Refactor Study Desk application structure

src/lib/limitedJson.ts

@@ -0,0 +1,24 @@
+import type { NextRequest } from "next/server";
+import { CONTENT_LIMITS } from "@/lib/validation/contentSchemas";
+
+export class RequestTooLargeError extends Error {}
+
+export async function readLimitedJson(
+  request: NextRequest,
+  maximumBytes = CONTENT_LIMITS.requestBytes
+): Promise<unknown> {
+  const declaredLength = Number(request.headers.get("content-length"));
+  if (Number.isFinite(declaredLength) && declaredLength > maximumBytes) {
+    throw new RequestTooLargeError(`Request body must not exceed ${maximumBytes} bytes`);
+  }
+
+  const body = await request.text();
+  if (new TextEncoder().encode(body).byteLength > maximumBytes) {
+    throw new RequestTooLargeError(`Request body must not exceed ${maximumBytes} bytes`);
+  }
+  try {
+    return JSON.parse(body) as unknown;
+  } catch {
+    return null;
+  }
+}