Merge branch 'develop' into f/logger

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

@@ -1,6 +1,7 @@
 package envoy.client;
 
-import java.util.logging.Logger;
+import java.util.HashMap;
+import java.util.Map;
 
 import javax.ws.rs.client.ClientBuilder;
 import javax.ws.rs.client.Entity;
@@ -10,7 +11,7 @@ import javax.xml.bind.JAXBContext;
 import javax.xml.bind.JAXBException;
 import javax.xml.bind.Marshaller;
 
-import envoy.client.util.EnvoyLog;
+import envoy.exception.EnvoyException;
 import envoy.schema.ObjectFactory;
 import envoy.schema.Sync;
 import envoy.schema.User;
@@ -30,14 +31,28 @@ public class Client {
 	private ObjectFactory	objectFactory	= new ObjectFactory();
 	private Config			config;
 	private User			sender, recipient;
+	private boolean			online			= false;
 
-	private static final Logger logger = EnvoyLog.getLogger(Client.class.getSimpleName());
+	/**
+	 * Initializes the client. At this state, the client user has yet to be
+	 * initialized, which can be done by calling {@link Client#onlineInit(String).
+	 * 
+	 * @param config The {@link Config} instance to use in this client
+	 * @since Envoy v0.2-alpha
+	 */
+	public Client(Config config) { this.config = config; }
 
-	public Client(Config config, String username) {
+	/**
-		this.config	= config;
+	 * Enters the online mode by acquiring a user ID from the server.
-		sender		= getUser(username);
+	 * 
-
+	 * @param userName the name of the client user
-		logger.info("ID: " + sender.getID());
+	 * @throws EnvoyException if the online mode could not be entered or the request
+	 *                        failed for some other reason
+	 * @since Envoy v0.2-alpha
+	 */
+	public void onlineInit(String userName) throws EnvoyException {
+		sender	= getUser(userName);
+		online	= true;
 	}
 
 	private <T, R> R post(String uri, T body, Class<R> responseBodyClass) {
@@ -49,26 +64,26 @@ public class Client {
 		client.close();
 
 		return responseBody;
-
 	}
 
 	/**
-	 * Returns a {@link Sync} with all users on the server.
+	 * @return a {@code Map<String, User>} of all users on the server with their
-	 * 
+	 *         user names as keys
-	 * @return Sync - List of all users on the server.
+	 * @since Envoy v0.2-alpha
-	 * @since Envoy v0.1-alpha
 	 */
-	public Sync getUsersListXml() {
+	public Map<String, User> getUsers() {
 		Sync	sendSync	= objectFactory.createSync();
 		User	user		= objectFactory.createUser();
 		user.setID(-1);
 		sendSync.getUsers().add(user);
 
-		Sync returnSendSync = post(String.format("%s:%d/envoy-server/rest/sync/syncData?userId=%d", config.getServer(), config.getPort(), 0),
+		Sync returnSync = post(String.format("%s:%d/envoy-server/rest/sync/syncData?userId=%d", config.getServer(), config.getPort(), 0),
 				sendSync,
 				Sync.class);
-		return returnSendSync;
 
+		Map<String, User> users = new HashMap<>();
+		returnSync.getUsers().forEach(u -> users.put(u.getName(), u));
+		return users;
 	}
 
 	/**
@@ -76,27 +91,29 @@ public class Client {
 	 * 
 	 * @param name - the name of the {@link User}
 	 * @return a {@link User} with the specified name
+	 * @throws EnvoyException if the server does not return the requested ID
 	 * @since Envoy v0.1-alpha
 	 */
-	private User getUser(String name) {
+	private User getUser(String name) throws EnvoyException {
+		// Create a sync with only a user with the requested name
 		Sync	senderSync	= objectFactory.createSync();
 		User	user		= objectFactory.createUser();
 		user.setName(name);
 		senderSync.getUsers().add(user);
 
-		Sync returnSenderSync = post(String.format("%s:%d/envoy-server/rest/sync/syncData?userId=%d", config.getServer(), config.getPort(), 0),
+		try {
+			Sync sync = post(String.format("%s:%d/envoy-server/rest/sync/syncData?userId=%d", config.getServer(), config.getPort(), 0),
 					senderSync,
 					Sync.class);
 
-		User returnSender = objectFactory.createUser();
+			// Expecting a single user with an ID
-
+			if (sync.getUsers().size() == 1) {
-		if (returnSenderSync.getUsers().size() == 1) {
+				online = true;
-			returnSender = returnSenderSync.getUsers().get(0);
+				return sync.getUsers().get(0);
-		} else {
+			} else throw new EnvoyException("Unexpected response from Envoy Server");
-			logger.warning("ERROR exiting...");
+		} catch (Exception e) {
+			throw new EnvoyException("Could not connect to server", e);
 		}
-
-		return returnSender;
 	}
 
 	/**
@@ -134,9 +151,12 @@ public class Client {
 	 * @param sync   the sync object (yet to be converted from java class to
 	 *               sync.xml)
 	 * @return a returnSync.xml file
+	 * @throws EnvoyException if the client is not in online mode
 	 * @since Envoy v0.1-alpha
 	 */
-	public Sync sendSync(long userId, Sync sync) {
+	public Sync sendSync(long userId, Sync sync) throws EnvoyException {
+		if(!isOnline())
+			throw new EnvoyException("Client is not in online mode");
 		// Print sync XML to console
 		JAXBContext jc;
 		try {
@@ -158,6 +178,14 @@ public class Client {
 	 */
 	public User getSender() { return sender; }
 
+	/**
+	 * Sets the client user which is used to send messages.
+	 * 
+	 * @param sender the client user to set
+	 * @since Envoy v0.2-alpha
+	 */
+	public void setSender(User sender) { this.sender = sender; }
+
 	/**
 	 * @return the current recipient of the current chat.
 	 * @since Envoy v0.1-alpha
@@ -167,7 +195,7 @@ public class Client {
 	/**
 	 * Sets the recipient.
 	 * 
-	 * @param recipient - the recipient to set
+	 * @param recipient the recipient to set
 	 * @since Envoy v0.1-alpha
 	 */
 	public void setRecipient(User recipient) { this.recipient = recipient; }
@@ -177,4 +205,10 @@ public class Client {
 	 * @since Envoy v0.1-alpha
 	 */
 	public boolean hasRecipient() { return recipient != null; }
+
+	/**
+	 * @return {@code true} if a connection to the server could be established
+	 * @since Envoy v0.2-alpha
+	 */
+	public boolean isOnline() { return online; }
 }

src/main/java/envoy/client/Config.java

@@ -3,6 +3,8 @@ package envoy.client;
 import java.io.File;
 import java.util.Properties;
 
+import envoy.exception.EnvoyException;
+
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>Config.java</strong><br>
@@ -29,17 +31,26 @@ public class Config {
 
 	/**
 	 * Defaults to the {@code client.properties} file for information.
-	 * 
+	 * This file contains information about
-	 * @param properties a {@link Properties} object containing information about
 	 * the server and port, as well as the path to the local
 	 * database and the synchronization timeout
+	 * 
+	 * @throws EnvoyException if the {@code client.properties} file could not be
+	 *                        loaded
 	 * @since Envoy v0.1-alpha
 	 */
-	public void load(Properties properties) {
+	public void load() throws EnvoyException {
+		ClassLoader loader = getClass().getClassLoader();
+		try {
+			Properties properties = new Properties();
+			properties.load(loader.getResourceAsStream("client.properties"));
 			if (properties.containsKey("server")) server = properties.getProperty("server");
 			if (properties.containsKey("port")) port = Integer.parseInt(properties.getProperty("port"));
 			localDB		= new File(properties.getProperty("localDB", ".\\localDB"));
 			syncTimeout	= Integer.parseInt(properties.getProperty("syncTimeout", "1000"));
+		} catch (Exception e) {
+			throw new EnvoyException("Failed to load client.properties", e);
+		}
 	}
 
