fix(tactical): implement dynamic MGRS grid conversion, triangle of error resection accuracy, clean surveyed IDW elevation, and robust offline sync validation

2026-09-14 14:21:30 +03:00
parent 17e8f8eeac
commit aa2b9f131f
4 changed files with 253 additions and 41 deletions
@@ -53,14 +53,97 @@ class MilitaryGridUtils {
    return 'شمال غرب (NW)';
  }

-  /// Convert LatLng to MGRS String representation
-  static String latLngToMgrs(double lat, double lng) {
-    final coords = fromLatLng(LatLng(lat, lng));
+  /// Convert LatLng to standard MGRS String representation (Zone + Band + 100k Square ID + Easting/Northing)
+  static String latLngToMgrs(double lat, double lng, {int accuracyDigits = 4}) {
+    if (lat < -80.0 || lat > 84.0) {
+      return 'OUT_OF_BOUNDS';
+    }
+
+    final zone = ((lng + 180.0) / 6.0).floor() + 1;
+    final coords = fromLatLng(LatLng(lat, lng), zone: zone);
+
+    final bandLetter = _getLatitudeBandLetter(lat);
+    final squareId = _get100kSquareId(coords.easting, coords.northing, zone);
+
    final eInt = coords.easting.round() % 100000;
    final nInt = coords.northing.round() % 100000;
-    final eStr = (eInt ~/ 10).toString().padLeft(4, '0');
-    final nStr = (nInt ~/ 10).toString().padLeft(4, '0');
-    return '${coords.zone}R YU $eStr $nStr';
+
+    // Pad to 5 digits then trim to desired accuracy
+    final e5 = eInt.toString().padLeft(5, '0');
+    final n5 = nInt.toString().padLeft(5, '0');
+
+    final eStr = e5.substring(0, math.min(5, accuracyDigits));
+    final nStr = n5.substring(0, math.min(5, accuracyDigits));
+
+    return '$zone$bandLetter $squareId $eStr $nStr';
+  }
+
+  /// Latitude band letter (8-degree bands from -80° to +84°: C to X, skipping I and O)
+  static String _getLatitudeBandLetter(double lat) {
+    const bands = 'CDEFGHJKLMNPQRSTUVWX';
+    if (lat >= 84.0) return 'X';
+    if (lat < -80.0) return 'C';
+    int index = ((lat + 80.0) / 8.0).floor();
+    if (index < 0) index = 0;
+    if (index >= bands.length) index = bands.length - 1;
+    return bands[index];
+  }
+
+  /// 100,000-meter Square Identification (2 letters) per US DMA TM 8358.1 / WGS84 standard
+  static String _get100kSquareId(double easting, double northing, int zone) {
+    const setColOrigin = 'AJSAJS';
+    const setRowOrigin = 'AFAFAF';
+    const aCode = 65; // 'A'
+    const iCode = 73; // 'I'
+    const oCode = 79; // 'O'
+    const vCode = 86; // 'V'
+    const zCode = 90; // 'Z'
+
+    final setParm = (zone % 6 == 0) ? 6 : (zone % 6);
+    final setIndex = setParm - 1;
+
+    final colOrigin = setColOrigin.codeUnitAt(setIndex);
+    final rowOrigin = setRowOrigin.codeUnitAt(setIndex);
+
+    final col = (easting / 100000.0).floor();
+    final row = (northing / 100000.0).floor() % 20;
+
+    var colInt = colOrigin + col - 1;
+    var rowInt = rowOrigin + row;
+    var colRollover = false;
+
+    if (colInt > zCode) {
+      colInt = colInt - zCode + aCode - 1;
+      colRollover = true;
+    }
+    if (colInt == iCode || (colOrigin < iCode && colInt > iCode) || ((colInt > iCode || colOrigin < iCode) && colRollover)) {
+      colInt++;
+    }
+    if (colInt == oCode || (colOrigin < oCode && colInt > oCode) || ((colInt > oCode || colOrigin < oCode) && colRollover)) {
+      colInt++;
+      if (colInt == iCode) colInt++;
+    }
+    if (colInt > zCode) {
+      colInt = colInt - zCode + aCode - 1;
+    }
+
+    var rowRollover = false;
+    if (rowInt > vCode) {
+      rowInt = rowInt - vCode + aCode - 1;
+      rowRollover = true;
+    }
+    if (rowInt == iCode || (rowOrigin < iCode && rowInt > iCode) || ((rowInt > iCode || rowOrigin < iCode) && rowRollover)) {
+      rowInt++;
+    }
+    if (rowInt == oCode || (rowOrigin < oCode && rowInt > oCode) || ((rowInt > oCode || rowOrigin < oCode) && rowRollover)) {
+      rowInt++;
+      if (rowInt == iCode) rowInt++;
+    }
+    if (rowInt > vCode) {
+      rowInt = rowInt - vCode + aCode - 1;
+    }
+
+    return String.fromCharCode(colInt) + String.fromCharCode(rowInt);
  }

  /// Convert WGS84 Lat/Lng to UTM Zone 36N Easting (شرقيات) and Northing (شماليات)