feat: proper chat message styling without rerendering

client/src/components/ChatMessage.tsx

@@ -0,0 +1,33 @@
+import React from "react";
+import { ChatMessage } from "../../../shared";
+
+function ChatMessageDisplay({
+  message,
+  userId,
+}: {
+  message: ChatMessage;
+  userId: string | undefined; // pass userId as string to avoid rerendering. if we useChatState here, it would rerender every single message every time a new chat message is added.
+}) {
+  const isOwn = userId === message.author.userId;
+
+  return (
+    <div key={message.id} className={`mb-4 ${isOwn ? "ml-auto" : "mr-auto"}`}>
+      <div
+        className={`flex items-center gap-2 text-sm text-gray-600 mb-1
+        ${isOwn ? "justify-end" : "justify-start"}`}
+      >
+        {!isOwn && <span className="font-medium">{message.author.name}</span>}
+        <span>{new Date(message.timestamp).toLocaleTimeString()}</span>
+        {isOwn && <span className="font-medium">{message.author.name}</span>}
+      </div>
+      <div
+        className={`max-w-[80%] p-3 rounded-2xl shadow-sm bg-gray-200
+        ${isOwn ? "ml-auto rounded-tr-none" : "mr-auto rounded-tl-none"}`}
+      >
+        {message.content}
+      </div>
+    </div>
+  );
+}
+
+export default React.memo(ChatMessageDisplay);

client/src/components/MessageDisplay.tsx

@@ -1,19 +1,15 @@
 import React from "react";
 import { useChatState } from "../contexts/ChatContext";
+import ChatMessage from "./ChatMessage";
 
 function ChatMessages() {
   const { state } = useChatState();
+  const userId = state.currentUser?.userId;
 
   return (
     <>
       {state.messages.map((message) => (
-        <div key={message.id}>
-          <div>
-            <span>{message.author.name}</span>
-            <span>{new Date(message.timestamp).toLocaleTimeString()}</span>
-          </div>
-          <div>{message.content}</div>
-        </div>
+        <ChatMessage message={message} userId={userId} />
       ))}
     </>
   );

client/src/contexts/ChatContext.tsx

@@ -34,3 +34,8 @@ export const useChatState = () => {
   }
   return context;
 };
+
+export const useCurrentUser = () => {
+  const { state } = useChatState();
+  return state.currentUser;
+};

client/src/hooks/useWebSocket.ts

@@ -9,7 +9,7 @@ import { useChatState } from "../contexts/ChatContext";
 export function useWebSocket(roomId: string) {
   const [ws, setWs] = useState<WebSocket | null>(null);
   const [isConnected, setIsConnected] = useState(false);
-  const { state, actions } = useChatState();
+  const { actions } = useChatState();
 
   // Handle incoming messages
   const handleMessage = useCallback(
@@ -17,20 +17,22 @@ export function useWebSocket(roomId: string) {
       const message = JSON.parse(event.data) as ServerMessage;
 
       switch (message.type) {
-        case "USER_JOINED":
-          console.log("User joined", message.payload);
-          if (message.payload.user.name === state.currentUser?.name) {
-            actions.setUser(message.payload.user);
-          }
+        case "REGISTRATION_CONFIRMED":
+          actions.setUser(message.payload.user);
           break;
+
+        case "USER_JOINED":
+          break;
+
         case "CHAT_MESSAGE":
           actions.addMessage(message.payload);
           break;
+
         default:
           console.error("Unknown message type", message);
       }
     },
-    [state.currentUser, actions],
+    [actions],
   );
 
   // Send a message to the server

client/src/pages/Room.tsx

@@ -2,7 +2,7 @@ import { useParams } from "react-router-dom";
 import Layout from "../components/Layout";
 import Connect from "../components/ConnectWithName";
 import { useWebSocket } from "../hooks/useWebSocket";
-import ChatMessages from "../components/ChatMessages";
+import ChatMessages from "../components/MessageDisplay";
 import ChatInput from "../components/ChatInput";
 import { useChatState } from "../contexts/ChatContext";
 

server/src/handleClientMessage.ts

@@ -2,6 +2,7 @@ import { randomUUIDv7, type ServerWebSocket } from "bun";
 import type {
   ClientMessage,
   ServerChatMessage,
+  ServerRegistrationConfirmed,
   ServerUserJoinedMessage,
   User,
 } from "../../shared";
@@ -18,21 +19,23 @@ export default function handleClientMessage(
 
   switch (data.type) {
     case "JOIN":
-      const userId = randomUUIDv7();
-      const name = data.payload.username;
+      const user = {
+        name: data.payload.username,
+        userId: randomUUIDv7(),
+      };
+      room.userConnections.set(client, user);
 
-      room.userConnections.set(client, {
-        name,
-        userId,
-      });
+      const registrationConfirm: ServerRegistrationConfirmed = {
+        type: "REGISTRATION_CONFIRMED",
+        payload: { user },
+      };
+      client.send(JSON.stringify(registrationConfirm));
 
+      // notify everyone else that a new user has joined
       const joinMessage: ServerUserJoinedMessage = {
         type: "USER_JOINED",
         payload: {
-          user: {
-            name,
-            userId,
-          },
+          user,
         },
       };
 

shared.ts

@@ -58,6 +58,15 @@ export interface ChatMessage {
   author: User;
 }
 
+// sent to the newly registered client to confirm that the username was not taken
+export interface ServerRegistrationConfirmed {
+  type: "REGISTRATION_CONFIRMED";
+  payload: {
+    user: User;
+  };
+}
+
+// sent to all clients when a new client has joined the chat
 export interface ServerUserJoinedMessage {
   type: "USER_JOINED";
   payload: {
@@ -100,6 +109,7 @@ export interface ServerUserListMessage {
 }
 
 export type ServerMessage =
+  | ServerRegistrationConfirmed
   | ServerUserJoinedMessage
   | ServerUserLeftMessage
   | ServerChatMessage