Shrink code in the ConnectionHandlers

Fixes issue #37

client/src/main/java/ch/zhaw/pm2/multichat/client/ChatWindowController.java

@@ -1,7 +1,8 @@
 package ch.zhaw.pm2.multichat.client;
 
-import ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State;
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 import javafx.application.Platform;
 import javafx.beans.value.ChangeListener;
@@ -15,10 +16,8 @@ import javafx.scene.layout.Pane;
 import javafx.stage.WindowEvent;
 
 import java.io.IOException;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
-import static ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State.*;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 
 public class ChatWindowController {
     private ClientConnectionHandler connectionHandler;
@@ -48,6 +47,10 @@ public class ChatWindowController {
         messageListener();
     }
 
+    public void setConnectionHandler(ClientConnectionHandler connectionHandler){
+        this.connectionHandler = connectionHandler;
+    }
+
     private void applicationClose() {
         disconnect();
     }
@@ -106,11 +109,10 @@ public class ChatWindowController {
 
     private void startConnectionHandler() throws IOException {
         String userName = userNameField.getText();
+        if(!userName.contains(" ")) {
             String serverAddress = serverAddressField.getText();
             int serverPort = Integer.parseInt(serverPortField.getText());
-        connectionHandler = new ClientConnectionHandler(
-            NetworkHandler.openConnection(serverAddress, serverPort), userName,
-            messages);
+            connectionHandler.initialize(serverAddress, serverPort, userName);
             new Thread(connectionHandler).start();
 
             //register Listener
@@ -118,14 +120,8 @@ public class ChatWindowController {
 
             // register window close handler
             rootPane.getScene().getWindow().addEventHandler(WindowEvent.WINDOW_CLOSE_REQUEST, windowCloseHandler);
-    }
-
-    private void terminateConnectionHandler() {
-        // unregister window close handler
-        rootPane.getScene().getWindow().removeEventHandler(WindowEvent.WINDOW_CLOSE_REQUEST, windowCloseHandler);
-        if (connectionHandler != null) {
-            connectionHandler.stopReceiving();
-            connectionHandler = null;
+        } else {
+            addError("It is not allowed to have spaces in username!");
         }
     }
 
@@ -138,7 +134,7 @@ public class ChatWindowController {
             }
         });
         if(newState == DISCONNECTED){
-            terminateConnectionHandler();
+            connectionHandler.stopReceiving();
         }
     }
 

client/src/main/java/ch/zhaw/pm2/multichat/client/ClientConnectionHandler.java

@@ -1,6 +1,7 @@
 package ch.zhaw.pm2.multichat.client;
 
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 import javafx.beans.property.SimpleIntegerProperty;
 import javafx.beans.property.SimpleObjectProperty;
@@ -12,23 +13,11 @@ import java.net.SocketException;
 import java.util.Scanner;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 
-import static ch.zhaw.pm2.multichat.client.ClientConnectionHandler.State.*;
+public class ClientConnectionHandler extends ConnectionHandler implements Runnable {
 
-public class ClientConnectionHandler implements Runnable {
-    private final NetworkHandler.NetworkConnection<String> connection;
-
-    // Data types used for the Chat Protocol
-    private static final String DATA_TYPE_CONNECT = "CONNECT";
-    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
-    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
-    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
-    private static final String DATA_TYPE_ERROR = "ERROR";
-
-    public static final String USER_NONE = "";
-    public static final String USER_ALL = "*";
-
-    private final Pattern messagePattern = Pattern.compile( "^(?:@(\\w*))?\\s*(.*)$" );
+    private final Pattern messagePattern = Pattern.compile( "^(?:@(\\S*))?\\s*(.*)$" );
 
     private SimpleStringProperty userName;
     private SimpleObjectProperty<State> state;
@@ -36,19 +25,21 @@ public class ClientConnectionHandler implements Runnable {
     private SimpleStringProperty serverAddress;
     private SimpleIntegerProperty serverPort;
 
