Replace sorting by distance with scoring by distance (#280)

app/controllers/Application.java

@@ -17,6 +17,8 @@
 import org.elasticsearch.index.query.GeoPolygonQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryBuilders;
+import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilder;
+import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilders;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.aggregations.AggregationBuilders;
 import org.elasticsearch.search.aggregations.metrics.tophits.TopHitsBuilder;
@@ -308,22 +310,29 @@ private static String buildDistanceQuery(String q, int from, int size,
 	}
 
 	static SearchResponse executeQuery(int from, int size, QueryBuilder query) {
-		SearchRequestBuilder searchRequest =
-				Index.CLIENT.prepareSearch(ES_NAME).setTypes(ES_TYPE)//
-						.setSearchType(SearchType.QUERY_THEN_FETCH).setQuery(query)//
-						.setFrom(from)//
-						.setSize(size);
+		SearchRequestBuilder searchRequest = Index.CLIENT.prepareSearch(ES_NAME)
+				.setTypes(ES_TYPE).setSearchType(SearchType.QUERY_THEN_FETCH)
+				.setQuery(preprocess(query)).setFrom(from).setSize(size);
 		searchRequest = withAggregations(searchRequest, "type.raw",
 				localizedLabel("classification.label.raw"),
 				localizedLabel("fundertype.label.raw"),
 				localizedLabel("collects.extent.label.raw"));
+		return searchRequest.execute().actionGet();
+	}
+
+	private static QueryBuilder preprocess(QueryBuilder query) {
 		String position = session("position");
 		if (position != null) {
 			Logger.info("Sorting by distance to current position {}", position);
-			searchRequest.addSort(new GeoDistanceSortBuilder("location.geo")
-					.points(new GeoPoint(position)));
+			ScoreFunctionBuilder locationScore = ScoreFunctionBuilders
+					.linearDecayFunction("location.geo", new GeoPoint(position), "3km")
+					.setOffset("0km");
+			return QueryBuilders.functionScoreQuery(query).boostMode("sum")
+					.add(QueryBuilders.existsQuery("location.geo"), locationScore)
+					.add(ScoreFunctionBuilders.scriptFunction(new Script("zero")))
+					.scoreMode("first");
 		}
-		return searchRequest.execute().actionGet();
+		return query;
 	}
 
 	private static SearchRequestBuilder withAggregations(

app/controllers/Index.java

@@ -60,11 +60,10 @@ public ConfigurableNode(Settings settings,
 							Application.CONFIG.getString("index.es.port.tcp"))
 					.put("script.default_lang", "native").build();
 
-	private static Node node =
-			new ConfigurableNode(
-					nodeBuilder().settings(clientSettings).local(true).getSettings()
-							.build(),
-					Arrays.asList(BundlePlugin.class, LocationAggregation.class)).start();
+	private static Node node = new ConfigurableNode(
+			nodeBuilder().settings(clientSettings).local(true).getSettings().build(),
+			Arrays.asList(BundlePlugin.class, LocationAggregation.class, Zero.class))
+					.start();
 	/**
 	 * The Elasticsearch client to be used by all parts of the application
 	 */

app/controllers/Zero.java

@@ -0,0 +1,78 @@
+/* Copyright 2016, hbz. Licensed under the Eclipse Public License 1.0 */
+
+package controllers;
+
+import java.util.Map;
+
+import javax.annotation.Nullable;
+
+import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.script.AbstractSearchScript;
+import org.elasticsearch.script.ExecutableScript;
+import org.elasticsearch.script.NativeScriptFactory;
+import org.elasticsearch.script.ScriptModule;
+
+/**
+ * Native script plugin to return 0.
+ * 
+ * Yes, this seems completely nuts. Let me explain: <br/>
+ * 
+ * We need a script that simply returns 0 as a workaround for location scoring,
+ * see: <br/>
+ * 
+ * https://github.com/elastic/elasticsearch/issues/7788#issuecomment-57196342
+ * https://github.com/elastic/elasticsearch/issues/18892#issuecomment-226544977
+ * <br/>
+ * 
+ * With Groovy scripting this would be straight-forward, but we run in embedded
+ * mode and use native scripting for security reasons, see: <br/>
+ * 
+ * https://github.com/hbz/lobid-organisations/commit/acefce9ba980f2f955c79da71e3ccc8068489d56
+ * https://github.com/hbz/lobid-organisations/commit/1027537db9b26911d7294532d4f1ae44244205ce
+ * <br/>
+ * 
+ * So we have a full native script for this very simple functionality.
+ * 
+ * @author Fabian Steeg (fsteeg)
+ * 
+ */
+public class Zero extends Plugin {
+	@Override
+	public String name() {
+		return "zero";
+	}
+
+	@Override
+	public String description() {
+		return "Native script to return 0";
+	}
+
+	/**
+	 * @param scriptModule The scriptModule to register this script on
+	 */
+	public void onModule(ScriptModule scriptModule) {
+		scriptModule.registerScript(name(), ZeroScriptFactory.class);
+	}
+
+	/** Factory to construct the script. */
+	public static class ZeroScriptFactory implements NativeScriptFactory {
+		@Override
+		public ExecutableScript newScript(@Nullable Map<String, Object> params) {
+			return new ZeroScript();
+		}
+
+		@Override
+		public boolean needsScores() {
+			return false;
+		}
+	}
+
+	/** The actual script. */
+	public static class ZeroScript extends AbstractSearchScript {
+
+		@Override
+		public Object run() {
+			return 0;
+		}
+	}
+}