// Display formatting shared by the screens. Unknown values render as "—"
// rather than 0, so a missing Remote ID field never reads as a real reading.

String fmtMeters(double? m, {int digits = 0}) => m == null ? '—' : '${m.toStringAsFixed(digits)} m';

String fmtDistance(double? m) {
  if (m == null) return '—';
  if (m < 1000) return '${m.round()} m';
  return '${(m / 1000).toStringAsFixed(2)} km';
}

String fmtSpeed(double? ms) => ms == null ? '—' : '${ms.toStringAsFixed(1)} m/s';

String fmtDuration(Duration d) {
  final int h = d.inHours;
  final String m = (d.inMinutes % 60).toString().padLeft(2, '0');
  final String s = (d.inSeconds % 60).toString().padLeft(2, '0');
  return h > 0 ? '$h:$m:$s' : '$m:$s';
}

String fmtAgo(DateTime t, [DateTime? now]) {
  final Duration d = (now ?? DateTime.now()).difference(t);
  if (d.inSeconds < 2) return 'now';
  if (d.inSeconds < 60) return '${d.inSeconds} s ago';
  if (d.inMinutes < 60) return '${d.inMinutes} min ago';
  return '${d.inHours} h ago';
}

String fmtClock(DateTime t) {
  final DateTime l = t.toLocal();
  return '${l.hour.toString().padLeft(2, '0')}:${l.minute.toString().padLeft(2, '0')}';
}

const Map<String, String> purposeLabels = <String, String>{
  'commercial': 'Commercial',
  'hobby': 'Hobby',
  'research': 'Research',
  'public': 'Public service',
  'club_area': 'Club area',
};

const Map<String, String> categoryLabels = <String, String>{
  'open': 'Open',
  'specific': 'Specific',
  'certified': 'Certified',
};

String transportLabel(String t) => switch (t) {
      'ble' => 'Bluetooth',
      'ble5' => 'Bluetooth 5 LR',
      'nan' => 'Wi-Fi NaN',
      'beacon' => 'Wi-Fi Beacon',
      _ => t,
    };