Add initial project files

apps/web/app/api/revalidate/route.ts

@@ -0,0 +1,52 @@
+import { revalidateTag } from 'next/cache';
+
+const MAX_TAGS = 50;
+const MAX_TAG_LENGTH = 256;
+
+function parseTags(payload: unknown): string[] | null {
+  if (typeof payload !== 'object' || payload === null) {
+    return null;
+  }
+
+  const tags = (payload as { tags?: unknown }).tags;
+
+  if (!Array.isArray(tags) || tags.length === 0 || tags.length > MAX_TAGS) {
+    return null;
+  }
+  if (
+    !tags.every((tag) => typeof tag === 'string' && tag.length > 0 && tag.length <= MAX_TAG_LENGTH)
+  ) {
+    return null;
+  }
+
+  return tags;
+}
+
+export async function POST(request: Request) {
+  const secret = process.env['REVALIDATE_SECRET'];
+
+  if (!secret || request.headers.get('x-revalidate-secret') !== secret) {
+    return Response.json({ message: 'Unauthorized' }, { status: 401 });
+  }
+
+  let payload: unknown;
+  try {
+    payload = await request.json();
+  } catch {
+    return Response.json({ message: 'Invalid JSON body' }, { status: 400 });
+  }
+
+  const tags = parseTags(payload);
+  if (!tags) {
+    return Response.json(
+      { message: 'Body must contain a non-empty "tags" array of strings' },
+      { status: 400 }
+    );
+  }
+
+  for (const tag of tags) {
+    revalidateTag(tag, 'max');
+  }
+
+  return Response.json({ revalidated: tags });
+}