Merge branch 'main' into fix/game-turn-and-action-bugs

2026-04-16 13:41:46 +02:00
parent 181f538038 4855e937e6
commit a5f0735a08
23 changed files with 869 additions and 167 deletions
@@ -39,6 +39,10 @@ public class ClientApp {
        return sharedUsername;
    }

+    public static void updateSharedUsername(String username) {
+        setSharedUsername(username != null && !username.isBlank() ? username.trim() : null);
+    }
+
    private static void setSharedUsername(String username) {
        sharedUsername = username;
        LOGGER.info("sharedUsername set to '{}'", getSharedUsername());
@@ -1,15 +1,20 @@
 package ch.unibas.dmi.dbis.cs108.casono.client.chat;

+import ch.unibas.dmi.dbis.cs108.casono.client.ClientApp;
 import ch.unibas.dmi.dbis.cs108.casono.client.network.ChatClient;
 import ch.unibas.dmi.dbis.cs108.casono.client.network.ClientService;
 import ch.unibas.dmi.dbis.cs108.casono.client.ui.chatui.ChatBoxController;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.RequestParameter;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.Timer;
 import java.util.TimerTask;
 import java.util.WeakHashMap;
+import java.util.function.Consumer;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.jspecify.annotations.Nullable;
@@ -24,7 +29,7 @@ public class ChatController {
    private static final Map<ClientService, ChatController> ACTIVE_CONTROLLERS =
            new WeakHashMap<>();

-    private final String username;
+    private volatile String username;

    private final ClientService clientService;

@@ -37,6 +42,7 @@ public class ChatController {
    private final ChatBoxController chatBoxController;
    private int lobbyId = -1;
    private final Timer timer;
+    private final Consumer<List<String>> serverEventListener;

    public record ChatKey(ChatType type, @Nullable String targetUser) {
        public ChatKey(ChatType type) {
@@ -71,8 +77,10 @@ public class ChatController {
        localUserList = new ArrayList<>();
        this.chatBoxController = new ChatBoxController(username, this);
        this.logger = LogManager.getLogger(ChatController.class);
+        this.serverEventListener = this::handleServerEvent;

        registerAsActiveController(clientService);
+        clientService.addEventListener(serverEventListener);

        this.timer = new Timer(true);
        timer.schedule(
@@ -131,6 +139,7 @@ public class ChatController {
     * <p>All Messages get added to a particular {@link ChatModel}, if the checks passed.
     */
    public void receiveMessage() {
+        String currentUsername = getCurrentUsername();
        List<Message> newMessages = chatClient.getMessages();
        if (!newMessages.isEmpty()) {
            for (Message msg : newMessages) {
@@ -146,16 +155,17 @@ public class ChatController {
                                            (_key) ->
                                                    new ChatModel(
                                                            ChatType.LOBBY,
-                                                            username,
+                                                            currentUsername,
                                                            msg.lobbyId,
                                                            null))
                                    .addMessage(msg);
                        }
                        break;
                    case ChatType.WHISPER:
-                        if (msg.target.equals(username) || msg.sender.equals(username)) {
+                        if (msg.target.equals(currentUsername)
+                                || msg.sender.equals(currentUsername)) {
                            ChatKey key;
-                            if (msg.target.equals(username)) {
+                            if (msg.target.equals(currentUsername)) {
                                key = new ChatKey(ChatType.WHISPER, msg.sender);
                            } else {
                                key = new ChatKey(ChatType.WHISPER, msg.target);
@@ -166,7 +176,7 @@ public class ChatController {
                                ChatModel chatModel =
                                        new ChatModel(
                                                ChatType.WHISPER,
-                                                username,
+                                                currentUsername,
                                                lobbyId,
                                                key.targetUser());
                                chatBoxController.addWhisperChat(key.targetUser(), chatModel);
@@ -203,13 +213,29 @@ public class ChatController {
     */
    public synchronized void checkWhisperUsers() {
        List<String> users = chatClient.getUsers();
-        logger.info(users);
-        if (!users.isEmpty()) {
-            for (String user : users) {
-                String value = user.split("\\=")[1];
-                logger.info(value);
-                addWhisperUser(value);
+        Set<String> remoteUsers = new HashSet<>();
+        String currentUsername = getCurrentUsername();
+
+        for (String user : users) {
+            if (user == null || !user.contains("=")) {
+                continue;
            }
+            String value = user.split("\\=", 2)[1].trim();
+            if (value.isBlank() || value.equals(currentUsername)) {
+                continue;
+            }
+            remoteUsers.add(value);
+        }
+
+        for (String known : new ArrayList<>(localUserList)) {
+            if (!remoteUsers.contains(known)) {
+                localUserList.remove(known);
+                chatBoxController.removeWhisperUser(known);
+            }
+        }
+
+        for (String remote : remoteUsers) {
+            addWhisperUser(remote);
        }
    }

