refactor: move access guards logic into reusable functions (#4535)

* refactor: move access guards logic into reusable functions

* Update src/common/access.js

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Alexandr <qwerty541zxc@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

api/index.js

@@ -1,13 +1,12 @@
 // @ts-check
 
 import { renderStatsCard } from "../src/cards/stats.js";
-import { blacklist } from "../src/common/blacklist.js";
+import { guardAccess } from "../src/common/access.js";
 import {
   resolveCacheSeconds,
   setCacheHeaders,
   setErrorCacheHeaders,
 } from "../src/common/cache.js";
-import { whitelist } from "../src/common/envs.js";
 import {
   CONSTANTS,
   parseArray,
@@ -49,38 +48,20 @@ export default async (req, res) => {
   } = req.query;
   res.setHeader("Content-Type", "image/svg+xml");
 
-  if (whitelist && !whitelist.includes(username)) {
-    return res.send(
-      renderError(
-        "This username is not whitelisted",
-        "Please deploy your own instance",
-        {
-          title_color,
-          text_color,
-          bg_color,
-          border_color,
-          theme,
-          show_repo_link: false,
-        },
-      ),
-    );
-  }
-
-  if (whitelist === undefined && blacklist.includes(username)) {
-    return res.send(
-      renderError(
-        "This username is blacklisted",
-        "Please deploy your own instance",
-        {
-          title_color,
-          text_color,
-          bg_color,
-          border_color,
-          theme,
-          show_repo_link: false,
-        },
-      ),
-    );
+  const access = guardAccess({
+    res,
+    id: username,
+    type: "username",
+    colors: {
+      title_color,
+      text_color,
+      bg_color,
+      border_color,
+      theme,
+    },
+  });
+  if (!access.isPassed) {
+    return access.result;
   }
 
   if (locale && !isLocaleAvailable(locale)) {