client/src/main/java/envoy/client/ui/controller/ChatScene.java

@@ -191,7 +191,6 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Set the design of the box in the upper-left corner
 		settingsButton.setAlignment(Pos.BOTTOM_RIGHT);
-		HBox.setHgrow(spaceBetweenUserAndSettingsButton, Priority.ALWAYS);
 		generateOwnStatusControl();
 
 		Platform.runLater(() -> {
@@ -727,6 +726,7 @@ public final class ChatScene implements EventListener, Restorable {
 			// Else prepend it to the HBox children
 			final var ownUserControl = new ContactControl(localDB.getUser());
 			ownUserControl.setAlignment(Pos.CENTER_LEFT);
+			HBox.setHgrow(ownUserControl, Priority.NEVER);
 			ownContactControl.getChildren().add(0, ownUserControl);
 		}
 	}

client/src/main/resources/fxml/ChatScene.fxml

@@ -167,7 +167,7 @@
 				<HBox id="transparent-background" fx:id="ownContactControl">
 					<children>
 						<Region id="transparent-background" prefWidth="120"
-							fx:id="spaceBetweenUserAndSettingsButton" />
+							fx:id="spaceBetweenUserAndSettingsButton" HBox.hgrow="ALWAYS" />
 						<Button fx:id="settingsButton" mnemonicParsing="false"
 							onAction="#settingsButtonClicked" prefHeight="30.0"
 							prefWidth="30.0" text="" alignment="CENTER">

common/src/main/java/envoy/event/contact/ContactDeletionSinceLastLogin.java

@@ -0,0 +1,15 @@
+package envoy.event.contact;
+
+import envoy.event.Event.Valueless;
+
+/**
+ * Conveys that either a direct contact or a group member has been deleted while
+ * the user has been offline.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Common v0.3-beta
+ */
+public class ContactDeletionSinceLastLogin extends Valueless {
+
+	private static final long serialVersionUID = 1L;
+}

common/src/main/java/envoy/util/SerializationUtils.java

@@ -105,7 +105,7 @@ public final class SerializationUtils {
 			file.createNewFile();
 		}
 		try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file))) {
-			for (var obj : objs)
+			for (final var obj : objs)
 				out.writeObject(obj);
 		}
 	}
@@ -119,7 +119,7 @@ public final class SerializationUtils {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public static byte[] writeToByteArray(Object obj) throws IOException {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+		final var baos = new ByteArrayOutputStream();
 		try (ObjectOutputStream oout = new ObjectOutputStream(baos)) {
 			oout.writeObject(obj);
 		}
@@ -137,10 +137,10 @@ public final class SerializationUtils {
 	 */
 	public static void writeBytesWithLength(Object obj, OutputStream out) throws IOException {
 		// Serialize object to byte array
-		byte[] objBytes = writeToByteArray(obj);
+		final var objBytes = writeToByteArray(obj);
 
 		// Get length of byte array in bytes
-		byte[] objLen = intToBytes(objBytes.length);
+		final var objLen = intToBytes(objBytes.length);
 
 		// Write length and byte array
 		out.write(objLen);

server/src/main/java/envoy/server/data/Message.java

@@ -55,7 +55,7 @@ public class Message {
 	@JoinColumn
 	protected User sender;
 
-	@ManyToOne
+	@ManyToOne(cascade = CascadeType.REMOVE)
 	@JoinColumn
 	protected Contact recipient;
 

server/src/main/java/envoy/server/data/PersistenceManager.java

@@ -97,7 +97,20 @@ public final class PersistenceManager {
 	 * @param contact the {@link Contact} to delete
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void deleteContact(Contact contact) { remove(contact); }
+	public void deleteContact(Contact contact) {
+		transaction(() -> {
+
+			// Remove this contact from the contact list of his contacts
+			for (final var remainingContact : contact.getContacts())
+				remainingContact.getContacts().remove(contact);
+
+			// Delete messages sent or received by this contact
+			entityManager.createQuery("DELETE FROM Message m WHERE (m.sender = :contact OR m.recipient = :contact )")
+				.setParameter("contact", contact)
+				.executeUpdate();
+		});
+		remove(contact);
+	}
 
 	/**
 	 * Deletes a {@link Message} in the database.
@@ -232,7 +245,7 @@ public final class PersistenceManager {
 		final var	c1	= getContactByID(contactID1);
 		final var	c2	= getContactByID(contactID2);
 
-		// Add users to each others contact lists
+		// Add users to each others contact list
 		c1.getContacts().add(c2);
 		c2.getContacts().add(c1);
 
@@ -240,6 +253,27 @@ public final class PersistenceManager {
 		transaction(() -> { entityManager.merge(c1); entityManager.merge(c2); });
 	}
 
+	/**
+	 * Removes a contact from the contact list of another contact and vice versa.
+	 *
+	 * @param contactID1 the ID of the first contact
+	 * @param contactID2 the ID of the second contact
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void removeContactBidirectional(long contactID1, long contactID2) {
+
+		// Get users by ID
+		final var	c1	= getContactByID(contactID1);
+		final var	c2	= getContactByID(contactID2);
+
+		// Remove users from each others contact list
+		c1.getContacts().remove(c2);
+		c2.getContacts().remove(c1);
+
+		// Synchronize changes with the database
+		transaction(() -> { entityManager.merge(c1); entityManager.merge(c2); });
+	}
+
 	/**
 	 * @param user the User whose contacts should be retrieved
 	 * @return the contacts of this User

server/src/main/java/envoy/server/data/User.java

@@ -70,6 +70,9 @@ public final class User extends Contact {
 	@Column(name = "last_seen")
 	private Instant lastSeen;
 