@@ -222,16 +248,110 @@ public class ChatController {
        if (user == null || user.isBlank()) {
            return;
        }
-        if (!(localUserList.contains(user) || user.equals(username))) {
+        if (!(localUserList.contains(user) || user.equals(getCurrentUsername()))) {
            localUserList.add(user);
            logger.info("adding new whisper user");
            chatBoxController.addWhisperUser(user);
        }
    }

+    public synchronized void updateUsername(String newUsername) {
+        if (newUsername == null || newUsername.isBlank()) {
+            return;
+        }
+        String oldUsername = this.username;
+        this.username = newUsername.trim();
+        chatBoxController.setUsername(this.username);
+
+        if (oldUsername != null && !oldUsername.equals(this.username)) {
+            localUserList.remove(oldUsername);
+            chatBoxController.removeWhisperUser(oldUsername);
+        }
+    }
+
+    private void handleServerEvent(List<String> lines) {
+        if (lines == null || lines.isEmpty()) {
+            return;
+        }
+
+        List<RequestParameter> params;
+        try {
+            params = ClientService.convertToRequestParameters(lines);
+        } catch (RuntimeException e) {
+            return;
+        }
+        String event = null;
+        String oldUsername = null;
+        String newUsername = null;
+
+        for (RequestParameter p : params) {
+            if ("EVENT".equalsIgnoreCase(p.key())) {
+                event = p.value();
+            } else if ("OLD_USERNAME".equalsIgnoreCase(p.key())) {
+                oldUsername = p.value();
+            } else if ("NEW_USERNAME".equalsIgnoreCase(p.key())) {
+                newUsername = p.value();
+            }
+        }
+
+        if (!"USERNAME_CHANGED".equalsIgnoreCase(event)) {
+            return;
+        }
+
+        applyUsernameMigration(oldUsername, newUsername);
+    }
+
+    private synchronized void applyUsernameMigration(String oldUsername, String newUsername) {
+        if (oldUsername == null
+                || newUsername == null
+                || oldUsername.isBlank()
+                || newUsername.isBlank()
+                || oldUsername.equals(newUsername)) {
+            return;
+        }
+
+        String currentUsername = getCurrentUsername();
+        if (oldUsername.equals(currentUsername)) {
+            updateUsername(newUsername);
+        }
+
+        ChatKey oldKey = new ChatKey(ChatType.WHISPER, oldUsername);
+        ChatKey newKey = new ChatKey(ChatType.WHISPER, newUsername);
+
+        ChatModel oldModel = chatModelMap.remove(oldKey);
+        ChatModel existingNewModel = chatModelMap.get(newKey);
+        if (oldModel != null) {
+            oldModel.setTarget(newUsername);
+            if (existingNewModel == null) {
+                chatModelMap.put(newKey, oldModel);
+            } else {
+                // Merge possible parallel history into the already existing new-key model.
+                for (Message msg : oldModel.messages) {
+                    existingNewModel.addMessage(msg);
+                }
+            }
+            chatBoxController.renameWhisperUser(oldUsername, newUsername);
+        }
+
+        localUserList.remove(oldUsername);
+        chatBoxController.removeWhisperUser(oldUsername);
+        if (!newUsername.equals(getCurrentUsername())) {
+            addWhisperUser(newUsername);
+        }
+    }
+
+    public String getCurrentUsername() {
+        String shared = ClientApp.getSharedUsername();
+        if (shared != null && !shared.isBlank()) {
+            return shared.trim();
+        }
+        return username;
+    }
+
    /** Stops polling background tasks for this chat controller instance. */
    public void shutdown() {
        timer.cancel();
+        clientService.removeEventListener(serverEventListener);
        synchronized (ACTIVE_CONTROLLERS) {
            if (ACTIVE_CONTROLLERS.get(clientService) == this) {
                ACTIVE_CONTROLLERS.remove(clientService);
@@ -22,7 +22,7 @@ public class ChatModel {
    public final String username;

    /** The person to send the message to If the chat is a whisper chat */
-    private final String target;
+    private String target;

    private final IntegerProperty count;

@@ -82,4 +82,8 @@ public class ChatModel {
    public String getTarget() {
        return target;
    }
+
+    public void setTarget(String target) {
+        this.target = target;
+    }
 }
@@ -131,6 +131,29 @@ public class LobbyClient {
        return new LoginResult(assigned, id);
    }

+    /**
+     * Changes the username for the currently logged-in session.
+     *
+     * @param newUsername desired new username
+     * @return a {@link LoginResult} containing assigned username and id as returned by the server
+     */
+    public LoginResult changeUsername(String newUsername) {
+        List<String> lines = client.processCommand("CHANGE_USERNAME USERNAME=" + newUsername);
+
+        List<RequestParameter> params = ClientService.convertToRequestParameters(lines);
+
+        String assigned = newUsername;
+        String id = null;
+        for (RequestParameter p : params) {
+            if ("USERNAME".equalsIgnoreCase(p.key())) {
+                assigned = p.value();
+            } else if ("ID".equalsIgnoreCase(p.key())) {
+                id = p.value();
+            }
+        }
+        return new LoginResult(assigned, id);
+    }
+
    /**
     * Request the server for the list of available lobbies.
     *
@@ -60,6 +60,12 @@ public class ChatBoxController {
        usernameTabMap = new HashMap<>();
    }