-    enum State {
-        NEW, CONFIRM_CONNECT, CONNECTED, CONFIRM_DISCONNECT, DISCONNECTED;
+    public ClientConnectionHandler(ClientMessageList messages)  {
+        super();
+        this.messages = messages;
+        state = new SimpleObjectProperty<>(State.NEW);
+        serverAddress = new SimpleStringProperty(NetworkHandler.DEFAULT_ADDRESS.getCanonicalHostName());
+        serverPort = new SimpleIntegerProperty(NetworkHandler.DEFAULT_PORT);
+        this.userName = new SimpleStringProperty(null);
     }
 
-    public ClientConnectionHandler(NetworkHandler.NetworkConnection<String> connection,
-                                   String userName,
-                                   ClientMessageList messages)  {
-        this.connection = connection;
+    public void initialize(String serverAddress, int serverPort, String userName) throws IOException {
+        state.set(NEW);
+        this.serverAddress.set(serverAddress);
+        this.serverPort.set(serverPort);
+        setConnection(NetworkHandler.openConnection(serverAddress, serverPort));
         this.userName = new SimpleStringProperty((userName == null || userName.isBlank())? USER_NONE : userName);
-        this.messages = messages;
-        state = new SimpleObjectProperty<>(NEW);
-        serverAddress = new SimpleStringProperty();
-        serverPort = new SimpleIntegerProperty();
     }
 
     public SimpleStringProperty getServerAddressProperty() { return serverAddress; }
@@ -63,19 +54,18 @@ public class ClientConnectionHandler implements Runnable {
 
     public void setState (State newState) {
         state.set(newState);
-
     }
 
     public void run () {
         startReceiving();
     }
 
-    public void startReceiving() {
+    private void startReceiving() {
         System.out.println("Starting Connection Handler");
         try {
             System.out.println("Start receiving data...");
-            while (connection.isAvailable()) {
-                String data = connection.receive();
+            while (getConnection().isAvailable()) {
+                String data = getConnection().receive();
                 processData(data);
             }
             System.out.println("Stopped recieving data");
@@ -99,7 +89,7 @@ public class ClientConnectionHandler implements Runnable {
         System.out.println("Closing Connection Handler to Server");
         try {
             System.out.println("Stop receiving data...");
-            connection.close();
+            getConnection().close();
             System.out.println("Stopped receiving data.");
         } catch (IOException e) {
             System.err.println("Failed to close connection." + e.getMessage());
@@ -109,38 +99,38 @@ public class ClientConnectionHandler implements Runnable {
 
