Experimental feature to merge multiple OSM layers together

src/main/java/org/neo4j/gis/spatial/AbstractGeometryEncoder.java

@@ -29,11 +29,10 @@
 public abstract class AbstractGeometryEncoder implements GeometryEncoder, Constants {
 
 	protected String bboxProperty = PROP_BBOX;
-
-	// Public methods
+	protected Layer layer;
 
 	@Override
-	public void init(Layer layer) {
+	public void init(Transaction tx, Layer layer) {
 		this.layer = layer;
 	}
 
@@ -116,8 +115,4 @@ public Object getAttribute(Node geomNode, String name) {
 	public String getSignature() {
 		return "GeometryEncoder(bbox='" + bboxProperty + "')";
 	}
-
-	// Attributes
-
-	protected Layer layer;
 }

src/main/java/org/neo4j/gis/spatial/DefaultLayer.java

@@ -40,6 +40,7 @@
 import org.neo4j.gis.spatial.rtree.filter.SearchFilter;
 import org.neo4j.gis.spatial.utilities.GeotoolsAdapter;
 import org.neo4j.graphdb.Node;
+import org.neo4j.graphdb.Relationship;
 import org.neo4j.graphdb.Transaction;
 
 /**
@@ -55,7 +56,12 @@
  */
 public class DefaultLayer implements Constants, Layer, SpatialDataset {
 
-	// Public methods
+	private String name;
+	protected String layerNodeId;
+	private GeometryEncoder geometryEncoder;
+	private GeometryFactory geometryFactory;
+	protected LayerIndexReader indexReader;
+	protected SpatialIndexWriter indexWriter;
 
 	@Override
 	public String getName() {
@@ -231,7 +237,7 @@ public void initialize(Transaction tx, IndexManager indexManager, String name, N
 		} else {
 			this.geometryEncoder = new WKBGeometryEncoder();
 		}
-		this.geometryEncoder.init(this);
+		this.geometryEncoder.init(tx, this);
 
 		// index must be created *after* geometryEncoder
 		if (layerNode.hasProperty(PROP_INDEX_CLASS)) {
@@ -273,6 +279,10 @@ public Node getLayerNode(Transaction tx) {
 	public void delete(Transaction tx, Listener monitor) {
 		indexWriter.removeAll(tx, true, monitor);
 		Node layerNode = getLayerNode(tx);
+		for (Relationship rel : layerNode.getRelationships()) {
+			System.out.printf("Unexpected relationship in layer %s: %s%n", getName(), rel);
+			rel.delete();
+		}
 		layerNode.delete();
 		layerNodeId = null;
 	}
@@ -283,15 +293,6 @@ public void delete(Transaction tx, Listener monitor) {
 //        return spatialDatabase.getDatabase();
 //    }
 
-	// Attributes
-
-	//private SpatialDatabaseService spatialDatabase;
-	private String name;
-	protected String layerNodeId = null;
-	private GeometryEncoder geometryEncoder;
-	private GeometryFactory geometryFactory;
-	protected LayerIndexReader indexReader;
-	protected SpatialIndexWriter indexWriter;
 
 	@Override
 	public SpatialDataset getDataset() {

src/main/java/org/neo4j/gis/spatial/GeometryEncoder.java

@@ -53,10 +53,8 @@ public interface GeometryEncoder extends EnvelopeDecoder {
 	 * that represents a layer. This node is expected to have a property containing the class name
 	 * of the GeometryEncoder for that layer, and it will be constructed and passed the layer using
 	 * this method, allowing the Layer and the GeometryEncoder to interact.
-	 *
-	 * @param layer recently created Layer class
 	 */
-	void init(Layer layer);
+	void init(Transaction tx, Layer layer);
 
 	/**
 	 * This method is called to store a bounding box for the geometry to the database. It should write it to the

src/main/java/org/neo4j/gis/spatial/SpatialTopologyUtils.java

@@ -152,7 +152,7 @@ public static List<PointResult> findClosestEdges(Transaction tx, Point point, La
 	 * @see <a
 	 * href="https://download.oracle.com/docs/cd/B13789_01/appdev.101/b10826/sdo_lrs_ref.htm#i85478">SDO_LRS.LOCATE_PT</a>
 	 * @see <a
-	 * href="https://www.vividsolutions.com/jts/javadoc/com/vividsolutions/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
+	 * href="https://locationtech.github.io/jts/javadoc/org/locationtech/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
 	 */
 	public static Point locatePoint(Layer layer, Geometry geometry, double measure) {
 		return layer.getGeometryFactory().createPoint(locatePoint(geometry, measure));
@@ -171,7 +171,7 @@ public static Point locatePoint(Layer layer, Geometry geometry, double measure)
 	 * @see <a
 	 * href="https://download.oracle.com/docs/cd/B13789_01/appdev.101/b10826/sdo_lrs_ref.htm#i85478">SDO_LRS.LOCATE_PT</a>
 	 * @see <a
-	 * href="https://www.vividsolutions.com/jts/javadoc/com/vividsolutions/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
+	 * href="https://locationtech.github.io/jts/javadoc/org/locationtech/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
 	 */
 	public static Coordinate locatePoint(Geometry geometry, double measure) {
 		return new LengthIndexedLine(geometry).extractPoint(measure);
@@ -194,7 +194,7 @@ public static Coordinate locatePoint(Geometry geometry, double measure) {
 	 * @see <a
 	 * href="https://download.oracle.com/docs/cd/B13789_01/appdev.101/b10826/sdo_lrs_ref.htm#i85478">SDO_LRS.LOCATE_PT</a>
 	 * @see <a
-	 * href="https://www.vividsolutions.com/jts/javadoc/com/vividsolutions/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
+	 * href="https://locationtech.github.io/jts/javadoc/org/locationtech/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
 	 */
 	public static Point locatePoint(Layer layer, Geometry geometry, double measure, double offset) {
 		return layer.getGeometryFactory().createPoint(locatePoint(geometry, measure, offset));
@@ -215,7 +215,7 @@ public static Point locatePoint(Layer layer, Geometry geometry, double measure,
 	 * @see <a
 	 * href="https://download.oracle.com/docs/cd/B13789_01/appdev.101/b10826/sdo_lrs_ref.htm#i85478">SDO_LRS.LOCATE_PT</a>
 	 * @see <a
-	 * href="https://www.vividsolutions.com/jts/javadoc/com/vividsolutions/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
+	 * href="https://locationtech.github.io/jts/javadoc/org/locationtech/jts/linearref/LengthIndexedLine.html">LengthIndexedLine</a>
 	 */
 	public static Coordinate locatePoint(Geometry geometry, double measure, double offset) {
 		return new LengthIndexedLine(geometry).extractPoint(measure, offset);

