Support subdirectories in document writer

document_writer.py

@@ -10,10 +10,12 @@ class DocumentWriter():
 
     def write_document(self, document: Document) -> None:
         main_file_name = os.path.join(self.target, document.get_name())
+        os.makedirs(os.path.dirname(main_file_name), exist_ok=True)
         with open(main_file_name, "w") as f:
             f.write(document.get_main_content())
 
         meta_file_name = os.path.join(self.target, ".meta", document.get_name() + ".json")
+        os.makedirs(os.path.dirname(meta_file_name), exist_ok=True)
         with open(meta_file_name, "w") as f:
             f.write(json.dumps({
                 "title": document.get_title(),