initial import: random background api

functions/api/random.js

@@ -0,0 +1,36 @@
+import { buildAssetUrl, detectVariant, getVariantPayload, loadManifest, pickRandom } from '../lib/background.js';
+
+export async function onRequestGet(context) {
+  const { request } = context;
+  const url = new URL(request.url);
+  const format = (url.searchParams.get('format') || 'redirect').toLowerCase();
+  const manifest = await loadManifest(request);
+  const variant = detectVariant(request);
+  const { folder, images } = getVariantPayload(manifest, variant);
+
+  if (!images.length) {
+    return Response.json(
+      { error: 'no images available', variant, folder },
+      { status: 404, headers: { 'Cache-Control': 'no-store, max-age=0', 'Access-Control-Allow-Origin': '*' } },
+    );
+  }
+
+  const filename = pickRandom(images);
+  const assetUrl = buildAssetUrl(request, folder, filename);
+
+  if (format === 'json') {
+    return Response.json(
+      { variant, folder, filename, url: assetUrl, count: images.length },
+      { headers: { 'Cache-Control': 'no-store, max-age=0', 'Access-Control-Allow-Origin': '*' } },
+    );
+  }
+
+  return new Response(null, {
+    status: 302,
+    headers: {
+      Location: assetUrl,
+      'Cache-Control': 'no-store, max-age=0',
+      'Access-Control-Allow-Origin': '*',
+    },
+  });
+}