class Mission {

    Logbook logbook;
    LocalDate start;

    void update(String author, String message) {
        LocalDate today = LocalDate.now();
        String month = String.valueOf(today.getMonthValue());
        String formattedMonth = month.length() < 2 ? "0" + month : month; 
        String entry = author.toUpperCase() + ": [" + formattedMonth + "-" + 
                today.getDayOfMonth() + "-" + today.getYear() + "](Day " + 
                (ChronoUnit.DAYS.between(start, today) + 1) + ")> " + 
                message + System.lineSeparator();
        logbook.write(entry);
    }
}