src/main/java/com/university/chat/Client/ServerListener.java

@@ -1,20 +1,32 @@
 package com.university.chat.Client;
 
-public class ServerListener implements Runnable{
-    // TODO: store the ObjectInputStream from the user socket
-    //          (this should be the same input stream the
-    //           chatClient created when connecting)
+import com.university.chat.Common.ChatMessage;
+import com.university.chat.Common.FileMessage;
+
+import java.io.ObjectInputStream;
+
+public class ServerListener implements Runnable {
+
+    private final ObjectInputStream in;
+
+    public ServerListener(ObjectInputStream in) {
+        this.in = in;
+    }
 
     @Override
     public void run() {
         try {
-            // TODO: In an infinite loop read objects from the server
-            //   - if it's a ChatMessage  -> print "<sender>: <content>"
-            //   - if it's a FileMessage  -> print that a file was received
-            //                               (filename + sender), it's already
-            //                               saved to disk by the server.
-        } catch (Exception e){
+            while (true) {
+                Object received = in.readObject();
+
+                if (received instanceof ChatMessage msg) {
+                    System.out.println(msg.getSender() + ": " + msg.getContent());
+                } else if (received instanceof FileMessage fileMsg) {
+                    System.out.println("Received file '" + fileMsg.getFilename() + "' from " + fileMsg.getSender());
+                }
+            }
+        } catch (Exception e) {
             System.out.println("Disconnected from server");
         }
     }
-}
+}

src/main/java/com/university/chat/Client/chatClient.java

@@ -1,29 +1,77 @@
 package com.university.chat.Client;
 
+import com.university.chat.Common.ChatMessage;
+import com.university.chat.Common.FileMessage;
+import com.university.chat.Common.MessageType;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.net.Socket;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Scanner;
+
 public class chatClient {
     public static void main() {
-        // TODO: Connecting to the server
-        //  1. Create a socket and connect to the server
-        //  2. Create an ObjectOutputStream (out) and ObjectInputStream (in)
-        //      from the socket's streams — output FIRST, then input.
-        //  2. Get the username, and send a LOGIN ChatMessage with that username
-        //  3. Start a new Thread running a ServerListener(in) so incoming
-        //      messages are handled concurrently.
+        String host = "localhost";
+        int port = 5000;
+        Scanner scanner = new Scanner(System.in);
 
-        while (true){
-            try {
-                // TODO: Program loop — read a line from the console and act on it:
-                //   - "/msg <user> <text>"        -> build & send a PRIVATE_MESSAGE
-                //   - "/users"                    -> build & send a USER_LIST request
-                //   - "/sendfile <user> <path>"   -> read the file into a byte[]
-                //                                     (you can use TransferProgress
-                //                                     to show progress)
-                //                                     and send it as a FileMessage
-                //   - anything else               -> send a PUBLIC_MESSAGE
-                //   Remember to flush() the output stream after writeObject().
-            } catch (Exception e){
-                System.out.println("command failed: " + e.getMessage());
+        try {
+            Socket socket = new Socket(host, port);
+            ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
+            out.flush();
+            ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
+
+            System.out.print("Enter your username: ");
+            String username = scanner.nextLine();
+
+            out.writeObject(new ChatMessage(MessageType.LOGIN, username, null, null));
+            out.flush();
+
+            Thread listenerThread = new Thread(new ServerListener(in));
+            listenerThread.start();
+
+            while (true) {
+                try {
+                    String line = scanner.nextLine();
+
+                    if (line.startsWith("/msg ")) {
+                        String[] parts = line.substring(5).split(" ", 2);
+                        String receiver = parts[0];
+                        String text = parts.length > 1 ? parts[1] : "";
+                        out.writeObject(new ChatMessage(MessageType.PRIVATE_MESSAGE, username, receiver, text));
+                        out.flush();
+
+                    } else if (line.equals("/users")) {
+                        out.writeObject(new ChatMessage(MessageType.USER_LIST, username, null, null));
+                        out.flush();
+
+                    } else if (line.startsWith("/sendfile ")) {
+                        String[] parts = line.substring(10).split(" ", 2);
+                        String receiver = parts[0];
+                        String path = parts[1];
+
+                        Path filePath = Paths.get(path);
+                        byte[] data = Files.readAllBytes(filePath);
+                        String filename = filePath.getFileName().toString();
+
+                        out.writeObject(new FileMessage(username, receiver, filename, data));
+                        out.flush();
+
+                    } else {
+                        out.writeObject(new ChatMessage(MessageType.PUBLIC_MESSAGE, username, null, line));
+                        out.flush();
+                    }
+                } catch (Exception e) {
+                    System.out.println("command failed: " + e.getMessage());
+                }
             }
+
+        } catch (IOException e) {
+            System.out.println("Could not connect to server: " + e.getMessage());
         }
     }
-}
+}

src/main/java/com/university/chat/Server/ChatServer.java

@@ -1,15 +1,27 @@
 package com.university.chat.Server;
 
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+
 public class ChatServer {
-    // TODO: declare a single shared UserManager instance (static final)
-    //         This MUST be shared by all ClientSession threads so that
-    //         broadcasting and private messaging work correctly.
+
+    private static final UserManager userManager = new UserManager();
 
     public static void main(String[] args) {
-        // TODO: Create a ServerSocket
+        int port = 5000;
 
