Flutter Insert text to TextField

// Insert text to TextField
  void insertText(String insert, TextEditingController controller) {
    final int cursorPos = controller.selection.base.offset;
    controller.value = controller.value.copyWith(
        text: controller.text.replaceRange(max(cursorPos, 0), max(cursorPos, 0), insert),
        selection: TextSelection.fromPosition(TextPosition(offset: max(cursorPos, 0) + insert.length))
    );
  }