Fix getProxyModeBasePath (#2896)

Author: taranvohra

.changeset/funny-clouds-cheat.md

@@ -0,0 +1,5 @@
+---
+'gitbook': patch
+---
+
+Fix getProxyModeBasePath that was computing incorrect base path in some scenarios

packages/gitbook/src/lib/paths.ts

@@ -18,3 +18,14 @@ export function removeTrailingSlash(path: string): string {
 export function removeLeadingSlash(path: string): string {
     return path.replace(/^\/+/, '');
 }
+
+/**
+ * Normalize a pathname to make it start with a slash
+ */
+export function normalizePathname(pathname: string): string {
+    if (!pathname.startsWith('/')) {
+        pathname = `/${pathname}`;
+    }
+
+    return pathname;
+}

packages/gitbook/src/lib/proxy.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, it } from 'bun:test';
+import { getProxyModeBasePath } from './proxy';
+
+describe('getProxyModeBasePath', () => {
+    it('should return the base path for proxy mode (base = /, path = /)', () => {
+        const input = new URL('https://example.com/docs');
+        const resolved = { basePath: '/', pathname: '/' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/');
+    });
+
+    it('should return the base path for proxy mode (base = /, path = /hello/world)', () => {
+        const input = new URL('https://example.com/docs/hello/world');
+        const resolved = { basePath: '/', pathname: '/hello/world' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/');
+    });
+
+    it('should return the base path for proxy mode (base = /v1, path = /)', () => {
+        const input = new URL('https://example.com/docs/v1');
+        const resolved = { basePath: '/v1', pathname: '/' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/v1/');
+    });
+
+    it('should return the base path for proxy mode (base = /v1/, path = /)', () => {
+        const input = new URL('https://example.com/docs/v1/');
+        const resolved = { basePath: '/v1/', pathname: '/' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/v1/');
+    });
+
+    it('should return the base path for proxy mode (base = /v1, path = /hello/world)', () => {
+        const input = new URL('https://example.com/docs/v1/hello/world');
+        const resolved = { basePath: '/v1', pathname: '/hello/world' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/v1/');
+    });
+
+    it('should return the base path for proxy mode (base = /v1/, path = /hello/world)', () => {
+        const input = new URL('https://example.com/docs/v1/hello/world');
+        const resolved = { basePath: '/v1/', pathname: '/hello/world' };
+        expect(getProxyModeBasePath(input, resolved)).toEqual('/docs/v1/');
+    });
+});

packages/gitbook/src/lib/proxy.ts

@@ -0,0 +1,21 @@
+import type { PublishedSiteContent } from '@gitbook/api';
+import { joinPath, normalizePathname, removeTrailingSlash } from './paths';
+
+/**
+ * Compute the final base path for a site served in proxy mode.
+ * For e.g. if the input URL is `https://example.com/docs/v2/foo/bar` on which
+ * the site is served at `https://example.com/docs` and the resolved base path is `/v2`
+ * then the proxy site path would be `/docs/v2/`.
+ */
+export function getProxyModeBasePath(
+    input: URL,
+    resolved: Pick<PublishedSiteContent, 'basePath' | 'pathname'>
+): string {
+    const inputPathname = new URL(input).pathname;
+    const proxySitePath = inputPathname
+        .replace(removeTrailingSlash(resolved.pathname), '')
+        .replace(removeTrailingSlash(resolved.basePath), '');
+
+    const result = joinPath(normalizePathname(proxySitePath), resolved.basePath);
+    return result.endsWith('/') ? result : `${result}/`;
+}

packages/gitbook/src/middleware.ts

@@ -1,9 +1,4 @@
-import {
-    type ContentAPITokenPayload,
-    CustomizationThemeMode,
-    GitBookAPI,
-    type PublishedSiteContent,
-} from '@gitbook/api';
+import { type ContentAPITokenPayload, CustomizationThemeMode, GitBookAPI } from '@gitbook/api';
 import { setContext, setTag } from '@sentry/nextjs';
 import { getURLLookupAlternatives, normalizeURL } from '@v2/lib/data';
 import assertNever from 'assert-never';
@@ -35,7 +30,8 @@ import {
     normalizeVisitorAuthURL,
 } from '@/lib/visitor-token';
 
-import { joinPath } from './lib/paths';
+import { joinPath, normalizePathname } from '@/lib/paths';
+import { getProxyModeBasePath } from '@/lib/proxy';
 
 export const config = {
     matcher:
@@ -854,15 +850,6 @@ function stripURLBasePath(url: URL, basePath: string): URL {
     return stripped;
 }
 
-/** Normalize a pathname to make it start with a slash */
-function normalizePathname(pathname: string): string {
-    if (!pathname.startsWith('/')) {
-        pathname = `/${pathname}`;
-    }
-
-    return pathname;
-}
-
 function stripURLSearch(url: URL): URL {
     const stripped = new URL(url.toString());
     stripped.search = '';
@@ -918,21 +905,3 @@ function writeCookies<R extends NextResponse>(
 
     return response;
 }
-
-/**
- * Compute the final base path for a site served in proxy mode.
- * For e.g. if the input URL is `https://example.com/docs/v2/foo/bar` on which
- * the site is served at `https://example.com/docs` and the resolved base path is `/v2`
- * then the proxy site path would be `/docs/v2/`.
- */
-function getProxyModeBasePath(
-    input: URL,
-    resolved: Pick<PublishedSiteContent, 'basePath' | 'pathname'>
-): string {
-    const inputPathname = stripURLSearch(input).pathname;
-    const proxySitePath = inputPathname
-        .replace(resolved.pathname, '')
-        .replace(resolved.basePath, '');
-
-    return joinPath(normalizePathname(proxySitePath), resolved.basePath);
-}