-        // TODO: In an infinite loop:
-        //  accept an incoming client connection
-        //  make a new thread running ClientSession for each user.
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            System.out.println("Server started on port " + port);
+
+            while (true) {
+                Socket clientSocket = serverSocket.accept();
+                ClientSession session = new ClientSession(clientSocket, userManager);
+                Thread thread = new Thread(session);
+                thread.start();
+            }
+        } catch (IOException e) {
+            System.out.println("Server error: " + e.getMessage());
+        }
     }
-}
+}

src/main/java/com/university/chat/Server/ClientSession.java

@@ -2,70 +2,107 @@ package com.university.chat.Server;
 
 import com.university.chat.Common.ChatMessage;
 import com.university.chat.Common.FileMessage;
+import com.university.chat.Common.MessageType;
 
 import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.net.Socket;
 import java.nio.file.Files;
 
 public class ClientSession implements Runnable {
 
     private String username;
+    private final Socket socket;
+    private final UserManager userManager;
+    private ObjectOutputStream out;
+    private ObjectInputStream in;
 
     public ClientSession(Socket socket, UserManager userManager) {
-        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
-        //         and an ObjectInputStream from socket.getInputStream().
+        this.socket = socket;
+        this.userManager = userManager;
+        try {
+            this.out = new ObjectOutputStream(socket.getOutputStream());
+            this.out.flush();
+            this.in = new ObjectInputStream(socket.getInputStream());
+        } catch (IOException e) {
+            System.out.println("Failed to set up streams: " + e.getMessage());
+        }
     }
 
     @Override
     public void run() {
         try {
+            Object first = in.readObject();
+            if (first instanceof ChatMessage loginMsg && loginMsg.getType() == MessageType.LOGIN) {
+                username = loginMsg.getSender();
 
-            // TODO: Welcome the user (login step)
-            //  1. Read the first object sent by the client.
-            //  2. Check it's a ChatMessage with type LOGIN.
-            //  3. Extract the username.
-            //  4. Try to register the user via userManager.addUser(...).
-            //  5. If the username is taken, send back LOGIN_FAILED and close the socket.
-            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
-            //      and send back LOGIN_SUCCESS.
+                if (!userManager.addUser(username, this)) {
+                    sendMessage(new ChatMessage(MessageType.LOGIN_FAILED, "Server", username, "Username already taken"));
+                    socket.close();
+                    return;
+                }
 
-            // TODO: Main message loop
-            //   In a loop, call in.readObject(), you can separate messages by their type:
-            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
-            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
-            //   Keep looping until the connection is closed (an exception will be thrown).
+                FileManager.createUserFolders(username);
+                sendMessage(new ChatMessage(MessageType.LOGIN_SUCCESS, "Server", username, "Welcome, " + username + "!"));
+            } else {
+                socket.close();
+                return;
+            }
+
+            while (true) {
+                Object received = in.readObject();
+                if (received instanceof ChatMessage msg) {
+                    handleChatMessage(msg);
+                } else if (received instanceof FileMessage fileMsg) {
+                    handleFileMessage(fileMsg);
+                }
+            }
 
         } catch (Exception e) {
             System.out.println("Disconnected: " + username);
         } finally {
-            // TODO: Remove the user from UserManager so they no longer
-            //        receive broadcasts or appear in users list
+            if (username != null) {
+                userManager.removeUser(username);
+            }
         }
     }
 
+    public void sendMessage(Object obj) throws IOException {
+        out.writeObject(obj);
+        out.flush();
+    }
 
     private void handleChatMessage(ChatMessage msg) throws IOException {
         switch (msg.getType()) {
             case PUBLIC_MESSAGE -> {
-                // TODO: Broadcast this message to every connected client.
+                for (ClientSession session : userManager.getAllSessions()) {
+                    session.sendMessage(msg);
+                }
             }
             case PRIVATE_MESSAGE -> {
-                // TODO: Forward this message to the receiver user.
+                ClientSession receiver = userManager.getUser(msg.getReceiver());
+                if (receiver != null) {
+                    receiver.sendMessage(msg);
+                }
             }
             case USER_LIST -> {
-                // TODO: Reply to the requester with the list of online users.
+                ChatMessage reply = new ChatMessage(MessageType.USER_LIST, "Server", msg.getSender(), userManager.listUsers());
+                sendMessage(reply);
             }
         }
     }
 
     private void handleFileMessage(FileMessage fileMsg) throws IOException {
-        // Storing the file
         var sentPath = FileManager.getSentPath(fileMsg.getSender(), fileMsg.getFilename());
         var recvPath = FileManager.getReceivedPath(fileMsg.getReceiver(), fileMsg.getFilename());
 
         Files.write(sentPath, fileMsg.getData());
         Files.write(recvPath, fileMsg.getData());
 
-        // TODO: Forward the received file-message to the destination user.
+        ClientSession receiver = userManager.getUser(fileMsg.getReceiver());
+        if (receiver != null) {
+            receiver.sendMessage(fileMsg);
+        }
     }
 }