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

@@ -1,18 +1,54 @@
 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.ObjectInputStream;
+
 public class ServerListener implements Runnable{
-    // TODO: store the ObjectInputStream from the user socket
+    private final ObjectInputStream in;
-    //          (this should be the same input stream the
+
-    //           chatClient created when connecting)
+    public ServerListener(ObjectInputStream in) {
+        this.in = in;
+    }
+
 
     @Override
     public void run() {
         try {
-            // TODO: In an infinite loop read objects from the server
+            while (true) {
-            //   - if it's a ChatMessage  -> print "<sender>: <content>"
+                Object obj = in.readObject();
-            //   - if it's a FileMessage  -> print that a file was received
+                if (obj instanceof ChatMessage) {
-            //                               (filename + sender), it's already
+                    ChatMessage msg = (ChatMessage) obj;
-            //                               saved to disk by the server.
+                    switch (msg.getType()) {
+                        case LOGIN_SUCCESS:
+                            System.out.println("\n[Server] " + msg.getContent());
+                            break;
+                        case LOGIN_FAILED:
+                            System.out.println("\n[Server] " + msg.getContent());
+                            System.exit(0);
+                            break;
+                        case PUBLIC_MESSAGE:
+                            System.out.println("\n[" + msg.getSender() + "]: " + msg.getContent());
+                            break;
+                        case PRIVATE_MESSAGE:
+                            System.out.println("\n[Private from " + msg.getSender() + "]: " + msg.getContent());
+                            break;
+                        case USER_LIST:
+                            System.out.println("\n[Online users]: " + msg.getContent());
+                            break;
+                        default:
+                            System.out.println("\n[Server] " + msg.getContent());
+                    }
+                    System.out.print("> ");
+                } else if (obj instanceof FileMessage) {
+                    FileMessage fileMsg = (FileMessage) obj;
+                    System.out.println("\n[File received] from " + fileMsg.getSender() +
+                            ": " + fileMsg.getFilename() + " (saved to server_data)");
+                    System.out.print("> ");
+                }
+            }
         } catch (Exception e){
             System.out.println("Disconnected from server");
         }

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

@@ -1,29 +1,112 @@
 package com.university.chat.Client;
 
-public class chatClient {
+import com.university.chat.Common.ChatMessage;
-    public static void main() {
+import com.university.chat.Common.FileMessage;
-        // TODO: Connecting to the server
+import com.university.chat.Common.MessageType;
-        //  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.
 
