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mobile/lib/utils/polyline_utility.dart

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+import '../models/gps_coordinate.dart';
+
+/// أداة ترميز وفك ترميز Polyline
+/// تستخدم خوارزمية Google Encoded Polyline لضغط المسارات بنسبة ~95%
+class PolylineUtility {
+  /// Encode a list of GPS coordinates to a polyline string
+  static String encode(List<GpsCoordinate> coordinates) {
+    if (coordinates.isEmpty) return '';
+
+    final buffer = StringBuffer();
+    int prevLat = 0;
+    int prevLng = 0;
+
+    for (final point in coordinates) {
+      int lat = (point.latitude * 1e5).round();
+      int lng = (point.longitude * 1e5).round();
+
+      _encodeValue(lat - prevLat, buffer);
+      _encodeValue(lng - prevLng, buffer);
+
+      prevLat = lat;
+      prevLng = lng;
+    }
+
+    return buffer.toString();
+  }
+
+  /// Decode a polyline string back to coordinates
+  static List<GpsCoordinate> decode(String encoded) {
+    if (encoded.isEmpty) return [];
+
+    final coordinates = <GpsCoordinate>[];
+    int index = 0;
+    int lat = 0;
+    int lng = 0;
+
+    while (index < encoded.length) {
+      lat += _decodeValue(encoded, index);
+      index = _lastIndex;
+
+      if (index >= encoded.length) break;
+
+      lng += _decodeValue(encoded, index);
+      index = _lastIndex;
+
+      coordinates.add(GpsCoordinate(
+        latitude: lat / 1e5,
+        longitude: lng / 1e5,
+        timestamp: DateTime.now(), // Polylines don't store timestamps
+      ));
+    }
+
+    return coordinates;
+  }
+
+  // Internal tracking for decode position
+  static int _lastIndex = 0;
+
+  static void _encodeValue(int value, StringBuffer buffer) {
+    int v = value < 0 ? ~(value << 1) : (value << 1);
+    while (v >= 0x20) {
+      buffer.writeCharCode((0x20 | (v & 0x1f)) + 63);
+      v >>= 5;
+    }
+    buffer.writeCharCode(v + 63);
+  }
+
+  static int _decodeValue(String encoded, int startIndex) {
+    int result = 0;
+    int shift = 0;
+    int index = startIndex;
+
+    while (index < encoded.length) {
+      int byte = encoded.codeUnitAt(index) - 63;
+      index++;
+      result |= (byte & 0x1f) << shift;
+      shift += 5;
+      if (byte < 0x20) break;
+    }
+
+    _lastIndex = index;
+    return (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
+  }
+}