 	/**
@@ -47,9 +58,10 @@ public class Config {
 	 * -s, --port / -p and --localDB / -db.
 	 * 
 	 * @param args the command line arguments to parse
+	 * @throws EnvoyException if the command line arguments contain an unknown token
 	 * @since Envoy v0.1-alpha
 	 */
-	public void load(String[] args) {
+	public void load(String[] args) throws EnvoyException {
 		for (int i = 0; i < args.length; i++)
 			switch (args[i]) {
 				case "--server":
@@ -64,6 +76,8 @@ public class Config {
 				case "-db":
 					localDB = new File(args[++i]);
 					break;
+				default:
+					throw new EnvoyException("Unknown token " + args[i] + " found");
 			}
 	}
 

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

@@ -8,7 +8,9 @@ import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.time.Instant;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.logging.Logger;
 
 import javax.xml.datatype.DatatypeConfigurationException;
@@ -35,9 +37,11 @@ import envoy.schema.User;
  */
 public class LocalDB {
 
-	private File			localDB;
+	private File				localDBDir, localDBFile, usersFile;
-	private User			sender;
+	private User				user;
+	private Map<String, User>	users	= new HashMap<>();
 	private List<Chat>			chats	= new ArrayList<>();
+
 	private ObjectFactory	objectFactory	= new ObjectFactory();
 	private DatatypeFactory	datatypeFactory;
 
@@ -48,64 +52,91 @@ public class LocalDB {
   private static final Logger logger = EnvoyLog.getLogger(LocalDB.class.getSimpleName());
 
 	/**
-	 * Constructs an empty local database.
+	 * Constructs an empty local database. To serialize any chats to the file
+	 * system, call {@link LocalDB#initializeDBFile(File)}.
 	 *
-	 * @param sender the user that is logged in with this client
+	 * @param localDBDir the directory in which to store users and chats
 	 * @since Envoy v0.1-alpha
 	 */
-	public LocalDB(User sender) {
+	public LocalDB(File localDBDir) throws IOException {
-		this.sender = sender;
+		this.localDBDir = localDBDir;
+
 		try {
 			datatypeFactory = DatatypeFactory.newInstance();
 		} catch (DatatypeConfigurationException e) {
 			e.printStackTrace();
 		}
+
+		// Initialize local database directory
+		if (localDBDir.exists() && !localDBDir.isDirectory())
+			throw new IOException(String.format("LocalDBDir '%s' is not a directory!", localDBDir.getAbsolutePath()));
+		usersFile = new File(localDBDir, "users.db");
 	}
 
 	/**
-	 * Initializes the local database and fills it with values
+	 * Creates a database file for a user-specific list of chats.
-	 * if the user has already sent or received messages.
 	 *
-	 * @param localDBDir the directory where we wish to save/load the database from.
+	 * @throws NullPointerException if the client user is not yet specified
-	 * @throws EnvoyException if the directory selected is not an actual directory.
 	 * @since Envoy v0.1-alpha
 	 */
-	public void initializeDBFile(File localDBDir) throws EnvoyException {
+	public void initializeDBFile() {
-		if (localDBDir.exists() && !localDBDir.isDirectory())
+		if (user == null) throw new NullPointerException("Client user is null");
-			throw new EnvoyException(String.format("LocalDBDir '%s' is not a directory!", localDBDir.getAbsolutePath()));
+		localDBFile = new File(localDBDir, user.getID() + ".db");
-		localDB = new File(localDBDir, sender.getID() + ".db");
-		if (localDB.exists()) loadFromLocalDB();
 	}
 
 	/**
-	 * Saves the database into a file for future use.
+	 * Stores all users to the local database. If the client user is specified, the
+	 * chats related to this user are stored as well.
 	 *
 	 * @throws IOException if something went wrong during saving
 	 * @since Envoy v0.1-alpha
 	 */
-	public void saveToLocalDB() throws IOException {
+	public void save() throws IOException {
-		localDB.getParentFile().mkdirs();
+		// Save users
-		localDB.createNewFile();
+		write(usersFile, users);
-		try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(localDB))) {
+
-			out.writeObject(chats);
+		// Save chats
-		} catch (IOException ex) {
+		write(localDBFile, chats);
-			throw ex;
-		}
 	}
 
+	/**
+	 * Loads all users that are stored in the local database.
+	 * 
+	 * @throws EnvoyException if the loading process failed
+	 * @since Envoy v0.2-alpha
+	 */
+	@SuppressWarnings("unchecked")
+	public void loadUsers() throws EnvoyException { users = read(usersFile, HashMap.class); }
+
 	/**
 	 * Loads all chats saved by Envoy for the client user.
 	 *
-	 * @throws EnvoyException if something fails while loading.
+	 * @throws EnvoyException if the loading process failed
 	 * @since Envoy v0.1-alpha
 	 */
 	@SuppressWarnings("unchecked")
-	private void loadFromLocalDB() throws EnvoyException {
+	public void loadChats() throws EnvoyException { chats = read(localDBFile, ArrayList.class); }
-		try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(localDB))) {
+
-			Object obj = in.readObject();
+	private <T> T read(File file, Class<T> serializedClass) throws EnvoyException {
-			if (obj instanceof ArrayList<?>) chats = (ArrayList<Chat>) obj;
+		if (file == null) throw new NullPointerException("File is null");
+		try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(file))) {
+			return serializedClass.cast(in.readObject());
 		} catch (ClassNotFoundException | IOException e) {
-			throw new EnvoyException(e);
+			throw new EnvoyException("Could not load serialized object", e);
+		}
+	}
+
+	private <T> void write(File file, T obj) throws IOException {
+		if (file == null) throw new NullPointerException("File is null");
+		if (obj == null) throw new NullPointerException("Object to serialize is null");
+		if (!file.exists()) {
+			file.getParentFile().mkdirs();
+			file.createNewFile();
+		}
+		try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file))) {
+			out.writeObject(obj);
+		} catch (IOException e) {
+			throw e;
 		}
 	}
 
@@ -119,7 +150,7 @@ public class LocalDB {
 	 */
 	public Message createMessage(String textContent, long recipientID) {
 		Message.Metadata metaData = objectFactory.createMessageMetadata();
-		metaData.setSender(sender.getID());
+		metaData.setSender(user.getID());
 		metaData.setRecipient(recipientID);
 		metaData.setState(MessageState.WAITING);
 		metaData.setDate(datatypeFactory.newXMLGregorianCalendar(Instant.now().toString()));
@@ -281,6 +312,17 @@ public class LocalDB {
 	 */
 	public void clearUnreadMessagesSync() { unreadMessagesSync.getMessages().clear(); }
 
+	/**
+	 * @return a {@code Map<String, User>} of all users stored locally with their user names as keys
+	 * @since Envoy v0.2-alpha
+	 */
+	public Map<String, User> getUsers() { return users; }
+
+	/**
+	 * @param users the users to set
+	 */
+	public void setUsers(Map<String, User> users) { this.users = users; }
+
 	/**
 	 * @return all saved {@link Chat} objects that list the client user as the
 	 *         sender
@@ -289,8 +331,19 @@ public class LocalDB {
 	public List<Chat> getChats() { return chats; }
 