-        while (true){
+import java.io.*;
-            try {
+import java.net.Socket;
-                // TODO: Program loop — read a line from the console and act on it:
+import java.nio.file.Files;
-                //   - "/msg <user> <text>"        -> build & send a PRIVATE_MESSAGE
+import java.nio.file.Path;
-                //   - "/users"                    -> build & send a USER_LIST request
+import java.nio.file.Paths;
-                //   - "/sendfile <user> <path>"   -> read the file into a byte[]
+import java.util.Scanner;
-                //                                     (you can use TransferProgress
+
-                //                                     to show progress)
+public class chatClient {
-                //                                     and send it as a FileMessage
+
-                //   - anything else               -> send a PUBLIC_MESSAGE
+    private static ObjectOutputStream out;
-                //   Remember to flush() the output stream after writeObject().
+    private static ObjectInputStream in;
-            } catch (Exception e){
+    private static String username;
+
+
+    public static void main(String[] args) {
+        try {
+
+            Socket socket = new Socket("localhost", 12345);
+
+            out = new ObjectOutputStream(socket.getOutputStream());
+            in = new ObjectInputStream(socket.getInputStream());
+
+            Scanner scanner = new Scanner(System.in);
+            System.out.print("Enter your username: ");
+            username = scanner.nextLine().trim();
+
+            ChatMessage loginMsg = new ChatMessage(MessageType.LOGIN, username, null, "");
+            out.writeObject(loginMsg);
+            out.flush();
+
+
+            ServerListener listener = new ServerListener(in);
+            new Thread(listener).start();
+            while (true){
+                try {
+                    System.out.print("> ");
+                    String line = scanner.nextLine();
+                    if (line == null) break;
+
+                    if (line.equals("/exit") || line.equals("/quit")) {
+                        System.out.println("Disconnecting...");
+                        break;
+                    }
+
+                    if (line.startsWith("/msg ")) {
+                        String[] parts = line.split(" ", 3);
+                        if (parts.length < 3) {
+                            System.out.println("Usage: /msg <username> <message>");
+                            continue;
+                        }
+                        String target = parts[1];
+                        String content = parts[2];
+                        ChatMessage privateMsg = new ChatMessage(MessageType.PRIVATE_MESSAGE,
+                                username, target, content);
+                        out.writeObject(privateMsg);
+                        out.flush();
+                    } else if (line.equals("/users")) {
+                        ChatMessage userListReq = new ChatMessage(MessageType.USER_LIST,
+                                username, null, "");
+                        out.writeObject(userListReq);
+                        out.flush();
+                    } else if (line.startsWith("/sendfile ")) {
+                        String[] parts = line.split(" ", 3);
+                        if (parts.length < 3) {
+                            System.out.println("Usage: /sendfile <username> <filepath>");
+                            continue;
+                        }
+                        String target = parts[1];
+                        String filePath = parts[2];
+
+                        Path path = Paths.get(filePath);
+                        if (!Files.exists(path) || Files.isDirectory(path)) {
+                            System.out.println("File does not exist or is a directory.");
+                            continue;
+                        }
+
+                        byte[] data = Files.readAllBytes(path);
+                        String filename = path.getFileName().toString();
+
+                        TransferProgress progress = new TransferProgress(data.length);
+                        progress.update(data.length);
+
+                        FileMessage fileMsg = new FileMessage(username, target, filename, data);
+                        out.writeObject(fileMsg);
+                        out.flush();
+                        System.out.println("File sent to " + target);
+                    } else {
+                        ChatMessage publicMsg = new ChatMessage(MessageType.PUBLIC_MESSAGE,
+                                username, null, line);
+                        out.writeObject(publicMsg);
+                        out.flush();
+                    }
+                }catch (IOException e) {
+                    System.out.println("Connection lost. Exiting...");
+                    break;
+                } catch (Exception e){
                 System.out.println("command failed: " + e.getMessage());
             }
         }
+            socket.close();
+            scanner.close();
+        } catch (Exception e) {
+            System.out.println("Connection error: " + e.getMessage());
+        }
     }
 }

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

@@ -1,15 +1,26 @@
 package com.university.chat.Server;
 
+import java.net.ServerSocket;
+import java.net.Socket;
+
 public class ChatServer {
-    // TODO: declare a single shared UserManager instance (static final)
+    private static final UserManager userManager = new UserManager();
-    //         This MUST be shared by all ClientSession threads so that
-    //         broadcasting and private messaging work correctly.
 
     public static void main(String[] args) {
-        // TODO: Create a ServerSocket
+        final int PORT = 12345;
+
+        try (ServerSocket serverSocket = new ServerSocket(PORT)) {
+            System.out.println("Chat Server started on port " + PORT);
+
+            while (true) {
+                Socket clientSocket = serverSocket.accept();
+                System.out.println("New client connected: " + clientSocket.getInetAddress());
+                ClientSession session = new ClientSession(clientSocket, userManager);
+                new Thread(session).start();
+            }
+        } catch (Exception e) {
+            System.err.println("Server error: " + e.getMessage());
+        }
 
-        // TODO: In an infinite loop:
-        //  accept an incoming client connection
-        //  make a new thread running ClientSession for each user.
     }
 }

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

@@ -2,44 +2,94 @@ 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 final Socket socket;
+    private final UserManager userManager;
+    private ObjectOutputStream out;
+    private ObjectInputStream in;
     private String username;
 
     public ClientSession(Socket socket, UserManager userManager) {
-        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
+        this.socket = socket;
-        //         and an ObjectInputStream from socket.getInputStream().
+        this.userManager = userManager;
+        try {
+            out = new ObjectOutputStream(socket.getOutputStream());
+            in = new ObjectInputStream(socket.getInputStream());
+        } catch (IOException e) {
+            System.err.println("Error initializing streams: " + e.getMessage());
+            try {
+                socket.close();
+            } catch (IOException ignored) {}
+        }
     }
 
     @Override
     public void run() {
         try {
+            if (out == null || in == null) {
+                return;
+            }
 
-            // TODO: Welcome the user (login step)
+            Object first = in.readObject();
-            //  1. Read the first object sent by the client.
+            if (!(first instanceof ChatMessage)) {
-            //  2. Check it's a ChatMessage with type LOGIN.
+                socket.close();
-            //  3. Extract the username.
+                return;
-            //  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.
 
