From 64579f7d74944dc01fdbab4ac8fdd917e9ded4d6 Mon Sep 17 00:00:00 2001
From: sebastienlorber <lorber.sebastien@gmail.com>
Date: Wed, 23 Feb 2022 17:46:52 +0100
Subject: [PATCH] fix breadcrumb home link bug with useHomePageRoute()

---
 .../src/index.d.ts                            |  2 +-
 .../src/theme/DocBreadcrumbs/index.tsx        |  9 ++-
 packages/docusaurus-theme-common/package.json |  2 +-
 packages/docusaurus-theme-common/src/index.ts |  2 +
 .../src/utils/__tests__/routesUtils.test.ts   | 73 +++++++++++++++++++
 .../src/utils/routesUtils.ts                  | 39 ++++++++++
 6 files changed, 123 insertions(+), 4 deletions(-)
 create mode 100644 packages/docusaurus-theme-common/src/utils/__tests__/routesUtils.test.ts
 create mode 100644 packages/docusaurus-theme-common/src/utils/routesUtils.ts

diff --git a/packages/docusaurus-module-type-aliases/src/index.d.ts b/packages/docusaurus-module-type-aliases/src/index.d.ts
index 7292518fc3b9..0ca795ee13b4 100644
--- a/packages/docusaurus-module-type-aliases/src/index.d.ts
+++ b/packages/docusaurus-module-type-aliases/src/index.d.ts
@@ -37,7 +37,7 @@ declare module '@generated/registry' {
 declare module '@generated/routes' {
   import type {RouteConfig} from 'react-router-config';
 
-  type Route = {
+  export type Route = {
     readonly path: string;
     readonly component: RouteConfig['component'];
     readonly exact?: boolean;
diff --git a/packages/docusaurus-theme-classic/src/theme/DocBreadcrumbs/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocBreadcrumbs/index.tsx
index 8eecbe54170a..f912aac438a4 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocBreadcrumbs/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocBreadcrumbs/index.tsx
@@ -6,7 +6,11 @@
  */
 
 import React, {type ReactNode} from 'react';
-import {ThemeClassNames, useSidebarBreadcrumbs} from '@docusaurus/theme-common';
+import {
+  ThemeClassNames,
+  useSidebarBreadcrumbs,
+  useHomePageRoute,
+} from '@docusaurus/theme-common';
 import styles from './styles.module.css';
 import clsx from 'clsx';
 import Link from '@docusaurus/Link';
@@ -59,6 +63,7 @@ function HomeBreadcrumbItem() {
 
 export default function DocBreadcrumbs(): JSX.Element | null {
   const breadcrumbs = useSidebarBreadcrumbs();
+  const homePageRoute = useHomePageRoute();
 
   if (!breadcrumbs) {
     return null;
@@ -72,7 +77,7 @@ export default function DocBreadcrumbs(): JSX.Element | null {
       )}
       aria-label="breadcrumbs">
       <ul className="breadcrumbs">
-        <HomeBreadcrumbItem />
+        {homePageRoute && <HomeBreadcrumbItem />}
         {breadcrumbs.map((item, idx) => (
           <BreadcrumbsItem key={idx} active={idx === breadcrumbs.length - 1}>
             <BreadcrumbsItemLink href={item.href}>
diff --git a/packages/docusaurus-theme-common/package.json b/packages/docusaurus-theme-common/package.json
index 01e7cde1a8a3..2d1bc0bb156c 100644
--- a/packages/docusaurus-theme-common/package.json
+++ b/packages/docusaurus-theme-common/package.json
@@ -18,6 +18,7 @@
   },
   "license": "MIT",
   "dependencies": {
+    "@docusaurus/module-type-aliases": "2.0.0-beta.15",
     "@docusaurus/plugin-content-blog": "2.0.0-beta.15",
     "@docusaurus/plugin-content-docs": "2.0.0-beta.15",
     "@docusaurus/plugin-content-pages": "2.0.0-beta.15",
@@ -29,7 +30,6 @@
   },
   "devDependencies": {
     "@docusaurus/core": "2.0.0-beta.15",
-    "@docusaurus/module-type-aliases": "2.0.0-beta.15",
     "@docusaurus/types": "2.0.0-beta.15",
     "@testing-library/react-hooks": "^7.0.2",
     "fs-extra": "^10.0.0",
diff --git a/packages/docusaurus-theme-common/src/index.ts b/packages/docusaurus-theme-common/src/index.ts
index 40d4536f4fe6..2e0cbbe9eae7 100644
--- a/packages/docusaurus-theme-common/src/index.ts
+++ b/packages/docusaurus-theme-common/src/index.ts
@@ -124,6 +124,8 @@ export {
 
 export {isRegexpStringMatch} from './utils/regexpUtils';
 
