authenticate.py

from __future__ import print_function
from googleapiclient.errors import HttpError
from google.oauth2.credentials import Credentials
from google.auth.transport.requests import Request
from google_auth_oauthlib.flow import InstalledAppFlow
import os.path
    
    
    
    
def authenticate():
    creds = None
    SCOPES = ['https://www.googleapis.com/auth/spreadsheets']
    # The file token.json stores the user's access and refresh tokens, and is
    # created automatically when the authorization flow completes for the first
    # time.
    # if os.path.exists('token.json'):
    #     creds = Credentials.from_authorized_user_file('token.json', SCOPES)
        
    # 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, redirect_uri=REDIRECT_URI)
            authorization_url, _ = flow.authorization_url(access_type='offline', prompt='consent')

    # Instead of running a local server, you can redirect the user to the
    # Google authorization URL. After granting permission, they will be
    # redirected back to your application's /callback route.
            return redirect(authorization_url)
            
        # Save the credentials for the next run
        with open('token.json', 'w') as token:
            token.write(creds.to_json())
    
    return creds