feat: navigates subsection breadcrumb to first unit page (#2329)

- navigates the breadcrumb to the first unit under the subsection
instead of the outline page.

Closes #1924

src/CourseAuthoringRoutes.jsx

@@ -17,7 +17,7 @@ import ScheduleAndDetails from './schedule-and-details';
 import { GradingSettings } from './grading-settings';
 import CourseTeam from './course-team/CourseTeam';
 import { CourseUpdates } from './course-updates';
-import { CourseUnit } from './course-unit';
+import { CourseUnit, SubsectionUnitRedirect } from './course-unit';
 import { Certificates } from './certificates';
 import CourseExportPage from './export-page/CourseExportPage';
 import CourseOptimizerPage from './optimizer-page/CourseOptimizerPage';
@@ -82,6 +82,10 @@ const CourseAuthoringRoutes = () => {
           path="custom-pages/*"
           element={<PageWrap><CustomPages courseId={courseId} /></PageWrap>}
         />
+        <Route
+          path="/subsection/:subsectionId"
+          element={<PageWrap><SubsectionUnitRedirect courseId={courseId} /></PageWrap>}
+        />
         {DECODED_ROUTES.COURSE_UNIT.map((path) => (
           <Route
             key={path}

src/course-outline/data/apiHooks.ts

@@ -1,5 +1,6 @@
-import { useMutation } from '@tanstack/react-query';
+import { useMutation, useQuery } from '@tanstack/react-query';
 import { createCourseXblock } from '@src/course-unit/data/api';
+import { getCourseItem } from './api';
 
 export const courseOutlineQueryKeys = {
   all: ['courseOutline'],
@@ -7,6 +8,8 @@ export const courseOutlineQueryKeys = {
    * Base key for data specific to a course in outline
    */
   contentLibrary: (courseId?: string) => [...courseOutlineQueryKeys.all, courseId],
+  courseItemId: (itemId?: string) => [...courseOutlineQueryKeys.all, itemId],
+
 };
 
 /**
@@ -22,3 +25,11 @@ export const useCreateCourseBlock = (
     callback?.(data.locator, data.parent_locator);
   },
 });
+
+export const useCourseItemData = (itemId?: string, enabled: boolean = true) => (
+  useQuery({
+    queryKey: courseOutlineQueryKeys.courseItemId(itemId),
+    queryFn: () => getCourseItem(itemId!),
+    enabled: enabled && itemId !== undefined,
+  })
+);

src/course-unit/SubsectionUnitRedirect.test.tsx

@@ -0,0 +1,79 @@
+import {
+  initializeMocks, waitFor, render, screen,
+} from '../testUtils';
+import SubsectionUnitRedirect from './SubsectionUnitRedirect';
+import { getXBlockApiUrl } from '../course-outline/data/api';
+
+let axiosMock;
+const courseId = '123';
+const subsectionId = 'block-v1+edX+DemoX+Demo_Course+type@sequential+block@19a30717eff543078a5d94ae9d6c18a5';
+const path = '/subsection/:subsectionId';
+
+const expectedCourseItemDataWithUnit = {
+  childInfo: {
+    children: [
+      {
+        id: 'unitId',
+      },
+    ],
+  },
+};
+
+const expectedCourseItemDataWithoutUnit = [{
+  childInfo: {
+    children: [],
+  },
+}];
+
+const renderSubsectionRedirectPage = () => {
+  render(<SubsectionUnitRedirect courseId={courseId} />, {
+    path,
+    routerProps: {
+      initialEntries: [`/subsection/${subsectionId}`],
+    },
+  });
+};
+
+jest.mock('react-router-dom', () => {
+  const originalModule = jest.requireActual('react-router-dom');
+  return {
+    ...originalModule,
+    Navigate: ({ to }: { to: string }) => <div data-testid="mock-navigate" data-to={to}>Mocked Navigate</div>,
+  };
+});
+describe('SubsectionUnitRedirect', () => {
+  beforeEach(() => {
+    const mocks = initializeMocks();
+    axiosMock = mocks.axiosMock;
+  });
+
+  it('navigates to first unit if available', async () => {
+    axiosMock
+      .onGet(getXBlockApiUrl(subsectionId))
+      .reply(200, expectedCourseItemDataWithUnit);
+
+    renderSubsectionRedirectPage();
+
+    await waitFor(() => {
+      // Confirm redirection by checking the final URL
+      const mockNavigate = screen.getByTestId('mock-navigate');
+      expect(mockNavigate).toBeInTheDocument();
+      expect(mockNavigate).toHaveAttribute('data-to', `/course/${courseId}/container/unitId`);
+    });
+  });
+
+  it('navigates to course page with show param if no units present', async () => {
+    axiosMock
+      .onGet(getXBlockApiUrl(subsectionId))
+      .reply(200, expectedCourseItemDataWithoutUnit);
+
+    renderSubsectionRedirectPage();
+
+    await waitFor(() => {
+      // Confirm redirection by checking the final URL
+      const mockNavigate = screen.getByTestId('mock-navigate');
+      expect(mockNavigate).toBeInTheDocument();
+      expect(mockNavigate).toHaveAttribute('data-to', `/course/${courseId}?show=${encodeURIComponent(subsectionId)}`);
+    });
+  });
+});

