diff --git a/src/app/chat/chat.py b/src/app/chat/chat.py
index 97d3287..a6d4b5c 100644
--- a/src/app/chat/chat.py
+++ b/src/app/chat/chat.py
@@ -1,32 +1,43 @@
 import asyncio
 from fastapi import WebSocket
+import asyncio
 
 
 class Chat:
     members: dict[str, WebSocket]
 
     """Represents the chatting room."""
+
     def __init__(self):
         self.members = {}
-    
+        self.illegal_ids = ["system"]
+
     async def join(self, user: str, websocket: WebSocket):
         """Connect to the user and add user to the members on success."""
 
-        ######### [ TODO ] #########
         # TODO Establish connection
-        ############################
+        await websocket.accept()
+        close_reason = ""
 
         ######### [ TODO ] #########
         # TODO Close connection on duplicate and exit method.
         ############################
-
+        if user in self.members.keys():
+            close_reason = "User {} already exists".format(user)
+            await websocket.close(reason=close_reason)
+        elif user in self.illegal_ids:
+            close_reason = "Cannot use Username {}".format(user)
+            await websocket.close(reason=close_reason)
         ######### [ TODO ] #########
         # TODO Otherwise, add user to the members.
         ############################
-
-        ######### [ TODO ] #########
-        # TODO Optionally, broadcast the system message that the user joined the chat.
-        ############################
+        else:
+            self.members[user] = websocket
+            json = {
+                "from": "system",
+                "msg": "User {} joined the chat".format(user)
+            }
+            await self.broadcast(json)
 
     async def leave(self, user: str):
         """Remove user from the members."""
@@ -34,10 +45,16 @@ async def leave(self, user: str):
         ######### [ TODO ] #########
         # TODO Remove user from the members.
         ############################
-    
+        del self.members[user]
+
         ######### [ TODO ] #########
         # TODO Optionally, broadcast the system message that the user left the chat.
         ############################
+        json = {
+            "from": "system",
+            "msg": "User {} left the chat".format(user)
+        }
+        await self.broadcast(json)
 
     async def handle_message(self, user: str, message: dict[str, str]):
         """Handler message from user."""
@@ -45,6 +62,34 @@ async def handle_message(self, user: str, message: dict[str, str]):
         ######### [ TODO ] #########
         # TODO Check the message type and receiver.
         ############################
+        msg_type = message["type"]
+        msg = message["msg"]
+        if msg_type == "direct":
+            dst_user = message["to"]
+            try:
+                dst_socket = self.members[dst_user]
+                await dst_socket.send_json(
+                    {
+                        "from": dst_user,
+                        "msg": msg
+                    }
+                )
+            except KeyError:
+                src_socket = self.members[user]
+                await src_socket.send_json(
+                    {
+                        "from": "system",
+                        "msg": "User {} does not exist.".format(dst_user)
+                    }
+                )
+
+        else:
+            await self.broadcast(
+                {
+                    "from":user,
+                    "msg":msg
+                }, 1, user
+            )
 
         ######### [ TODO ] #########
         # TODO If the valid receiver does not exist, send error message back to the sender.
@@ -54,3 +99,14 @@ async def handle_message(self, user: str, message: dict[str, str]):
         # TODO Otherwise, forward the message to the receiver.
         # If broadcasting the message, DO NOT send to the original sender.
         ############################
+
+    async def broadcast(self, msg: dict, type = 0, sender = None):
+        tasks = []
+        for user, socket in self.members.items():
+            if type == 1 and sender == user:
+                continue
+            task = asyncio.create_task(socket.send_json(msg))
+            tasks.append(task)
+
+        for task in tasks:
+            await task
diff --git a/src/app/chat/router.py b/src/app/chat/router.py
index 23ecb2b..28dbc68 100644
--- a/src/app/chat/router.py
+++ b/src/app/chat/router.py
@@ -19,19 +19,14 @@ async def get() -> HTMLResponse:
 @router.websocket("/ws")
 async def websocket(user: str, websocket: WebSocket):
     """Interact with user via connection."""
-
-    ######### [ TODO ] #########
     # TODO Join the chat
-    ############################
+    await chat.join(user, websocket)
 
     try:
         while True:
-            ######### [ TODO ] #########
             # TODO Receive message from the user and handle
-            ############################
-            pass
+            data = await websocket.receive_json()
+            await chat.handle_message(user, data)
     except WebSocketDisconnect:
-        ######### [ TODO ] #########
         # TODO Handle disconnection: leave the chat
-        ############################
-        pass
+        await chat.leave(user)
diff --git a/src/app/main.py b/src/app/main.py
index caf3226..eafc889 100644
--- a/src/app/main.py
+++ b/src/app/main.py
@@ -5,3 +5,8 @@
 
 app = FastAPI()
 app.include_router(chat_router)
+
+
+@app.get("/")
+def root():
+    return {"messgae": "Hello, world!"}
\ No newline at end of file