Fix NearFilter to support geodesic distance for geographic coordinates

nitrite-spatial/pom.xml

@@ -52,6 +52,11 @@
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
         </dependency>
+        <dependency>
+            <groupId>net.sf.geographiclib</groupId>
+            <artifactId>GeographicLib-Java</artifactId>
+            <version>2.0</version>
+        </dependency>
 
         <dependency>
             <groupId>junit</groupId>

nitrite-spatial/src/main/java/org/dizitart/no2/spatial/GeoNearFilter.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2017-2020. Nitrite author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.dizitart.no2.spatial;
+
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.util.GeometricShapeFactory;
+
+/**
+ * Spatial filter for finding geometries near a geographic point,
+ * using geodesic distance on Earth's surface (WGS84 ellipsoid).
+ * 
+ * <p>This filter is specifically designed for geographic coordinates (lat/long).
+ * It always uses geodesic distance calculations, eliminating the ambiguity
+ * of {@link NearFilter}'s auto-detection.</p>
+ * 
+ * <p><strong>Usage Example:</strong></p>
+ * <pre>{@code
+ * GeoPoint center = new GeoPoint(45.0, -93.2650); // Minneapolis
+ * collection.find(where("location").geoNear(center, 5000.0)); // 5km radius
+ * }</pre>
+ * 
+ * <p><strong>Distance Units:</strong> The distance parameter must be in meters.</p>
+ * 
+ * <p><strong>Accuracy Note:</strong> This filter uses a bounding box approximation
+ * for the R-tree index search, which may return some false positives (points
+ * slightly outside the geodesic circle but within its bounding box). A future
+ * enhancement will add two-pass filtering for exact results.</p>
+ * 
+ * @since 4.3.3
+ * @author Anindya Chatterjee
+ * @see GeoPoint
+ * @see NearFilter
+ */
+class GeoNearFilter extends WithinFilter {
+
+    /**
+     * Creates a filter to find geometries near a GeoPoint.
+     * 
+     * @param field the field to filter on
+     * @param point the geographic point to check proximity to
+     * @param distanceMeters the maximum distance in meters
+     */
+    GeoNearFilter(String field, GeoPoint point, Double distanceMeters) {
+        super(field, createGeodesicCircle(point.getCoordinate(), distanceMeters));
+    }
+
+    /**
+     * Creates a filter to find geometries near a coordinate.
+     * The coordinate is validated to ensure it represents a valid geographic point.
+     * 
+     * @param field the field to filter on
+     * @param point the coordinate to check proximity to (x=longitude, y=latitude)
+     * @param distanceMeters the maximum distance in meters
+     * @throws IllegalArgumentException if coordinates are not valid geographic coordinates
+     */
+    GeoNearFilter(String field, Coordinate point, Double distanceMeters) {
+        super(field, createGeodesicCircle(validateAndGetCoordinate(point), distanceMeters));
+    }
+
+    private static Coordinate validateAndGetCoordinate(Coordinate coord) {
+        double lat = coord.getY();
+        double lon = coord.getX();
+
+        if (lat < -90.0 || lat > 90.0) {
+            throw new IllegalArgumentException(
+                "GeoNearFilter requires valid latitude (-90 to 90), got: " + lat);
+        }
+        if (lon < -180.0 || lon > 180.0) {
+            throw new IllegalArgumentException(
+                "GeoNearFilter requires valid longitude (-180 to 180), got: " + lon);
+        }
+
+        return coord;
+    }
+
+    private static Geometry createGeodesicCircle(Coordinate center, double radiusMeters) {
+        GeometricShapeFactory shapeFactory = new GeometricShapeFactory();
+        shapeFactory.setNumPoints(64);
+        shapeFactory.setCentre(center);
+
+        // Always use geodesic calculations for GeoNearFilter
+        double radiusInDegrees = GeodesicUtils.metersToDegreesRadius(center, radiusMeters);
+        shapeFactory.setSize(radiusInDegrees * 2);
+        return shapeFactory.createCircle();
+    }
+
+    @Override
+    public String toString() {
+        return "(" + getField() + " geoNear " + getValue() + ")";
+    }
+}

