Sort non-n6 spatial entries by ID, not by label (RPB-47)

Except for n6 itself, which is the first entry on the top level

app/controllers/nwbib/Classification.java

@@ -21,6 +21,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
+import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -117,7 +118,7 @@ public Pair<List<JsonNode>, Map<String, List<JsonNode>>> buildHierarchy() {
 					|| Play.isTest())) { /* SpatialToSkos uses Play test server */
 				addFromCsv(subClasses);
 			}
-			Collections.sort(topClasses, comparator);
+			Collections.sort(topClasses, comparator(Classification::idText));
 			return Pair.of(topClasses, subClasses);
 		}
 
@@ -154,7 +155,7 @@ private static void addFromCsv(
 		 */
 		public JsonNode buildRegister() {
 			final List<JsonNode> result = ids(classificationData()).stream()
-					.sorted(comparator).collect(Collectors.toList());
+					.sorted(comparator(Classification::labelText)).collect(Collectors.toList());
 			return Json.toJson(result);
 		}
 
@@ -188,14 +189,20 @@ private enum Label {
 	private static Node node;
 
 	/** Compare German strings */
-	public static Comparator<JsonNode> comparator =
-			(JsonNode o1, JsonNode o2) -> Collator.getInstance(Locale.GERMAN)
-					.compare(labelText(o1), labelText(o2));
+	public static Comparator<JsonNode> comparator(Function<JsonNode, String> fun) {
+		return (JsonNode o1, JsonNode o2) -> Collator.getInstance(Locale.GERMAN)
+				.compare(fun.apply(o1), fun.apply(o2));
+	}
 
 	private Classification() {
 		/* Use via static functions, no instantiation. */
 	}
 
+	private static String idText(JsonNode node) {
+		String[] segments = node.get("value").asText().split("#");
+		return segments[segments.length-1].replaceAll("^n6$", "n0");
+	}
+
 	/**
 	 * @param turtleUrl The URL of the RDF in TURTLE format
 	 * @return The input, converted to JSON-LD, or null
@@ -293,7 +300,7 @@ static List<JsonNode> ids(SearchResponse response) {
 		return result;
 	}
 
-	private static String labelText(JsonNode json) {
+	public static String labelText(JsonNode json) {
 		String label = json.get("label").asText();
 		if (label.contains("Stadtbezirk")) {
 			List<Pair<String, String>> roman = Arrays.asList(Pair.of("I", "a"),
@@ -346,7 +353,7 @@ public static Pair<List<JsonNode>, Map<String, List<JsonNode>>> buildHierarchyCs
 							subClasses.put(broaderId, new ArrayList<JsonNode>());
 						List<JsonNode> sub = subClasses.get(broaderId);
 						sub.add(Json.toJson(ImmutableMap.of("value", thisId, "label", vg + ", Verbandsgemeinde", "notation", thisNotation, "hits", hits)));
-						Collections.sort(sub, comparator);
+						Collections.sort(sub, comparator(Classification::labelText));
 						broader = thisNotation;
 					}
 				} 
@@ -359,13 +366,13 @@ public static Pair<List<JsonNode>, Map<String, List<JsonNode>>> buildHierarchyCs
 						subClasses.put(broaderId, new ArrayList<JsonNode>());
 					List<JsonNode> sub = subClasses.get(broaderId);
 					sub.add(Json.toJson(ImmutableMap.of("value", id, "label", label, "notation", notation, "hits", hits)));
-					Collections.sort(sub, comparator);
+					Collections.sort(sub, comparator(Classification::labelText));
 				}
 			}
 		} catch (IOException e) {
 			e.printStackTrace();
 		}
-		Collections.sort(topClasses, comparator);
+		Collections.sort(topClasses, comparator(Classification::labelText));
 		return Pair.of(topClasses, removeDuplicates(subClasses));
 	}
 
@@ -416,7 +423,9 @@ private static void addAsSubClass(Map<String, List<JsonNode>> subClasses,
 			subClasses.put(broader, new ArrayList<JsonNode>());
 		List<JsonNode> list = subClasses.get(broader);
 		list.addAll(valueAndLabelWithNotation(hit, json));
-		Collections.sort(list, comparator);
+		// non-n6 entries have 2-digit IDs or a second `n` -> sort by ID (RPB-47)
+		boolean sortById = idText(list.get(0)).matches("^n\\d{2}$|^n\\d+n\\d+$");
+		Collections.sort(list, comparator(sortById ? Classification::idText : Classification::labelText));
 	}
 
 	private static String focus(JsonNode json) {

test/tests/ApplicationTest.java

@@ -115,7 +115,7 @@ public void sortArabicNumerals() {
 				Json.newObject().put("label", "Stadtbezirk 8"),
 				Json.newObject().put("label", "Stadtbezirk 9"),
 				Json.newObject().put("label", "Stadtbezirk 10") };
-		Arrays.sort(in, Classification.comparator);
+		Arrays.sort(in, Classification.comparator(Classification::labelText));
 		Assert.assertArrayEquals(correct, in);
 	}
 
@@ -143,7 +143,7 @@ public void sortRomanNumerals() {
 				Json.newObject().put("label", "Stadtbezirk VIII"),
 				Json.newObject().put("label", "Stadtbezirk IX"),
 				Json.newObject().put("label", "Stadtbezirk X") };
-		Arrays.sort(in, Classification.comparator);
+		Arrays.sort(in, Classification.comparator(Classification::labelText));
 		Assert.assertArrayEquals(correct, in);
 	}