feat: complete TODO tasks in ChatServer.java

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

@@ -1,15 +1,37 @@
 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();
+    private static ServerSocket serverSocket;
 
     public static void main(String[] args) {
-        // TODO: Create a ServerSocket
 
-        // TODO: In an infinite loop:
-        //  accept an incoming client connection
-        //  make a new thread running ClientSession for each user.
+        try {
+            serverSocket = new ServerSocket(9000);
+            System.out.printf("server started. port: %s\n" ,9000);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        try {
+            while (true) {
+
+                Socket s = serverSocket.accept();
+                System.out.println("new client accepted.");
+                ClientSession clientSession = new ClientSession(s, userManager);
+                Thread thread = new Thread(clientSession);
+                thread.start();
+
+            }
+        }
+        catch (IOException e) {
+
+            System.err.println("Error running thread.");
+        }
     }
 }