+    public void setUsername(String username) {
+        if (username != null && !username.isBlank()) {
+            this.username = username.trim();
+        }
+    }
+
    /**
     * Initializes the chat interface by creating the global chat model and adding the corresponding
     * "GLOBAL" tab to the interface. It also registers the global chat in the {@link
@@ -84,6 +90,11 @@ public class ChatBoxController {
    public void addWhisperUser(String targetUserName) {
        Platform.runLater(
                () -> {
+                    for (MenuItem existing : addWhisperChatButton.getItems()) {
+                        if (targetUserName.equals(existing.getText())) {
+                            return;
+                        }
+                    }
                    MenuItem menuItem = new MenuItem(targetUserName);
                    addWhisperChatButton.getItems().add(menuItem);
                    menuItem.setOnAction(
@@ -98,6 +109,54 @@ public class ChatBoxController {
                });
    }

+    public void removeWhisperUser(String targetUserName) {
+        Platform.runLater(
+                () ->
+                        addWhisperChatButton
+                                .getItems()
+                                .removeIf(item -> targetUserName.equals(item.getText())));
+    }
+
+    public void renameWhisperUser(String oldUsername, String newUsername) {
+        if (oldUsername == null
+                || newUsername == null
+                || oldUsername.isBlank()
+                || newUsername.isBlank()
+                || oldUsername.equals(newUsername)) {
+            return;
+        }
+
+        Platform.runLater(
+                () -> {
+                    for (MenuItem item : addWhisperChatButton.getItems()) {
+                        if (oldUsername.equals(item.getText())) {
+                            item.setText(newUsername);
+                            item.setOnAction(
+                                    event ->
+                                            addWhisperChat(
+                                                    newUsername,
+                                                    new ChatModel(
+                                                            ChatType.WHISPER,
+                                                            username,
+                                                            -1,
+                                                            newUsername)));
+                            break;
+                        }
+                    }
+
+                    Tab tab = usernameTabMap.remove(oldUsername);
+                    if (tab != null) {
+                        tab.setText(newUsername);
+                        usernameTabMap.put(newUsername, tab);
+                    }
+
+                    int idx = activeWhisperChats.indexOf(oldUsername);
+                    if (idx >= 0) {
+                        activeWhisperChats.set(idx, newUsername);
+                    }
+                });
+    }
+
    /**
     * Creates a new private (whisper) chat model for a specific target user, registers it within
     * the chat system, and opens a new chat tab.
@@ -68,11 +68,12 @@ public class ChatViewController implements Initializable {
        String message = inputField.getText().trim();
        if (!message.isEmpty()) {
            inputField.clear();
+            String currentUsername = controller.getCurrentUsername();
            Message msg =
                    new Message(
                            chatModel.getChattype(),
                            chatModel.lobbyId,
-                            username,
+                            currentUsername,
                            chatModel.getTarget(),
                            message);
            controller.onSendToNetwork(msg);
@@ -104,6 +104,13 @@ public class CasinomainuiController {
        casinoTable.getChildren().add(gridManager.getGridPane());
        gridManager.renderLobbyButtons();

+        String sharedUsername = ClientApp.getSharedUsername();
+        updateUsernameFieldPresentation(sharedUsername);
+        if (loginButton != null) {
+            loginButton.setText(
+                    sharedUsername != null && !sharedUsername.isBlank() ? "Change Name" : "Login");
+        }
+
        initializeChat(clientService);
    }