     private void processData(String data) {
         try {
-            // parse data content
             Scanner scanner = new Scanner(data);
-            String sender = null;
-            String reciever = null;
-            String type = null;
-            String payload = null;
-            if (scanner.hasNextLine()) {
-                sender = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Sender found");
-            }
-            if (scanner.hasNextLine()) {
-                reciever = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Reciever found");
-            }
-            if (scanner.hasNextLine()) {
-                type = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Type found");
-            }
-            if (scanner.hasNextLine()) {
-                payload = scanner.nextLine();
-            }
+            StringBuilder sender = new StringBuilder();
+            StringBuilder reciever = new StringBuilder();
+            StringBuilder type = new StringBuilder();
+            StringBuilder payload = new StringBuilder();
+            super.processData(scanner,sender,reciever,type,payload);
+
             // dispatch operation based on type parameter
-            if (type.equals(DATA_TYPE_CONNECT)) {
+            if (type.toString().equals(getDataTypeConnect())) {
                 System.err.println("Illegal connect request from server");
-            } else if (type.equals(DATA_TYPE_CONFIRM)) {
+            } else if (type.toString().equals(getDataTypeConfirm())) {
+                caseConfirm(sender.toString(), reciever.toString(), payload.toString());
+            } else if (type.toString().equals(getDataTypeDisconnect())) {
+                caseDisconnect(sender.toString(),reciever.toString(),payload.toString());
+            } else if (type.toString().equals(getDataTypeMessage())) {
+                caseMessage(sender.toString(),reciever.toString(),payload.toString());
+            } else if (type.toString().equals(getDataTypeError())) {
+                caseError(sender.toString(), reciever.toString(), payload.toString());
+            } else {
+                System.out.println("Unknown data type received: " + type);
+            }
+        } catch (ChatProtocolException e) {
+            System.err.println("Error while processing data: " + e.getMessage());
+            sendData(USER_NONE, userName.get(), getDataTypeError(), e.getMessage());
+        }
+    }
+
+    private void caseConfirm(String sender, String reciever, String payload) {
         if (state.get() == CONFIRM_CONNECT) {
             this.userName.set(reciever);
-                    this.serverPort.set(connection.getRemotePort());
-                    this.serverAddress.set(connection.getRemoteHost());
+            this.serverPort.set(getConnection().getRemotePort());
+            this.serverAddress.set(getConnection().getRemoteHost());
             messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
             System.out.println("CONFIRM: " + payload);
             this.setState(CONNECTED);
@@ -151,7 +141,9 @@ public class ClientConnectionHandler implements Runnable {
         } else {
             System.err.println("Got unexpected confirm message: " + payload);
         }
-            } else if (type.equals(DATA_TYPE_DISCONNECT)) {
+    }
+
+    private void caseDisconnect(String sender, String reciever, String payload) {
         if (state.get() == DISCONNECTED) {
             System.out.println("DISCONNECT: Already in disconnected: " + payload);
             return;
@@ -159,55 +151,31 @@ public class ClientConnectionHandler implements Runnable {
         messages.addMessage(new Message(Message.MessageType.INFO,sender,reciever,payload));
         System.out.println("DISCONNECT: " + payload);
         this.setState(DISCONNECTED);
-            } else if (type.equals(DATA_TYPE_MESSAGE)) {
+    }
+
+    private void caseMessage(String sender, String reciever, String payload) {
         if (state.get() != CONNECTED) {
             System.out.println("MESSAGE: Illegal state " + state + " for message: " + payload);
             return;
         }
         messages.addMessage(new Message(Message.MessageType.MESSAGE,sender,reciever,payload));
         System.out.println("MESSAGE: From " + sender + " to " + reciever + ": "+  payload);
-            } else if (type.equals(DATA_TYPE_ERROR)) {
-                messages.addMessage(new Message(Message.MessageType.ERROR,sender,reciever,payload));
-                System.out.println("ERROR: " + payload);
-            } else {
-                System.out.println("Unknown data type received: " + type);
-            }
-        } catch (ChatProtocolException e) {
-            System.err.println("Error while processing data: " + e.getMessage());
-            sendData(USER_NONE, userName.get(), DATA_TYPE_ERROR, e.getMessage());
-        }
     }
 
-    public void sendData(String sender, String receiver, String type, String payload) {
-        if (connection.isAvailable()) {
-            new StringBuilder();
-            String data = new StringBuilder()
-                .append(sender+"\n")
-                .append(receiver+"\n")
-                .append(type+"\n")
-                .append(payload+"\n")
-                .toString();
-            try {
-                connection.send(data);
-            } catch (SocketException e) {
-                System.err.println("Connection closed: " + e.getMessage());
-            } catch (EOFException e) {
-                System.out.println("Connection terminated by remote");
-            } catch(IOException e) {
-                System.err.println("Communication error: " + e.getMessage());
-            }
-        }
+    private void caseError(String sender, String reciever, String payload) {
+        messages.addMessage(new Message(Message.MessageType.ERROR,sender,reciever,payload));
+        System.out.println("ERROR: " + payload);
     }
 
     public void connect() throws ChatProtocolException {
         if (state.get() != NEW) throw new ChatProtocolException("Illegal state for connect: " + state);
-        this.sendData(userName.get(), USER_NONE, DATA_TYPE_CONNECT,null);
+        this.sendData(userName.get(), USER_NONE, getDataTypeConnect(),null);
         this.setState(CONFIRM_CONNECT);
     }
 
