add shape-type metadata to geo_shape's doc-value

This commit serializes the ShapeType of the indexed
geometry. The ShapeType can be useful for other future
features. For one thing: elastic#49887 depends on the ability
to determine what the highest dimensional shape is
for centroid calculations.

GeometryCollection is reduced to the sub-shape of the
higest dimension

relates elastic#37206.

Author: talevy

libs/geo/src/main/java/org/elasticsearch/geometry/ShapeType.java

@@ -36,6 +36,11 @@ public enum ShapeType {
     ENVELOPE, // not part of the actual WKB spec
     CIRCLE; // not part of the actual WKB spec
 
+    private static ShapeType[] values = values();
+
+    public static ShapeType forOrdinal(int ordinal) {
+        return values[ordinal];
+    }
     public static ShapeType forName(String shapeName) {
         return ShapeType.valueOf(shapeName.toUpperCase(Locale.ROOT));
     }

server/src/main/java/org/elasticsearch/common/geo/TriangleTreeReader.java

@@ -20,6 +20,7 @@
 
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.io.stream.ByteBufferStreamInput;
+import org.elasticsearch.geometry.ShapeType;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -34,8 +35,8 @@
  * relations against the serialized triangle tree.
  */
 public class TriangleTreeReader {
+    private static final int SKIP_CENTROID = 8;
 
-    private final int extentOffset = 8;
     private ByteBufferStreamInput input;
     private final CoordinateEncoder coordinateEncoder;
     private final Rectangle2D rectangle2D;
@@ -58,7 +59,9 @@ public void reset(BytesRef bytesRef) throws IOException {
      */
     public Extent getExtent() throws IOException {
         if (treeOffset == 0) {
-            input.position(extentOffset);
+            input.position(SKIP_CENTROID);
+            input.readVInt(); // skip ShapeType
+
             int top = input.readInt();
             int bottom = Math.toIntExact(top - input.readVLong());
             int posRight = input.readInt();
@@ -89,6 +92,11 @@ public double getCentroidY() throws IOException {
         return coordinateEncoder.decodeY(input.readInt());
     }
 
+    public ShapeType getShapeType() throws IOException {
+        input.position(SKIP_CENTROID);
+        return ShapeType.forOrdinal(input.readVInt());
+    }
+
     /**
      * Compute the relation with the provided bounding box. If the result is CELL_INSIDE_QUERY
      * then the bounding box is within the shape.

server/src/main/java/org/elasticsearch/common/geo/TriangleTreeWriter.java

@@ -71,6 +71,7 @@ public TriangleTreeWriter(Geometry geometry, CoordinateEncoder coordinateEncoder
     public void writeTo(StreamOutput out) throws IOException {
         out.writeInt(coordinateEncoder.encodeX(centroidCalculator.getX()));
         out.writeInt(coordinateEncoder.encodeY(centroidCalculator.getY()));
+        out.writeEnum(type);
         out.writeInt(extent.top);
         out.writeVLong((long) extent.top - extent.bottom);
         out.writeInt(extent.posRight);

server/src/main/java/org/elasticsearch/index/fielddata/MultiGeoValues.java

@@ -29,6 +29,7 @@
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.geometry.Geometry;
 import org.elasticsearch.geometry.Rectangle;
+import org.elasticsearch.geometry.ShapeType;
 import org.elasticsearch.geometry.utils.GeographyValidator;
 import org.elasticsearch.geometry.utils.WellKnownText;
 import org.elasticsearch.search.aggregations.support.ValuesSourceType;
@@ -107,6 +108,11 @@ public GeoRelation relate(Rectangle rectangle) {
             return GeoRelation.QUERY_DISJOINT;
         }
 
+        @Override
+        public ShapeType shapeType() {
+            return ShapeType.POINT;
+        }
+
         @Override
         public double lat() {
             return geoPoint.lat();
@@ -157,6 +163,15 @@ public GeoRelation relate(Rectangle rectangle) {
             }
         }
 
+        @Override
+        public ShapeType shapeType() {
+            try {
+                return reader.getShapeType();
+            } catch (IOException e) {
+                throw new IllegalStateException("unable to reach ShapeType", e);
+            }
+        }
+
         @Override
         public double lat() {
             try {
@@ -202,6 +217,7 @@ public interface GeoValue {
         double lon();
         BoundingBox boundingBox();
         GeoRelation relate(Rectangle rectangle);
+        ShapeType shapeType();
     }
 
     public static class BoundingBox {

server/src/test/java/org/elasticsearch/common/geo/TriangleTreeTests.java

@@ -18,6 +18,7 @@
  */
 package org.elasticsearch.common.geo;
 
+import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.geo.GeometryTestUtils;
 import org.elasticsearch.geometry.Geometry;
 import org.elasticsearch.geometry.GeometryCollection;
@@ -46,6 +47,21 @@
 
 public class TriangleTreeTests extends ESTestCase {
 
+    public void testShapeType() throws IOException {
+        Geometry geometry = randomGeometryTreeGeometry();
+        TriangleTreeWriter writer = new TriangleTreeWriter(geometry, GeoShapeCoordinateEncoder.INSTANCE);
+        assertThat(writer.getShapeType(), equalTo(geometry.type()));
+
+        BytesStreamOutput output = new BytesStreamOutput();
+        writer.writeTo(output);
+        output.close();
+
+        TriangleTreeReader reader = new TriangleTreeReader(GeoShapeCoordinateEncoder.INSTANCE);
+        reader.reset(output.bytes().toBytesRef());
+
+        assertThat(reader.getShapeType(), equalTo(geometry.type()));
+    }
+
     public void testRectangleShape() throws IOException {
         for (int i = 0; i < 1000; i++) {
             int minX = randomIntBetween(-80, 70);