initial commit

lib/utils/sar_message_parser.dart

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+import 'package:latlong2/latlong.dart';
+import '../models/sar_marker.dart';
+import '../models/message.dart';
+
+/// Parser for SAR (Search & Rescue) special messages
+/// Format: S:<emoji>:<latitude>,<longitude>
+/// Examples:
+///   S:🧑:37.7749,-122.4194
+///   S:🔥:40.7128,-74.0060
+///   S:🏕️:34.0522,-118.2437
+class SarMessageParser {
+  static final RegExp _sarPattern = RegExp(
+    r'^S:(.):(-?\d+\.?\d*),(-?\d+\.?\d*)$',
+    multiLine: false,
+  );
+
+  /// Check if a message is a SAR marker message
+  static bool isSarMessage(String text) {
+    return text.trim().startsWith('S:') && _sarPattern.hasMatch(text.trim());
+  }
+
+  /// Parse a SAR message and extract marker information
+  /// Returns null if the message is not a valid SAR message
+  static SarMarkerInfo? parse(String text) {
+    final trimmed = text.trim();
+    if (!trimmed.startsWith('S:')) return null;
+
+    final match = _sarPattern.firstMatch(trimmed);
+    if (match == null) return null;
+
+    try {
+      final emoji = match.group(1)!;
+      final latitude = double.parse(match.group(2)!);
+      final longitude = double.parse(match.group(3)!);
+
+      // Validate coordinates
+      if (latitude < -90 || latitude > 90) return null;
+      if (longitude < -180 || longitude > 180) return null;
+
+      final markerType = SarMarkerType.fromEmoji(emoji);
+      final location = LatLng(latitude, longitude);
+
+      return SarMarkerInfo(
+        type: markerType,
+        location: location,
+        emoji: emoji,
+      );
+    } catch (e) {
+      return null;
+    }
+  }
+
+  /// Enhance a Message with SAR marker information
+  static Message enhanceMessage(Message message) {
+    final sarInfo = parse(message.text);
+    if (sarInfo == null) return message;
+
+    return message.copyWith(
+      isSarMarker: true,
+      sarMarkerType: sarInfo.type,
+      sarGpsCoordinates: sarInfo.location,
+    );
+  }
+
+  /// Create a SAR marker message text
+  static String createSarMessage({
+    required SarMarkerType type,
+    required LatLng location,
+    String? notes,
+  }) {
+    final text = 'S:${type.emoji}:${location.latitude},${location.longitude}';
+    if (notes != null && notes.isNotEmpty) {
+      return '$text\n$notes';
+    }
+    return text;
+  }
+
+  /// Extract additional notes from SAR message (text after the marker)
+  static String? extractNotes(String text) {
+    final trimmed = text.trim();
+    final lines = trimmed.split('\n');
+    if (lines.length <= 1) return null;
+
+    // Everything after the first line is considered notes
+    return lines.sublist(1).join('\n').trim();
+  }
+
+  /// Validate SAR message format
+  static bool isValidFormat(String text) {
+    return isSarMessage(text) && parse(text) != null;
+  }
+
+  /// Get a user-friendly error message for invalid SAR format
+  static String? getFormatError(String text) {
+    if (!text.trim().startsWith('S:')) {
+      return 'SAR message must start with "S:"';
+    }
+
+    final parts = text.trim().split(':');
+    if (parts.length < 3) {
+      return 'Invalid format. Use: S:<emoji>:<latitude>,<longitude>';
+    }
+
+    final emoji = parts[1];
+    if (emoji.isEmpty) {
+      return 'Missing emoji marker (🧑, 🔥, or 🏕️)';
+    }
+
+    final coords = parts[2];
+    if (!coords.contains(',')) {
+      return 'Coordinates must be separated by comma';
+    }
+
+    final coordParts = coords.split(',');
+    if (coordParts.length != 2) {
+      return 'Invalid coordinates format';
+    }
+
+    try {
+      final lat = double.parse(coordParts[0]);
+      final lon = double.parse(coordParts[1]);
+
+      if (lat < -90 || lat > 90) {
+        return 'Latitude must be between -90 and 90';
+      }
+      if (lon < -180 || lon > 180) {
+        return 'Longitude must be between -180 and 180';
+      }
+    } catch (e) {
+      return 'Invalid coordinate values';
+    }
+
+    return null;
+  }
+}
+
+/// Parsed SAR marker information
+class SarMarkerInfo {
+  final SarMarkerType type;
+  final LatLng location;
+  final String emoji;
+
+  SarMarkerInfo({
+    required this.type,
+    required this.location,
+    required this.emoji,
+  });
+
+  @override
+  String toString() {
+    return 'SarMarkerInfo(type: ${type.displayName}, location: $location)';
+  }
+}