+	@Column(name = "latest_contact_deletion")
+	private Instant latestContactDeletion;
+
 	private UserStatus status;
 
 	@Override
@@ -140,4 +143,16 @@ public final class User extends Contact {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public void setStatus(UserStatus status) { this.status = status; }
+
+	/**
+	 * @return the latestContactDeletion
+	 * @since Envoy Server v0.3-beta
+	 */
+	public Instant getLatestContactDeletion() { return latestContactDeletion; }
+
+	/**
+	 * @param latestContactDeletion the latestContactDeletion to set
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void setLatestContactDeletion(Instant latestContactDeletion) { this.latestContactDeletion = latestContactDeletion; }
 }

server/src/main/java/envoy/server/processors/ContactOperationProcessor.java

@@ -1,10 +1,11 @@
 package envoy.server.processors;
 
-import java.util.logging.Logger;
+import java.time.Instant;
+import java.util.logging.*;
 
 import envoy.event.ElementOperation;
 import envoy.event.contact.ContactOperation;
-import envoy.server.data.PersistenceManager;
+import envoy.server.data.*;
 import envoy.server.net.*;
 import envoy.util.EnvoyLog;
 
@@ -16,21 +17,53 @@ public final class ContactOperationProcessor implements ObjectProcessor<ContactO
 
 	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
 	private static final Logger				logger				= EnvoyLog.getLogger(ContactOperationProcessor.class);
+	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
 
 	@Override
 	public void process(ContactOperation evt, long socketId, ObjectWriteProxy writeProxy) {
+		final long	userID		= ConnectionManager.getInstance().getUserIDBySocketID(socketId);
+		final long	contactID	= evt.get().getID();
+		final var	sender		= persistenceManager.getUserByID(userID);
 		switch (evt.getOperationType()) {
 			case ADD:
-				final long userID = ConnectionManager.getInstance().getUserIDBySocketID(socketId);
-				final long contactId = evt.get().getID();
-
-				logger.fine(String.format("Adding user %s to the contact list of user %d.%n", evt.get(), userID));
-				PersistenceManager.getInstance().addContactBidirectional(userID, contactId);
+				logger.log(Level.FINE, String.format("Adding %s to the contact list of user %d.", evt.get(), userID));
+				persistenceManager.addContactBidirectional(userID, contactID);
 
 				// Notify the contact if online
-				if (ConnectionManager.getInstance().isOnline(contactId))
-					writeProxy.write(connectionManager.getSocketID(contactId),
-							new ContactOperation(PersistenceManager.getInstance().getUserByID(userID).toCommon(), ElementOperation.ADD));
+				if (connectionManager.isOnline(contactID))
+					writeProxy.write(connectionManager.getSocketID(contactID), new ContactOperation(sender.toCommon(), ElementOperation.ADD));
+				break;
+			case REMOVE:
+
+				// Remove the relationships and notify sender if he logs in using another
+				// LocalDB
+				persistenceManager.removeContactBidirectional(userID, contactID);
+				final var contact = persistenceManager.getContactByID(contactID);
+				sender.setLatestContactDeletion(Instant.now());
+
+				// The sender wants to remove a normal contact
+				if (contact instanceof User) {
+
+					// Notify the removed contact on next startup(s) of this deletion
+					persistenceManager.getUserByID(contactID).setLatestContactDeletion(Instant.now());
+
+					// Notify the removed contact if online
+					if (connectionManager.isOnline(contactID))
+						writeProxy.write(connectionManager.getSocketID(contactID), new ContactOperation(sender.toCommon(), ElementOperation.REMOVE));
+				} else {
+
+					// The sender wants to be removed from a Group
+					final var group = persistenceManager.getGroupByID(contactID);
+
+					// The group has no more members and hence will be deleted
+					if (group.getContacts().isEmpty()) persistenceManager.deleteContact(group);
+					else {
+
+						// Informing the other members
+						writeProxy.writeToOnlineContacts(group.getContacts(), new ContactOperation(sender.toCommon(), ElementOperation.REMOVE));
+						group.getContacts().forEach(c -> ((User) c).setLatestContactDeletion(Instant.now()));
+					}
+				}
 				break;
 			default:
 				logger.warning(String.format("Received %s with an unsupported operation.", evt));

server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java

@@ -13,6 +13,7 @@ import javax.persistence.NoResultException;
 
 import envoy.data.LoginCredentials;
 import envoy.event.*;
+import envoy.event.contact.ContactDeletionSinceLastLogin;
 import envoy.server.data.*;
 import envoy.server.net.*;
 import envoy.server.util.*;
@@ -104,6 +105,7 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 				user.setStatus(ONLINE);
 				user.setPasswordHash(PasswordUtil.hash(credentials.getPassword()));
 				user.setContacts(new HashSet<>());
+				user.setLatestContactDeletion(Instant.EPOCH);
 				persistenceManager.addContact(user);
 				logger.info("Registered new " + user);
 			}
@@ -208,5 +210,8 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 
 		// Complete the handshake
 		writeProxy.write(socketID, user.toCommon());
+
+		// Notify the user if a contact deletion has happened since he last logged in
+		if (user.getLatestContactDeletion().isAfter(user.getLastSeen())) writeProxy.write(socketID, new ContactDeletionSinceLastLogin());
 	}
 }