refactor isSimpleRequest

apps/app/src/server/util/is-simple-request.ts

@@ -2,47 +2,56 @@ import type { Request } from 'express';
 
 import type { AccessTokenParserReq } from '~/server/middlewares/access-token-parser/interfaces';
 
+// 1. Check if the request method is allowed
+const allowedMethods = ['GET', 'HEAD', 'POST'] as const;
+type AllowedMethod = typeof allowedMethods[number];
+function isAllowedMethod(method: string): method is AllowedMethod {
+  return allowedMethods.includes(method as AllowedMethod);
+}
+
+// 2. Check if the request headers are safe
+const safeRequestHeaders = [
+  'accept',
+  'accept-language',
+  'content-language',
+  'content-type',
+  'range',
+  'referer',
+  'dpr',
+  'downlink',
+  'save-data',
+  'viewport-width',
+  'width',
+] as const;
+type SafeRequestHeader = typeof safeRequestHeaders[number];
+
+// 3. Content-Type is
+const allowedContentTypes = [
+  'application/x-www-form-urlencoded',
+  'multipart/form-data',
+  'text/plain',
+] as const;
+type AllowedContentType = typeof allowedContentTypes[number];
+
 const isSimpleRequest = (req: Request | AccessTokenParserReq): boolean => {
-  // 1. Check if the request method is allowed
-  const allowedMethods = ['GET', 'HEAD', 'POST'];
-  if (!allowedMethods.includes(req.method)) {
+  if (!isAllowedMethod(req.method)) {
     return false;
   }
 
-  // 2. Check if the request headers are safe
-  const safeRequestHeaders = [
-    'accept',
-    'accept-language',
-    'content-language',
-    'content-type',
-    'range',
-    'referer',
-    'dpr',
-    'downlink',
-    'save-Data',
-    'viewport-Width',
-    'width',
-  ];
   const nonSafeHeaders = Object.keys(req.headers).filter((header) => {
     const headerLower = header.toLowerCase();
-    return !safeRequestHeaders.includes(headerLower);
+    return !safeRequestHeaders.includes(headerLower as SafeRequestHeader);
   });
 
   if (nonSafeHeaders.length > 0) {
     return false;
   }
 
-  // 3. Content-Type is
-  const allowedContentTypes = [
-    'application/x-www-form-urlencoded',
-    'multipart/form-data',
-    'text/plain',
-  ];
   const contentType = req.headers['content-type'];
-
-  if (contentType != null && !allowedContentTypes.includes(contentType.toLowerCase())) {
+  if (contentType != null && !allowedContentTypes.includes(contentType.toLowerCase() as AllowedContentType)) {
     return false;
   }
+
   // Return true if all conditions are met
   return true;
 };