src/main/java/org/neo4j/gis/spatial/merge/MergeUtils.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [http://neo4j.com]
+ *
+ * This file is part of Neo4j Spatial.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.gis.spatial.merge;
+
+import java.util.ArrayList;
+import org.locationtech.jts.geom.Geometry;
+import org.neo4j.gis.spatial.EditableLayer;
+import org.neo4j.gis.spatial.GeometryEncoder;
+import org.neo4j.gis.spatial.encoders.Configurable;
+import org.neo4j.graphdb.Node;
+import org.neo4j.graphdb.Transaction;
+
+public class MergeUtils {
+
+	public interface Mergeable {
+
+		long mergeFrom(Transaction tx, EditableLayer other);
+	}
+
+	private static boolean encodersIdentical(EditableLayer layer, EditableLayer mergeLayer) {
+		GeometryEncoder layerEncoder = layer.getGeometryEncoder();
+		GeometryEncoder mergeEncoder = mergeLayer.getGeometryEncoder();
+		Class<? extends GeometryEncoder> layerGeometryClass = layerEncoder.getClass();
+		Class<? extends GeometryEncoder> mergeGeometryClass = mergeEncoder.getClass();
+		if (layerGeometryClass.isAssignableFrom(mergeGeometryClass)) {
+			if (mergeEncoder instanceof Configurable && layerEncoder instanceof Configurable) {
+				String mergeConfig = ((Configurable) mergeEncoder).getConfiguration();
+				String layerConfig = ((Configurable) layerEncoder).getConfiguration();
+				return mergeConfig.equals(layerConfig);
+			} else {
+				// If one is configurable, but not the other, they are not identical
+				return !(mergeEncoder instanceof Configurable || layerEncoder instanceof Configurable);
+			}
+		}
+		return false;
+	}
+
+	public static long mergeLayerInto(Transaction tx, EditableLayer layer, EditableLayer mergeLayer) {
+		long count;
+		Class<? extends EditableLayer> layerClass = layer.getClass();
+		Class<? extends EditableLayer> mergeClass = mergeLayer.getClass();
+		if (layer instanceof Mergeable) {
+			count = ((Mergeable) layer).mergeFrom(tx, mergeLayer);
+		} else if (layerClass.isAssignableFrom(mergeClass)) {
+			if (encodersIdentical(layer, mergeLayer)) {
+				// With identical encoders, we can simply add the node as is, but must remove it first
+				ArrayList<Node> toAdd = new ArrayList<>();
+				for (Node node : mergeLayer.getIndex().getAllIndexedNodes(tx)) {
+					toAdd.add(node);
+				}
+				for (Node node : toAdd) {
+					// Remove each from the previous index before adding to the new index, so as not to have multiple incoming RTREE_REFERENCE
+					mergeLayer.removeFromIndex(tx, node.getElementId());
+					layer.add(tx, node);
+				}
+				count = toAdd.size();
+			} else {
+				// With differing encoders, we must decode and re-encode each geometry, so we also create new nodes and remove and delete the actual nodes later
+				ArrayList<Node> toRemove = new ArrayList<>();
+				GeometryEncoder fromEncoder = mergeLayer.getGeometryEncoder();
+				for (Node node : mergeLayer.getIndex().getAllIndexedNodes(tx)) {
+					toRemove.add(node);
+					Geometry geometry = fromEncoder.decodeGeometry(node);
+					layer.add(tx, geometry);
+				}
+				for (Node remove : toRemove) {
+					mergeLayer.removeFromIndex(tx, remove.getElementId());
+					remove.delete();
+				}
+				count = toRemove.size();
+			}
+		} else {
+			throw new IllegalArgumentException(String.format(
+					"Cannot merge '%s' into '%s': layer classes are not compatible: '%s' cannot be caste as '%s'",
+					mergeLayer.getName(), layer.getName(), mergeClass.getSimpleName(), layerClass.getSimpleName()));
+		}
+		return count;
+	}
+}