refactor: move cache headers logic into reusable functions (#4533)

* refactor: move cache headers logic into reusable functions

* dev

---------

Co-authored-by: Alexandr <qwerty541zxc@gmail.com>

api/index.js

@@ -2,7 +2,11 @@
 
 import { renderStatsCard } from "../src/cards/stats.js";
 import { blacklist } from "../src/common/blacklist.js";
-import { resolveCacheSeconds } from "../src/common/cache.js";
+import {
+  resolveCacheSeconds,
+  setCacheHeaders,
+  setErrorCacheHeaders,
+} from "../src/common/cache.js";
 import { whitelist } from "../src/common/envs.js";
 import {
   CONSTANTS,
@@ -104,16 +108,13 @@ export default async (req, res) => {
       parseInt(commits_year, 10),
     );
     const cacheSeconds = resolveCacheSeconds({
-      requested: cache_seconds,
+      requested: parseInt(cache_seconds, 10),
       def: CONSTANTS.CARD_CACHE_SECONDS,
       min: CONSTANTS.TWELVE_HOURS,
       max: CONSTANTS.TWO_DAY,
     });
 
-    res.setHeader(
-      "Cache-Control",
-      `max-age=${cacheSeconds}, s-maxage=${cacheSeconds}, stale-while-revalidate=${CONSTANTS.ONE_DAY}`,
-    );
+    setCacheHeaders(res, cacheSeconds);
 
     return res.send(
       renderStatsCard(stats, {
@@ -144,12 +145,7 @@ export default async (req, res) => {
       }),
     );
   } catch (err) {
-    res.setHeader(
-      "Cache-Control",
-      `max-age=${CONSTANTS.ERROR_CACHE_SECONDS / 2}, s-maxage=${
-        CONSTANTS.ERROR_CACHE_SECONDS
-      }, stale-while-revalidate=${CONSTANTS.ONE_DAY}`,
-    ); // Use lower cache period for errors.
+    setErrorCacheHeaders(res);
     return res.send(
       renderError(err.message, err.secondaryMessage, {
         title_color,