 	/**
-	 * @return the {@link User} who initialized the local database
+	 * @param chats the chats to set
-	 * @since Envoy v0.1-alpha
 	 */
-	public User getUser() { return sender; }
+	public void setChats(List<Chat> chats) { this.chats = chats; }
+
+	/**
+	 * @return the {@link User} who initialized the local database
+	 * @since Envoy v0.2-alpha
+	 */
+	public User getUser() { return user; }
+
+	/**
+	 * @param user the user to set
+	 * @since Envoy v0.2-alpha
+	 */
+	public void setUser(User user) { this.user = user; }
 }

src/main/java/envoy/client/Settings.java

@@ -26,8 +26,6 @@ import envoy.client.ui.Theme;
 public class Settings {
 
 	// Actual settings accessible by the rest of the application
-	private String				username;
-	private String				email;
 	private boolean				enterToSend	= true;
 	private Map<String, Theme>	themes;
 	private String				currentTheme;
@@ -65,8 +63,6 @@ public class Settings {
 
 	@SuppressWarnings("unchecked")
 	private void load() {
-		setUsername(prefs.get("username", ""));
-		setEmail(prefs.get("email", ""));
 		setEnterToSend(prefs.getBoolean("enterToSend", true));
 		setCurrentTheme(prefs.get("theme", "dark"));
 
@@ -90,14 +86,12 @@ public class Settings {
 	}
 
 	/**
-	 * updates prefs when save button is clicked
+	 * Updates the preferences when the save button is clicked.
 	 * 
 	 * @throws IOException if saving was not successful
 	 * @since Envoy v0.2-alpha
 	 */
 	public void save() throws IOException {
-		prefs.put("username", getUsername());
-		prefs.put("email", getEmail());
 		prefs.put("theme", currentTheme);
 		prefs.putBoolean("enterToSend", isEnterToSend());
 
@@ -116,7 +110,7 @@ public class Settings {
 	 */
 	public void addNewThemeToMap(Theme theme) {
 		settings.getThemes().put(theme.getThemeName(), theme);
-		currentTheme = theme.getThemeName();
+		// currentTheme = theme.getThemeName();
 	}
 
 	/**
@@ -133,30 +127,6 @@ public class Settings {
 	 */
 	public void setCurrentTheme(String themeName) { currentTheme = themeName; }
 
-	/**
-	 * @return the user name
-	 * @since Envoy v0.2-alpha
-	 */
-	public String getUsername() { return username; }
-
-	/**
-	 * @param username the user name to set
-	 * @since Envoy v0.2-alpha
-	 */
-	public void setUsername(String username) { this.username = username; }
-
-	/**
-	 * @return the email associated with that user.
-	 * @since Envoy v0.2-alpha
-	 */
-	public String getEmail() { return email; }
-
-	/**
-	 * @param email the email to set
-	 * @since Envoy v0.2-alpha
-	 */
-	public void setEmail(String email) { this.email = email; }
-
 	/**
 	 * @return true, if "enter" suffices to send a message, else it has to be "ctrl"
 	 *         + "enter"

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

@@ -1,8 +1,8 @@
 package envoy.client.event;
 
 /**
- * Project: <strong>envoy-clientChess</strong><br>
+ * Project: <strong>envoy-client</strong><br>
- * File: <strong>Event.javaEvent.java</strong><br>
+ * File: <strong>Event.java</strong><br>
  * Created: <strong>04.12.2019</strong><br>
  *
  * @author Kai S. K. Engelbart

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

@@ -1,8 +1,9 @@
 package envoy.client.event;
 
 import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 /**
  * This class handles events by allowing {@link EventHandler} object to register
@@ -10,7 +11,8 @@ import java.util.List;
  * bus.<br>
  * <br>
  * The event bus is a singleton and can be used across the entire application to
- * guarantee the propagation of events.
+ * guarantee the propagation of events.<br>
+ *
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>EventBus.java</strong><br>
  * Created: <strong>04.12.2019</strong><br>
@@ -22,9 +24,10 @@ public class EventBus {
 
 	/**
 	 * Contains all {@link EventHandler} instances registered at this
-	 * {@link EventBus}.
+	 * {@link EventBus} as values mapped to by their supported {@link Event}
+	 * classes.
 	 */
-	private List<EventHandler> handlers = new ArrayList<>();
+	private Map<Class<? extends Event<?>>, List<EventHandler>> handlers = new HashMap<>();
 
 	/**
 	 * The singleton instance of this {@link EventBus} that is used across the
@@ -46,13 +49,17 @@ public class EventBus {
 	public static EventBus getInstance() { return eventBus; }
 
 	/**
-	 * Registers a list of {@link EventHandler} objects to be notified when a
+	 * Registers an {@link EventHandler} to be notified when a
-	 * {@link Event} is dispatched that they are subscribed to.
+	 * {@link Event} of a certain type is dispatched.
 	 *
-	 * @param handlers the {@link EventHandler} objects to register
+	 * @param eventClass the class which the {@link EventHandler} is subscribed to
+	 * @param handler    the {@link EventHandler} to register
 	 * @since Envoy v0.2-alpha
 	 */
-	public void register(EventHandler... handlers) { this.handlers.addAll(Arrays.asList(handlers)); }
+	public void register(Class<? extends Event<?>> eventClass, EventHandler handler) {
+		if (!handlers.containsKey(eventClass)) handlers.put(eventClass, new ArrayList<>());
+		handlers.get(eventClass).add(handler);
+	}
 
 	/**
 	 * Dispatches a {@link Event} to every {@link EventHandler} subscribed to it.
@@ -60,12 +67,15 @@ public class EventBus {
 	 * @param event the {@link Event} to dispatch
 	 * @since Envoy v0.2-alpha
 	 */
-	public void dispatch(Event<?> event) { handlers.stream().filter(h -> h.supports().contains(event.getClass())).forEach(h -> h.handle(event)); }
+	public void dispatch(Event<?> event) {
+		handlers.keySet().stream().filter(event.getClass()::isAssignableFrom).map(handlers::get).flatMap(List::stream).forEach(h -> h.handle(event));
+	}
 
 	/**
-	 * @return a list of all {@link EventHandler} instances currently registered at
+	 * @return a map of all {@link EventHandler} instances currently registered at
-	 *         this {@link EventBus}
+	 *         this {@link EventBus} with the {@link Event} classes they are
+	 *         subscribed to as keys
 	 * @since Envoy v0.2-alpha
 	 */
-	public List<EventHandler> getHandlers() { return handlers; }
+	public Map<Class<? extends Event<?>>, List<EventHandler>> getHandlers() { return handlers; }
 }

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

@@ -1,7 +1,5 @@
 package envoy.client.event;
 
-import java.util.Set;
-
 /**
  * Project: <strong>envoy-clientChess</strong><br>
  * File: <strong>EventHandler.javaEvent.java</strong><br>
@@ -17,9 +15,4 @@ public interface EventHandler {
 	 * @param event The event dispatched by the event bus, only of supported type
 	 */
 	void handle(Event<?> event);
-
-	/**
-	 * @return A set of classes this class is supposed to handle in events
-	 */
-	Set<Class<? extends Event<?>>> supports();
 }

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

@@ -0,0 +1,20 @@
+package envoy.client.event;
+
+import envoy.client.ui.Theme;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>ThemeChangeEvent.java</strong><br>
+ * Created: <strong>15 Dec 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ */
+public class ThemeChangeEvent implements Event<Theme> {
+
+	private final Theme theme;
+
+	public ThemeChangeEvent(Theme theme) { this.theme = theme; }
+
+	@Override
+	public Theme get() { return theme; }
+}

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

@@ -15,13 +15,10 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import javax.swing.DefaultListModel;
-import javax.swing.JButton;
 import javax.swing.JFrame;
 import javax.swing.JList;
 import javax.swing.JOptionPane;
 import javax.swing.JPanel;
-import javax.swing.JScrollPane;
-import javax.swing.JTextArea;
 import javax.swing.JTextPane;
 import javax.swing.ListSelectionModel;
 import javax.swing.SwingUtilities;
@@ -34,8 +31,10 @@ import envoy.client.Config;
 import envoy.client.LocalDB;
 import envoy.client.Settings;
 import envoy.client.util.EnvoyLog;
+import envoy.client.event.EventBus;
+import envoy.client.event.ThemeChangeEvent;
+
 import envoy.schema.Message;
-import envoy.schema.Sync;
 import envoy.schema.User;
 