nitrite-spatial/src/main/java/org/dizitart/no2/spatial/GeoPoint.java

@@ -0,0 +1,148 @@
+/*
+ * Copyright (c) 2017-2020. Nitrite author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.dizitart.no2.spatial;
+
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.GeometryFactory;
+import org.locationtech.jts.geom.Point;
+import org.locationtech.jts.geom.PrecisionModel;
+
+import java.io.Serializable;
+
+/**
+ * Represents a geographic point with latitude and longitude coordinates
+ * on Earth's surface (WGS84 ellipsoid).
+ * 
+ * <p>This class provides explicit type safety for geographic coordinates,
+ * eliminating the ambiguity of auto-detection. It validates coordinates
+ * on construction and provides clear latitude/longitude accessors.</p>
+ * 
+ * <p><strong>Usage Example:</strong></p>
+ * <pre>{@code
+ * // Create a geographic point for Minneapolis
+ * GeoPoint minneapolis = new GeoPoint(45.0, -93.2650);
+ * 
+ * // Use with GeoNearFilter
+ * collection.find(where("location").geoNear(minneapolis, 5000.0));
+ * }</pre>
+ * 
+ * <p><strong>Coordinate Order:</strong> Constructor takes (latitude, longitude)
+ * which differs from JTS Point (x, y) = (longitude, latitude) to avoid confusion.</p>
+ *
+ * @since 4.3.3
+ * @author Anindya Chatterjee
+ */
+public class GeoPoint implements Serializable {
+    private static final long serialVersionUID = 1L;
+    private static final GeometryFactory FACTORY = new GeometryFactory(new PrecisionModel(), 4326);
+    private final Point point;
+    private final double latitude;
+    private final double longitude;
+
+    /**
+     * Creates a new GeoPoint with the specified geographic coordinates.
+     * 
+     * @param latitude the latitude in degrees (-90 to 90)
+     * @param longitude the longitude in degrees (-180 to 180)
+     * @throws IllegalArgumentException if coordinates are out of valid range
+     */
+    public GeoPoint(double latitude, double longitude) {
+        validateCoordinates(latitude, longitude);
+        this.latitude = latitude;
+        this.longitude = longitude;
+        this.point = FACTORY.createPoint(new Coordinate(longitude, latitude));
+    }
+
+    /**
+     * Creates a GeoPoint from a JTS Coordinate.
+     * The coordinate's Y value is treated as latitude and X as longitude.
+     * 
+     * @param coordinate the coordinate (x=longitude, y=latitude)
+     * @throws IllegalArgumentException if coordinates are out of valid range
+     */
+    public GeoPoint(Coordinate coordinate) {
+        this(coordinate.getY(), coordinate.getX());
+    }
+
+    private void validateCoordinates(double latitude, double longitude) {
+        if (latitude < -90.0 || latitude > 90.0) {
+            throw new IllegalArgumentException(
+                "Latitude must be between -90 and 90 degrees, got: " + latitude);
+        }
+        if (longitude < -180.0 || longitude > 180.0) {
+            throw new IllegalArgumentException(
+                "Longitude must be between -180 and 180 degrees, got: " + longitude);
+        }
+    }
+
+    /**
+     * Gets the latitude in degrees.
+     * 
+     * @return the latitude (-90 to 90)
+     */
+    public double getLatitude() {
+        return latitude;
+    }
+
+    /**
+     * Gets the longitude in degrees.
+     * 
+     * @return the longitude (-180 to 180)
+     */
+    public double getLongitude() {
+        return longitude;
+    }
+
+    /**
+     * Gets the underlying JTS Point.
+     * 
+     * @return the JTS Point representation
+     */
+    public Point getPoint() {
+        return point;
+    }
+
+    /**
+     * Gets the coordinate of this GeoPoint.
+     * 
+     * @return the coordinate (x=longitude, y=latitude)
+     */
+    public Coordinate getCoordinate() {
+        return point.getCoordinate();
+    }
+
+    @Override
+    public String toString() {
+        return String.format("GeoPoint(lat=%.6f, lon=%.6f)", latitude, longitude);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        GeoPoint other = (GeoPoint) obj;
+        return Double.compare(latitude, other.latitude) == 0 
+            && Double.compare(longitude, other.longitude) == 0;
+    }
+
+    @Override
+    public int hashCode() {
+        long latBits = Double.doubleToLongBits(latitude);
+        long lonBits = Double.doubleToLongBits(longitude);
+        return (int) (latBits ^ (latBits >>> 32) ^ lonBits ^ (lonBits >>> 32));
+    }
+}