-            // TODO: Main message loop
+            ChatMessage loginMsg = (ChatMessage) first;
-            //   In a loop, call in.readObject(), you can separate messages by their type:
+            if (loginMsg.getType() != MessageType.LOGIN) {
-            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
+                socket.close();
-            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
+                return;
-            //   Keep looping until the connection is closed (an exception will be thrown).
+            }
+
+            String requestedUsername = loginMsg.getSender();
+
+            if (!userManager.addUser(requestedUsername, this)) {
+                ChatMessage failure = new ChatMessage(MessageType.LOGIN_FAILED, "Server", null,
+                        "Username '" + requestedUsername + "' is already taken.");
+                out.writeObject(failure);
+                out.flush();
+                socket.close();
+                return;
+            }
+
+            this.username = requestedUsername;
+            FileManager.createUserFolders(username);
+
+            ChatMessage success = new ChatMessage(MessageType.LOGIN_SUCCESS, "Server", null,
+                    "Welcome " + username + "!");
+            out.writeObject(success);
+            out.flush();
+
+            System.out.println("User logged in: " + username);
+
+            while (true) {
+                Object obj = in.readObject();
+                if (obj instanceof ChatMessage) {
+                    handleChatMessage((ChatMessage) obj);
+                } else if (obj instanceof FileMessage) {
+                    handleFileMessage((FileMessage) obj);
+                }
+            }
 
         } catch (Exception e) {
             System.out.println("Disconnected: " + username);
         } finally {
-            // TODO: Remove the user from UserManager so they no longer
+            if (username != null) {
-            //        receive broadcasts or appear in users list
+                userManager.removeUser(username);
+            }
+            try {
+                socket.close();
+            } catch (IOException ignored) {}
         }
     }
 
@@ -47,14 +97,34 @@ public class ClientSession implements Runnable {
     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.out.writeObject(msg);
+                    session.out.flush();
+                }
             }
             case PRIVATE_MESSAGE -> {
-                // TODO: Forward this message to the receiver user.
+                String receiver = msg.getReceiver();
+                ClientSession target = userManager.getUser(receiver);
+                if (target != null) {
+                    target.out.writeObject(msg);
+                    target.out.flush();
+                } else {
+                    ChatMessage error = new ChatMessage(MessageType.PRIVATE_MESSAGE, "Server",
+                            msg.getSender(), "User '" + receiver + "' is not online.");
+                    out.writeObject(error);
+                    out.flush();
+                }
             }
             case USER_LIST -> {
-                // TODO: Reply to the requester with the list of online users.
+                String list = userManager.listUsers();
+                ChatMessage reply = new ChatMessage(MessageType.USER_LIST, "Server",
+                        msg.getSender(), list);
+                out.writeObject(reply);
+                out.flush();
             }
+            default -> {
+            }
+
         }
     }
 
@@ -66,6 +136,15 @@ public class ClientSession implements Runnable {
         Files.write(sentPath, fileMsg.getData());
         Files.write(recvPath, fileMsg.getData());
 
-        // TODO: Forward the received file-message to the destination user.
+        ClientSession target = userManager.getUser(fileMsg.getReceiver());
+        if (target != null) {
+            target.out.writeObject(fileMsg);
+            target.out.flush();
+        }else {
+            ChatMessage error = new ChatMessage(MessageType.PRIVATE_MESSAGE, "Server",
+                    fileMsg.getSender(), "User '" + fileMsg.getReceiver() + "' is not online. File saved on server.");
+            out.writeObject(error);
+            out.flush();
+        }
     }
 }