Desktop: Resolves #2059: Add option to transform HTML notes into Markdown (#12730)

Co-authored-by: Laurent Cozic <laurent22@users.noreply.github.com>

packages/app-desktop/commands/convertNoteToMarkdown.ts

@@ -0,0 +1,52 @@
+import { _ } from '@joplin/lib/locale';
+import Note from '@joplin/lib/models/Note';
+import { stateUtils } from '@joplin/lib/reducer';
+import { CommandRuntime, CommandDeclaration, CommandContext } from '@joplin/lib/services/CommandService';
+import { MarkupLanguage } from '@joplin/renderer';
+import { runtime as convertHtmlToMarkdown } from '@joplin/lib/commands/convertHtmlToMarkdown';
+import bridge from '../services/bridge';
+
+export const declaration: CommandDeclaration = {
+	name: 'convertNoteToMarkdown',
+	label: () => _('Convert note to Markdown'),
+};
+
+export const runtime = (): CommandRuntime => {
+	return {
+		execute: async (context: CommandContext, noteId: string = null) => {
+			noteId = noteId || stateUtils.selectedNoteId(context.state);
+
+			const note = await Note.load(noteId);
+
+			if (!note) return;
+
+			try {
+				const markdownBody = await convertHtmlToMarkdown().execute(context, note.body);
+
+				const newNote = await Note.duplicate(note.id);
+
+				newNote.body = markdownBody;
+				newNote.markup_language = MarkupLanguage.Markdown;
+
+				await Note.save(newNote);
+
+				await Note.delete(note.id, { toTrash: true });
+
+				context.dispatch({
+					type: 'NOTE_HTML_TO_MARKDOWN_DONE',
+					value: note.id,
+				});
+
+				context.dispatch({
+					type: 'NOTE_SELECT',
+					id: newNote.id,
+				});
+			} catch (error) {
+				bridge().showErrorMessageBox(_('Could not convert note to Markdown: %s', error.message));
+			}
+
+
+		},
+		enabledCondition: 'oneNoteSelected && noteIsHtml && !noteIsReadOnly',
+	};
+};