authenticate_account.py

import os
import pickle

from google.auth.transport.requests import Request
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build

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

def authenticate():
    creds = None
    service = None

    # Check if token.pickle file exists, which stores the user's access and refresh tokens.
    if os.path.exists('token.pickle'):
        with open('token.pickle', 'rb') as token:
            creds = pickle.load(token)

    # If there are no valid credentials available, let the user log in.
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
            creds = flow.run_local_server(port=0)

            # Save the credentials for the next run.
            with open('token.pickle', 'wb') as token:
                pickle.dump(creds, token)

    if creds:
        service = build('drive', 'v3', credentials=creds)
    else:
        print("Failed to authenticate.")

    return service