TF-3267 Implement HTML attachment preview

core/lib/utils/string_convert.dart

@@ -1,7 +1,10 @@
 import 'dart:convert';
+import 'dart:typed_data';
 
 import 'app_logger.dart';
 
+import 'package:core/domain/exceptions/string_exception.dart';
+
 class StringConvert {
   static const String separatorPattern = r'[ ,;]+';
 
@@ -38,4 +41,24 @@ class StringConvert {
       return [];
     }
   }
+
+  static String decodeFromBytes(
+    Uint8List bytes, {
+    required String? charset,
+    bool isHtml = false,
+  }) {
+    if (isHtml) {
+      return utf8.decode(bytes);
+    } else if (charset == null) {
+      throw const NullCharsetException();
+    } else if (charset.toLowerCase().contains('utf-8')) {
+      return utf8.decode(bytes);
+    } else if (charset.toLowerCase().contains('latin')) {
+      return latin1.decode(bytes);
+    } else if (charset.toLowerCase().contains('ascii')) {
+      return ascii.decode(bytes);
+    } else {
+      throw const UnsupportedCharsetException();
+    }
+  }
 }