Refactor code structure for improved readability and maintainability

app/frontend/middleware.ts

@@ -0,0 +1,30 @@
+import { NextRequest, NextResponse } from 'next/server'
+
+export function middleware(req: NextRequest) {
+  const { pathname } = req.nextUrl
+  const token = req.cookies.get('pb_token')?.value
+  const role = req.cookies.get('pb_role')?.value
+
+  const isAdminPath = pathname.startsWith('/admin')
+  const isAppPath = pathname.startsWith('/app')
+
+  if (!token) {
+    if (isAdminPath || isAppPath) {
+      return NextResponse.redirect(new URL('/auth', req.url))
+    }
+    return NextResponse.next()
+  }
+
+  if (isAdminPath && role !== 'admin') {
+    return NextResponse.redirect(new URL(role === 'employee' ? '/app' : '/auth', req.url))
+  }
+  if (isAppPath && role !== 'employee') {
+    return NextResponse.redirect(new URL(role === 'admin' ? '/admin' : '/auth', req.url))
+  }
+
+  return NextResponse.next()
+}
+
+export const config = {
+  matcher: ['/admin/:path*', '/app/:path*'],
+}