feat: edit and resubmit messages (#592)

app/(chat)/actions.ts

@@ -4,6 +4,10 @@ import { type CoreUserMessage, generateText } from 'ai';
 import { cookies } from 'next/headers';
 
 import { customModel } from '@/lib/ai';
+import {
+  deleteMessagesByChatIdAfterTimestamp,
+  getMessageById,
+} from '@/lib/db/queries';
 
 export async function saveModelId(model: string) {
   const cookieStore = await cookies();
@@ -27,3 +31,12 @@ export async function generateTitleFromUserMessage({
 
   return title;
 }
+
+export async function deleteTrailingMessages({ id }: { id: string }) {
+  const [message] = await getMessageById({ id });
+
+  await deleteMessagesByChatIdAfterTimestamp({
+    chatId: message.chatId,
+    timestamp: message.createdAt,
+  });
+}

app/(chat)/api/chat/route.ts

@@ -81,14 +81,21 @@ export async function POST(request: Request) {
     await saveChat({ id, userId: session.user.id, title });
   }
 
+  const userMessageId = generateUUID();
+
   await saveMessages({
     messages: [
-      { ...userMessage, id: generateUUID(), createdAt: new Date(), chatId: id },
+      { ...userMessage, id: userMessageId, createdAt: new Date(), chatId: id },
     ],
   });
 
   const streamingData = new StreamData();
 
+  streamingData.append({
+    type: 'user-message-id',
+    content: userMessageId,
+  });
+
   const result = streamText({
     model: customModel(model.apiIdentifier),
     system: systemPrompt,