     public void disconnect() throws ChatProtocolException {
         if (state.get() != NEW && state.get() != CONNECTED) throw new ChatProtocolException("Illegal state for disconnect: " + state);
-        this.sendData(userName.get(), USER_NONE, DATA_TYPE_DISCONNECT,null);
+        this.sendData(userName.get(), USER_NONE, getDataTypeDisconnect(),null);
         this.setState(CONFIRM_DISCONNECT);
     }
 
@@ -222,11 +190,10 @@ public class ClientConnectionHandler implements Runnable {
                 return false;
             }
             if (receiver == null || receiver.isBlank()) receiver = ClientConnectionHandler.USER_ALL;
-            this.sendData(userName.get(), receiver, DATA_TYPE_MESSAGE,message);
+            this.sendData(userName.get(), receiver, getDataTypeMessage(),message);
             return true;
         } else {
             return false;
         }
     }
-
 }

client/src/main/java/ch/zhaw/pm2/multichat/client/ClientUI.java

@@ -8,6 +8,7 @@ import javafx.stage.Stage;
 
 public class ClientUI extends Application {
     private ClientMessageList clientMessageList = new ClientMessageList();
+    private ClientConnectionHandler connectionHandler = new ClientConnectionHandler(clientMessageList);
 
     @Override
     public void start(Stage primaryStage) {
@@ -21,6 +22,7 @@ public class ClientUI extends Application {
 
             ChatWindowController chatWindowController = loader.getController();
             chatWindowController.setMessages(clientMessageList);
+            chatWindowController.setConnectionHandler(connectionHandler);
 
             // fill in scene and stage setup
             Scene scene = new Scene(rootPane);

protocol/src/main/java/ch/zhaw/pm2/multichat/protocol/ConnectionHandler.java

@@ -0,0 +1,95 @@
+package ch.zhaw.pm2.multichat.protocol;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.net.SocketException;
+import java.util.Scanner;
+
+public abstract class ConnectionHandler {
+    private NetworkHandler.NetworkConnection<String> connection;
+
+    // Data types used for the Chat Protocol
+    private static final String DATA_TYPE_CONNECT = "CONNECT";
+    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
+    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
+    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
+    private static final String DATA_TYPE_ERROR = "ERROR";
+
+    public static final String USER_NONE = "";
+    public static final String USER_ALL = "*";
+
+    public enum State {
+        NEW, CONFIRM_CONNECT, CONNECTED, CONFIRM_DISCONNECT, DISCONNECTED, ERROR;
+    }
+
+    public static String getDataTypeConnect() {
+        return DATA_TYPE_CONNECT;
+    }
+
+    public static String getDataTypeConfirm() {
+        return DATA_TYPE_CONFIRM;
+    }
+
+    public static String getDataTypeDisconnect() {
+        return DATA_TYPE_DISCONNECT;
+    }
+
+    public static String getDataTypeMessage() {
+        return DATA_TYPE_MESSAGE;
+    }
+
+    public static String getDataTypeError() {
+        return DATA_TYPE_ERROR;
+    }
+
+    public NetworkHandler.NetworkConnection<String> getConnection() {
+        return connection;
+    }
+
+    protected void setConnection(NetworkHandler.NetworkConnection<String> connection) {
+        this.connection = connection;
+    }
+
+    protected void processData(Scanner scanner, StringBuilder sender, StringBuilder reciever, StringBuilder type, StringBuilder payload) throws ChatProtocolException {
+        // parse data content
+        if (scanner.hasNextLine()) {
+            sender.append(scanner.nextLine());
+        } else {
+            throw new ChatProtocolException("No Sender found");
+        }
+        if (scanner.hasNextLine()) {
+            reciever.append(scanner.nextLine());
+        } else {
+            throw new ChatProtocolException("No Reciever found");
+        }
+        if (scanner.hasNextLine()) {
+            type.append(scanner.nextLine());
+        } else {
+            throw new ChatProtocolException("No Type found");
+        }
+        if (scanner.hasNextLine()) {
+            payload.append(scanner.nextLine());
+        }
+    }
+
+    protected void sendData(String sender, String receiver, String type, String payload) {
+        if (connection.isAvailable()) {
+            new StringBuilder();
+            String data = new StringBuilder()
+                    .append(sender+"\n")
+                    .append(receiver+"\n")
+                    .append(type+"\n")
+                    .append(payload+"\n")
+                    .toString();
+            try {
+                getConnection().send(data);
+            } catch (SocketException e) {
+                System.err.println("Connection closed: " + e.getMessage());
+            } catch (EOFException e) {
+                System.out.println("Connection terminated by remote");
+            } catch(IOException e) {
+                System.err.println("Communication error: " + e.getMessage());
+            }
+        }
+    }
+}

