refactor (#2858)

### What problem does this PR solve?

### Type of change

- [x] Refactoring

api/apps/document_app.py

@@ -13,16 +13,8 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License
 #
-import datetime
-import hashlib
-import json
-import os
 import pathlib
 import re
-import traceback
-from concurrent.futures import ThreadPoolExecutor
-from copy import deepcopy
-from io import BytesIO
 
 import flask
 from elasticsearch_dsl import Q
@@ -30,26 +22,22 @@ from flask import request
 from flask_login import login_required, current_user
 
 from api.db.db_models import Task, File
-from api.db.services.dialog_service import DialogService, ConversationService
 from api.db.services.file2document_service import File2DocumentService
 from api.db.services.file_service import FileService
-from api.db.services.llm_service import LLMBundle
 from api.db.services.task_service import TaskService, queue_tasks
-from api.db.services.user_service import TenantService, UserTenantService
-from graphrag.mind_map_extractor import MindMapExtractor
-from rag.app import naive
+from api.db.services.user_service import UserTenantService
 from rag.nlp import search
 from rag.utils.es_conn import ELASTICSEARCH
 from api.db.services import duplicate_name
 from api.db.services.knowledgebase_service import KnowledgebaseService
 from api.utils.api_utils import server_error_response, get_data_error_result, validate_request
 from api.utils import get_uuid
-from api.db import FileType, TaskStatus, ParserType, FileSource, LLMType
+from api.db import FileType, TaskStatus, ParserType, FileSource
 from api.db.services.document_service import DocumentService, doc_upload_and_parse
-from api.settings import RetCode, stat_logger
+from api.settings import RetCode
 from api.utils.api_utils import get_json_result
 from rag.utils.storage_factory import STORAGE_IMPL
-from api.utils.file_utils import filename_type, thumbnail, get_project_base_directory
+from api.utils.file_utils import filename_type, thumbnail
 from api.utils.web_utils import html2pdf, is_valid_url
 from api.contants import IMG_BASE64_PREFIX