Added SSE function and add readAt for notification

src/routes/api/notify.ts

@@ -0,0 +1,48 @@
+import { auth } from '@/lib/auth';
+import { addClient, removeClient } from '@/lib/notification';
+import { createFileRoute } from '@tanstack/react-router';
+import { getRequestHeaders } from '@tanstack/react-start/server';
+
+export const Route = createFileRoute('/api/notify')({
+  server: {
+    handlers: {
+      GET: async ({ request }) => {
+        const headers = getRequestHeaders();
+        const session = await auth.api.getSession({ headers });
+
+        if (!session?.session.userId) {
+          return new Response('Unauthorized', { status: 401 });
+        }
+
+        const clientId = session.session.userId;
+
+        const stream = new ReadableStream({
+          start(controller) {
+            addClient(clientId, controller);
+
+            controller.enqueue(
+              `data: ${JSON.stringify({ type: `connected` })}\n\n`,
+            );
+
+            const heartbeat = setInterval(() => {
+              controller.enqueue(`: keepalive\n\n`);
+            }, 20000);
+
+            request.signal.addEventListener('abort', () => {
+              clearInterval(heartbeat);
+              removeClient(clientId, controller);
+            });
+          },
+        });
+
+        return new Response(stream, {
+          headers: {
+            'Content-Type': 'text/event-stream',
+            'Cache-Control': 'no-cache',
+            Connection: 'keep-alive',
+          },
+        });
+      },
+    },
+  },
+});