GGA, GST és RMC nmea mondat értelemző refraktorálás

lib/gnss_sentences/gngga.dart

@@ -1,35 +1,55 @@
 import 'package:nmea/nmea.dart';
 
 class Gngga extends TalkerSentence {
-  static const String id = "GNGGA";
+  static const String id = "GxGGA";
   Gngga({required super.raw});
 
   @override
-  bool get valid => super.valid && fields.length == 15;
+  bool get valid => super.valid && fields.length >= 15;
 
-  String get utcOfPositionFix => fields[1];
-  int get gpsQualityIndicator => int.parse(fields[6]);
-  double get latitude => _getCoordinateFromGpsLatitude(fields[2]);
-  String get latitudeDirection => fields[3];
-  double get longitude => _getCoordinateFromGpsLongitude(fields[4]);
-  String get longitudeDirection => fields[5];
-  int get numberOfSvsInUse => int.parse(fields[7]);
-  double get hdop => double.parse(fields[8]);
-  double get altitudeAboveMeanSeaLevel => double.parse(fields[9]);
-  double get geoidSeparation => double.parse(fields[11]);
+  String get utcOfPositionFix => _field(1);
+  int get gpsQualityIndicator => _parseInt(_field(6), fallback: 0);
+  String get latitudeDirection => _field(3).toUpperCase();
+  double get latitude => _parseLatitude(_field(2), latitudeDirection) ?? 0.0;
+  String get longitudeDirection => _field(5).toUpperCase();
+  double get longitude => _parseLongitude(_field(4), longitudeDirection) ?? 0.0;
+  int get numberOfSvsInUse => _parseInt(_field(7), fallback: 0);
+  double get hdop => _parseDouble(_field(8), fallback: 0.0);
+  double get altitudeAboveMeanSeaLevel =>
+      _parseDouble(_field(9), fallback: 0.0);
+  double get geoidSeparation => _parseDouble(_field(11), fallback: 0.0);
 
-  double _getCoordinateFromGpsLongitude(String coordinate) {
-    double result =
-        double.parse("${coordinate[0]}${coordinate[1]}${coordinate[2]}") +
-            double.parse(coordinate.substring(3)) / 60;
+  String _field(int index) {
+    if (index < 0 || index >= fields.length) return '';
 
-    return result;
+    return fields[index].trim();
   }
 
-  double _getCoordinateFromGpsLatitude(String coordinate) {
-    double result = double.parse("${coordinate[0]}${coordinate[1]}") +
-        double.parse(coordinate.substring(2)) / 60;
+  int _parseInt(String value, {required int fallback}) {
+    return int.tryParse(value) ?? fallback;
+  }
 
-    return result;
+  double _parseDouble(String value, {required double fallback}) {
+    return double.tryParse(value) ?? fallback;
+  }
+
+  double? _parseLatitude(String value, String direction) {
+    if (value.length < 4) return null; // ddmm.mmmm
+    final deg = double.tryParse(value.substring(0, 2));
+    final min = double.tryParse(value.substring(2));
+    if (deg == null || min == null) return null;
+
+    final result = deg + (min / 60.0);
+    return direction == 'S' ? -result : result;
+  }
+
+  double? _parseLongitude(String value, String direction) {
+    if (value.length < 5) return null; // dddmm.mmmm
+    final deg = double.tryParse(value.substring(0, 3));
+    final min = double.tryParse(value.substring(3));
+    if (deg == null || min == null) return null;
+
+    final result = deg + (min / 60.0);
+    return direction == 'W' ? -result : result;
   }
 }