refactor(pages): refine Topic pages

* add useTopic and useTopicsList hooks to refresh data
* add a table of contents
* add Cypress tests

3 files changed, 95 insertions, 0 deletions

diff --git a/src/utils/hooks/use-topics-list/index.ts b/src/utils/hooks/use-topics-list/index.ts
new file mode 100644
index 0000000..c08400f
--- /dev/null
+++ b/src/utils/hooks/use-topics-list/index.ts
@@ -0,0 +1 @@
+export * from './use-topics-list';
diff --git a/src/utils/hooks/use-topics-list/use-topics-list.test.ts b/src/utils/hooks/use-topics-list/use-topics-list.test.ts
new file mode 100644
index 0000000..c8fa607
--- /dev/null
+++ b/src/utils/hooks/use-topics-list/use-topics-list.test.ts
@@ -0,0 +1,48 @@
+import {
+  afterEach,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  jest,
+} from '@jest/globals';
+import { renderHook, waitFor } from '@testing-library/react';
+import { useTopicsList } from './use-topics-list';
+
+describe('useTopicsList', () => {
+  beforeEach(() => {
+    /* Not sure why it is needed, but without it Jest was complaining with
+     * `Jest worker encountered 4 child process exceptions`... Maybe because of
+     * useSWR? */
+    jest.useFakeTimers({
+      doNotFake: ['queueMicrotask'],
+    });
+  });
+
+  afterEach(() => {
+    jest.runOnlyPendingTimers();
+    jest.useRealTimers();
+  });
+
+  /* eslint-disable max-statements */
+  it('fetch the requested topics list', async () => {
+    const { result } = renderHook(() => useTopicsList());
+
+    // Inaccurate assertions count because of waitFor...
+    //expect.assertions(8);
+    expect.hasAssertions();
+
+    expect(result.current.topics).toBeUndefined();
+    expect(result.current.isError).toBe(false);
+    expect(result.current.isLoading).toBe(true);
+    expect(result.current.isValidating).toBe(true);
+
+    jest.advanceTimersToNextTimer();
+
+    await waitFor(() => expect(result.current.topics).toBeDefined());
+    expect(result.current.isError).toBe(false);
+    expect(result.current.isLoading).toBe(false);
+    expect(result.current.isValidating).toBe(false);
+  });
+  /* eslint-enable max-statements */
+});
diff --git a/src/utils/hooks/use-topics-list/use-topics-list.ts b/src/utils/hooks/use-topics-list/use-topics-list.ts
new file mode 100644
index 0000000..7860486
--- /dev/null
+++ b/src/utils/hooks/use-topics-list/use-topics-list.ts
@@ -0,0 +1,46 @@
+import useSWR from 'swr';
+import {
+  type FetchTopicsListInput,
+  fetchTopicsList,
+} from '../../../services/graphql';
+import type { GraphQLConnection, Maybe, WPTopicPreview } from '../../../types';
+
+export type UseTopicsListReturn<
+  T extends Maybe<GraphQLConnection<WPTopicPreview>>,
+> = {
+  isError: boolean;
+  isLoading: boolean;
+  isValidating: boolean;
+  topics: T extends undefined
+    ? Maybe<GraphQLConnection<WPTopicPreview>>
+    : GraphQLConnection<WPTopicPreview>;
+};
+
+export type UseTopicsListConfig<
+  T extends Maybe<GraphQLConnection<WPTopicPreview>>,
+> = {
+  input?: FetchTopicsListInput;
+  fallback?: T;
+};
+
+export const useTopicsList = <
+  T extends Maybe<GraphQLConnection<WPTopicPreview>>,
+>(
+  config?: UseTopicsListConfig<T>
+): UseTopicsListReturn<T> => {
+  const { fallback, input } = config ?? {};
+  const { data, error, isLoading, isValidating } = useSWR(
+    input ?? {},
+    fetchTopicsList,
+    { fallbackData: fallback }
+  );
+
+  if (error) console.error(error);
+
+  return {
+    isError: !!error,
+    isLoading,
+    isValidating,
+    topics: data,
+  } as UseTopicsListReturn<T>;
+};