fix: automatically convert Super notes to Markdown for the Plaintext Backups feature

packages/web/src/javascripts/Components/SuperEditor/Tools/InvisibleMarkdownConverter.tsx

@@ -0,0 +1,57 @@
+import { createHeadlessEditor } from '@lexical/headless'
+import { $convertToMarkdownString } from '@lexical/markdown'
+import { SuperConverterServiceInterface } from '@standardnotes/snjs'
+import { LexicalEditor } from 'lexical'
+import BlocksEditorTheme from '../Lexical/Theme/Theme'
+import { BlockEditorNodes } from '../Lexical/Nodes/AllNodes'
+import { MarkdownTransformers } from '../MarkdownTransformers'
+import { $generateHtmlFromNodes } from '@lexical/html'
+
+export class InvisibleSuperConverter implements SuperConverterServiceInterface {
+  private editor: LexicalEditor
+
+  constructor() {
+    this.editor = createHeadlessEditor({
+      namespace: 'BlocksEditor',
+      theme: BlocksEditorTheme,
+      editable: false,
+      onError: (error: Error) => console.error(error),
+      nodes: [...BlockEditorNodes],
+    })
+  }
+
+  convertString(superString: string, format: 'txt' | 'md' | 'html' | 'json'): string {
+    if (superString.length === 0) {
+      return superString
+    }
+
+    this.editor.setEditorState(this.editor.parseEditorState(superString))
+
+    let content: string | undefined
+
+    this.editor.update(
+      () => {
+        switch (format) {
+          case 'txt':
+          case 'md':
+            content = $convertToMarkdownString(MarkdownTransformers)
+            break
+          case 'html':
+            content = $generateHtmlFromNodes(this.editor)
+            break
+          case 'json':
+          default:
+            content = superString
+            break
+        }
+      },
+      { discrete: true },
+    )
+
+    if (!content) {
+      throw new Error('Could not export note')
+    }
+
+    return content
+  }
+}