 /**
@@ -52,20 +51,20 @@ public class ChatWindow extends JFrame {
 
 	private static final long serialVersionUID = 6865098428255463649L;
 
-	// user specific objects
+	// User specific objects
 	private Client	client;
 	private LocalDB	localDB;
+
 	// GUI components
 	private JPanel				contentPane				= new JPanel();
-	private JTextArea		messageEnterTextArea	= new JTextArea();
+	private PrimaryTextArea		messageEnterTextArea	= new PrimaryTextArea(space);
 	private JList<User>			userList				= new JList<>();
 	private Chat				currentChat;
 	private JList<Message>		messageList				= new JList<>();
-	private JScrollPane		scrollPane				= new JScrollPane();
+	private PrimaryScrollPane	scrollPane				= new PrimaryScrollPane();
 	private JTextPane			textPane				= new JTextPane();
-	// private JCheckBox jCbChangeMode;
+	private PrimaryButton		postButton				= new PrimaryButton("Post");
-	private JButton	postButton		= new JButton("Post");
+	private PrimaryButton		settingsButton			= new PrimaryButton("Settings");
-	private JButton	settingsButton	= new JButton("Settings");
 
 	private static int space = 4;
 
@@ -87,7 +86,7 @@ public class ChatWindow extends JFrame {
 			@Override
 			public void windowClosing(WindowEvent evt) {
 				try {
-					localDB.saveToLocalDB();
+					localDB.save();
 					Settings.getInstance().save();
 				} catch (IOException e1) {
 					e1.printStackTrace();
@@ -116,7 +115,6 @@ public class ChatWindow extends JFrame {
 		messageList.setBorder(new EmptyBorder(space, space, space, space));
 
 		scrollPane.setViewportView(messageList);
-		scrollPane.setBorder(null);
 
 		GridBagConstraints gbc_scrollPane = new GridBagConstraints();
 		gbc_scrollPane.fill			= GridBagConstraints.BOTH;
@@ -138,12 +136,6 @@ public class ChatWindow extends JFrame {
 				}
 			}
 		});
-		// Checks for changed Message
-		messageEnterTextArea.setWrapStyleWord(true);
-		messageEnterTextArea.setLineWrap(true);
-		messageEnterTextArea.setBorder(null);
-		messageEnterTextArea.setFont(new Font("Arial", Font.PLAIN, 17));
-		messageEnterTextArea.setBorder(new EmptyBorder(space, space, space, space));
 
 		GridBagConstraints gbc_messageEnterTextfield = new GridBagConstraints();
 		gbc_messageEnterTextfield.fill	= GridBagConstraints.BOTH;
@@ -155,7 +147,6 @@ public class ChatWindow extends JFrame {
 		contentPane.add(messageEnterTextArea, gbc_messageEnterTextfield);
 
 		// Post Button
-		postButton.setBorderPainted(false);
 		GridBagConstraints gbc_moveSelectionPostButton = new GridBagConstraints();
 
 		gbc_moveSelectionPostButton.fill	= GridBagConstraints.BOTH;
@@ -168,8 +159,6 @@ public class ChatWindow extends JFrame {
 		contentPane.add(postButton, gbc_moveSelectionPostButton);
 
 		// Settings Button
-		settingsButton.setBorderPainted(false);
-
 		GridBagConstraints gbc_moveSelectionSettingsButton = new GridBagConstraints();
 
 		gbc_moveSelectionSettingsButton.fill	= GridBagConstraints.BOTH;
@@ -208,7 +197,6 @@ public class ChatWindow extends JFrame {
 				@SuppressWarnings("unchecked")
 				final JList<User>	selectedUserList	= (JList<User>) listSelectionEvent.getSource();
 				final User			user				= selectedUserList.getSelectedValue();
-				client.setRecipient(user);
 
 				currentChat = localDB.getChats().stream().filter(chat -> chat.getRecipient().getID() == user.getID()).findFirst().get();
 
@@ -219,6 +207,7 @@ public class ChatWindow extends JFrame {
 				textPane.setText(currentChat.getRecipient().getName());
 
 				messageList.setModel(currentChat.getModel());
+				scrollPane.setChatOpened(true);
 				contentPane.revalidate();
 			}
 		});
@@ -233,25 +222,27 @@ public class ChatWindow extends JFrame {
 		gbc_userList.anchor	= GridBagConstraints.PAGE_START;
 		gbc_userList.insets	= new Insets(space, space, space, space);
 
-		changeChatWindowColors(Settings.getInstance().getCurrentTheme());
+		changeChatWindowColors(Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()));
 
 		contentPane.add(userList, gbc_userList);
 		contentPane.revalidate();
 
+		EventBus.getInstance().register(ThemeChangeEvent.class, (evt) -> changeChatWindowColors((Theme) evt.get()));
+
 		loadUsersAndChats();
-		startSyncThread(Config.getInstance().getSyncTimeout());
+
+		if (client.isOnline()) startSyncThread(Config.getInstance().getSyncTimeout());
 
 		contentPane.revalidate();
 	}
 
 	/**
 	 * Used to immediately reload the ChatWindow when settings were changed.
-	 * @param themeName the name of the theme to change the colors into
+     *
+     * @param theme the theme to change colors into
 	 * @since Envoy v0.1-alpha
 	 */
-	public void changeChatWindowColors(String themeName) {
+	private void changeChatWindowColors(Theme theme) {
-		Theme theme = Settings.getInstance().getThemes().get(themeName);
-
 		// contentPane
 		contentPane.setBackground(theme.getBackgroundColor());
 		contentPane.setForeground(theme.getUserNameColor());
@@ -261,8 +252,9 @@ public class ChatWindow extends JFrame {
 		messageList.setForeground(theme.getMessageColorChat());
 		messageList.setBackground(theme.getCellColor());
 		// scrollPane
-		scrollPane.setForeground(theme.getBackgroundColor());
+		scrollPane.applyTheme(theme);
-		scrollPane.setBackground(theme.getCellColor());
+		scrollPane.autoscroll();
+
 		// messageEnterTextArea
 		messageEnterTextArea.setCaretColor(theme.getTypingMessageColor());
 		messageEnterTextArea.setForeground(theme.getTypingMessageColor());
@@ -316,9 +308,8 @@ public class ChatWindow extends JFrame {
 	 */
 	private void loadUsersAndChats() {
 		new Thread(() -> {
-			Sync					users			= client.getUsersListXml();
 			DefaultListModel<User> userListModel = new DefaultListModel<>();
-			users.getUsers().forEach(user -> {
+			localDB.getUsers().values().forEach(user -> {
 				userListModel.addElement(user);
 
 				// Check if user exists in local DB
@@ -342,7 +333,11 @@ public class ChatWindow extends JFrame {
 			new Thread(() -> {
 
 				// Synchronize
+				try {
 					localDB.applySync(client.sendSync(client.getSender().getID(), localDB.fillSync(client.getSender().getID())));
+				} catch (Exception e) {
+					logger.log(Level.SEVERE, "Could not perform sync", e);
+				}
 
 				// Process unread messages
 				localDB.addUnreadMessagesToLocalDB();

