Add working leaving of a group

Additionally fixed a two bugs:
- one group member will no longer show "1 members"
- deletion of empty groups no longer throws an exception

server/src/main/java/envoy/server/Startup.java

@@ -49,6 +49,7 @@ public final class Startup {
 						new MessageStatusChangeProcessor(),
 						new GroupMessageStatusChangeProcessor(),
 						new UserStatusChangeProcessor(),
+						new GroupResizeProcessor(),
 						new IDGeneratorRequestProcessor(),
 						new UserSearchProcessor(),
 						new UserOperationProcessor(),

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

@@ -51,7 +51,7 @@ public class Message {
 	@Id
 	protected long id;
 
-	@ManyToOne
+	@ManyToOne(cascade = CascadeType.REMOVE)
 	@JoinColumn
 	protected User sender;
 

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

@@ -105,11 +105,6 @@ public final class PersistenceManager {
 			// 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);
 	}

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

@@ -1,8 +1,12 @@
 package envoy.server.processors;
 
+import java.time.Instant;
+import java.util.logging.Level;
+
 import envoy.event.GroupResize;
 import envoy.server.data.*;
-import envoy.server.net.*;
+import envoy.server.net.ObjectWriteProxy;
+import envoy.util.EnvoyLog;
 
 /**
  * @author Maximilian Käfer
@@ -10,35 +14,38 @@ import envoy.server.net.*;
  */
 public final class GroupResizeProcessor implements ObjectProcessor<GroupResize> {
 
-	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
+	private static final PersistenceManager persistenceManager = PersistenceManager.getInstance();
 
 	@Override
 	public void process(GroupResize groupResize, long socketID, ObjectWriteProxy writeProxy) {
 
 		// Acquire the group to resize from the database
-		var group = persistenceManager.getGroupByID(groupResize.getGroupID());
+		final var	group	= persistenceManager.getGroupByID(groupResize.getGroupID());
+		final var	sender	= persistenceManager.getUserByID(groupResize.get().getID());
 
 		// Perform the desired operation
 		switch (groupResize.getOperation()) {
 			case ADD:
-				group.getContacts().add(persistenceManager.getUserByID(groupResize.get().getID()));
-				break;
+				persistenceManager.addContactBidirectional(sender, group);
+				writeProxy.writeToOnlineContacts(group.getContacts(), group.toCommon());
+				return;
 			case REMOVE:
+				persistenceManager.removeContactBidirectional(sender, group);
+				sender.setLatestContactDeletion(Instant.now());
+
+				// The group has no more members and hence will be deleted
+				if (group.getContacts().isEmpty()) {
+					EnvoyLog.getLogger(GroupResizeProcessor.class).log(Level.INFO, "Deleting now empty group " + group.getName());
+					persistenceManager.deleteContact(group);
+				} else {
+
+					// Informing the other members
+					writeProxy.writeToOnlineContacts(group.getContacts(), groupResize);
+					group.getContacts().forEach(c -> ((User) c).setLatestContactDeletion(Instant.now()));
+				}
+
 				group.getContacts().remove(persistenceManager.getUserByID(groupResize.get().getID()));
-				break;
+				return;
 		}
-
-		// Update the group in the database
-		persistenceManager.updateContact(group);
-
-		// Send the updated group to all of its members
-		var commonGroup = group.toCommon();
-		group.getContacts()
-			.stream()
-			.map(Contact::getID)
-			.filter(connectionManager::isOnline)
-			.map(connectionManager::getSocketID)
-			.forEach(memberSocketID -> writeProxy.write(memberSocketID, commonGroup));
 	}
 }