import os
from google.oauth2.credentials import Credentials
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from googleapiclient.discovery import build
from googleapiclient.http import MediaFileUpload
import pickle

SCOPES = ['https://www.googleapis.com/auth/drive.file']

class GoogleDriveUploader:
    def __init__(self, credentials_file, token_file):
        self.credentials_file = credentials_file
        self.token_file = token_file
        self.service = None
        self._authenticate()
    
    def _authenticate(self):
        """구글 드라이브 인증"""
        creds = None
        
        # 기존 토큰 파일이 있으면 로드
        if os.path.exists(self.token_file):
            with open(self.token_file, 'rb') as token:
                creds = pickle.load(token)
        
        # 유효한 인증 정보가 없으면 새로 인증
        if not creds or not creds.valid:
            if creds and creds.expired and creds.refresh_token:
                creds.refresh(Request())
            else:
                if not os.path.exists(self.credentials_file):
                    raise FileNotFoundError(
                        f"구글 드라이브 인증 파일을 찾을 수 없습니다: {self.credentials_file}\n"
                        "Google Cloud Console에서 OAuth 2.0 클라이언트 ID를 다운로드하여 "
                        "credentials.json으로 저장해주세요."
                    )
                flow = InstalledAppFlow.from_client_secrets_file(
                    self.credentials_file, SCOPES)
                creds = flow.run_local_server(port=0)
            
            # 토큰 저장
            with open(self.token_file, 'wb') as token:
                pickle.dump(creds, token)
        
        self.service = build('drive', 'v3', credentials=creds)
    
    def upload_file(self, file_path, file_name, folder_id=None):
        """파일을 구글 드라이브에 업로드"""
        if not self.service:
            raise Exception("구글 드라이브 서비스가 초기화되지 않았습니다.")
        
        file_metadata = {'name': file_name}
        if folder_id:
            file_metadata['parents'] = [folder_id]
        
        media = MediaFileUpload(file_path, mimetype='application/vnd.openxmlformats-officedocument.wordprocessingml.document')
        
        file = self.service.files().create(
            body=file_metadata,
            media_body=media,
            fields='id'
        ).execute()
        
        return file.get('id')