implemented user backups

app/lib/utils/form_validators.dart

@@ -17,7 +17,10 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
+import 'dart:io';
+
 import 'package:nullability/nullability.dart';
+import 'package:path/path.dart' as p;
 import 'package:weblibre/utils/uri_parser.dart' as uri_parser;
 
 String? validateUrl(
@@ -55,3 +58,87 @@ String? validateRequired(String? value, {String message = 'Value required'}) {
 
   return message;
 }
+
+String? validatePath(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Path cannot be empty';
+  }
+
+  // Check for invalid characters
+  // ignore: unnecessary_raw_strings
+  final invalidChars = RegExp(r'[<>"|?*]');
+  if (invalidChars.hasMatch(value)) {
+    return 'Path contains invalid characters';
+  }
+
+  // Validate path structure
+  try {
+    p.normalize(value);
+  } catch (e) {
+    return 'Invalid path format';
+  }
+
+  return null;
+}
+
+String? validateDirectoryExisting(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Path cannot be empty';
+  }
+
+  if (!Directory(value).existsSync()) {
+    return 'Directory is not existing';
+  }
+
+  return null;
+}
+
+String? validateDirectoryNotExisting(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Path cannot be empty';
+  }
+
+  if (Directory(value).existsSync()) {
+    return 'Directory already exisits';
+  }
+
+  return null;
+}
+
+String? validateFileNotExisting(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Path cannot be empty';
+  }
+
+  if (File(value).existsSync()) {
+    return 'File already exisits';
+  }
+
+  return null;
+}
+
+String? validateFileExisting(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Path cannot be empty';
+  }
+
+  if (!File(value).existsSync()) {
+    return 'File not existing';
+  }
+
+  return null;
+}
+
+final _profileNamePattern = RegExp(r"""^[^~)('!*<>:;,?"*|/_]+$""");
+
+String? validateProfileName(String? value) {
+  if (value == null || value.isEmpty) {
+    return 'Name required';
+  }
+
+  if (!_profileNamePattern.hasMatch(value)) {
+    return 'Name contains invalid caharcters';
+  }
+
+  return null;
+}