`ALTER TABLE users ADD COLUMN auto_backup_services TEXT DEFAULT '[]'`); } catch (_) {}
+        try { await db.execAsync(`ALTER TABLE users ADD COLUMN theme_preference TEXT DEFAULT 'light'`); } catch (_) {}
 
         console.log('Database initialized successfully');
         return true;
@@ -89,9 +83,6 @@ const DatabaseService = {
     if (!db) throw new Error('Database not initialized');
   },
 
-  /**
-   * Create a new user with hashed password
-   */
   createUser: async (username, email, password) => {
     try {
       await DatabaseService.ensureDb();
@@ -107,9 +98,7 @@ const DatabaseService = {
     }
   },
 
-  /**
-   * Login user by username or email, verify hashed password
-   */
+  // Authenticate by username or email
   loginUser: async (identifier, password) => {
     try {
       await DatabaseService.ensureDb();
@@ -129,9 +118,6 @@ const DatabaseService = {
     }
   },
 
-  /**
-   * Check if username or email already exists
-   */
   userExists: async (username, email) => {
     try {
       await DatabaseService.ensureDb();
@@ -150,34 +136,26 @@ const DatabaseService = {
     try {
       await DatabaseService.ensureDb();
       if (!userId && userId !== 0) throw new Error('User ID is required');
-      const row = await db.getFirstAsync('SELECT * FROM users WHERE id = ?', [userId]);
-      return row || null;
+      return (await db.getFirstAsync('SELECT * FROM users WHERE id = ?', [userId])) || null;
     } catch (error) {
       console.error('Error getting user:', error);
       throw error;
     }
   },
 
-  /**
-   * Link an external service account to a user
-   */
+  // Link an external service account (Google, iCloud, NAS) to a local user
   linkAccount: async (userId, serviceType, accountData, isDefault = false) => {
     try {
       await DatabaseService.ensureDb();
       if (!userId) throw new Error('User ID is required');
       if (!serviceType) throw new Error('Service type is required');
-      if (!accountData || typeof accountData !== 'object') {
-        throw new Error('Account data must be a valid object');
-      }
+      if (!accountData || typeof accountData !== 'object') throw new Error('Account data must be a valid object');
 
       const encryptedData = CredentialEncryption.encrypt(accountData);
       if (!encryptedData) throw new Error('Encryption returned empty data');
 
-      // Remove existing account of same type first
-      await db.runAsync(
-        'DELETE FROM linked_accounts WHERE user_id = ? AND service_type = ?',
-        [userId, serviceType]
-      );
+      // Replace any existing link for the same service type
+      await db.runAsync('DELETE FROM linked_accounts WHERE user_id = ? AND service_type = ?', [userId, serviceType]);
 
       const result = await db.runAsync(
         'INSERT INTO linked_accounts (user_id, service_type, account_data, is_default) VALUES (?, ?, ?, ?)',
@@ -195,13 +173,9 @@ const DatabaseService = {
       await DatabaseService.ensureDb();
       if (!userId && userId !== 0) throw new Error('User ID is required');
       const rows = await db.getAllAsync(
-        'SELECT * FROM linked_accounts WHERE user_id = ? AND is_enabled = 1',
-        [userId]
+        'SELECT * FROM linked_accounts WHERE user_id = ? AND is_enabled = 1', [userId]
       );
-      return rows.map((row) => ({
-        ...row,
-        account_data: CredentialEncryption.decrypt(row.account_data),
-      }));
+      return rows.map((row) => ({ ...row, account_data: CredentialEncryption.decrypt(row.account_data) }));
     } catch (error) {
       console.error('Error getting linked accounts:', error);
       throw error;
@@ -238,8 +212,7 @@ const DatabaseService = {
     try {
       await DatabaseService.ensureDb();
       const row = await db.getFirstAsync(
-        'SELECT * FROM linked_accounts WHERE user_id = ? AND is_default = 1',
-        [userId]
+        'SELECT * FROM linked_accounts WHERE user_id = ? AND is_default = 1', [userId]
       );
       if (!row) return null;
       return { ...row, account_data: CredentialEncryption.decrypt(row.account_data) };
@@ -270,10 +243,7 @@ const DatabaseService = {
     try {
       await DatabaseService.ensureDb();
       if (!userId && userId !== 0) throw new Error('User ID is required');
-      return await db.getAllAsync(
-        'SELECT * FROM media WHERE user_id = ? ORDER BY created_date DESC',
-        [userId]
-      );
+      return await db.getAllAsync('SELECT * FROM media WHERE user_id = ? ORDER BY created_date DESC', [userId]);
     } catch (error) {
       console.error('Error getting media:', error);
       throw error;
@@ -352,14 +322,8 @@ const DatabaseService = {
   getAllLinkedAccounts: async (userId) => {
     try {
       await DatabaseService.ensureDb();
-      const rows = await db.getAllAsync(
-        'SELECT * FROM linked_accounts WHERE user_id = ?',
-        [userId]
-      );
-      return rows.map((row) => ({
-        ...row,
-        account_data: CredentialEncryption.decrypt(row.account_data),
-      }));
+      const rows = await db.getAllAsync('SELECT * FROM linked_accounts WHERE user_id = ?', [userId]);
+      return rows.map((row) => ({ ...row, account_data: CredentialEncryption.decrypt(row.account_data) }));
     } catch (error) {
       console.error('Error getting all linked accounts:', error);
       throw error;

src/services/ThemeContext.js

@@ -3,6 +3,7 @@ import * as SecureStore from 'expo-secure-store';
 
 const THEME_KEY = 'app_theme_preference';
 
+// Available theme definitions
 const lightTheme = {
   name: 'light',
   background: '#ffffff',