Implemented receiving unread messages using a message cache

Fixes #98

src/main/java/envoy/client/Chat.java

@@ -24,8 +24,8 @@ public class Chat implements Serializable {
 
 	private static final long serialVersionUID = -7751248474547242056L;
 
-	private User						recipient;
-	private ComponentListModel<Message>	model	= new ComponentListModel<>();
+	private final User							recipient;
+	private final ComponentListModel<Message>	model	= new ComponentListModel<>();
 
 	/**
 	 * Provides the list of messages that the recipient receives.<br>

src/main/java/envoy/client/Client.java

@@ -10,6 +10,7 @@ import java.util.logging.Logger;
 import javax.naming.TimeLimitExceededException;
 
 import envoy.client.database.LocalDb;
+import envoy.client.net.MessageCache;
 import envoy.client.net.ReceivedMessageProcessor;
 import envoy.client.net.Receiver;
 import envoy.client.util.EnvoyLog;
@@ -51,11 +52,13 @@ public class Client implements Closeable {
 	 * @param credentials the login credentials of the user
 	 * @param localDb     the local database used to persist the current
 	 *                    {@link IdGenerator}
+	 * @return a message cache containing all unread messages from the server that
+	 *         can be relayed after initialization
 	 * @throws Exception if the online mode could not be entered or the request
 	 *                   failed for some other reason
 	 * @since Envoy v0.2-alpha
 	 */
-	public void onlineInit(LoginCredentials credentials, LocalDb localDb) throws Exception {
+	public MessageCache onlineInit(LoginCredentials credentials, LocalDb localDb) throws Exception {
 		// Establish TCP connection
 		logger.info(String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
@@ -64,9 +67,13 @@ public class Client implements Closeable {
 		// Create message receiver
 		receiver = new Receiver(socket.getInputStream());
 
-		// Register user creation processor
+		// Create cache for unread messages
+		final MessageCache cache = new MessageCache();
+
+		// Register user creation processor, contact list processor and message cache
 		receiver.registerProcessor(User.class, sender -> { logger.info("Acquired user object " + sender); this.sender = sender; });
 		receiver.registerProcessor(Contacts.class, contacts -> { logger.info("Acquired contacts object " + contacts); this.contacts = contacts; });
+		receiver.registerProcessor(Message.class, cache);
 
 		// Start receiver
 		new Thread(receiver).start();
@@ -89,7 +96,12 @@ public class Client implements Closeable {
 		receiver.removeAllProcessors();
 
 		// Register processors for message and status handling
-		receiver.registerProcessor(Message.class, new ReceivedMessageProcessor());
+		final ReceivedMessageProcessor receivedMessageProcessor = new ReceivedMessageProcessor();
+		receiver.registerProcessor(Message.class, receivedMessageProcessor);
+
+		// Relay cached unread messages
+		cache.setProcessor(receivedMessageProcessor);
+
 		// TODO: Status handling
 
 		// Process message ID generation
@@ -97,6 +109,8 @@ public class Client implements Closeable {
 
 		// Request a generator if none is present
 		if (!localDb.hasIdGenerator() || !localDb.getIdGenerator().hasNext()) requestIdGenerator();
+
+		return cache;
 	}
 
 	/**

src/main/java/envoy/client/net/MessageCache.java

@@ -0,0 +1,54 @@
+package envoy.client.net;
+
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.function.Consumer;
+import java.util.logging.Logger;
+
+import envoy.client.util.EnvoyLog;
+import envoy.data.Message;
+
+/**
+ * Stores messages in a queue until the application initialization is complete.
+ * The messages can then be relayed to a processor.<br>
+ * <br>
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>MessageCache.java</strong><br>
+ * Created: <strong>4 Feb 2020</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.3-alpha
+ */
+public class MessageCache implements Consumer<Message> {
+
+	private final Queue<Message>	messages	= new LinkedList<>();
+	private Consumer<Message>		processor;
+
+	private static final Logger logger = EnvoyLog.getLogger(MessageCache.class.getSimpleName());
+
+	/**
+	 * Adds a message to the cache.
+	 *
+	 * @since Envoy v0.3-alpha
+	 */
+	@Override
+	public void accept(Message message) {
+		logger.info(String.format("Adding message %s to cache", message));
+		messages.add(message);
+	}
+
+	/**
+	 * Sets the processor to which messages are relayed.
+	 *
+	 * @param processor the processor to set
+	 * @since Envoy v0.3-alpha
+	 */
+	public void setProcessor(Consumer<Message> processor) { this.processor = processor; }
+
+	/**
+	 * Relays all cached messages to the processor.
+	 *
+	 * @since Envoy v0.3-alpha
+	 */
+	public void relayMessages() { messages.forEach(processor::accept); }
+}

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

@@ -17,6 +17,7 @@ import envoy.client.Settings;
 import envoy.client.database.LocalDb;
 import envoy.client.database.PersistentLocalDb;
 import envoy.client.database.TransientLocalDb;
+import envoy.client.net.MessageCache;
 import envoy.client.util.EnvoyLog;
 import envoy.data.LoginCredentials;
 import envoy.data.User;
@@ -107,10 +108,11 @@ public class Startup {
 		// Acquire the client user (with ID) either from the server or from the local
 		// database, which triggers offline mode
 		Client			client	= new Client();
+		MessageCache	cache	= null;
 		try {
 			// Try entering online mode first
 			localDb.loadIdGenerator();
-			client.onlineInit(credentials, localDb);
+			cache = client.onlineInit(credentials, localDb);
 		} catch (Exception e1) {
 			logger.warning("Could not connect to server. Trying offline mode...");
 			e1.printStackTrace();
@@ -151,6 +153,7 @@ public class Startup {
 		// Save all users to the local database
 		if (client.isOnline()) localDb.setUsers(client.getUsers());
 
+		// Display ChatWindow and StatusTrayIcon
 		EventQueue.invokeLater(() -> {
 			try {
 				chatWindow.setClient(client);
@@ -174,6 +177,9 @@ public class Startup {
 			}
 		});
 
+		// Relay unread messages from cache
+		if (cache != null) cache.relayMessages();
+
 		// Save Settings and PersistentLocalDb on shutdown
 		Runtime.getRuntime().addShutdownHook(new Thread(() -> {
 			try {