diff --git a/ChatServer/CS3.1.py b/ChatServer/CS3.1.py
new file mode 100644
index 0000000..7274975
--- /dev/null
+++ b/ChatServer/CS3.1.py
@@ -0,0 +1,187 @@
+import threading
+import json
+from flask import Flask, jsonify, request
+import sqlite3
+import socket
+import base64
+import secrets
+import time
+app = Flask(__name__)
+socket_server = socket.socket()
+socket_server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+active_users = {}
+chat_connections = []
+tokens = {}
+
+def get_db_connection():
+    conn = sqlite3.connect("usr.db")
+    conn.row_factory = sqlite3.Row
+    return conn
+
+def isuserxist(name):
+    cn = get_db_connection()
+    csr = cn.cursor()
+    csr.execute('SELECT * FROM users WHERE name = ?', (name,))
+    rst = csr.fetchone()
+    cn.close()
+    if rst is not None:
+        return True
+    else:
+        return False
+
+def ispsswdright(name,passwd):
+    cn = get_db_connection()
+    csr = cn.cursor()
+    csr.execute("SELECT COUNT(*) FROM users WHERE name=?", (name,))
+    row_count = csr.fetchone()[0]
+    password = None
+    if row_count > 0:
+        csr.execute("SELECT passwd FROM users WHERE name=?", (name,))
+        password = csr.fetchone()[0]
+    if password == passwd:
+        return True
+    else:
+        return False
+
+def register_user(usr, pwd):
+    conn = get_db_connection()
+    csr2 = conn.cursor()
+    csr2.execute('SELECT * FROM users WHERE name = ?', (usr,))
+    result = csr2.fetchone()
+    if result is not None:
+        return {"type": "register_0", "success": False, "message": "Username already exists"}
+    else:
+        try:
+            cursor = conn.cursor()
+            cursor.execute("INSERT INTO users (name, passwd) VALUES (?, ?)", (usr, pwd))
+            conn.commit()
+            return {"type": "register_1", "success": True, "message": "User registered successfully"}
+        except sqlite3.Error as e:
+            return {"type": "register_0", "success": False, "message": str(e)}
+        finally:
+            conn.close()
+
+def generate_token(username):
+    token = secrets.token_hex(16)
+    tokens[token] = {'username': username, 'timestamp': time.time()}
+    return token
+
+def validate_token(token):
+    if token in tokens:
+        if time.time() - tokens[token]['timestamp'] < 3600:
+            tokens[token]['timestamp'] = time.time()
+            return tokens[token]['username']
+    return None
+
+@app.route("/api/register", methods=['POST'])
+def register1():
+    vl = request.get_json()
+    usr = vl.get('username')
+    pwd = vl.get('password')
+    result = register_user(usr, pwd)
+    if result['success']:
+        return jsonify(result)
+    else:
+        return jsonify(result), 403 if result['message'] == "Username already exists" else 500
+
+@app.route("/api/login", methods=['POST'])
+def login():
+    data = request.get_json()
+    if isuserxist(data['username']):
+        if ispsswdright(data['username'], data['password']):
+            token = generate_token(data['username'])
+            return jsonify({"type": "login_1", "status": "success", "token": token})
+    return jsonify({"type": "login_0", "status": "error"}), 401
+
+@app.route("/api/chat", methods=['POST'])
+def chat():
+    token = request.headers.get('Authorization')
+    username = validate_token(token)
+    if not username:
+        return jsonify({"type": "chat", "status": "error"}), 401
+    data = request.get_json()
+    message = {
+        "type": "chat",
+        "user": username,
+        "message": data['message']
+    }
+    broadcast_message(message)
+    return jsonify({"type": "chat", "status": "success"})
+
+def broadcast_message(message, sender=None):
+    for conn in chat_connections:
+        try:
+            conn.sendall(json.dumps(message).encode())
+        except:
+            chat_connections.remove(conn)
+
+def handle_socket_message(data, addr, conn):
+    try:
+        action = data.get('type')
+        if action == 'register':
+            result = register_user(data.get('username'), data.get('password'))
+            if result['success']:
+                return {"type": "register_1","status": "success", "message": result['message']}
+            else:
+                return {"type": "register_0","status": "error", "message": result['message']}
+
+        elif action == 'login':
+            if isuserxist(data['username']):
+                if ispsswdright(data['username'], data['password']):
+                    active_users[addr[0]] = data['username']
+                    tk = base64.b64encode(data['username'].encode('utf-8'))
+                    chat_connections.append(conn)
+                    return {"type": "login_1", "status": "success", "message": "Login successful", "token": generate_token(data['username']), "username": data['username']}
+            return {"type": "login_0", "status": "error", "message": "Invalid credentials", "username": data['username']}
+        elif action == 'chat':
+            if addr[0] in active_users:
+                message = {
+                    "type": "chat",
+                    "user": active_users[addr[0]],
+                    "message": data['message']
+                }
+                broadcast_message(message)
+                return {"type": "chat", "status": "success"}
+            return {"type": "chat", "status": "error", "message": "Not logged in"}
+    except Exception as e:
+        return {"status": "error", "message": str(e)}
+
+def run_socket_server():
+    socket_server.bind(("localhost", 8889))
+    socket_server.listen()
+    print("Socket server running on port 8889")
+    while True:
+        conn, addr = socket_server.accept()
+        print(f"Socket client connected: {addr}")
+        try:
+            while True:
+                data = conn.recv(1024)
+                if not data:
+                    if addr[0] in active_users:
+                        del active_users[addr[0]]
+                    break
+
+                try:
+                    json_data = json.loads(data.decode())
+                    response = handle_socket_message(json_data, addr, conn)
+                    conn.sendall(json.dumps(response).encode())
+                except json.JSONDecodeError:
+                    conn.sendall(json.dumps(
+                        {"type": "register_0", "status": "error", "message": "Invalid JSON"}
+                    ).encode())
+        except ConnectionResetError:
+            if addr[0] in active_users:
+                del active_users[addr[0]]
+            print(f"Client {addr} disconnected")
+        finally:
+            if conn in chat_connections:
+                chat_connections.remove(conn)
+            conn.close()
+
+if __name__ == '__main__':
+    with get_db_connection() as conn:
+        conn.execute('''CREATE TABLE IF NOT EXISTS users
+                      (name TEXT, passwd TEXT)''')
+    threading.Thread(target=run_socket_server).start()
+    app.run(port=5001)
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