src/course-unit/SubsectionUnitRedirect.tsx

@@ -0,0 +1,29 @@
+import { LoadingSpinner } from '@src/generic/Loading';
+import { useParams, Navigate } from 'react-router-dom';
+import { useCourseItemData } from '../course-outline/data/apiHooks';
+
+const SubsectionUnitRedirect = ({ courseId }: { courseId: string }) => {
+  let { subsectionId } = useParams();
+  // if the call is made via the click on breadcrumbs the re won't be courseId available
+  // in such cases the page should redirect to the 1st unit of he subsection
+  const { data: courseItemData, isLoading } = useCourseItemData(subsectionId);
+  let firstUnitId = courseItemData?.childInfo?.children?.[0]?.id;
+
+  if (isLoading) {
+    return <LoadingSpinner />;
+  }
+
+  if (firstUnitId) {
+    firstUnitId = encodeURIComponent(firstUnitId);
+    return <Navigate replace to={`/course/${courseId}/container/${firstUnitId}`} />;
+  }
+  if (subsectionId) {
+    // if no unit then navigate to the subsection outline
+    subsectionId = encodeURIComponent(subsectionId);
+    return <Navigate replace to={`/course/${courseId}?show=${subsectionId}`} />;
+  }
+
+  // navigate to the course page if no subsectionId and no unitId
+  return <Navigate replace to={`/course/${courseId}`} />;
+};
+export default SubsectionUnitRedirect;

src/course-unit/__mocks__/courseSectionVertical.js

@@ -19,22 +19,27 @@ module.exports = {
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40chapter%2Bblock%40d8a6192ade314473a78242dfeedfbf5b',
           display_name: 'Introduction 2',
+          usage_key: 'block-v1:edX+DemoX+Demo_Course+type@chapter+block@v3v57d5h5j4a8s33a78242dfeedfbf5b',
         },
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40chapter%2Bblock%40interactive_demonstrations',
           display_name: 'Example Week 1: Getting Started',
+          usage_key: 'block-v1:edX+DemoX+Demo_Course+type@chapter+block@4bgkas5384h6f686f8ghj53feedfbf2f',
         },
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40chapter%2Bblock%40graded_interactions',
           display_name: 'Example Week 2: Get Interactive',
+          usage_key: 'block-v1:edX+DemoX+Demo_Course+type@chapter+block@v3v57d5h5j4a8s33nsdajdsh876fbf3g',
         },
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40chapter%2Bblock%40social_integration',
           display_name: 'Example Week 3: Be Social',
+          usage_key: 'block-v1:edX+DemoX+Demo_Course+type@chapter+block@sg8b76g7b68s7s33a78242dfeedfbf4c',
         },
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40chapter%2Bblock%401414ffd5143b4b508f739b563ab468b7',
           display_name: 'About Exams and Certificates',
+          usage_key: 'block-v1:edX+DemoX+Demo_Course+type@chapter+block@jhk76823jh42j5kl23kjl2dfeedfbf8d',
         },
       ],
       title: 'Example Week 1: Getting Started',
@@ -45,10 +50,12 @@ module.exports = {
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40sequential%2Bblock%4019a30717eff543078a5d94ae9d6c18a5',
           display_name: 'Lesson 1 - Getting Started',
+          usage_key: 'block-v1+edX+DemoX+Demo_Course+type@sequential+block@19a30717eff543078a5d94ae9d6c18a5',
         },
         {
           url: '/course/course-v1:edX+DemoX+Demo_Course?show=block-v1%3AedX%2BDemoX%2BDemo_Course%2Btype%40sequential%2Bblock%40basic_questions',
           display_name: 'Homework - Question Styles',
+          usage_key: 'block-v1+edX+DemoX+Demo_Course+type@sequential+block@basic_questions',
         },
       ],
       title: 'Lesson 1 - Getting Started',

src/course-unit/breadcrumbs/Breadcrumbs.test.tsx

@@ -117,6 +117,23 @@ describe('<Breadcrumbs />', () => {
     });
   });
 