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

@@ -0,0 +1,63 @@
+package envoy.client.ui;
+
+import java.awt.Graphics;
+
+import javax.swing.JButton;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>PrimaryButton.javaEvent.java</strong><br>
+ * Created: <strong>07.12.2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @author Maximilian K&auml;fer
+ * @since Envoy v0.2-alpha
+ */
+public class PrimaryButton extends JButton {
+
+	private static final long serialVersionUID = 3662266120667728364L;
+
+	private int arcSize;
+
+	/**
+	 * Creates a primary button
+	 *
+	 * @param title the title of the button
+	 * @since Envoy 0.2-alpha
+	 */
+	public PrimaryButton(String title) { this(title, 6); }
+
+	/**
+	 * Creates a primary button
+	 *
+	 * @param title   the title of the button
+	 * @param arcSize the size of the arc used to draw the round button edges
+	 * @since Envoy 0.2-alpha
+	 */
+	public PrimaryButton(String title, int arcSize) {
+		super(title);
+		setBorderPainted(false);
+		setFocusPainted(false);
+		setContentAreaFilled(false);
+		this.arcSize = arcSize;
+	}
+
+	@Override
+	protected void paintComponent(Graphics g) {
+		g.setColor(getBackground());
+		g.fillRoundRect(0, 0, getWidth(), getHeight(), arcSize, arcSize);
+		super.paintComponent(g);
+	}
+
+	/**
+	 * @return the arcSize
+	 * @since Envoy 0.2-alpha
+	 */
+	public int getArcSize() { return arcSize; }
+
+	/**
+	 * @param arcSize the arcSize to set
+	 * @since Envoy 0.2-alpha
+	 */
+	public void setArcSize(int arcSize) { this.arcSize = arcSize; }
+}

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

@@ -0,0 +1,115 @@
+package envoy.client.ui;
+
+import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.Graphics;
+import java.awt.Graphics2D;
+import java.awt.Rectangle;
+import java.awt.RenderingHints;
+
+import javax.swing.JButton;
+import javax.swing.JComponent;
+import javax.swing.JScrollBar;
+import javax.swing.plaf.basic.BasicScrollBarUI;
+
+import envoy.client.Settings;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>PrimaryScrollBar.java</strong><br>
+ * Created: <strong>14.12.2019</strong><br>
+ *
+ * @author Maximilian K&auml;fer
+ * @since Envoy v0.2-alpha
+ */
+public class PrimaryScrollBar extends BasicScrollBarUI {
+
+	private final Dimension	d	= new Dimension();
+	private final int		arcSize;
+	private final Color		scrollBarColor;
+	private final Color		hoverColor;
+	private final Color		draggingColor;
+	private final boolean	isVertical;
+
+	/**
+	 * Initializes a {@link PrimaryScrollBar} with a color scheme.
+	 *
+	 * @param arcSize        the size of the arc used to draw the round scroll bar
+	 *                       edges
+	 * @param scrollBarColor the default color
+	 * @param hoverColor     the color while hovering
+	 * @param draggingColor  the color while dragging
+	 * @param isVertical     indicates whether this is a vertical
+	 *                       {@link PrimaryScrollBar}
+	 */
+	public PrimaryScrollBar(int arcSize, Color scrollBarColor, Color hoverColor, Color draggingColor, boolean isVertical) {
+		this.arcSize		= arcSize;
+		this.scrollBarColor	= scrollBarColor;
+		this.hoverColor		= hoverColor;
+		this.draggingColor	= draggingColor;
+		this.isVertical		= isVertical;
+	}
+
+	/**
+	 * Initializes a {@link PrimaryScrollBar} using a color scheme specified in a
+	 * {@link Theme}
+	 *
+	 * @param theme      the {@link Theme} to be applied to this
+	 *                   {@link PrimaryScrollBar}
+	 * @param isVertical indicates whether this is a vertical
+	 *                   {@link PrimaryScrollBar}
+	 */
+	public PrimaryScrollBar(Theme theme, boolean isVertical) {
+		this(5, theme.getInteractableBackgroundColor(), new Color(theme.getInteractableBackgroundColor().getRGB() - 50),
+				new Color(theme.getInteractableBackgroundColor().getRGB() + 170), isVertical);
+	}
+
+	@Override
+	protected JButton createDecreaseButton(int orientation) {
+		JButton button = new JButton();
+		button.setPreferredSize(d);
+		return button;
+	}
+
+	@Override
+	protected JButton createIncreaseButton(int orientation) {
+		JButton button = new JButton();
+		button.setPreferredSize(d);
+		return button;
+	}
+
+	@Override
+	protected void paintTrack(Graphics g, JComponent c, Rectangle r) {}
+
+	@Override
+	protected void paintThumb(Graphics g, JComponent c, Rectangle r) {
+		Graphics2D g2 = (Graphics2D) g.create();
+		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
+		Color		color;
+		JScrollBar	sb	= (JScrollBar) c;
+
+		if (!sb.isEnabled()) return;
+
+		if (isDragging) color = draggingColor;
+		else if (isThumbRollover()) color = hoverColor;
+		else color = scrollBarColor;
+
+		g2.setPaint(color);
+		if (isVertical) {
+			g2.fillRoundRect(r.x - 9, r.y, r.width, r.height, arcSize, arcSize);
+			g2.setPaint(Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getCellColor());
+			g2.drawRoundRect(r.x - 9, r.y, r.width, r.height, arcSize, arcSize);
+		} else {
+			g2.fillRoundRect(r.x, r.y + 9, r.width, r.height - 10, arcSize, arcSize);
+			g2.setPaint(Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getCellColor());
+			g2.drawRoundRect(r.x, r.y + 9, r.width, r.height - 10, arcSize, arcSize);
+		}
+		g2.dispose();
+	}
+
+	@Override
+	protected void setThumbBounds(int x, int y, int width, int height) {
+		super.setThumbBounds(x, y, width, height);
+		scrollbar.repaint();
+	}
+}

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

@@ -0,0 +1,83 @@
+package envoy.client.ui;
+
+import javax.swing.JScrollPane;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>PrimaryScrollPane.java</strong><br>
+ * Created: <strong>15 Dec 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @author Maximilian K&auml;fer
+ */
+public class PrimaryScrollPane extends JScrollPane {
+
+	private static final long serialVersionUID = -4786837444056228439L;
+
+	private int		verticalScrollBarMaximum	= getVerticalScrollBar().getMaximum();
+	private boolean	chatOpened					= false;
+
+	/**
+	 * Initializes a {@link JScrollPane} with the primary Envoy design scheme
+	 *
+	 * @since Envoy v0.2-alpha
+	 */
+	public PrimaryScrollPane() { setBorder(null); }
+
+	/**
+	 * Styles the vertical and horizontal scroll bars.
+	 *
+	 * @param theme
+	 * @since Envoy v0.2-alpha
+	 */
+	public void applyTheme(Theme theme) {
+		setForeground(theme.getBackgroundColor());
+		setBackground(theme.getCellColor());
+
+		getVerticalScrollBar().setBackground(theme.getCellColor());
+		getVerticalScrollBar().setUI(new PrimaryScrollBar(theme, true));
+
+		getHorizontalScrollBar().setBackground(theme.getCellColor());
+		getHorizontalScrollBar().setUI(new PrimaryScrollBar(theme, false));
+	}
+
+	/**
+	 * Implements <b>autoscroll functionality</b> for the vertical scroll bar. </br>
+	 * </br>
+	 * Functionality to automatically scroll down when user views </br>
+	 * the bottom of the chat while there are new messages added. </br>
+	 * </br>
+	 * When chat is opened, the vertical scroll bar starts at the bottom. </br>
+	 * </br>
+	 * When rereading messages, the chat doesn't scroll down if new messages </br>
+	 * are added. (Besides see first point)
+	 *
+	 * @since Envoy v0.2-alpha
+	 */
+	public void autoscroll() {
+		// Automatic scrolling to the bottom
+		getVerticalScrollBar().addAdjustmentListener(e -> {
+			if (verticalScrollBarMaximum == e.getAdjustable().getMaximum()) return;
+
+			if (chatOpened) {
+				e.getAdjustable().setValue(e.getAdjustable().getMaximum());
+				verticalScrollBarMaximum	= getVerticalScrollBar().getMaximum();
+				chatOpened					= false;
+				return;
+			}
+			if (getVerticalScrollBar().getValue() + getVerticalScrollBar().getVisibleAmount() + 100 >= getVerticalScrollBar().getMaximum()) {
+				e.getAdjustable().setValue(e.getAdjustable().getMaximum());
+				verticalScrollBarMaximum = getVerticalScrollBar().getMaximum();
+			}
+		});
+	}
+
+	/**
+	 * Indicates a chat being opened by the user to this {@link PrimaryScrollPane}
+	 * triggering it to automatically scroll down.
+	 *
+	 * @param chatOpened indicates the chat opening status
+	 * @since Envoy v0.2-alpha
+	 */
+	public void setChatOpened(boolean chatOpened) { this.chatOpened = chatOpened; }
+}