@@ -156,7 +163,7 @@ public class CasinomainuiController {
    /** Handles the login button action. Validates input and calls LobbyClient.login(). */
    @FXML
    public void handleLoginButton() {
-        String username = usernameField.getText();
+        String username = usernameField == null ? null : usernameField.getText();
        if (username == null || username.isBlank()) {
            showAlert("Please enter a username.");
            return;
@@ -170,12 +177,63 @@ public class CasinomainuiController {
            showAlert("Offline mode: cannot send login to server.");
            return;
        }
+
+        String trimmed = username.trim();
        try {
-            lobbyClient.login(username);
-            showAlert("Login sent: " + username);
+            var result = lobbyClient.login(trimmed);
+            String assigned = result != null ? result.getUsername() : trimmed;
+            ClientApp.updateSharedUsername(assigned);
+            if (chatController != null) {
+                chatController.updateUsername(assigned);
+            }
+            updateUsernameFieldPresentation(assigned);
+            if (loginButton != null) {
+                loginButton.setText("Change Name");
+            }
+            return;
+        } catch (RuntimeException loginError) {
+            if (!containsProtocolError(loginError, "ALREADY_LOGGED_IN")) {
+                LOGGER.error("Login failed: {}", loginError.getMessage());
+                showAlert("Login failed: " + loginError.getMessage());
+                return;
+            }
+            LOGGER.info("Session already logged in, trying username change");
+        }
+
+        try {
+            var result = lobbyClient.changeUsername(trimmed);
+            String assigned = result != null ? result.getUsername() : trimmed;
+            ClientApp.updateSharedUsername(assigned);
+            if (chatController != null) {
+                chatController.updateUsername(assigned);
+            }
+            updateUsernameFieldPresentation(assigned);
+            if (loginButton != null) {
+                loginButton.setText("Change Name");
+            }
        } catch (RuntimeException e) {
-            LOGGER.error("Login failed: {}", e.getMessage());
-            showAlert("Login failed: " + e.getMessage());
+            LOGGER.error("Change username failed: {}", e.getMessage());
+            showAlert("Change username failed: " + e.getMessage());
+        }
+    }
+
+    private boolean containsProtocolError(RuntimeException error, String code) {
+        String msg = error.getMessage();
+        return msg != null && msg.contains(code);
+    }
+
+    private void updateUsernameFieldPresentation(String username) {
+        if (usernameField == null) {
+            return;
+        }
+
+        if (username != null && !username.isBlank()) {
+            usernameField.setText(username.trim());
+            usernameField.positionCaret(usernameField.getText().length());
+            usernameField.setPromptText("Username");
+        } else {
+            usernameField.clear();
+            usernameField.setPromptText("Username");
        }
    }

@@ -1,8 +1,26 @@
 package ch.unibas.dmi.dbis.cs108.casono.server;

+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username.ChangeUsernameHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username.ChangeUsernameParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username.ChangeUsernameRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.check_nick.CheckUsernameHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.check_nick.CheckUsernameParser;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.check_nick.CheckUsernameRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call.PlayerCallHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call.PlayerCallParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call.PlayerCallRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state.GetGameStateHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state.GetGameStateParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state.GetGameStateRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise.PlayerRaiseHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise.PlayerRaiseParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise.PlayerRaiseRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.get_message_count.GetMessageCountHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.get_message_count.GetMessageCountParser;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.get_message_count.GetMessageCountRequest;
@@ -12,6 +30,21 @@ import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.get_next_message.GetN
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.list_users.ListUsersHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.list_users.ListUsersParser;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.list_users.ListUsersRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby.CreateLobbyHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby.CreateLobbyParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby.CreateLobbyRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list.GetLobbyListHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list.GetLobbyListParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list.GetLobbyListRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_status.GetLobbyStatusHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_status.GetLobbyStatusParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_status.GetLobbyStatusRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby.JoinLobbyHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby.JoinLobbyParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby.JoinLobbyRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game.StartGameHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game.StartGameParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game.StartGameRequest;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.login.LoginHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.login.LoginParser;
 import ch.unibas.dmi.dbis.cs108.casono.server.app.commands.login.LoginRequest;
@@ -28,6 +61,7 @@ import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserCleanupJob;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.NetworkManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandlerExecutor;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandRouter;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParserDispatcher;
@@ -168,6 +202,15 @@ public class ServerApp {
        commandRouter.register(
                LoginRequest.class, new LoginHandler(responseDispatcher, userRegistry));

+        parserDispatcher.register("CHANGE_USERNAME", new ChangeUsernameParser());
+        commandRouter.register(
+                ChangeUsernameRequest.class,
+                new ChangeUsernameHandler(
+                        responseDispatcher,
+                        userRegistry,
+                        context.lobbyManager(),
+                        context.sessionManager()));
+
        parserDispatcher.register("LOGOUT", new LogoutParser());
        commandRouter.register(
                LogoutRequest.class, new LogoutHandler(responseDispatcher, userRegistry));
@@ -192,152 +235,84 @@ public class ServerApp {
                ListUsersRequest.class, new ListUsersHandler(responseDispatcher, userRegistry));

        // GET_LOBBY_LIST registration
-        parserDispatcher.register(
-                "GET_LOBBY_LIST",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list
-                        .GetLobbyListParser());
+        parserDispatcher.register("GET_LOBBY_LIST", new GetLobbyListParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list
-                        .GetLobbyListRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby
-                                        .get_lobby_list.GetLobbyListRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_list
-                                .GetLobbyListHandler(responseDispatcher, context.lobbyManager()));
+                GetLobbyListRequest.class,
+                (CommandHandler<GetLobbyListRequest>)
+                        new GetLobbyListHandler(responseDispatcher, context.lobbyManager()));

