feat: add cache header to spotify and newsletter

src/pages/api/newsletter/count.ts

@@ -15,7 +15,13 @@ export default function count(req: NextApiRequest, res: NextApiResponse) {
       )
       .then((response) => {
         const count = response.data.length;
-        res.status(200).json({ count });
+
+        // Cache for an hour
+        res.setHeader(
+          'Cache-Control',
+          'public, s-maxage=3600, stale-while-revalidate=60'
+        );
+        return res.status(200).json({ count });
       })
       .catch(() => res.status(500).json({ error: 'Something was wrong' }));
   } else {

src/pages/api/spotify.ts

@@ -68,6 +68,11 @@ export default async function spotify(
       response.status > 400 ||
       response.data.currently_playing_type !== 'track'
     ) {
+      //? s-maxage=180 because song usually lasts 3 minutes
+      res.setHeader(
+        'Cache-Control',
+        'public, s-maxage=180, stale-while-revalidate=90'
+      );
       return res.status(200).json({ isPlaying: false });
     }
 
@@ -82,6 +87,10 @@ export default async function spotify(
       songUrl: response.data.item.external_urls.spotify,
     };
 
-    res.status(200).json(data);
+    res.setHeader(
+      'Cache-Control',
+      'public, s-maxage=180, stale-while-revalidate=90'
+    );
+    return res.status(200).json(data);
   }
 }