how handle multipolygon

multipolygon_laravel_dart.dart

import 'dart:math';

/// Checks if a point is inside any of the geofences
bool isInsideGeofences(dynamic geofences, double lat, double lng) {
  // Iterate through each geofence in the list
  for (var geofence in geofences) {
    // Each geofence is an array with one polygon
    var polygon = geofence[0];
    
    if (isPointInPolygon(lat, lng, polygon)) {
      return true;
    }
  }
  return false;
}

/// Checks if a point is inside a specific polygon using Ray Casting algorithm
bool isPointInPolygon(double lat, double lng, List<List<double>> polygon) {
  bool isInside = false;
  int j = polygon.length - 1;

  for (int i = 0; i < polygon.length; i++) {
    // Get current and next point coordinates
    double currentLat = polygon[i][1];
    double currentLng = polygon[i][0];
    double prevLat = polygon[j][1];
    double prevLng = polygon[j][0];

    // Check if point is within the polygon bounds
    if (((currentLat > lat) != (prevLat > lat)) &&
        (lng < (prevLng - currentLng) * (lat - currentLat) / 
        (prevLat - currentLat) + currentLng)) {
      isInside = !isInside;
    }
    j = i;
  }

  return isInside;
}

/// Helper function to check if point is within polygon bounds
bool isPointInBounds(double lat, double lng, List<List<double>> polygon) {
  double minLat = double.infinity;
  double maxLat = -double.infinity;
  double minLng = double.infinity;
  double maxLng = -double.infinity;

  for (var point in polygon) {
    minLat = min(minLat, point[1]);
    maxLat = max(maxLat, point[1]);
    minLng = min(minLng, point[0]);
    maxLng = max(maxLng, point[0]);
  }

  return lat >= minLat && lat <= maxLat && lng >= minLng && lng <= maxLng;
}

// Example usage:
void main() {
  var geofences = [
  [
    [
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.6875149558,
        -6.0994096811751
      ],
      [
        106.68991821508,
        -6.1454938899684
      ],
      [
        106.63266914586,
        -6.14924872414
      ],
      [
        106.6152455161,
        -6.1337171928233
      ],
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.62228363256,
        -6.1135767313781
      ],
      [
        106.62228363256,
        -6.1135767313781
      ]
    ]
  ],
  [
    [
      [
        106.60734909277,
        -6.0893549021962
      ],
      [
        106.65867584447,
        -6.0861117290764
      ],
      [
        106.61215561132,
        -6.1081307824039
      ],
      [
        106.60734909277,
        -6.0893549021962
      ]
    ]
  ],
  [
    [
      [
        106.64401556055,
        -6.1035327059797
      ],
      [
        106.66873479883,
        -6.1190651155563
      ],
      [
        106.63354421655,
        -6.1289646576213
      ],
      [
        106.62616277734,
        -6.1054102739414
      ],
      [
        106.64401556055,
        -6.1035327059797
      ]
    ]
  ]
];

  // Test some locations
  //-6.130824125494702, 106.64221594991493
  double currentLat = -6.130824125494702;
  double currentLng = 106.64221594991493;
  
  bool isInside = isInsideGeofences(geofences, currentLat, currentLng);
  print('Location is ${isInside ? "inside" : "outside"} the geofences');
}





//// raw response data
[
  {
    type: MultiPolygon,
    coordinates: [
      [
        [
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.6875149558,
            -6.0994096811751
          ],
          [
            106.68991821508,
            -6.1454938899684
          ],
          [
            106.63266914586,
            -6.14924872414
          ],
          [
            106.6152455161,
            -6.1337171928233
          ],
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.62228363256,
            -6.1135767313781
          ],
          [
            106.62228363256,
            -6.1135767313781
          ]
        ]
      ],
      [
        [
          [
            106.60734909277,
            -6.0893549021962
          ],
          [
            106.65867584447,
            -6.0861117290764
          ],
          [
            106.61215561132,
            -6.1081307824039
          ],
          [
            106.60734909277,
            -6.0893549021962
          ]
        ]
      ]
    ]
  },
  {
    type: MultiPolygon,
    coordinates: [
      [
        [
          [
            106.64401556055,
            -6.1035327059797
          ],
          [
            106.66873479883,
            -6.1190651155563
          ],
          [
            106.63354421655,
            -6.1289646576213
          ],
          [
            106.62616277734,
            -6.1054102739414
          ],
          [
            106.64401556055,
            -6.1035327059797
          ]
        ]
      ]
    ]
  }
]

class MultiPolygon {
  static merge(multiPolygons) {
    var mergedCoordinates = [];
    for (var polygon in multiPolygons) {
      if (polygon['type'] == 'MultiPolygon' &&
          polygon.containsKey('coordinates')) {
        for (var coordinatesGroup in polygon['coordinates']) {
          mergedCoordinates.addAll([coordinatesGroup]);
        }
      }
    }
    return mergedCoordinates;
  }

  /// Checks if a point is inside a specific polygon using Ray Casting algorithm
  static bool isInsideZones(dynamic geofences, double lat, double lng) {
    bool isPointInPolygon(double lat, double lng, List<List<double>> polygon) {
      if (polygon.length < 3) return false;

      bool isInside = false;
      int j = polygon.length - 1;

      for (int i = 0; i < polygon.length; i++) {
        double currentLat = polygon[i][1];
        double currentLng = polygon[i][0];
        double prevLat = polygon[j][1];
        double prevLng = polygon[j][0];

        if (((currentLat > lat) != (prevLat > lat)) &&
            (lng <
                (prevLng - currentLng) *
                        (lat - currentLat) /
                        (prevLat - currentLat) +
                    currentLng)) {
          isInside = !isInside;
        }
        j = i;
      }

      return isInside;
    }

    try {
      if (geofences == null) return false;
      List<List<List<List<double>>>> typedZones = [];

      if (geofences is List) {
        for (var zone in geofences) {
          if (zone is List && zone.isNotEmpty) {
            List<List<List<double>>> polygonGroup = [];
            for (var polygon in zone) {
              if (polygon is List) {
                List<List<double>> coordinates = [];
                for (var point in polygon) {
                  if (point is List && point.length >= 2) {
                    try {
                      double lng = double.parse(point[0].toString());
                      double lat = double.parse(point[1].toString());
                      coordinates.add([lng, lat]);
                    } catch (e) {
                      debugPrint('Error parsing coordinate: $e');
                      continue;
                    }
                  }
                }
                if (coordinates.isNotEmpty) {
                  polygonGroup.add(coordinates);
                }
              }
            }
            if (polygonGroup.isNotEmpty) {
              typedZones.add(polygonGroup);
            }
          }
        }
      }

      // Check each polygon in the zones
      for (var zoneGroup in typedZones) {
        for (var polygon in zoneGroup) {
          if (isPointInPolygon(lat, lng, polygon)) {
            return true;
          }
        }
      }

      return false;
    } catch (e) {
      debugPrint('Error checking zones: $e');
      return false;
    }
  }
}