feat: add hook useBlockSuitePagePreview (#2603)

packages/hooks/src/__tests__/index.spec.ts

@@ -9,8 +9,10 @@ import type { Page } from '@blocksuite/store';
 import { assertExists } from '@blocksuite/store';
 import { Workspace as BlockSuiteWorkspace } from '@blocksuite/store';
 import { renderHook } from '@testing-library/react';
+import { useBlockSuitePagePreview } from '@toeverything/hooks/use-block-suite-page-preview';
 import { useBlockSuiteWorkspacePageIsPublic } from '@toeverything/hooks/use-block-suite-workspace-page-is-public';
 import { useBlockSuiteWorkspacePageTitle } from '@toeverything/hooks/use-block-suite-workspace-page-title';
+import { useAtomValue } from 'jotai';
 import { describe, expect, test, vitest } from 'vitest';
 import { beforeEach } from 'vitest';
 
@@ -86,3 +88,24 @@ describe('useBlockSuiteWorkspacePageIsPublic', () => {
     expect(hook.result.current[0]).toBe(true);
   });
 });
+
+describe('useBlockSuitePagePreview', () => {
+  test('basic', async () => {
+    const page = blockSuiteWorkspace.getPage('page0') as Page;
+    const id = page.addBlock(
+      'affine:paragraph',
+      {
+        text: new page.Text('Hello, world!'),
+      },
+      page.getBlockByFlavour('affine:frame')[0].id
+    );
+    const hook = renderHook(() => useAtomValue(useBlockSuitePagePreview(page)));
+    expect(hook.result.current).toBe('\nHello, world!');
+    page.transact(() => {
+      page.getBlockById(id)!.text!.insert('Test', 0);
+    });
+    await new Promise(resolve => setTimeout(resolve, 100));
+    hook.rerender();
+    expect(hook.result.current).toBe('\nTestHello, world!');
+  });
+});

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

@@ -0,0 +1,32 @@
+import type { ParagraphBlockModel } from '@blocksuite/blocks/models';
+import type { Page } from '@blocksuite/store';
+import type { Atom } from 'jotai';
+import { atom } from 'jotai';
+
+const weakMap = new WeakMap<Page, Atom<string>>();
+
+const getPagePreviewText = (page: Page) => {
+  const paragraphBlocks = page.getBlockByFlavour(
+    'affine:paragraph'
+  ) as ParagraphBlockModel[];
+  const text = paragraphBlocks.map(block => block.text.toString()).join('\n');
+  return text.slice(0, 30);
+};
+
+export function useBlockSuitePagePreview(page: Page): Atom<string> {
+  if (weakMap.has(page)) {
+    return weakMap.get(page) as Atom<string>;
+  } else {
+    const baseAtom = atom<string>(getPagePreviewText(page));
+    baseAtom.onMount = set => {
+      const disposable = page.slots.yUpdated.on(() => {
+        set(getPagePreviewText(page));
+      });
+      return () => {
+        disposable.dispose();
+      };
+    };
+    weakMap.set(page, baseAtom);
+    return baseAtom;
+  }
+}