pom.xml

@@ -9,8 +9,8 @@
     <version>1.0-SNAPSHOT</version>
 
     <properties>
-        <maven.compiler.source>25</maven.compiler.source>
+        <maven.compiler.source>21</maven.compiler.source>
-        <maven.compiler.target>25</maven.compiler.target>
+        <maven.compiler.target>21</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 

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

@@ -1,18 +1,37 @@
 package com.university.chat.Client;
 
+import com.university.chat.Common.ChatMessage;
+import com.university.chat.Common.FileMessage;
+
+import java.io.ObjectInputStream;
+import java.net.Socket;
+
 public class ServerListener implements Runnable{
-    // TODO: store the ObjectInputStream from the user socket
+
-    //          (this should be the same input stream the
+    private final ObjectInputStream in;
-    //           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
+
-            //   - if it's a ChatMessage  -> print "<sender>: <content>"
+            while (true) {
-            //   - if it's a FileMessage  -> print that a file was received
+                Object obj = in.readObject();
-            //                               (filename + sender), it's already
+                if (obj instanceof ChatMessage msg) {
-            //                               saved to disk by the server.
+                    System.out.println(msg.getSender() + ": " + msg.getContent());
+                }
+                else if (obj instanceof FileMessage file) {
+                    System.out.println("[File received] '" + file.getFilename()
+                            + "' from " + file.getSender());
+                }
+                else if (obj instanceof String str) {
+                    System.out.println(str);
+                }
+            }
+
         } catch (Exception e){
             System.out.println("Disconnected from server");
         }

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

@@ -1,29 +1,97 @@
 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;
+import java.io.ObjectOutputStream;
+import java.net.Socket;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.Scanner;
+
 public class chatClient {
-    public static void main() {
+    public static void main(String[] args) {
-        // TODO: Connecting to the server
+
-        //  1. Create a socket and connect to the server
+        String host = "localhost";
-        //  2. Create an ObjectOutputStream (out) and ObjectInputStream (in)
+        int port = 9000;
-        //      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){
         try {
-                // TODO: Program loop — read a line from the console and act on it:
+
-                //   - "/msg <user> <text>"        -> build & send a PRIVATE_MESSAGE
+            Socket socket = new Socket(host, port);
-                //   - "/users"                    -> build & send a USER_LIST request
+            ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
-                //   - "/sendfile <user> <path>"   -> read the file into a byte[]
+            ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
-                //                                     (you can use TransferProgress
+
-                //                                     to show progress)
+            Scanner sc = new Scanner(System.in);
-                //                                     and send it as a FileMessage
+            System.out.println("Enter your username: ");
-                //   - anything else               -> send a PUBLIC_MESSAGE
+            String username = sc.nextLine();
-                //   Remember to flush() the output stream after writeObject().
+
-            } catch (Exception e){
+            out.writeObject(new ChatMessage(MessageType.LOGIN, username, null, null));
+            out.flush();
+
+            Object loginResponse = in.readObject();
+            if (loginResponse instanceof ChatMessage response) {
+                if (response.getType() == MessageType.LOGIN_FAILED) {
+                    System.out.println("Login failed: " + response.getContent());
+                    socket.close();
+                    return;
+                }
+                System.out.println(response.getContent());
+            }
+
+            Thread listenerThread = new Thread(new ServerListener(in));
+            listenerThread.setDaemon(true);
+            listenerThread.start();
+
+            while (true) {
+                try {
+                    String line = sc.nextLine();
+
+                    if (line.startsWith("/msg ")) {
+                        String[] parts = line.split(" ", 3);
+                        if (parts.length < 3) {
+                            System.out.println("Usage: /msg <user> <text>");
+                            continue;
+                        }
+                        String target = parts[1];
+                        String text = parts[2];
+                        out.writeObject(new ChatMessage(MessageType.PRIVATE_MESSAGE, username, target, 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.split(" ", 3);
+                        if (parts.length < 3) {
+                            System.out.println("Usage: /sendfile <user> <filepath>");
+                            continue;
+                        }
+                        String target = parts[1];
+                        String filePath = parts[2];
+
+                        byte[] fileData = Files.readAllBytes(Paths.get(filePath));
+                        String filename = Paths.get(filePath).getFileName().toString();
+
+                        TransferProgress progress = new TransferProgress(fileData.length);
+                        progress.update(fileData.length);
+
+                        out.writeObject(new FileMessage(username, target, filename, fileData));
+                        out.flush();
+                        System.out.println("File '" + filename + "' sent to " + target + ".");
+
+                    } else {
+                        out.writeObject(new ChatMessage(MessageType.PUBLIC_MESSAGE, username, null, line));
+                        out.flush();
+                    }
+                } catch (Exception e) {
                     System.out.println("command failed: " + e.getMessage());
                 }
             }
+        } catch (Exception e) {
+            System.out.println(" could not connect to " + host + ":" + port);
+        }
     }
 }