        // GET_GAME_STATE registration
-        parserDispatcher.register(
-                "GET_GAME_STATE",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state
-                        .GetGameStateParser());
+        parserDispatcher.register("GET_GAME_STATE", new GetGameStateParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state
-                        .GetGameStateRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game
-                                        .get_game_state.GetGameStateRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.get_game_state
-                                .GetGameStateHandler(
+                GetGameStateRequest.class,
+                (CommandHandler<GetGameStateRequest>)
+                        new GetGameStateHandler(
                                responseDispatcher, context.lobbyManager(), userRegistry));

        // BET registration
-        parserDispatcher.register(
-                "BET",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetParser());
+        parserDispatcher.register("BET", new PlayerBetParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet.PlayerBetRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet
-                                        .PlayerBetRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.bet
-                                .PlayerBetHandler(
+                PlayerBetRequest.class,
+                (CommandHandler<PlayerBetRequest>)
+                        new PlayerBetHandler(
                                responseDispatcher, userRegistry, context.lobbyManager()));

        // RAISE registration
-        parserDispatcher.register(
-                "RAISE",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise
-                        .PlayerRaiseParser());
+        parserDispatcher.register("RAISE", new PlayerRaiseParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise.PlayerRaiseRequest
-                        .class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise
-                                        .PlayerRaiseRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.raise
-                                .PlayerRaiseHandler(
+                PlayerRaiseRequest.class,
+                (CommandHandler<PlayerRaiseRequest>)
+                        new PlayerRaiseHandler(
                                responseDispatcher, userRegistry, context.lobbyManager()));

        // CALL registration
-        parserDispatcher.register(
-                "CALL",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call
-                        .PlayerCallParser());
+        parserDispatcher.register("CALL", new PlayerCallParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call.PlayerCallRequest
-                        .class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call
-                                        .PlayerCallRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.call
-                                .PlayerCallHandler(
+                PlayerCallRequest.class,
+                (CommandHandler<PlayerCallRequest>)
+                        new PlayerCallHandler(
                                responseDispatcher, userRegistry, context.lobbyManager()));

        // FOLD registration
-        parserDispatcher.register(
-                "FOLD",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
-                        .PlayerFoldParser());
+        parserDispatcher.register("FOLD", new PlayerFoldParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold.PlayerFoldRequest
-                        .class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
-                                        .PlayerFoldRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.game.fold
-                                .PlayerFoldHandler(
+                PlayerFoldRequest.class,
+                (CommandHandler<PlayerFoldRequest>)
+                        new PlayerFoldHandler(
                                responseDispatcher, userRegistry, context.lobbyManager()));

        // GET_LOBBY_STATUS registration
-        parserDispatcher.register(
-                "GET_LOBBY_STATUS",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_status
-                        .GetLobbyStatusParser());
+        parserDispatcher.register("GET_LOBBY_STATUS", new GetLobbyStatusParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.get_lobby_status
-                        .GetLobbyStatusRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby
-                                        .get_lobby_status.GetLobbyStatusRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby
-                                .get_lobby_status.GetLobbyStatusHandler(
+                GetLobbyStatusRequest.class,
+                (CommandHandler<GetLobbyStatusRequest>)
+                        new GetLobbyStatusHandler(
                                responseDispatcher, context.lobbyManager(), userRegistry));

        // CREATE_LOBBY registration
-        parserDispatcher.register(
-                "CREATE_LOBBY",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby
-                        .CreateLobbyParser());
+        parserDispatcher.register("CREATE_LOBBY", new CreateLobbyParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby
-                        .CreateLobbyRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby
-                                        .create_lobby.CreateLobbyRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.create_lobby
-                                .CreateLobbyHandler(
+                CreateLobbyRequest.class,
+                (CommandHandler<CreateLobbyRequest>)
+                        new CreateLobbyHandler(
                                responseDispatcher,
                                context.lobbyManager(),
                                context.sessionManager()));

        // JOIN_LOBBY registration
-        parserDispatcher.register(
-                "JOIN_LOBBY",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby
-                        .JoinLobbyParser());
+        parserDispatcher.register("JOIN_LOBBY", new JoinLobbyParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby
-                        .JoinLobbyRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby
-                                        .JoinLobbyRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.join_lobby
-                                .JoinLobbyHandler(
+                JoinLobbyRequest.class,
+                (CommandHandler<JoinLobbyRequest>)
+                        new JoinLobbyHandler(
                                responseDispatcher, context.lobbyManager(), userRegistry));

