def append_user_signature(body, user):
    body_text = str(body or '').strip()
    if user is None:
        return body_text

    signature = ''
    get_signature = getattr(user, 'get_email_signature', None)
    if callable(get_signature):
        signature = str(get_signature() or '').strip()
    else:
        signature = str(getattr(user, 'signature', '') or '').strip()

    if not signature:
        return body_text
    if not body_text:
        return signature
    return f"{body_text}\n\n{signature}"