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

@@ -0,0 +1,67 @@
+package envoy.client.ui;
+
+import java.awt.Font;
+import java.awt.Graphics;
+
+import javax.swing.JTextArea;
+import javax.swing.border.EmptyBorder;
+
+/**
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>PrimaryTextArea.javaEvent.java</strong><br>
+ * Created: <strong>07.12.2019</strong><br>
+ * 
+ * @author Maximilian K&auml;fer
+ * @since Envoy v0.2-alpha
+ */
+public class PrimaryTextArea extends JTextArea {
+
+	private static final long	serialVersionUID	= -5829028696155434913L;
+	private int					arcSize;
+
+	/**
+	 * Creates the text area
+	 * 
+	 * @param borderSpace
+	 * @since Envoy 0.2-alpha
+	 */
+	public PrimaryTextArea(int borderSpace) { this(6, borderSpace); }
+
+	/**
+	 * Creates the text area
+	 * 
+	 * @param arcSize     is the diameter of the arc at the four corners.
+	 * @param borderSpace is the insets of the border on all four sides.
+	 * @since Envoy 0.2-alpha
+	 */
+	public PrimaryTextArea(int arcSize, int borderSpace) {
+		super();
+		setWrapStyleWord(true);
+		setLineWrap(true);
+		setBorder(null);
+		setFont(new Font("Arial", Font.PLAIN, 17));
+		setBorder(new EmptyBorder(borderSpace, borderSpace, borderSpace, borderSpace));
+		setOpaque(false);
+
+		this.arcSize = arcSize;
+	}
+
+	@Override
+	protected void paintComponent(Graphics g) {
+		g.setColor(getBackground());
+		g.fillRoundRect(0, 0, getWidth(), getHeight(), arcSize, arcSize);
+		super.paintComponent(g);
+	}
+
+	/**
+	 * @return the arcSize - the diameter of the arc at the four corners.
+	 * @since Envoy 0.2-alpha
+	 */
+	public int getArcSize() { return arcSize; }
+
+	/**
+	 * @param arcSize the arcSize to set
+	 * @since Envoy 0.2-alpha
+	 */
+	public void setArcSize(int arcSize) { this.arcSize = arcSize; }
+}

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

@@ -28,6 +28,8 @@ import javax.swing.ListSelectionModel;
 
 import envoy.client.Settings;
 import envoy.client.util.EnvoyLog;
+import envoy.client.event.EventBus;
+import envoy.client.event.ThemeChangeEvent;
 
 /**
  * This class provides the GUI to change the user specific settings.
@@ -46,12 +48,12 @@ public class SettingsScreen extends JDialog {
 	private final JPanel		contentPanel		= new JPanel();
 
 	private DefaultListModel<String>	optionsListModel	= new DefaultListModel<>();
-	private final JList<String>			options				= new JList<String>();
+	private final JList<String>			options				= new JList<>();
 	private JPanel						buttonPane			= new JPanel();
 
 	private JPanel				themeContent	= new JPanel();
 	private String[]			themeArray		= Settings.getInstance().getThemes().keySet().toArray(new String[0]);
-	private JComboBox<String>	themes			= new JComboBox<String>(themeArray);
+	private JComboBox<String>	themes			= new JComboBox<>(themeArray);
 
 	private GridBagConstraints gbc_themeContent = new GridBagConstraints();
 
@@ -61,11 +63,13 @@ public class SettingsScreen extends JDialog {
 	private JButton	cancelButton			= new JButton("Cancel");
 
 	private static int	space			= 5;
-	private Theme		selectedTheme	= Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme());
+
 	private Theme temporaryTheme;
 
 	private static final Logger logger = EnvoyLog.getLogger(SettingsScreen.class.getSimpleName());
 
+	private static SettingsScreen settingsScreen;
+
 	// TODO: Add a JPanel with all the Information necessary:
 	// change (Picture,Username, Email, Password) and toggle(light/dark mode,
 	// "ctrl+enter"/"enter"
@@ -121,11 +125,6 @@ public class SettingsScreen extends JDialog {
 
 			Theme theme = Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme());
 
-			options.setSelectionForeground(theme.getUserNameColor());
-			options.setSelectionBackground(theme.getSelectionColor());
-			options.setForeground(theme.getUserNameColor());
-			options.setBackground(theme.getCellColor());
-
 			GridBagConstraints gbc_optionsList = new GridBagConstraints();
 			gbc_optionsList.fill	= GridBagConstraints.BOTH;
 			gbc_optionsList.gridx	= 0;
@@ -147,9 +146,6 @@ public class SettingsScreen extends JDialog {
 
 			GridBagLayout gbl_themeLayout = new GridBagLayout();
 
-			themeContent.setForeground(theme.getUserNameColor());
-			themeContent.setBackground(theme.getCellColor());
-
 			gbl_themeLayout.columnWidths	= new int[] { 1, 1 };
 			gbl_themeLayout.rowHeights		= new int[] { 1, 1 };
 			gbl_themeLayout.columnWeights	= new double[] { 1.0, 1.0 };
@@ -157,8 +153,6 @@ public class SettingsScreen extends JDialog {
 
 			themeContent.setLayout(gbl_themeLayout);
 
-			themes.setBackground(theme.getUserNameColor());
-			themes.setForeground(theme.getBackgroundColor());
 			themes.setSelectedItem(Settings.getInstance().getCurrentTheme());
 
 			themes.addItemListener(new ItemListener() {
@@ -183,27 +177,27 @@ public class SettingsScreen extends JDialog {
 			colorsPanel.setLayout(new BoxLayout(colorsPanel, BoxLayout.Y_AXIS));
 			colorsPanel.setAlignmentX(Component.LEFT_ALIGNMENT);
 
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getBackgroundColor(), "Background", 1);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getBackgroundColor(), "Background", 0);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getCellColor(), "Cells", 2);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getCellColor(), "Cells", 1);
 			buildCustomizeElement(new JPanel(),
 					new JButton(),
 					new JTextPane(),
 					theme,
 					theme.getInteractableForegroundColor(),
 					"Interactable Foreground",
-					3);
+					2);
 			buildCustomizeElement(new JPanel(),
 					new JButton(),
 					new JTextPane(),
 					theme,
 					theme.getInteractableBackgroundColor(),
 					"Interactable Background",
-					4);
+					3);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getMessageColorChat(), "Messages Chat", 5);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getMessageColorChat(), "Messages Chat", 4);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getDateColorChat(), "Date Chat", 6);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getDateColorChat(), "Date Chat", 5);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getSelectionColor(), "Selection", 7);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getSelectionColor(), "Selection", 6);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getTypingMessageColor(), "Typing Message", 8);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getTypingMessageColor(), "Typing Message", 7);
-			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getUserNameColor(), "User Names", 9);
+			buildCustomizeElement(new JPanel(), new JButton(), new JTextPane(), theme, theme.getUserNameColor(), "User Names", 8);
 