        // START_GAME registration
-        parserDispatcher.register(
-                "START_GAME",
-                new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game
-                        .StartGameParser());
+        parserDispatcher.register("START_GAME", new StartGameParser());
        commandRouter.register(
-                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game
-                        .StartGameRequest.class,
-                (ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler<
-                                ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game
-                                        .StartGameRequest>)
-                        new ch.unibas.dmi.dbis.cs108.casono.server.app.commands.lobby.start_game
-                                .StartGameHandler(
+                StartGameRequest.class,
+                (CommandHandler<StartGameRequest>)
+                        new StartGameHandler(
                                responseDispatcher, context.lobbyManager(), userRegistry));
    }
 }
@@ -0,0 +1,112 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.LobbyManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User;
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.RequestContext;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.ErrorResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.SuccessResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.builder.ResponseBodyBuilder;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.Session;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
+import java.util.Optional;
+import java.util.regex.Pattern;
+
+/** Handles CHANGE_USERNAME requests for already logged-in users. */
+public class ChangeUsernameHandler extends CommandHandler<ChangeUsernameRequest> {
+    private static final Pattern VALID_USERNAME = Pattern.compile("[a-zA-Z0-9_-]+");
+    private final UserRegistry userRegistry;
+    private final LobbyManager lobbyManager;
+    private final SessionManager sessionManager;
+
+    /**
+     * @param responseDispatcher dispatcher used for responses
+     * @param userRegistry registry containing all users
+     * @param lobbyManager lobby manager used to keep lobby/game mappings in sync
+     * @param sessionManager session manager used to broadcast rename events
+     */
+    public ChangeUsernameHandler(
+            ResponseDispatcher responseDispatcher,
+            UserRegistry userRegistry,
+            LobbyManager lobbyManager,
+            SessionManager sessionManager) {
+        super(responseDispatcher);
+        this.userRegistry = userRegistry;
+        this.lobbyManager = lobbyManager;
+        this.sessionManager = sessionManager;
+    }
+
+    @Override
+    public void execute(ChangeUsernameRequest request) {
+        Optional<User> user = userRegistry.getBySessionId(request.getSessionId());
+        if (user.isEmpty()) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(
+                            request.getContext(),
+                            "USER_NOT_LOGGED_IN",
+                            "This session is not associated with an active user."));
+            return;
+        }
+
+        String newUsername = request.getUsername() == null ? "" : request.getUsername().trim();
+        if (newUsername.isEmpty() || !VALID_USERNAME.matcher(newUsername).matches()) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(
+                            request.getContext(),
+                            "INVALID_USERNAME",
+                            "Only letters, numbers, '_' and '-' are allowed."));
+            return;
+        }
+
+        User currentUser = user.get();
+        String oldUsername = currentUser.getName();
+        boolean changed = userRegistry.changeUsername(currentUser.getId(), newUsername);
+        if (!changed) {
+            responseDispatcher.dispatch(
+                    new ErrorResponse(
+                            request.getContext(),
+                            "USERNAME_TAKEN",
+                            "The requested username is already taken."));
+            return;
+        }
+
+        boolean lobbySynced =
+                lobbyManager == null || lobbyManager.renamePlayer(oldUsername, newUsername);
+        if (!lobbySynced) {
+            userRegistry.changeUsername(currentUser.getId(), oldUsername);
+            responseDispatcher.dispatch(
+                    new ErrorResponse(
+                            request.getContext(),
+                            "RENAME_CONFLICT",
+                            "Could not update username in current lobby/game state."));
+            return;
+        }
+
+        responseDispatcher.dispatch(
+                new ChangeUsernameResponse(
+                        request.getContext(), currentUser.getName(), currentUser.getId()));
+
+        broadcastUsernameChanged(oldUsername, currentUser.getName());
+    }
+
+    private void broadcastUsernameChanged(String oldUsername, String newUsername) {
+        if (sessionManager == null) {
+            return;
+        }
+
+        for (Session session : sessionManager.getAllSessions()) {
+            RequestContext ctx = new RequestContext(session.getId(), 0);
+            SuccessResponse ev =
+                    new SuccessResponse(
+                            ctx,
+                            new ResponseBodyBuilder()
+                                    .param("EVENT", "USERNAME_CHANGED")
+                                    .param("OLD_USERNAME", oldUsername)
+                                    .param("NEW_USERNAME", newUsername)
+                                    .build()) {};
+            responseDispatcher.dispatch(ev);
+        }
+    }
+}
@@ -0,0 +1,15 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.command.parsing.CommandParser;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.PrimitiveRequest;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.accessor.RequestParameterAccessor;
+
+/** Parses CHANGE_USERNAME requests. */
+public class ChangeUsernameParser implements CommandParser<ChangeUsernameRequest> {
+    @Override
+    public ChangeUsernameRequest parse(PrimitiveRequest primitiveRequest) {
+        RequestParameterAccessor accessor =
+                new RequestParameterAccessor(primitiveRequest.parameters());
+        return new ChangeUsernameRequest(primitiveRequest.context(), accessor.require("USERNAME"));
+    }
+}
@@ -0,0 +1,25 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.Request;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.RequestContext;
+
+/** Request used to change the username of the current session user. */
+public class ChangeUsernameRequest extends Request {
+    private final String username;
+
+    /**
+     * @param context request context for responses
+     * @param username desired new username
+     */
+    public ChangeUsernameRequest(RequestContext context, String username) {
+        super(context);
+        this.username = username;
+    }
+
+    /**
+     * @return desired new username
+     */
+    public String getUsername() {
+        return username;
+    }
+}
@@ -0,0 +1,23 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.app.commands.change_username;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserId;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.request.RequestContext;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.SuccessResponse;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.builder.ResponseBodyBuilder;
+
+/** Response for successful username changes. */
+public class ChangeUsernameResponse extends SuccessResponse {
+    /**
+     * @param context request context
+     * @param username current username after the rename operation
+     * @param id user id of renamed user
+     */
+    public ChangeUsernameResponse(RequestContext context, String username, UserId id) {
+        super(
+                context,
+                new ResponseBodyBuilder()
+                        .param("USERNAME", username)
+                        .param("ID", id.value())
+                        .build());
+    }
+}
@@ -9,6 +9,7 @@ import ch.unibas.dmi.dbis.cs108.casono.server.domain.user.UserRegistry;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.command.execution.CommandHandler;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.OkResponse;
 import ch.unibas.dmi.dbis.cs108.casono.server.network.protocol.response.dispatcher.ResponseDispatcher;
+import java.util.Optional;

