class Logbook {

    void writeMessage(String message, Path location) throws IOException {
        if (Files.isDirectory(location)) {
            throw new IllegalArgumentException("The path is invalid!");
        }
        if (message.trim().equals("") || message == null) {
            throw new IllegalArgumentException("The message is invalid!");
        }
        String entry = LocalDate.now() + ": " + message;
        Files.write(location, Collections.singletonList(entry),
            StandardCharsets.UTF_8, StandardOpenOption.CREATE,
            StandardOpenOption.APPEND);
    }
}