feat: fav page references (#2422)

Co-authored-by: Himself65 <himself65@outlook.com>

packages/hooks/src/use-block-suite-page-references.ts

@@ -0,0 +1,38 @@
+import type { Page, Workspace } from '@blocksuite/store';
+import { atom, useAtomValue } from 'jotai';
+import { atomFamily } from 'jotai/utils';
+
+import { useBlockSuiteWorkspacePage } from './use-block-suite-workspace-page';
+
+function getPageReferences(page: Page): string[] {
+  // todo: is there a way to use page indexer to get all references?
+  return page
+    .getBlockByFlavour('affine:paragraph')
+    .flatMap(b => b.text?.toDelta())
+    .map(v => v?.attributes?.reference?.pageId)
+    .filter(Boolean);
+}
+
+const pageReferencesAtomFamily = atomFamily((page: Page | null) => {
+  if (page === null) {
+    return atom([]);
+  }
+  const baseAtom = atom<string[]>(getPageReferences(page));
+  baseAtom.onMount = set => {
+    const dispose = page.slots.yUpdated.on(() => {
+      set(getPageReferences(page));
+    });
+    return () => {
+      dispose.dispose();
+    };
+  };
+  return baseAtom;
+});
+
+export function useBlockSuitePageReferences(
+  blockSuiteWorkspace: Workspace,
+  pageId: string
+): string[] {
+  const page = useBlockSuiteWorkspacePage(blockSuiteWorkspace, pageId);
+  return useAtomValue(pageReferencesAtomFamily(page));
+}