Added message events, triggering message creation event

+ Abstract MessageEvent class with MessageCreationEvent and
MessageModificationEvent subclasses
+ Made StatusTrayIcon an event handler
- Fixed EventBus#getInstance not being static

src/main/java/envoy/client/LocalDB.java

@@ -13,6 +13,8 @@ import java.util.List;
 import javax.xml.datatype.DatatypeConfigurationException;
 import javax.xml.datatype.DatatypeFactory;
 
+import envoy.client.event.EventBus;
+import envoy.client.event.MessageCreationEvent;
 import envoy.exception.EnvoyException;
 import envoy.schema.Message;
 import envoy.schema.Message.Metadata.MessageState;
@@ -161,6 +163,9 @@ public class LocalDB {
 					&& returnSync.getMessages().get(i).getMetadata().getState() == MessageState.RECEIVED) {
 				// these are the unread Messages from the server
 				unreadMessagesSync.getMessages().add(returnSync.getMessages().get(i));
+
+				// Create and dispatch message creation event
+				EventBus.getInstance().dispatch(new MessageCreationEvent(returnSync.getMessages().get(i)));
 			}
 
 			if (returnSync.getMessages().get(i).getMetadata().getMessageId() != 0 && returnSync.getMessages().get(i).getMetadata().getSender() == 0

src/main/java/envoy/client/event/EventBus.java

@@ -19,7 +19,7 @@ public class EventBus {
 
 	private EventBus() {}
 
-	public EventBus getInstance() {
+	public static EventBus getInstance() {
 		if (eventBus == null) eventBus = new EventBus();
 		return eventBus;
 	}

src/main/java/envoy/client/event/MessageCreationEvent.java

@@ -0,0 +1,18 @@
+package envoy.client.event;
+
+import envoy.schema.Message;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>MessageCreationEvent.java</strong><br>
+ * Created: <strong>4 Dec 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ */
+public class MessageCreationEvent extends MessageEvent {
+
+	/**
+	 * @param message the {@link Message} that has been created
+	 */
+	public MessageCreationEvent(Message message) { super(message); }
+}

src/main/java/envoy/client/event/MessageEvent.java

@@ -0,0 +1,20 @@
+package envoy.client.event;
+
+import envoy.schema.Message;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>MessageCreationEvent.java</strong><br>
+ * Created: <strong>4 Dec 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ */
+public class MessageEvent implements Event<Message> {
+
+	protected final Message message;
+
+	public MessageEvent(Message message) { this.message = message; }
+
+	@Override
+	public Message get() { return message; }
+}

src/main/java/envoy/client/event/MessageModificationEvent.java

@@ -0,0 +1,18 @@
+package envoy.client.event;
+
+import envoy.schema.Message;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>MessageModificationEvent.java</strong><br>
+ * Created: <strong>4 Dec 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ */
+public class MessageModificationEvent extends MessageEvent {
+
+	/**
+	 * @param message the {@link Message} that has been modified
+	 */
+	public MessageModificationEvent(Message message) { super(message); }
+}

src/main/java/envoy/client/ui/StatusTrayIcon.java

@@ -8,9 +8,14 @@ import java.awt.SystemTray;
 import java.awt.Toolkit;
 import java.awt.TrayIcon;
 import java.awt.TrayIcon.MessageType;
+import java.util.HashSet;
+import java.util.Set;
 
+import envoy.client.event.Event;
+import envoy.client.event.EventBus;
+import envoy.client.event.EventHandler;
+import envoy.client.event.MessageCreationEvent;
 import envoy.exception.EnvoyException;
-import envoy.schema.Message;
 
 /**
  * Project: <strong>envoy-client</strong><br>
@@ -20,7 +25,7 @@ import envoy.schema.Message;
  * @author Kai S. K. Engelbart
  * @since Envoy v0.2-alpha
  */
-public class StatusTrayIcon {
+public class StatusTrayIcon implements EventHandler {
 
 	private TrayIcon trayIcon;
 
@@ -39,6 +44,7 @@ public class StatusTrayIcon {
 		popup.add(exitMenuItem);
 
 		trayIcon.setPopupMenu(popup);
+		EventBus.getInstance().register(this);
 	}
 
 	/**
@@ -55,12 +61,17 @@ public class StatusTrayIcon {
 	}
 
 	/**
-	 * Notifies the user of a message by displaying a popup.
-	 * 
-	 * @param message the {@link Message} object to display in the popup
+	 * Notifies the user of a message by displaying a pop-up.
 	 */
-	public void displayMessageNotification(Message message) {
-		// TODO: Add event listener
-		trayIcon.displayMessage("New message received", message.getContent().get(0).getText(), MessageType.INFO);
+	@Override
+	public void handle(Event<?> event) {
+		trayIcon.displayMessage("New message received", ((MessageCreationEvent) event).get().getContent().get(0).getText(), MessageType.INFO);
+	}
+
+	@Override
+	public Set<Class<? extends Event<?>>> supports() {
+		Set<Class<? extends Event<?>>> supportedEvents = new HashSet<>();
+		supportedEvents.add(MessageCreationEvent.class);
+		return supportedEvents;
 	}
 }