Normalize the URL by redirecting (#141)

src/lib/middleware.test.ts

@@ -64,4 +64,30 @@ describe('getURLLookupAlternatives', () => {
             },
         ]);
     });
+
+    it('should normalize duplicated slashes', () => {
+        expect(getURLLookupAlternatives(new URL('https://docs.mycompany.com//hello'))).toEqual([
+            {
+                extraPath: 'hello',
+                url: 'https://docs.mycompany.com/',
+            },
+            {
+                extraPath: '',
+                url: 'https://docs.mycompany.com/hello',
+            },
+        ]);
+    });
+
+    it('should normalize trailing slash', () => {
+        expect(getURLLookupAlternatives(new URL('https://docs.mycompany.com/hello/'))).toEqual([
+            {
+                extraPath: 'hello',
+                url: 'https://docs.mycompany.com/',
+            },
+            {
+                extraPath: '',
+                url: 'https://docs.mycompany.com/hello',
+            },
+        ]);
+    });
 });

src/lib/middleware.ts

@@ -2,7 +2,8 @@
  * For a given GitBook URL, return a list of alternative URLs that could be matched against to lookup the content.
  * The approach is optimized to aim at reusing cached lookup results as much as possible.
  */
-export function getURLLookupAlternatives(url: URL) {
+export function getURLLookupAlternatives(input: URL) {
+    const url = normalizeURL(input);
     const alternatives: Array<{ url: string; extraPath: string }> = [];
 
     const pushAlternative = (url: URL, extraPath: string) => {
@@ -85,3 +86,12 @@ export function getURLLookupAlternatives(url: URL) {
 
     return alternatives;
 }
+
+/**
+ * Normalize a URL to remove duplicate slashes and trailing slashes
+ */
+export function normalizeURL(url: URL) {
+    const result = new URL(url);
+    result.pathname = url.pathname.replace(/\/{2,}/g, '/').replace(/\/$/, '');
+    return result;
+}

src/middleware.ts

@@ -12,10 +12,9 @@ import {
     userAgent,
     withAPI,
 } from '@/lib/api';
+import { buildVersion } from '@/lib/build';
 import { createContentSecurityPolicyNonce, getContentSecurityPolicy } from '@/lib/csp';
-
-import { buildVersion } from './lib/build';
-import { getURLLookupAlternatives } from './lib/middleware';
+import { getURLLookupAlternatives, normalizeURL } from '@/lib/middleware';
 
 export const config = {
     matcher:
@@ -73,6 +72,12 @@ export async function middleware(request: NextRequest) {
         userAgent: userAgent(),
     });
 
+    // Redirect to normalize the URL
+    const normalized = normalizeURL(url);
+    if (normalized.toString() !== url.toString()) {
+        return NextResponse.redirect(normalized.toString());
+    }
+
     // The visitor authentication can either be passed as a query parameter
     // or can be stored in a cookie after the initial auth.
     const visitorAuthToken =