/// Finished diaries stay editable for this many calendar days back from today,
/// including today. Older finished days stay read-only.
const int diaryFinishedEditWindowInDays = 7;

bool canEditDiaryDay({
  required bool isConsultantView,
  required bool isDiaryCommented,
  required bool isDiaryFinished,
  required int closed,
  required String diaryDate,
  DateTime? now,
}) {
  if (isConsultantView || isDiaryCommented || closed != 0) {
    return false;
  }
  if (!isDiaryFinished) {
    return true;
  }
  final day = _calendarDate(diaryDate);
  if (day == null) {
    return false;
  }
  final clock = now ?? DateTime.now();
  final today = DateTime(clock.year, clock.month, clock.day);
  final oldestEditableDay = today.subtract(
    const Duration(days: diaryFinishedEditWindowInDays),
  );
  return !day.isBefore(oldestEditableDay) && !day.isAfter(today);
}

DateTime? _calendarDate(String raw) {
  final parsed = DateTime.tryParse(raw);
  if (parsed == null) {
    return null;
  }
  final local = parsed.toLocal();
  return DateTime(local.year, local.month, local.day);
}