fix(hubble): distinguish unstyled vertex labels with stable colors

hugegraph-hubble/hubble-be/src/main/java/org/apache/hugegraph/service/schema/VertexLabelService.java

@@ -63,6 +63,11 @@
 @Service
 public class VertexLabelService extends SchemaService {
 
+    private static final List<String> DEFAULT_LABEL_COLORS = List.of(
+            "#5C73E6", "#16817D", "#408AC9", "#9C67BD",
+            "#B57A43", "#B07724", "#DC667B", "#6D9953",
+            "#4F9DB5", "#785FC1", "#C46E4A", "#8D8550");
+
     @Autowired
     private PropertyKeyService pkService;
     @Autowired
@@ -352,7 +357,11 @@ private static VertexLabelStyle getStyle(SchemaElement element) {
         if (styleValue != null) {
             return JsonUtil.fromJson(styleValue, VertexLabelStyle.class);
         } else {
-            return new VertexLabelStyle();
+            VertexLabelStyle style = new VertexLabelStyle();
+            int colorIndex = Math.floorMod(element.name().hashCode(),
+                                          DEFAULT_LABEL_COLORS.size());
+            style.setColor(DEFAULT_LABEL_COLORS.get(colorIndex));
+            return style;
         }
     }
 

hugegraph-hubble/hubble-be/src/test/java/org/apache/hugegraph/unit/UnitTestSuite.java

@@ -137,6 +137,7 @@
     UrlUtilTest.class,
     UserCsvImportTest.class,
     EntityUtilTest.class,
+    VertexLabelStyleDefaultsTest.class,
     org.apache.hugegraph.util.HubbleDateTimeTest.class,
     HubbleUtilTest.class,
     DirectVermeerServiceTest.class,

hugegraph-hubble/hubble-be/src/test/java/org/apache/hugegraph/unit/VertexLabelStyleDefaultsTest.java

@@ -0,0 +1,129 @@
+/*
+ *
+ * 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.hugegraph.unit;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import org.apache.hugegraph.driver.HugeClient;
+import org.apache.hugegraph.driver.SchemaManager;
+import org.apache.hugegraph.entity.schema.VertexLabelEntity;
+import org.apache.hugegraph.entity.schema.VertexLabelStyle;
+import org.apache.hugegraph.service.schema.SchemaService;
+import org.apache.hugegraph.service.schema.VertexLabelService;
+import org.apache.hugegraph.structure.schema.VertexLabel;
+import org.apache.hugegraph.util.JsonUtil;
+
+public class VertexLabelStyleDefaultsTest {
+
+    @Test
+    public void testUnstyledLabelsHaveStableColorsAcrossReadOrder() {
+        VertexLabel person = label("Person");
+        VertexLabel team = label("Team");
+        VertexLabel project = label("Project");
+        HugeClient client = client(person, team, project);
+        Mockito.when(client.schema().getVertexLabels())
+               .thenReturn(List.of(person, team, project),
+                           List.of(project, person, team));
+
+        Map<String, String> first = colors(new VertexLabelService().list(client));
+        Map<String, String> reordered = colors(new VertexLabelService().list(client));
+
+        Assert.assertEquals(3, new HashSet<>(first.values()).size());
+        Assert.assertEquals(first, reordered);
+        first.forEach((name, color) -> {
+            Assert.assertTrue(color.matches("#[0-9A-Fa-f]{6}"));
+            Assert.assertEquals(color, new VertexLabelService().get(name, client)
+                                                              .getStyle().getColor());
+        });
+        for (VertexLabel label : List.of(person, team, project)) {
+            Assert.assertFalse(label.userdata().containsKey(SchemaService.USER_KEY_STYLE));
+        }
+    }
+
+    @Test
+    public void testSavedBluePreservesEveryCustomField() {
+        VertexLabel person = label("Person");
+        VertexLabelStyle saved = new VertexLabelStyle(
+                "person-icon", "#5C73E6", VertexLabelStyle.Size.BIG,
+                List.of("name", "community"), List.of(" / "));
+        String raw = JsonUtil.toJson(saved);
+        person.userdata().put(SchemaService.USER_KEY_STYLE, raw);
+        Map<String, Object> before = new HashMap<>(person.userdata());
+
+        VertexLabelStyle result = new VertexLabelService().get("Person", client(person))
+                                                         .getStyle();
+
+        Assert.assertEquals(saved.getIcon(), result.getIcon());
+        Assert.assertEquals(saved.getColor(), result.getColor());
+        Assert.assertEquals(saved.getSize(), result.getSize());
+        Assert.assertEquals(saved.getDisplayFields(), result.getDisplayFields());
+        Assert.assertEquals(saved.getJoinSymbols(), result.getJoinSymbols());
+        Assert.assertEquals(before, person.userdata());
+    }
+
+    @Test
+    public void testPartialSavedStylesKeepTheirExistingDefaults() {
+        for (String raw : List.of("{\"color\":\"#5C73E6\"}", "{\"size\":\"BIG\"}", "{}")) {
+            VertexLabel person = label("Person");
+            person.userdata().put(SchemaService.USER_KEY_STYLE, raw);
+
+            VertexLabelStyle result = new VertexLabelService().get("Person", client(person))
+                                                             .getStyle();
+
+            Assert.assertEquals("#5C73E6", result.getColor());
+            Assert.assertEquals(raw.contains("BIG") ? VertexLabelStyle.Size.BIG :
+                                VertexLabelStyle.Size.NORMAL, result.getSize());
+            Assert.assertEquals(List.of("~id"), result.getDisplayFields());
+            Assert.assertEquals(List.of("-"), result.getJoinSymbols());
+            Assert.assertEquals(raw, person.userdata().get(SchemaService.USER_KEY_STYLE));
+        }
+    }
+
+    private static VertexLabel label(String name) {
+        VertexLabel label = new VertexLabel.BuilderImpl(name, null)
+                                          .enableLabelIndex(true).build();
+        label.userdata().put(SchemaService.USER_KEY_CREATE_TIME, 0L);
+        return label;
+    }
+
+    private static HugeClient client(VertexLabel... labels) {
+        SchemaManager schema = Mockito.mock(SchemaManager.class);
+        HugeClient client = Mockito.mock(HugeClient.class);
+        Mockito.when(client.schema()).thenReturn(schema);
+        Mockito.when(schema.getIndexLabels()).thenReturn(Collections.emptyList());
+        for (VertexLabel label : labels) {
+            Mockito.when(schema.getVertexLabel(label.name())).thenReturn(label);
+        }
+        return client;
+    }
+
+    private static Map<String, String> colors(List<VertexLabelEntity> labels) {
+        return labels.stream().collect(Collectors.toMap(
+                VertexLabelEntity::getName, label -> label.getStyle().getColor()));
+    }
+}