fix(editor): handle footnote reference immediately follow URLs when importing markdown (#12449)

Closes: [BS-3525](https://linear.app/affine-design/issue/BS-3525/markdown-adapter-紧跟着链接的-footnote-reference-会被识别成链接的一部分)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- **New Features**
  - Improved handling of footnote references that immediately follow URLs in markdown, ensuring correct spacing and parsing.
- **Bug Fixes**
  - Footnote references after URLs are now parsed correctly, preventing formatting issues.
- **Tests**
  - Added comprehensive test suites to verify footnote reference preprocessing and markdown conversion.
- **Chores**
  - Introduced Vitest as a development dependency and added a dedicated test configuration for the footnote module.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

blocksuite/affine/inlines/footnote/src/__tests__/adapters/preprocessor.unit.spec.ts

@@ -0,0 +1,66 @@
+import { describe, expect, it } from 'vitest';
+
+import { preprocessFootnoteReference } from '../../adapters/markdown/preprocessor';
+
+describe('FootnoteReferenceMarkdownPreprocessorExtension', () => {
+  it('should add space before footnote reference when it follows a URL', () => {
+    const content = 'https://example.com[^label]';
+    const expected = 'https://example.com [^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should add space before footnote reference when URL has text prefix with space', () => {
+    const content = 'hello world https://example.com[^label]';
+    const expected = 'hello world https://example.com [^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should add space before footnote reference when URL has text prefix with dash', () => {
+    const content = 'text-https://example.com[^label]';
+    const expected = 'text-https://example.com [^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should not add space when footnote reference follows non-URL text', () => {
+    const content = 'normal text[^label]';
+    const expected = 'normal text[^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should not add space when there is already a space before footnote reference', () => {
+    const content = 'https://example.com [^label]';
+    const expected = 'https://example.com [^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should handle multiple footnote references with mixed URL and non-URL text', () => {
+    const content = 'https://example.com[^1]normal text[^2]http://test.com[^3]';
+    const expected =
+      'https://example.com [^1]normal text[^2]http://test.com [^3]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should not modify footnote definitions', () => {
+    const content = '[^label]: This is a footnote definition';
+    const expected = '[^label]: This is a footnote definition';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should handle content without footnote references', () => {
+    const content = 'This is a normal text without any footnotes';
+    const expected = 'This is a normal text without any footnotes';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should handle complex URLs with paths and parameters', () => {
+    const content = 'https://example.com/path?param=value[^label]';
+    const expected = 'https://example.com/path?param=value [^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+
+  it('should handle invalid URLs', () => {
+    const content = 'not-a-url[^label]';
+    const expected = 'not-a-url[^label]';
+    expect(preprocessFootnoteReference(content)).toBe(expected);
+  });
+});

blocksuite/affine/inlines/footnote/src/adapters/index.ts

@@ -1,2 +1,3 @@
 export * from './markdown/inline-delta';
 export * from './markdown/markdown-inline';
+export * from './markdown/preprocessor';

blocksuite/affine/inlines/footnote/src/adapters/markdown/preprocessor.ts

@@ -0,0 +1,54 @@
+import {
+  type MarkdownAdapterPreprocessor,
+  MarkdownPreprocessorExtension,
+} from '@blocksuite/affine-shared/adapters';
+
+/**
+ * Check if a string is a URL
+ * @param str
+ * @returns
+ */
+function isUrl(str: string): boolean {
+  try {
+    new URL(str);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+/**
+ * Preprocess footnote references to avoid markdown link parsing
+ * Only add space when footnote reference follows a URL
+ * @param content
+ * @returns
+ * @example
+ * ```md
+ * https://example.com[^label] -> https://example.com [^label]
+ * normal text[^label] -> normal text[^label]
+ * ```
+ */
+export function preprocessFootnoteReference(content: string) {
+  return content.replace(
+    /([^\s]+?)(\[\^[^\]]+\])(?!:)/g,
+    (match, prevText, footnoteRef) => {
+      // Only add space if the previous text is a URL
+      if (isUrl(prevText)) {
+        return prevText + ' ' + footnoteRef;
+      }
+      // Otherwise return the original match
+      return match;
+    }
+  );
+}
+
+const footnoteReferencePreprocessor: MarkdownAdapterPreprocessor = {
+  name: 'footnote-reference',
+  levels: ['block', 'slice', 'doc'],
+  preprocess: content => {
+    return preprocessFootnoteReference(content);
+  },
+};
+
+export const FootnoteReferenceMarkdownPreprocessorExtension =
+  MarkdownPreprocessorExtension(footnoteReferencePreprocessor);

blocksuite/affine/inlines/footnote/src/store.ts

@@ -5,6 +5,7 @@ import {
 
 import {
   footnoteReferenceDeltaToMarkdownAdapterMatcher,
+  FootnoteReferenceMarkdownPreprocessorExtension,
   markdownFootnoteReferenceToDeltaMatcher,
 } from './adapters';
 
@@ -15,5 +16,6 @@ export class FootnoteStoreExtension extends StoreExtensionProvider {
     super.setup(context);
     context.register(markdownFootnoteReferenceToDeltaMatcher);
     context.register(footnoteReferenceDeltaToMarkdownAdapterMatcher);
+    context.register(FootnoteReferenceMarkdownPreprocessorExtension);
   }
 }