mergeSettingsScalars function

String mergeSettingsScalars(String content, { required String themeName, required String? lastSelectedDeviceId, })

Replaces or inserts theme: and last_selected_device_id: lines while preserving the rest of the file (plugins, comments).

Implementation

String mergeSettingsScalars(
  String content, {
  required String themeName,
  required String? lastSelectedDeviceId,
}) {
  final deviceValue = lastSelectedDeviceId ?? '~';
  final lines = content.split('\n');
  var themeReplaced = false;
  var deviceReplaced = false;

  for (var i = 0; i < lines.length; i++) {
    final line = lines[i];
    if (line.startsWith('theme:')) {
      lines[i] = 'theme: $themeName';
      themeReplaced = true;
    } else if (line.startsWith('last_selected_device_id:')) {
      lines[i] = 'last_selected_device_id: $deviceValue';
      deviceReplaced = true;
    }
  }

  if (themeReplaced && deviceReplaced) {
    return lines.join('\n');
  }

  final insertAt = _insertIndexAfterHeader(lines);
  final toInsert = <String>[];
  if (!themeReplaced) toInsert.add('theme: $themeName');
  if (!deviceReplaced) {
    toInsert.add('last_selected_device_id: $deviceValue');
  }
  lines.insertAll(insertAt, toInsert);
  return lines.join('\n');
}