 public class SendMessageHandler extends CommandHandler<SendMessageRequest> {
    private final UserRegistry userRegistry;
@@ -39,6 +40,11 @@ public class SendMessageHandler extends CommandHandler<SendMessageRequest> {
    @Override
    public void execute(SendMessageRequest request) {
        Message message = request.getMessage();
+        Optional<ch.unibas.dmi.dbis.cs108.casono.server.domain.user.User> senderUser =
+                userRegistry.getBySessionId(request.getSessionId());
+        if (senderUser.isPresent()) {
+            message.sender = senderUser.get().getName();
+        }
        broadcast(request, message);
        OkResponse response = new OkResponse(request.getContext());
        responseDispatcher.dispatch(response);
@@ -61,6 +61,35 @@ public class GameController {
        engine.getState().addPlayer(name, chips);
    }

+    /**
+     * Renames a player id in the controller list and underlying game state.
+     *
+     * @param oldId old player id
+     * @param newId new player id
+     * @return true if rename succeeded
+     */
+    public boolean renamePlayer(PlayerId oldId, PlayerId newId) {
+        if (oldId == null || newId == null) {
+            return false;
+        }
+        if (oldId.equals(newId)) {
+            return true;
+        }
+
+        int idx = players.indexOf(oldId);
+        if (idx < 0 || players.contains(newId)) {
+            return false;
+        }
+
+        boolean stateRenamed = engine.getState().renamePlayerId(oldId, newId);
+        if (!stateRenamed) {
+            return false;
+        }
+
+        players.set(idx, newId);
+        return true;
+    }
+
    /**
     * Initializes a new hand by preparing the deck, setting the phase to PREFLOP, rotating the
     * dealer, dealing hole cards, posting blinds, and setting the first active player.
@@ -49,6 +49,16 @@ public class Player {
        return id;
    }

+    /**
+     * Updates the player's id. This is used when a username change is propagated into an already
+     * running game.
+     *
+     * @param id new player id
+     */
+    public void setId(PlayerId id) {
+        this.id = id;
+    }
+
    /**
     * Returns the display name of the player. Currently identical to the player ID.
     *
@@ -174,6 +174,51 @@ public class GameState {
        holeCards.computeIfAbsent(id, k -> new ArrayList<>());
    }

+    /**
+     * Renames a player id across all game-state structures.
+     *
+     * @param oldId existing player id
+     * @param newId new player id
+     * @return true if the rename was applied, false otherwise
+     */
+    public synchronized boolean renamePlayerId(PlayerId oldId, PlayerId newId) {
+        if (oldId == null || newId == null) {
+            return false;
+        }
+        if (!players.containsKey(oldId)) {
+            return false;
+        }
+        if (oldId.equals(newId)) {
+            return true;
+        }
+        if (players.containsKey(newId)) {
+            return false;
+        }
+
+        Player player = players.remove(oldId);
+        if (player == null) {
+            return false;
+        }
+        player.setId(newId);
+        players.put(newId, player);
+
+        int idx = playerOrder.indexOf(oldId);
+        if (idx >= 0) {
+            playerOrder.set(idx, newId);
+        }
+
+        moveMapEntry(currentBets, oldId, newId, 0);
+        moveMapEntry(playerBetCommitments, oldId, newId, 0);
+        moveMapEntry(holeCards, oldId, newId, new ArrayList<>());
+        return true;
+    }
+
+    private <T> void moveMapEntry(
+            Map<PlayerId, T> map, PlayerId oldId, PlayerId newId, T fallback) {
+        T value = map.remove(oldId);
+        map.put(newId, value != null ? value : fallback);
+    }
+
    // Betting
    public int getCurrentBet(PlayerId playerId) {
        return currentBets.getOrDefault(playerId, 0);
@@ -70,6 +70,30 @@ public class Lobby {
        return playerNames.remove(playerName);
    }

