[GH-2830] Improve Geography query support - core

common/src/main/java/org/apache/sedona/common/S2Geography/Distance.java

@@ -24,6 +24,22 @@
 
 public class Distance {
 
+  /**
+   * Compute distance from a single point to a ShapeIndex using PointTarget. This avoids building a
+   * ShapeIndex for the point side — only the complex geometry needs an index.
+   */
+  public static double S2_distancePointToIndex(S2Point point, ShapeIndexGeography geo) {
+    S2ClosestEdgeQuery query = S2ClosestEdgeQuery.builder().build(geo.shapeIndex);
+    S2ClosestEdgeQuery.PointTarget<S1ChordAngle> target =
+        new S2ClosestEdgeQuery.PointTarget<>(point);
+    Optional<S2BestEdgesQueryBase.Result> result = query.findClosestEdge(target);
+    if (!result.isPresent()) {
+      return Double.POSITIVE_INFINITY;
+    }
+    S1ChordAngle chordAngle = (S1ChordAngle) result.get().distance();
+    return chordAngle.toAngle().radians();
+  }
+
   public double S2_distance(ShapeIndexGeography geo1, ShapeIndexGeography geo2) {
     S2ShapeIndex index1 = geo1.shapeIndex;
     S2ShapeIndex index2 = geo2.shapeIndex;

common/src/main/java/org/apache/sedona/common/S2Geography/GeographyWKBSerializer.java

@@ -0,0 +1,74 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.sedona.common.S2Geography;
+
+import java.io.IOException;
+import java.util.Arrays;
+import org.locationtech.jts.io.ByteOrderValues;
+
+/**
+ * Serializer for Geography objects using WKB as the primary format. Byte layout: [4-byte SRID
+ * big-endian][WKB payload].
+ */
+public class GeographyWKBSerializer {
+
+  /** Header size: 4 bytes SRID. */
+  private static final int HEADER_SIZE = 4;
+
+  /**
+   * Serialize a Geography to bytes using WKB format.
+   *
+   * @param geog the Geography to serialize
+   * @return byte array with format: [SRID 4 bytes big-endian][WKB payload]
+   */
+  public static byte[] serialize(Geography geog) throws IOException {
+    byte[] wkb;
+    if (geog instanceof WKBGeography) {
+      wkb = ((WKBGeography) geog).getWKBBytes();
+    } else {
+      WKBWriter writer = new WKBWriter(2, ByteOrderValues.BIG_ENDIAN, false);
+      wkb = writer.write(geog);
+    }
+
+    byte[] result = new byte[HEADER_SIZE + wkb.length];
+    int srid = geog.getSRID();
+    result[0] = (byte) (srid >> 24);
+    result[1] = (byte) (srid >> 16);
+    result[2] = (byte) (srid >> 8);
+    result[3] = (byte) srid;
+    System.arraycopy(wkb, 0, result, HEADER_SIZE, wkb.length);
+    return result;
+  }
+
+  /**
+   * Deserialize bytes to a Geography using the WKB format.
+   *
+   * @param buffer the byte array to deserialize
+   * @return the deserialized Geography
+   */
+  public static Geography deserialize(byte[] buffer) throws IOException {
+    int srid =
+        ((buffer[0] & 0xFF) << 24)
+            | ((buffer[1] & 0xFF) << 16)
+            | ((buffer[2] & 0xFF) << 8)
+            | (buffer[3] & 0xFF);
+    byte[] wkb = Arrays.copyOfRange(buffer, HEADER_SIZE, buffer.length);
+    return WKBGeography.fromWKB(wkb, srid);
+  }
+}