 			GridBagConstraints gbc_colorsPanel = new GridBagConstraints();
 			gbc_colorsPanel.fill		= GridBagConstraints.HORIZONTAL;
@@ -239,8 +233,6 @@ public class SettingsScreen extends JDialog {
 					contentPanel.revalidate();
 					contentPanel.repaint();
 
-					// TODO: Create new Theme
-
 				} catch (Exception e) {
 					logger.info("New theme couldn't be created! " + e);
 					e.printStackTrace();
@@ -287,18 +279,15 @@ public class SettingsScreen extends JDialog {
 				getRootPane().setDefaultButton(okButton);
 				okButton.addActionListener((evt) -> {
 					try {
-						Settings.getInstance().setUsername(Settings.getInstance().getUsername());// still temporary
-
-						Settings.getInstance().setEmail(Settings.getInstance().getEmail());// still temporary value
-
 						Settings.getInstance().setEnterToSend(Settings.getInstance().isEnterToSend());// still temporary
 
 						Settings.getInstance().setCurrentTheme(selectedTheme.getThemeName());
 						logger.log(Level.FINER, selectedTheme.getThemeName());
 
-						changeSettingsScreenColors(Settings.getInstance().getCurrentTheme());
+						final Theme currentTheme = Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme());
-						updateColorVariables(Settings.getInstance().getCurrentTheme());
+						changeSettingsScreenColors(currentTheme);
-
+						updateColorVariables(currentTheme);
+						EventBus.getInstance().dispatch(new ThemeChangeEvent(currentTheme));
 						Settings.getInstance().save();
 
 						revalidate();
@@ -311,14 +300,14 @@ public class SettingsScreen extends JDialog {
 				});
 			}
 		}
-		changeSettingsScreenColors(Settings.getInstance().getCurrentTheme());
+
+		changeSettingsScreenColors(Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()));
         
         setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
 		setModal(true);
 	}
 
-	private void changeSettingsScreenColors(String key) {
+	private void changeSettingsScreenColors(Theme theme) {
-		Theme theme = Settings.getInstance().getThemes().get(key);
 		// whole JDialog
 		setBackground(theme.getBackgroundColor());
 		// contentPanel
@@ -340,8 +329,8 @@ public class SettingsScreen extends JDialog {
 		themeContent.setForeground(theme.getUserNameColor());
 		themeContent.setBackground(theme.getCellColor());
 		// themes
-		themes.setBackground(theme.getUserNameColor());
+		themes.setBackground(theme.getBackgroundColor());
-		themes.setForeground(theme.getBackgroundColor());
+		themes.setForeground(getInvertedColor(theme.getBackgroundColor()));
 
 		createNewThemeButton.setBackground(theme.getInteractableBackgroundColor());
 		createNewThemeButton.setForeground(theme.getInteractableForegroundColor());
@@ -349,19 +338,8 @@ public class SettingsScreen extends JDialog {
 
 	}
 
-	private void updateColorVariables(String key) {
+	private void updateColorVariables(Theme theme) {
-		Theme theme = Settings.getInstance().getThemes().get(key);
+		temporaryTheme = new Theme("temporaryTheme", theme);
-
-		temporaryTheme = new Theme("temporaryTheme",
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getBackgroundColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getCellColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getInteractableForegroundColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getInteractableBackgroundColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getMessageColorChat(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getDateColorChat(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getSelectionColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getTypingMessageColor(),
-				Settings.getInstance().getThemes().get(Settings.getInstance().getCurrentTheme()).getUserNameColor());
 
 		colorsPanel.removeAll();
 
@@ -372,7 +350,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getBackgroundColor(),
 				"Background",
-				1);
+				0);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -380,7 +358,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getCellColor(),
 				"Cells",
-				2);
+				1);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -388,7 +366,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getInteractableForegroundColor(),
 				"Interactable Foreground",
-				3);
+				2);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -396,7 +374,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getInteractableBackgroundColor(),
 				"Interactable Background",
-				4);
+				3);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -404,7 +382,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getMessageColorChat(),
 				"Messages Chat",
-				5);
+				4);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -412,7 +390,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getDateColorChat(),
 				"Date Chat",
-				6);
+				5);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -420,7 +398,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getSelectionColor(),
 				"Selection",
-				7);
+				6);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -428,7 +406,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getTypingMessageColor(),
 				"Typing Message",
-				8);
+				7);
 		buildCustomizeElement(new JPanel(),
 
 				new JButton(),
@@ -436,7 +414,7 @@ public class SettingsScreen extends JDialog {
 				theme,
 				theme.getUserNameColor(),
 				"User Names",
-				9);
+				8);
 
 		GridBagConstraints gbc_createNewTheme = new GridBagConstraints();
 		gbc_createNewTheme.gridx	= 0;
@@ -450,7 +428,7 @@ public class SettingsScreen extends JDialog {
 	private void buildCustomizeElement(JPanel panel, JButton button, JTextPane textPane, Theme theme, Color color, String name, int yIndex) {
 		textPane.setFont(new Font("Arial", Font.PLAIN, 14));
 		textPane.setBackground(theme.getBackgroundColor());
-		textPane.setForeground(theme.getUserNameColor());
+		textPane.setForeground(getInvertedColor(theme.getBackgroundColor()));
 		textPane.setText(name);
 		textPane.setEditable(false);
 
@@ -461,18 +439,13 @@ public class SettingsScreen extends JDialog {
 			try {
 				Color newColor = JColorChooser.showDialog(null, "Choose a color", color);
 				if (newColor.getRGB() != color.getRGB()) {
-					logger.log(Level.FINEST, String.valueOf(color.getRGB()));
+					logger.log(Level.FINEST, "New Color: " + String.valueOf(color.getRGB()));
-					Color[] colorsArray = temporaryTheme.getAllColors();
+					// TODO: When Theme changed in same settings screen, color variable doesnt
-					for (int i = 0; i < colorsArray.length; i++) {
+					// update.
-						if (color.getRGB() == colorsArray[i].getRGB()) {
+					temporaryTheme.setColor(yIndex, newColor);
-							temporaryTheme.setColor(i, newColor);
 					createNewThemeButton.setEnabled(true);
-							break;
-						}
-
 				}
 				button.setBackground(newColor);
-				}
 
 			} catch (Exception e) {
 				logger.info("An error occured while opening Color Chooser: " + e);
@@ -488,4 +461,5 @@ public class SettingsScreen extends JDialog {
 		colorsPanel.add(panel);
 	}
 
+	private Color getInvertedColor(Color color) { return new Color(255 - color.getRed(), 255 - color.getGreen(), 255 - color.getBlue()); }
 }

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

@@ -2,9 +2,9 @@ package envoy.client.ui;
 
 import java.awt.EventQueue;
 import java.io.IOException;
-import java.util.Properties;
 import java.util.logging.Logger;
 
+import javax.swing.JFrame;
 import javax.swing.JOptionPane;
 
 import envoy.client.Client;
@@ -12,11 +12,13 @@ import envoy.client.Config;
 import envoy.client.LocalDB;
 import envoy.client.Settings;
 import envoy.client.util.EnvoyLog;
+
 import envoy.exception.EnvoyException;
+import envoy.schema.User;
 
 /**
  * Starts the Envoy client and prompts the user to enter their name.
- * 
+ * <br>
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>Startup.java</strong><br>
  * Created: <strong>12 Oct 2019</strong><br>
@@ -33,34 +35,69 @@ public class Startup {
 	public static void main(String[] args) {
 		Config config = Config.getInstance();
 