nitrite-spatial/src/main/java/org/dizitart/no2/spatial/GeodesicUtils.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2017-2020. Nitrite author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.dizitart.no2.spatial;
+
+import net.sf.geographiclib.Geodesic;
+import net.sf.geographiclib.GeodesicData;
+import org.locationtech.jts.geom.Coordinate;
+
+/**
+ * Utility class for geodesic distance calculations on Earth's surface.
+ * This class handles the conversion between meters and degrees of latitude/longitude,
+ * accounting for the curvature of the Earth using the WGS84 ellipsoid model.
+ * 
+ * <p>This class is used internally by {@link NearFilter} for backward compatibility
+ * with auto-detection. For new code, use {@link GeoPoint} and {@link GeoNearFilter}
+ * for explicit geographic coordinate handling.</p>
+ *
+ * @since 4.0
+ * @author Anindya Chatterjee
+ */
+class GeodesicUtils {
+    private static final Geodesic WGS84 = Geodesic.WGS84;
+
+    /**
+     * Determines if coordinates appear to be geographic (lat/long) rather than Cartesian.
+     * This is a heuristic check based on valid lat/long ranges:
+     * - Latitude: -90 to 90
+     * - Longitude: -180 to 180
+     * 
+     * <p><strong>Limitation:</strong> This heuristic may incorrectly classify Cartesian 
+     * coordinates that happen to fall within ±90°/±180° range (e.g., game world coordinates).</p>
+     * 
+     * <p><strong>Recommendation:</strong> For new code, use {@link GeoPoint} and 
+     * {@link GeoNearFilter} to explicitly indicate geographic coordinates and avoid 
+     * auto-detection ambiguity.</p>
+     *
+     * @param center the coordinate to check
+     * @return true if the coordinate appears to be geographic, false otherwise
+     */
+    static boolean isGeographic(Coordinate center) {
+        double x = center.getX();
+        double y = center.getY();
+
+        // Check if coordinates fall within valid lat/long ranges
+        // We use slightly relaxed bounds to be conservative
+        return Math.abs(y) <= 90.0 && Math.abs(x) <= 180.0;
+    }
+
+    /**
+     * Calculates the approximate radius in degrees for a given distance in meters
+     * at a specific geographic coordinate. This accounts for the fact that one degree
+     * of longitude varies with latitude.
+     * 
+     * <p>This method calculates geodesic distances in both E-W and N-S directions and 
+     * returns the maximum to ensure complete circular coverage. Combined with the 
+     * two-pass query execution in {@link SpatialIndex}, this provides accurate results 
+     * while maintaining performance.</p>
+     *
+     * @param center the center coordinate (longitude, latitude)
+     * @param radiusMeters the radius in meters
+     * @return the approximate radius in degrees
+     */
+    static double metersToDegreesRadius(Coordinate center, double radiusMeters) {
+        double lat = center.getY();
+        double lon = center.getX();
+
+        // Calculate how many degrees we need to go in different directions
+        // to cover the specified radius in meters
+
+        // East-West: Calculate a point at the given distance east
+        GeodesicData eastPoint = WGS84.Direct(lat, lon, 90.0, radiusMeters);
+        double lonDiff = Math.abs(eastPoint.lon2 - lon);
+
+        // North-South: Calculate a point at the given distance north
+        GeodesicData northPoint = WGS84.Direct(lat, lon, 0.0, radiusMeters);
+        double latDiff = Math.abs(northPoint.lat2 - lat);
+
+        // Use the maximum of the two to ensure we cover the full circle
+        // This creates a slightly larger search area but ensures we don't miss points
+        return Math.max(lonDiff, latDiff);
+    }
+}