+  it('navigates to the first unit in subsection via the intermediate subsection redirect page', async () => {
+    const user = userEvent.setup();
+    // eslint-disable-next-line @typescript-eslint/naming-convention
+    const { ancestor_xblocks } = courseSectionVerticalMock;
+    const displayName = ancestor_xblocks[1].children[0].display_name;
+    const subsectionId = 'block-v1+edX+DemoX+Demo_Course+type@sequential+block@19a30717eff543078a5d94ae9d6c18a5';
+    const expectedUrl = `/course/${courseId}/subsection/${subsectionId}`;
+    const { getByText, getByRole } = renderComponent();
+
+    const dropdownBtn = getByText(breadcrumbsExpected.subsection.displayName);
+    await user.click(dropdownBtn);
+
+    const dropdownItem = getByRole('link', { name: displayName });
+    await user.click(dropdownItem);
+    expect(dropdownItem).toHaveAttribute('href', expectedUrl);
+  });
+
   it('navigates using the new course outline page when the waffle flag is enabled', async () => {
     const user = userEvent.setup();
     // eslint-disable-next-line @typescript-eslint/naming-convention

src/course-unit/breadcrumbs/Breadcrumbs.tsx

@@ -9,7 +9,7 @@ import { getConfig } from '@edx/frontend-platform';
 
 import { useWaffleFlags } from '../../data/apiHooks';
 import { getCourseSectionVertical } from '../data/selectors';
-import { adoptCourseSectionUrl } from '../utils';
+import { adoptCourseSectionUrl, subsectionFirstUnitEditUrl } from '../utils';
 
 const Breadcrumbs = ({ courseId, parentUnitId }: { courseId: string, parentUnitId: string }) => {
   const { ancestorXblocks = [] } = useSelector(getCourseSectionVertical);
@@ -22,9 +22,20 @@ const Breadcrumbs = ({ courseId, parentUnitId }: { courseId: string, parentUnitI
     ? adoptCourseSectionUrl({ url, courseId, parentUnitId })
     : `${getConfig().STUDIO_BASE_URL}${url}`);
 
-  const getPathToCoursePage = (isOutlinePage, url) => (
-    isOutlinePage ? getPathToCourseOutlinePage(url) : getPathToCourseUnitPage(url)
-  );
+  // based on the level of breadcrumbs the url will differ
+  // at the subsection level it should navigate to the first unit if available
+  // if no unit then navigate to the subsection outline
+  function getPathToCoursePage(index, url, usageKey: string) {
+    let navUrl: string;
+    if (index === 0) {
+      navUrl = getPathToCourseOutlinePage(url);
+    } else if (index === 1) {
+      navUrl = subsectionFirstUnitEditUrl({ courseId, subsectionId: usageKey });
+    } else {
+      navUrl = getPathToCourseUnitPage(url);
+    }
+    return navUrl;
+  }
 
   const hasChildWithUrl = (children = []) => (
     !!children.filter((child : any) => child?.url).length
@@ -55,11 +66,11 @@ const Breadcrumbs = ({ courseId, parentUnitId }: { courseId: string, parentUnitI
                   />
                 </Dropdown.Toggle>
                 <Dropdown.Menu>
-                  {children.map(({ url, displayName }) => (
+                  {children.map(({ url, displayName, usageKey }) => (
                     <Dropdown.Item
                       as={Link}
                       key={url}
-                      to={getPathToCoursePage(index < 2, url)}
+                      to={getPathToCoursePage(index, url, usageKey)}
                       className="small"
                       data-testid={`breadcrumbs-dropdown-item-level-${index}`}
                     >

src/course-unit/index.js

@@ -1 +1,2 @@
 export { default as CourseUnit } from './CourseUnit';
+export { default as SubsectionUnitRedirect } from './SubsectionUnitRedirect';

src/course-unit/utils.ts

@@ -28,3 +28,18 @@ export const adoptCourseSectionUrl = (
 
   return newUrl;
 };
+
+/**
+ * Generates the edit URL for the first unit of a given subsection in a course.
+ *
+ * @param {Object} params - The parameters required to build the URL.
+ * @param {string} params.courseId - The ID of the course.
+ * @param {string} params.subsectionId - The ID of the subsection.
+ * @returns {string} The constructed edit URL for the subsection's first unit.
+ */
+export const subsectionFirstUnitEditUrl = (
+  { courseId, subsectionId }: { courseId: string, subsectionId: string },
+): string => {
+  const url = `/course/${courseId}/subsection/${subsectionId}`;
+  return url;
+};