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

@@ -1,15 +1,26 @@
 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.
 
-    public static void main(String[] args) {
+    private static final  UserManager userManager = new UserManager();
-        // TODO: Create a ServerSocket
+    private static final  int port = 9000;
 
-        // TODO: In an infinite loop:
+    public static void main(String[] args) throws IOException {
-        //  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();
+                Thread clientThread = new Thread(new ClientSession(clientSocket,userManager));
+                clientThread.start();
+            }
+        }
+        catch (IOException e){
+            System.out.println("server error: " + e.getMessage());
+        }
     }
 }

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

@@ -2,70 +2,128 @@ 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 Socket socket;
+    private 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.in = new ObjectInputStream(socket.getInputStream());
+        }
+        catch (IOException e) {
+            System.out.println("Failed to create streams: "  + e.getMessage());
+        }
+
     }
 
     @Override
     public void run() {
         try {
 
-            // TODO: Welcome the user (login step)
+            Object firstObject = in.readObject();
-            //  1. Read the first object sent by the client.
+            if (!(firstObject instanceof ChatMessage loginMsg) || loginMsg.getType() != MessageType.LOGIN) {
-            //  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.
+            username = loginMsg.getSender();
-            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
-            //      and send back LOGIN_SUCCESS.
 
-            // TODO: Main message loop
+            boolean registered = userManager.addUser(username,this);
-            //   In a loop, call in.readObject(), you can separate messages by their type:
+
-            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
+            if (!registered) {
-            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
+                sendMessage(new ChatMessage(MessageType.LOGIN_FAILED, "Server", username, "Username already taken."));
-            //   Keep looping until the connection is closed (an exception will be thrown).
+                socket.close();
+                return;
+            }
+            FileManager.createUserFolders(username);
+            sendMessage(new ChatMessage(MessageType.LOGIN_SUCCESS, "Server", username, "Welcome " + username + "!"));
+            System.out.println(username + " logged in successfully.");
+
+            while(true) {
+                Object message = in.readObject();
+                if  (message instanceof FileMessage msg) {
+                    handleFileMessage(msg);
+                }
+                else if  (message instanceof ChatMessage msg) {
+                    handleChatMessage(msg);
+                }
+            }
 
         } 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 e) {}
+        }
+    }
+    public synchronized 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);
+                    sendMessage("Message sent!");
+                }
+                else {
+                    sendMessage(new ChatMessage(MessageType.PUBLIC_MESSAGE, "Server", username, "User '" + msg.getReceiver() + "' is not online."));
+                }
             }
             case USER_LIST -> {
-                // TODO: Reply to the requester with the list of online users.
+
+                sendMessage(new ChatMessage(MessageType.USER_LIST, "Server", username, userManager.listUsers()));
             }
         }
     }
 
     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);
+        } else {
+            sendMessage(new ChatMessage(
+                    MessageType.PUBLIC_MESSAGE,
+                    "Server", username,
+                    "User '" + fileMsg.getReceiver() + "' is not online. File saved on server."
+            ));
+        }
     }
 }