Fixed computation of topic segments for MQTT DevFactory context

southbound/mqtt/mqtt-device-factory/src/main/java/org/eclipse/sensinact/gateway/southbound/mqtt/factory/MqttDeviceFactoryHandler.java

@@ -12,9 +12,11 @@
 **********************************************************************/
 package org.eclipse.sensinact.gateway.southbound.mqtt.factory;
 
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Hashtable;
 import java.util.Map;
+import java.util.function.Predicate;
 
 import org.eclipse.sensinact.gateway.southbound.device.factory.DeviceFactoryException;
 import org.eclipse.sensinact.gateway.southbound.device.factory.IDeviceMappingHandler;
@@ -142,26 +144,32 @@ public void onMqttMessage(String handlerId, String topic, IMqttMessage message)
         }
     }
 
-    private void fillTopicSegments(String topic, Map<String, String> context) {
+    void fillTopicSegments(String topic, Map<String, String> context) {
         context.put("topic", topic);
 
-        int i = 0;
-        String segment;
-        int idx = 0;
-
-        do {
-            int slash = topic.indexOf('/', idx);
-            if (slash > 0) {
-                segment = topic.substring(idx, slash);
-                idx = slash + 1;
-            } else {
-                segment = topic.substring(idx);
-                idx = -1;
-            }
-            context.put("topic-".concat(Integer.toString(i)), segment);
-            i++;
-        } while (idx >= 0);
-
-        context.put("topic-last", segment);
+        boolean startingSlash = topic.indexOf('/') == 0;
+        boolean endingSlash = !topic.isEmpty() && topic.lastIndexOf('/') == topic.length() - 1;
+        String[] parts = Arrays.stream(topic.split("/")).filter(Predicate.not(String::isEmpty)).toArray(String[]::new);
+
+        int segmentIdx = 0;
+        if (startingSlash || parts.length == 0) {
+            context.put("topic-0", "");
+            segmentIdx++;
+        }
+
+        for (String part : parts) {
+            context.put("topic-" + segmentIdx, part);
+            segmentIdx++;
+        }
+
+        if (endingSlash) {
+            context.put("topic-" + segmentIdx, "");
+        }
+
+        if (endingSlash || parts.length == 0) {
+            context.put("topic-last", "");
+        } else {
+            context.put("topic-last", parts[parts.length - 1]);
+        }
     }
 }

southbound/mqtt/mqtt-device-factory/src/test/java/org/eclipse/sensinact/gateway/southbound/mqtt/factory/ContextTest.java

@@ -0,0 +1,96 @@
+/*********************************************************************
+* Copyright (c) 2024 Kentyou.
+*
+* This program and the accompanying materials are made
+* available under the terms of the Eclipse Public License 2.0
+* which is available at https://www.eclipse.org/legal/epl-2.0/
+*
+* SPDX-License-Identifier: EPL-2.0
+*
+* Contributors:
+*   Thomas Calmant (Kentyou) - initial implementation
+**********************************************************************/
+package org.eclipse.sensinact.gateway.southbound.mqtt.factory;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+public class ContextTest {
+
+    @Test
+    void testTopicContext() throws Exception {
+        final MqttDeviceFactoryHandler handler = new MqttDeviceFactoryHandler();
+        final Map<String, String> segments = new HashMap<>();
+
+        // Empty topic (shouldn't exist according to the specification)
+        handler.fillTopicSegments("", segments);
+        assertEquals("", segments.get("topic"));
+        assertEquals("", segments.get("topic-last"));
+        assertEquals("", segments.get("topic-0"));
+        assertFalse(segments.containsKey("topic-1"));
+
+        // Space topic
+        segments.clear();
+        handler.fillTopicSegments(" ", segments);
+        assertEquals(" ", segments.get("topic"));
+        assertEquals(" ", segments.get("topic-last"));
+        assertEquals(" ", segments.get("topic-0"));
+        assertFalse(segments.containsKey("topic-1"));
+
+        // Slash topic
+        segments.clear();
+        handler.fillTopicSegments("/", segments);
+        assertEquals("/", segments.get("topic"));
+        assertEquals("", segments.get("topic-last"));
+        assertEquals("", segments.get("topic-0"));
+        assertEquals("", segments.get("topic-1"));
+        assertFalse(segments.containsKey("topic-2"));
+
+        // Long topic
+        segments.clear();
+        handler.fillTopicSegments("foo/bar/foobar", segments);
+        assertEquals("foo/bar/foobar", segments.get("topic"));
+        assertEquals("foo", segments.get("topic-0"));
+        assertEquals("bar", segments.get("topic-1"));
+        assertEquals("foobar", segments.get("topic-2"));
+        assertEquals("foobar", segments.get("topic-last"));
+        assertFalse(segments.containsKey("topic-3"));
+
+        // Starting slash shall not be ignored, as explained in the MQTT specification
+        segments.clear();
+        handler.fillTopicSegments("/foo/bar/foobar", segments);
+        assertEquals("/foo/bar/foobar", segments.get("topic"));
+        assertEquals("", segments.get("topic-0"));
+        assertEquals("foo", segments.get("topic-1"));
+        assertEquals("bar", segments.get("topic-2"));
+        assertEquals("foobar", segments.get("topic-3"));
+        assertEquals("foobar", segments.get("topic-last"));
+        assertFalse(segments.containsKey("topic-4"));
+
+        // Trailing slash shall not be ignored, as explained in the MQTT specification
+        segments.clear();
+        handler.fillTopicSegments("foo/bar/foobar/", segments);
+        assertEquals("foo/bar/foobar/", segments.get("topic"));
+        assertEquals("foo", segments.get("topic-0"));
+        assertEquals("bar", segments.get("topic-1"));
+        assertEquals("foobar", segments.get("topic-2"));
+        assertEquals("", segments.get("topic-3"));
+        assertEquals("", segments.get("topic-last"));
+        assertFalse(segments.containsKey("topic-4"));
+
+        // Double-slashes shall be considered as 1, as explained in the MQTT
+        // specification
+        segments.clear();
+        handler.fillTopicSegments("foo//bar", segments);
+        assertEquals("foo//bar", segments.get("topic"));
+        assertEquals("foo", segments.get("topic-0"));
+        assertEquals("bar", segments.get("topic-1"));
+        assertEquals("bar", segments.get("topic-last"));
+        assertFalse(segments.containsKey("topic-3"));
+    }
+}