server/src/main/java/ch/zhaw/pm2/multichat/server/Server.java

@@ -1,5 +1,6 @@
 package ch.zhaw.pm2.multichat.server;
 
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 
 import java.io.IOException;
@@ -75,11 +76,17 @@ public class Server {
                  mutex.lock();
                  try {
                      nameComplete.await();
+                     if(connectionHandler.getState() == ConnectionHandler.State.ERROR) {
+                         System.out.println(String.format("Connecting failed for new Client with IP:Port <%s:%d>.\nReason: Name already taken.",
+                                 connection.getRemoteHost(),
+                                 connection.getRemotePort()));
+                     }
+                     else {
                          System.out.println(String.format("Connected new Client %s with IP:Port <%s:%d>",
                                  connectionHandler.getUserName(),
                                  connection.getRemoteHost(),
-                             connection.getRemotePort()
-                     ));
+                                 connection.getRemotePort()));
+                     }
                  }
                 finally {
                      mutex.unlock();

server/src/main/java/ch/zhaw/pm2/multichat/server/ServerConnectionHandler.java

@@ -1,12 +1,13 @@
 package ch.zhaw.pm2.multichat.server;
 
 import ch.zhaw.pm2.multichat.protocol.ChatProtocolException;
+import ch.zhaw.pm2.multichat.protocol.ConnectionHandler;
+import static ch.zhaw.pm2.multichat.protocol.ConnectionHandler.State.*;
 import ch.zhaw.pm2.multichat.protocol.NetworkHandler;
 
 import java.io.EOFException;
 import java.io.IOException;
 import java.net.SocketException;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Scanner;
@@ -14,24 +15,13 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 
-import static ch.zhaw.pm2.multichat.server.ServerConnectionHandler.State.*;
 
-public class ServerConnectionHandler implements Runnable{
+
+public class ServerConnectionHandler extends ConnectionHandler implements Runnable{
     private static final AtomicInteger connectionCounter = new AtomicInteger(0);
     private final int connectionId = connectionCounter.incrementAndGet();
-    private final NetworkHandler.NetworkConnection<String> connection;
     private final Map<String,ServerConnectionHandler> connectionRegistry;
 
-    // Data types used for the Chat Protocol
-    private static final String DATA_TYPE_CONNECT = "CONNECT";
-    private static final String DATA_TYPE_CONFIRM = "CONFIRM";
-    private static final String DATA_TYPE_DISCONNECT = "DISCONNECT";
-    private static final String DATA_TYPE_MESSAGE = "MESSAGE";
-    private static final String DATA_TYPE_ERROR = "ERROR";
-
-    private static final String USER_NONE = "";
-    private static final String USER_ALL = "*";
-
     private ReentrantLock mutex;
 
     private Condition nameComplete;
@@ -44,15 +34,12 @@ public class ServerConnectionHandler implements Runnable{
         startReceiving();
     }
 
