Format unix time into pretty string, WhatsApp style

timeformat.dart

final yMMMd = DateFormat.yMMMd();
final MMMd = DateFormat.MMMd();
final E = DateFormat.E().add_d();
final Hm = DateFormat.Hm();

String formatUnixTime(int unixMilli) {
  final sentTime = DateTime.fromMillisecondsSinceEpoch(unixMilli);
  final currTime = DateTime.now();

  DateFormat formatter;
  if (currTime.year - sentTime.year > 0) {
    // different year
    formatter = yMMMd;
  } else if (currTime.month - sentTime.month > 0) {
    // same year, different month
    formatter = MMMd;
  } else if (currTime.day - sentTime.day > 0) {
    // same month, different day
    formatter = currTime.day - sentTime.day >= 7 ? MMMd : E;
  } else {
    // same day
    return 'Today';
  }

  return formatter.format(sentTime);
}