+    /**
+     * Renames a player in this lobby's player list.
+     *
+     * @param oldName old username
+     * @param newName new username
+     * @return true if renamed successfully
+     */
+    public boolean renamePlayer(String oldName, String newName) {
+        if (oldName == null || newName == null) {
+            return false;
+        }
+        synchronized (playerNames) {
+            if (oldName.equals(newName)) {
+                return playerNames.contains(oldName);
+            }
+            int idx = playerNames.indexOf(oldName);
+            if (idx < 0 || playerNames.contains(newName)) {
+                return false;
+            }
+            playerNames.set(idx, newName);
+            return true;
+        }
+    }
+
    public void initGame(GameController controller) {
        this.gameController = controller;
    }
@@ -1,5 +1,6 @@
 package ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby;

+import ch.unibas.dmi.dbis.cs108.casono.server.domain.game.player.PlayerId;
 import ch.unibas.dmi.dbis.cs108.casono.server.domain.lobby.Lobby.AddResult;
 import java.time.Duration;
 import java.time.Instant;
@@ -170,6 +171,56 @@ public class LobbyManager {
        }
    }

+    /**
+     * Renames a player across lobby mapping, lobby player list and running game ids.
+     *
+     * @param oldUsername old username
+     * @param newUsername new username
+     * @return true if rename was applied
+     */
+    public synchronized boolean renamePlayer(String oldUsername, String newUsername) {
+        if (oldUsername == null || newUsername == null) {
+            return false;
+        }
+        if (oldUsername.equals(newUsername)) {
+            return true;
+        }
+
+        LobbyId lobbyId = playerToLobby.get(oldUsername);
+        if (lobbyId == null) {
+            return true;
+        }
+        if (playerToLobby.containsKey(newUsername)) {
+            return false;
+        }
+
+        Lobby lobby = activeLobbies.get(lobbyId);
+        if (lobby == null) {
+            playerToLobby.remove(oldUsername);
+            return true;
+        }
+
+        boolean lobbyRenamed = lobby.renamePlayer(oldUsername, newUsername);
+        if (!lobbyRenamed) {
+            return false;
+        }
+
+        if (lobby.getGameController() != null) {
+            boolean gameRenamed =
+                    lobby.getGameController()
+                            .renamePlayer(PlayerId.of(oldUsername), PlayerId.of(newUsername));
+            if (!gameRenamed) {
+                // Best-effort rollback to keep structures consistent.
+                lobby.renamePlayer(newUsername, oldUsername);
+                return false;
+            }
+        }
+
+        playerToLobby.remove(oldUsername);
+        playerToLobby.put(newUsername, lobbyId);
+        return true;
+    }
+
    /**
     * Apply the given action to every player username in the lobby identified by {@code lobbyId}.
     * This is a small helper that keeps iteration logic centralized and avoids leaking internal
@@ -200,6 +200,10 @@ public class UserRegistry {
            return false;
        }

+        if (user.getName().equals(newName)) {
+            return true;
+        }
+
        if (byName.containsKey(newName)) {
            return false;
        }
@@ -81,25 +81,24 @@
                        </GridPane.margin>
                    </Button>

-                        <!-- Username input and login button -->
-                            <!-- <HBox alignment="CENTER_LEFT" spacing="10"-->
-                            <!--             GridPane.rowIndex="0"-->
-                            <!--             GridPane.columnIndex="0"-->
-                            <!--             GridPane.halignment="LEFT"-->
-                            <!--             GridPane.valignment="TOP">-->
-                            <!--         <GridPane.margin>-->
-                            <!--                 &lt;!&ndash; place below the 'CREATE A LOBBY' button &ndash;&gt;-->
-                            <!--                 <Insets top="100" left="20" />-->
-                            <!--         </GridPane.margin>-->
-                            <!--         <TextField fx:id="usernameField"-->
-                            <!--                    promptText="Username"-->
-                            <!--                    styleClass="gray-input-field"-->
-                            <!--                    maxWidth="180" />-->
-                            <!--         <Button text="Login"-->
-                            <!--                         fx:id="loginButton"-->
-                            <!--                         onAction="#handleLoginButton"-->
-                            <!--                         styleClass="button-create-lobby" />-->
-                            <!-- </HBox>-->
+                        <!-- Username input and login/change button -->
+                        <HBox alignment="CENTER_LEFT" spacing="10"
+                              GridPane.rowIndex="0"
+                              GridPane.columnIndex="0"
+                              GridPane.halignment="LEFT"
+                              GridPane.valignment="TOP">
+                            <GridPane.margin>
+                                <Insets top="100" left="20" />
+                            </GridPane.margin>
+                            <TextField fx:id="usernameField"
+                                       promptText="Username"
+                                       styleClass="gray-input-field"
+                                       maxWidth="180" />
+                            <Button text="Apply Name"
+                                    fx:id="loginButton"
+                                    onAction="#handleLoginButton"
+                                    styleClass="button-create-lobby" />
+                        </HBox>

                    <VBox fx:id="casinoTable"
                          alignment="CENTER"