-    enum State {
-        NEW, CONNECTED, DISCONNECTED;
-    }
-
     public ServerConnectionHandler(NetworkHandler.NetworkConnection<String> connection,
                                    Map<String,ServerConnectionHandler> registry, ReentrantLock mutex, Condition nameComplete) {
+        super();
+        setConnection(connection);
         Objects.requireNonNull(connection, "Connection must not be null");
         Objects.requireNonNull(registry, "Registry must not be null");
-        this.connection = connection;
         this.connectionRegistry = registry;
         this.mutex = mutex;
         this.nameComplete = nameComplete;
@@ -62,12 +49,16 @@ public class ServerConnectionHandler implements Runnable{
         return this.userName;
     }
 
-    public void startReceiving() {
+    public State getState() {
+        return state;
+    }
+
+    private void startReceiving() {
             System.out.println("Starting Connection Handler for new User");
             try {
                 System.out.println("Start receiving data...");
-                while (connection.isAvailable()) {
-                    String data = connection.receive();
+                while (getConnection().isAvailable() && !(state == ERROR)) {
+                    String data = getConnection().receive();
                     processData(data);
                 }
                 System.out.println("Stopped recieving data");
@@ -84,78 +75,95 @@ public class ServerConnectionHandler implements Runnable{
             } catch (ClassNotFoundException e) {
                 System.err.println("Received object of unknown type: " + e.getMessage());
             }
+        if (state == ERROR) {
+            System.out.println("Stopping Connection Handler for Rejected Client");
+        } else {
             System.out.println("Stopping Connection Handler for " + userName);
+        }
 
     }
 
-    public void stopReceiving() {
+    private void stopReceiving() {
         System.out.println("Closing Connection Handler for " + userName);
         try {
             System.out.println("Stop receiving data...");
-            connection.close();
+            getConnection().close();
             System.out.println("Stopped receiving data.");
         } catch (IOException e) {
-            System.err.println("Failed to close connection." + e);
+            System.err.println("Failed to close connection." + e.getMessage());
         }
         System.out.println("Closed Connection Handler for " + userName);
     }
 
     private void processData(String data)  {
         try {
-            // parse data content
             Scanner scanner = new Scanner(data);
-            String sender = null;
-            String reciever = null;
-            String type = null;
-            String payload = null;
-            if (scanner.hasNextLine()) {
-                sender = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Sender found");
-            }
-            if (scanner.hasNextLine()) {
-                reciever = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Reciever found");
-            }
-            if (scanner.hasNextLine()) {
-                type = scanner.nextLine();
-            } else {
-                throw new ChatProtocolException("No Type found");
-            }
-            if (scanner.hasNextLine()) {
-                payload = scanner.nextLine();
-            }
+            StringBuilder sender = new StringBuilder();
+            StringBuilder reciever = new StringBuilder();
+            StringBuilder type = new StringBuilder();
+            StringBuilder payload = new StringBuilder();
+            super.processData(scanner,sender,reciever,type,payload);
 
