feat: support guest session (#919)

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

@@ -5,11 +5,12 @@ import {
   smoothStream,
   streamText,
 } from 'ai';
-import { auth } from '@/app/(auth)/auth';
+import { auth, type UserType } from '@/app/(auth)/auth';
 import { systemPrompt } from '@/lib/ai/prompts';
 import {
   deleteChatById,
   getChatById,
+  getMessageCountByUserId,
   saveChat,
   saveMessages,
 } from '@/lib/db/queries';
@@ -25,6 +26,7 @@ import { requestSuggestions } from '@/lib/ai/tools/request-suggestions';
 import { getWeather } from '@/lib/ai/tools/get-weather';
 import { isProductionEnvironment } from '@/lib/constants';
 import { myProvider } from '@/lib/ai/providers';
+import { entitlementsByUserType } from '@/lib/ai/entitlements';
 
 export const maxDuration = 60;
 
@@ -46,6 +48,22 @@ export async function POST(request: Request) {
       return new Response('Unauthorized', { status: 401 });
     }
 
+    const userType: UserType = session.user.type;
+
+    const messageCount = await getMessageCountByUserId({
+      id: session.user.id,
+      differenceInHours: 24,
+    });
+
+    if (messageCount > entitlementsByUserType[userType].maxMessagesPerDay) {
+      return new Response(
+        'You have exceeded your maximum number of messages for the day! Please try again later.',
+        {
+          status: 429,
+        },
+      );
+    }
+
     const userMessage = getMostRecentUserMessage(messages);
 
     if (!userMessage) {