[ONOS-5238] Add neighbour message handler for vpls

Change-Id: Iaef04233402864874af0c83231117c279e946d64
diff --git a/apps/vpls/src/main/java/org/onosproject/vpls/VplsNeighbourHandler.java b/apps/vpls/src/main/java/org/onosproject/vpls/VplsNeighbourHandler.java
new file mode 100644
index 0000000..9f3ea06
--- /dev/null
+++ b/apps/vpls/src/main/java/org/onosproject/vpls/VplsNeighbourHandler.java
@@ -0,0 +1,158 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed 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.onosproject.vpls;
+
+import com.google.common.collect.Maps;
+
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.incubator.net.intf.Interface;
+import org.onosproject.incubator.net.intf.InterfaceEvent;
+import org.onosproject.incubator.net.intf.InterfaceListener;
+import org.onosproject.incubator.net.intf.InterfaceService;
+import org.onosproject.incubator.net.neighbour.NeighbourMessageContext;
+import org.onosproject.incubator.net.neighbour.NeighbourMessageHandler;
+import org.onosproject.incubator.net.neighbour.NeighbourResolutionService;
+import org.onosproject.net.Host;
+import org.onosproject.net.host.HostService;
+import org.slf4j.Logger;
+
+import java.util.Map;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Handles neighbour messages for VPLS use case.
+ * Handlers will be changed automatically by interface or network configuration
+ * events.
+ */
+@Component(immediate = true)
+public class VplsNeighbourHandler {
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected CoreService coreService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected InterfaceService interfaceService;
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected NeighbourResolutionService neighbourService;
+
+    private VplsInterfaceListener interfaceListener
+            = new VplsInterfaceListener();
+
+    private VplsNeighbourMessageHandler neighbourHandler =
+            new VplsNeighbourMessageHandler();
+
+    private final Logger log = getLogger(getClass());
+
+    private Map<Interface, NeighbourMessageHandler> neighbourHandlers =
+            Maps.newHashMap();
+
+    private ApplicationId appId;
+
+
+    @Activate
+    protected void activate() {
+        appId = coreService.registerApplication(Vpls.VPLS_APP);
+        interfaceService.addListener(interfaceListener);
+
+        interfaceService.getInterfaces().forEach(intf -> {
+            neighbourHandlers.put(intf, neighbourHandler);
+
+            neighbourService.registerNeighbourHandler(intf, neighbourHandler, appId);
+        });
+
+        log.debug("Activated");
+    }
+
+    @Deactivate
+    protected void deactivate() {
+        interfaceService.removeListener(interfaceListener);
+        neighbourHandlers.entrySet().forEach(e -> {
+            neighbourService.unregisterNeighbourHandler(e.getKey(), e.getValue(), appId);
+        });
+        log.debug("Deactivated");
+    }
+
+    private void configNeighbourHandler(Interface intf,
+                                          NeighbourMessageHandler handler,
+                                          InterfaceEvent.Type eventType) {
+        switch (eventType) {
+            case INTERFACE_ADDED:
+                neighbourHandlers.put(intf, handler);
+                neighbourService.registerNeighbourHandler(intf, handler, appId);
+                break;
+            case INTERFACE_REMOVED:
+                neighbourHandlers.remove(intf, handler);
+                neighbourService.unregisterNeighbourHandler(intf, handler, appId);
+                break;
+            case INTERFACE_UPDATED:
+                break;
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Handler for neighbour messages.
+     */
+    private class VplsNeighbourMessageHandler implements NeighbourMessageHandler {
+
+        @Override
+        public void handleMessage(NeighbourMessageContext context,
+                                  HostService hostService) {
+
+            switch (context.type()) {
+                case REQUEST:
+                    interfaceService.getInterfacesByVlan(context.vlan())
+                            .stream()
+                            .map(Interface::connectPoint)
+                            .forEach(context::proxy);
+                    break;
+                case REPLY:
+                    hostService.getHostsByMac(context.dstMac())
+                            .stream()
+                            .filter(host -> host.vlan().equals(context.vlan()))
+                            .map(Host::location)
+                            .forEach(context::proxy);
+                    break;
+
+                default:
+                    log.warn("Unknown context type: {}", context.type());
+                    break;
+            }
+        }
+    }
+
+    /**
+     * Listener for interface configuration events.
+     */
+    private class VplsInterfaceListener implements InterfaceListener {
+
+        @Override
+        public void event(InterfaceEvent event) {
+            configNeighbourHandler(event.subject(), neighbourHandler, event.type());
+        }
+    }
+
+}