fix: remove unused hook useFeatureFlag (#1826)

apps/web/src/hooks/__tests__/use-feature-flag.spec.ts

@@ -1,25 +0,0 @@
-/**
- * @vitest-environment happy-dom
- */
-import { renderHook } from '@testing-library/react';
-import { beforeEach, describe, expect, test } from 'vitest';
-
-import { defaultRecord, useFeatureFlag } from '../use-feature-flag';
-
-beforeEach(() => {
-  globalThis.featureFlag.record = defaultRecord;
-  globalThis.featureFlag.callback.clear();
-});
-
-describe('useFeatureFlag', () => {
-  test('basic', () => {
-    const flagHook = renderHook(() =>
-      useFeatureFlag('enableIndexedDBProvider')
-    );
-    expect(flagHook.result.current).toBe(defaultRecord.enableIndexedDBProvider);
-    globalThis.featureFlag.record.enableIndexedDBProvider = false;
-    globalThis.featureFlag.callback.forEach(cb => cb());
-    flagHook.rerender();
-    expect(flagHook.result.current).toBe(false);
-  });
-});

apps/web/src/hooks/use-feature-flag.ts

@@ -1,45 +0,0 @@
-import { useCallback, useSyncExternalStore } from 'react';
-
-interface FeatureFlag {
-  enableIndexedDBProvider: boolean;
-}
-
-export const defaultRecord: FeatureFlag = {
-  enableIndexedDBProvider: true,
-} as const;
-
-const featureFlag = {
-  record: {
-    enableIndexedDBProvider: true,
-  } as FeatureFlag,
-  callback: new Set<() => void>(),
-};
-
-declare global {
-  // eslint-disable-next-line no-var
-  var featureFlag: {
-    record: FeatureFlag;
-    callback: Set<() => void>;
-  };
-}
-if (!globalThis.featureFlag) {
-  globalThis.featureFlag = featureFlag;
-}
-
-export const getFeatureFlag = <Key extends keyof FeatureFlag>(key: Key) =>
-  featureFlag.record[key];
-
-export function useFeatureFlag<Key extends keyof FeatureFlag>(
-  key: Key
-): FeatureFlag[Key] {
-  return useSyncExternalStore(
-    useCallback(onStoreChange => {
-      featureFlag.callback.add(onStoreChange);
-      return () => {
-        featureFlag.callback.delete(onStoreChange);
-      };
-    }, []),
-    useCallback(() => featureFlag.record[key], [key]),
-    useCallback(() => defaultRecord[key], [key])
-  );
-}