+export {useHomePageRoute} from './utils/routesUtils';
+
 export {useColorMode, ColorModeProvider} from './utils/colorModeUtils';
 export {
   useTabGroupChoice,
diff --git a/packages/docusaurus-theme-common/src/utils/__tests__/routesUtils.test.ts b/packages/docusaurus-theme-common/src/utils/__tests__/routesUtils.test.ts
new file mode 100644
index 000000000000..18a5167ef1ac
--- /dev/null
+++ b/packages/docusaurus-theme-common/src/utils/__tests__/routesUtils.test.ts
@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {type Route} from '@generated/routes';
+import {findHomePageRoute} from '../routesUtils';
+
+describe('routesUtils findHomePageRoute', () => {
+  const homePage: Route = {
+    path: '/',
+    exact: true,
+  };
+
+  test('should return undefined for no routes', () => {
+    expect(findHomePageRoute([])).toEqual(undefined);
+  });
+
+  test('should return undefined for no homepage', () => {
+    expect(
+      findHomePageRoute([
+        {path: '/a', exact: true},
+        {path: '/b', exact: false},
+        {path: '/c', exact: undefined},
+        {
+          path: '/d',
+          exact: false,
+          routes: [
+            {path: '/d/1', exact: true},
+            {path: '/d/2', exact: false},
+            {path: '/d/3', exact: undefined},
+          ],
+        },
+      ]),
+    ).toEqual(undefined);
+  });
+
+  test('should find top-level homepage', () => {
+    expect(
+      findHomePageRoute([
+        {path: '/a', exact: true},
+        {path: '/b', exact: false},
+        {path: '/c', exact: undefined},
+        {...homePage, exact: false},
+        homePage,
+        {...homePage, exact: undefined},
+      ]),
+    ).toEqual(homePage);
+  });
+
+  test('should find nested homepage', () => {
+    expect(
+      findHomePageRoute([
+        {path: '/a', exact: true},
+        {
+          path: '/',
+          exact: false,
+          routes: [
+            {path: '/b', exact: true},
+            {
+              path: '/',
+              exact: false,
+              routes: [{path: '/c', exact: true}, homePage],
+            },
+          ],
+        },
+        {path: '/d', exact: true},
+      ]),
+    ).toEqual(homePage);
+  });
+});
diff --git a/packages/docusaurus-theme-common/src/utils/routesUtils.ts b/packages/docusaurus-theme-common/src/utils/routesUtils.ts
new file mode 100644
index 000000000000..ece1ade95511
--- /dev/null
+++ b/packages/docusaurus-theme-common/src/utils/routesUtils.ts
@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import GeneratedRoutes, {type Route} from '@generated/routes';
+import {useMemo} from 'react';
+
+function isHomePageRoute(route: Route): boolean {
+  return route.path === '/' && route.exact === true;
+}
+
+function isHomeParentRoute(route: Route): boolean {
+  return route.path === '/' && route.exact === false;
+}
+
+// Note that all sites don't always have a homepage in practice
+// See https://github.com/facebook/docusaurus/pull/6517#issuecomment-1048709116
+export function findHomePageRoute(
+  routes: Route[] = GeneratedRoutes,
+): Route | undefined {
+  if (routes.length === 0) {
+    return undefined;
+  }
+  const homePage = routes.find(isHomePageRoute);
+  if (homePage) {
+    return homePage;
+  }
+  const indexSubRoutes = routes
+    .filter(isHomeParentRoute)
+    .flatMap((route) => route.routes ?? []);
+  return findHomePageRoute(indexSubRoutes);
+}
+
+export function useHomePageRoute(): Route | undefined {
+  return useMemo(() => findHomePageRoute(), []);
+}