First commit

lib/auth/requireTeacher.ts

@@ -0,0 +1,26 @@
+import { redirect } from "next/navigation";
+import { requireUser } from "@/lib/auth/requireUser";
+
+const readTeacherEmails = (): string[] =>
+  (process.env.TEACHER_EMAILS ?? "")
+    .split(",")
+    .map((email) => email.trim().toLowerCase())
+    .filter(Boolean);
+
+export const requireTeacher = async () => {
+  const user = await requireUser("/teacher");
+  if (!user?.email) {
+    redirect("/");
+  }
+
+  const allowed = readTeacherEmails();
+  if (allowed.length === 0) {
+    redirect("/");
+  }
+
+  if (!allowed.includes(user.email.toLowerCase())) {
+    redirect("/");
+  }
+
+  return user;
+};