             // dispatch operation based on type parameter
-            if (type.equals(DATA_TYPE_CONNECT)) {
+            if (type.toString().equals(getDataTypeConnect())) {
+                caseConnect(sender.toString());
+            } else if (type.toString().equals(getDataTypeConfirm())) {
+                System.out.println("Not expecting to receive a CONFIRM request from client");
+            } else if (type.toString().equals(getDataTypeDisconnect())) {
+                caseDisconnect();
+            } else if (type.toString().equals(getDataTypeMessage())) {
+                caseMessage(sender.toString(), reciever.toString(), type.toString(), payload.toString());
+            } else if (type.toString().equals(getDataTypeError())) {
+                System.err.println("Received error from client (" + sender + "): " + payload);
+            } else {
+                System.err.println("Unknown data type received: " + type);
+
+            }
+        } catch(ChatProtocolException e) {
+            System.out.println("Error while processing data " + e.getMessage());
+            sendData(USER_NONE, userName, getDataTypeError(), e.getMessage());
+        }
+    }
+
+    private void caseConnect(String sender) throws ChatProtocolException {
         if (this.state != NEW) throw new ChatProtocolException("Illegal state for connect request: " + state);
-                if (sender == null || sender.isBlank()) sender = this.userName;
-                if (connectionRegistry.containsKey(sender))
-                    throw new ChatProtocolException("User name already taken: " + sender);
+        if (sender.isBlank()) sender = this.userName;
+        if (connectionRegistry.containsKey(sender)) {
             mutex.lock();
             try {
-                    this.userName = sender;
+                state = ERROR;
+                nameComplete.signal();
+            }
+            finally {
+                mutex.unlock();
+            }
+            throw new ChatProtocolException("User name already taken: " + sender);
+        }
+        mutex.lock();
+        try {
+            this.userName = sender.toString();
             nameComplete.signal();
         }
         finally {
             mutex.unlock();
         }
         connectionRegistry.put(userName, this);
-                sendData(USER_NONE, userName, DATA_TYPE_CONFIRM, "Registration successfull for " + userName);
+        sendData(USER_NONE, userName, getDataTypeConfirm(), "Registration successfull for " + userName);
         this.state = CONNECTED;
-            } else if (type.equals(DATA_TYPE_CONFIRM)) {
-                System.out.println("Not expecting to receive a CONFIRM request from client");
-            } else if (type.equals(DATA_TYPE_DISCONNECT)) {
+    }
+
+    private void caseDisconnect() throws ChatProtocolException {
         if (state == DISCONNECTED)
             throw new ChatProtocolException("Illegal state for disconnect request: " + state);
         if (state == CONNECTED) {
             connectionRegistry.remove(this.userName);
         }
-                sendData(USER_NONE, userName, DATA_TYPE_CONFIRM, "Confirm disconnect of " + userName);
+        sendData(USER_NONE, userName, getDataTypeConfirm(), "Confirm disconnect of " + userName);
         this.state = DISCONNECTED;
         this.stopReceiving();
-            } else if (type.equals(DATA_TYPE_MESSAGE)) {
+    }
+
+    private void caseMessage(String sender, String reciever, String type, String payload) throws ChatProtocolException{
         if (state != CONNECTED) throw new ChatProtocolException("Illegal state for message request: " + state);
         if (USER_ALL.equals(reciever)) {
             for (ServerConnectionHandler handler : connectionRegistry.values()) {
@@ -169,38 +177,7 @@ public class ServerConnectionHandler implements Runnable{
                     sendData(sender, reciever, type, payload); //send message to sender if it's a direct message and sender is not receiver.
                 }
             } else {
-                        this.sendData(USER_NONE, userName, DATA_TYPE_ERROR, "Unknown User: " + reciever);
-                    }
-                }
-            } else if (type.equals(DATA_TYPE_ERROR)) {
-                System.err.println("Received error from client (" + sender + "): " + payload);
-            } else {
-                System.err.println("Unknown data type received: " + type);
-
-            }
-        } catch(ChatProtocolException e) {
-            System.out.println("Error while processing data" + e.getMessage());
-            sendData(USER_NONE, userName, DATA_TYPE_ERROR, e.getMessage());
-        }
-    }
-
-    public void sendData(String sender, String receiver, String type, String payload) {
-        if (connection.isAvailable()) {
-            new StringBuilder();
-            String data = new StringBuilder()
-                .append(sender+"\n")
-                .append(receiver+"\n")
-                .append(type+"\n")
-                .append(payload+"\n")
-                .toString();
-            try {
-                connection.send(data);
-            } catch (SocketException e) {
-                System.out.println("Connection closed: " + e.getMessage());
-            } catch (EOFException e) {
-                System.out.println("Connection terminated by remote");
-            } catch(IOException e) {
-                System.out.println("Communication error: " + e.getMessage());
+                this.sendData(USER_NONE, userName, getDataTypeError(), "Unknown User: " + reciever);
             }
         }
     }