-		// Load the configuration from client.properties first
-		ClassLoader loader = Thread.currentThread().getContextClassLoader();
 		try {
-			Properties configProperties = new Properties();
+			// Load the configuration from client.properties first
-			configProperties.load(loader.getResourceAsStream("client.properties"));
+			config.load();
-			config.load(configProperties);
-		} catch (IOException e) {
-			e.printStackTrace();
-		}
 
 			// Override configuration values with command line arguments
 			if (args.length > 0) config.load(args);
 
-		if (!config.isInitialized()) {
+			// Check if all configuration values have been initialized
-			logger.severe("Server or port are not defined. Exiting...");
+			if (!config.isInitialized()) throw new EnvoyException("Server or port are not defined");
-			JOptionPane.showMessageDialog(null, "Error loading configuration values.", "Configuration error", JOptionPane.ERROR_MESSAGE);
+		} catch (Exception e) {
+			JOptionPane
+				.showMessageDialog(null, "Error loading configuration values: \n" + e.toString(), "Configuration error", JOptionPane.ERROR_MESSAGE);
 			System.exit(1);
+			e.printStackTrace();
 		}
 
+		// Ask the user for their user name
 		String userName = JOptionPane.showInputDialog("Please enter your username");
 		if (userName == null || userName.isEmpty()) {
 			logger.severe("User name is not set or empty. Exiting...");
 			System.exit(1);
 		}
-		Client	client	= new Client(config, userName);
+		
-		LocalDB	localDB	= new LocalDB(client.getSender());
+		// Initialize the local database
+		LocalDB localDB;
 		try {
-			localDB.initializeDBFile(config.getLocalDB());
+			localDB = new LocalDB(config.getLocalDB());
+		} catch (IOException e3) {
+			logger.log(Level.SEVERE, "Could not initialize local database", e3);
+			JOptionPane.showMessageDialog(null, "Could not initialize local database!\n" + e3.toString());
+			System.exit(1);
+			return;
+		}
+
+		// Acquire the client user (with ID) either from the server or from the local
+		// database, which triggers offline mode
+		Client client = new Client(config);
+		try {
+			// Try entering online mode first
+			client.onlineInit(userName);
+		} catch (Exception e1) {
+			logger.warning("Could not connect to server. Trying offline mode...");
+			try {
+				// Try entering offline mode
+				localDB.loadUsers();
+				User clientUser = localDB.getUsers().get(userName);
+				if(clientUser == null)
+					throw new EnvoyException("Could not enter offline mode: user name unknown");
+				client.setSender(clientUser);
+			} catch(Exception e2) {
+				JOptionPane.showMessageDialog(null, e2.toString(), "Client error", JOptionPane.ERROR_MESSAGE);
+				System.exit(1);
+				return;
+			}
+		}
+		
+		// Set client user in local database
+		localDB.setUser(client.getSender());
+		
+		// Initialize chats in local database
+		try {
+			localDB.initializeDBFile();
+			localDB.loadChats();
 		} catch (EnvoyException e) {
 			e.printStackTrace();
 			JOptionPane.showMessageDialog(null,
@@ -68,7 +105,12 @@ public class Startup {
 					"Local DB error",
 					JOptionPane.WARNING_MESSAGE);
 		}
-		Settings.getInstance().setUsername(userName);
+		
+		logger.info("Client user ID: " + client.getSender().getID());
+
+		// Save all users to the local database
+		if(client.isOnline())
+			localDB.setUsers(client.getUsers());
 		
 		EventQueue.invokeLater(() -> {
 			try {
@@ -77,6 +119,9 @@ public class Startup {
 
 				try {
 					new StatusTrayIcon(chatWindow).show();
+					
+					// If the tray icon is supported, hide the chat window on close
+					chatWindow.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
 				} catch (EnvoyException e) {
 					logger.warning("The StatusTrayIcon is not supported on this platform!");
 				}

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

@@ -11,12 +11,8 @@ import java.awt.TrayIcon.MessageType;
 import java.awt.Window;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
-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;
@@ -29,7 +25,7 @@ import envoy.schema.Message;
  * @author Kai S. K. Engelbart
  * @since Envoy v0.2-alpha
  */
-public class StatusTrayIcon implements EventHandler {
+public class StatusTrayIcon {
 
 	/**
 	 * The {@link TrayIcon} provided by the System Tray API for controlling the
@@ -81,8 +77,14 @@ public class StatusTrayIcon implements EventHandler {
 			public void windowLostFocus(WindowEvent e) { displayMessages = true; }
 		});
 
+		// Show the window if the user clicks on the icon
+		trayIcon.addActionListener((evt) -> { focusTarget.setVisible(true); focusTarget.requestFocus(); });
+
 		// Start processing message events
-		EventBus.getInstance().register(this);
+		EventBus.getInstance().register(MessageCreationEvent.class, (evt) -> {
+			if (displayMessages)
+				trayIcon.displayMessage("New message received", ((MessageCreationEvent) evt).get().getContent().get(0).getText(), MessageType.INFO);
+		});
 	}
 
 	/**
@@ -99,31 +101,4 @@ public class StatusTrayIcon implements EventHandler {
 			throw new EnvoyException("Could not attach Envoy tray icon to system tray.", e);
 		}
 	}
-
-	/**
-	 * Notifies the user of a message by displaying a pop-up every time a new
-	 * message is received.
-	 *
-	 * @since Envoy v0.2-alpha
-	 */
-	@Override
-	public void handle(Event<?> event) {
-		System.out.println("Message received. Displaying message: " + displayMessages);
-		if (displayMessages)
-			trayIcon.displayMessage("New message received", ((MessageCreationEvent) event).get().getContent().get(0).getText(), MessageType.INFO);
-	}
-
-	/**
-	 * The {@link StatusTrayIcon} only reacts to {@link MessageCreationEvent}
-	 * instances which signify newly received messages.
-	 *
-	 * @return A set with the single element {@code MessageCreationEvent.class}
-	 * @since Envoy v0.2-alpha
-	 */
-	@Override
-	public Set<Class<? extends Event<?>>> supports() {
-		Set<Class<? extends Event<?>>> supportedEvents = new HashSet<>();
-		supportedEvents.add(MessageCreationEvent.class);
-		return supportedEvents;
-	}
 }

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

@@ -43,8 +43,9 @@ public class Theme implements Serializable {
 	}
 
 	public Theme(String name, Theme other) {
-		this(name, other.backgroundColor, other.cellColor, other.interactableBackgroundColor, other.interactableForegroundColor,
+		this(name, other.backgroundColor, other.cellColor, other.interactableForegroundColor,
-				other.messageColorChat, other.dateColorChat, other.selectionColor, other.typingMessageColor, other.userNameColor);
+				other.interactableBackgroundColor, other.messageColorChat, other.dateColorChat, other.selectionColor,
+				other.typingMessageColor, other.userNameColor);
 	}
 
 	/**
@@ -107,25 +108,6 @@ public class Theme implements Serializable {
 	 */
 	public Color getUserNameColor() { return userNameColor; }
 
-	/**
-	 * @return a color array containing all colors of this theme
-	 * @since Envoy v0.2-alpha
-	 */
-	public Color[] getAllColors() {
-		Color[] c = new Color[9];
-		c[0]	= backgroundColor;
-		c[1]	= cellColor;
-		c[2]	= interactableForegroundColor;
-		c[3]	= interactableBackgroundColor;
-		c[4]	= messageColorChat;
-		c[5]	= dateColorChat;
-		c[6]	= selectionColor;
-		c[7]	= typingMessageColor;
-		c[8]	= userNameColor;
-
-		return c;
-	}
-
 	/**
 	 * Sets the a specific {@link Color} in this theme to a new {@link Color}
 	 *