pythonGmailImap.py

#!/usr/bin/env python
# pylint: disable=unused-argument

import base64
import email
import imaplib
import json
import re
import time
import urllib
from urllib import request


GOOGLE_ACCOUNTS_BASE_URL = "https://accounts.google.com"
GOOGLE_CLIENT_ID = ""
GOOGLE_CLIENT_SECRET = ""
GOOGLE_REFRESH_TOKEN = ""
GOOGLE_EMAIL = '' # The e-mail used to obtain the above credentials
VIEW_X_LAST = 10 # Information from the last 10 received e-mails will be displayed


def call_refresh_token(client_id, client_secret, refresh_token):
    params = {}
    params['client_id'] = client_id
    params['client_secret'] = client_secret
    params['refresh_token'] = refresh_token
    params['grant_type'] = 'refresh_token'
    request_url = GOOGLE_ACCOUNTS_BASE_URL + '/o/oauth2/token'
    response = urllib.request.urlopen(request_url, urllib.parse.urlencode(params).encode('UTF-8')).read().decode('UTF-8')
    return json.loads(response)


def refresh_authorization(google_client_id, google_client_secret, refresh_token):
    response = call_refresh_token(google_client_id, google_client_secret, refresh_token)
    return response['access_token'], response['expires_in']


def generate_oauth2_string(username, access_token, as_base64=False):
    auth_string = 'user=%s\1auth=Bearer %s\1\1' % (username, access_token)
    if as_base64:
        auth_string = base64.b64encode(auth_string.encode('ascii')).decode('ascii')
    return auth_string


def gmail_auth():
    access_token, expires_in = refresh_authorization(GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET, GOOGLE_REFRESH_TOKEN) 
    auth_string = generate_oauth2_string(GOOGLE_EMAIL, access_token, as_base64=False)
    imap_conn = imaplib.IMAP4_SSL('imap.gmail.com', port=993)
    imap_conn.debug = 2
    imap_conn.authenticate('XOAUTH2 ', lambda x: auth_string)
    return imap_conn


def parse_uid(data):
    pattern_uid = re.compile(r'\d+ \(UID (?P<uid>\d+)\)')
    match = pattern_uid.match(data)
    return match.group('uid')


def check_email(imap_conn):
    imap_conn.select(mailbox="INBOX", readonly=False)
    retcode, messages = imap_conn.search(None, 'ALL')
    if retcode == 'OK':
        print(f"\tMail count: {len(messages[0].decode().split()[-2:])}") 
        selected_messages = messages[0].decode().split()[-VIEW_X_LAST:]
        selected_messages.reverse()
        a = 1
        for mail_id in selected_messages:
            resp_code, mail_data = imap_conn.fetch(mail_id, '(RFC822)')
            message = email.message_from_bytes(mail_data[0][1])
            print("\n\t------------------------------------------------")
            print(f"\tMail {a} from {len(selected_messages)}:")
            print("\t   Date:     {}".format(message.get("Date")))
            print("\t   Subject:  {}".format(message.get("Subject")))
            print("\t   From:     {}".format(message.get("From")))
            print("\t   To:       {}".format(message.get("To")))
            print("\t   Bcc:      {}".format(message.get("Bcc")))
            a += 1


def gmail_keepalive(imap_conn):
    e = 0
    while True:
        try:
            resp_code, response = imap_conn.noop() ## Keep connection Alive
            return imap_conn
        except Exception as err:
            e += 1
            print(f"Gmail access error: {err}")
            if "please login again" in str(err): # If you get this error, you'll need to generate a new refresh token
                print(f"Atention! Gmail oauth expired, create a new oaut by typing:\n\npython2 oauth2.py --generate_oauth2_token --client_id={GOOGLE_CLIENT_ID} --client_secret={GOOGLE_CLIENT_SECRET}")
                time.sleep(5*60*60)
            if e > 3:
                print("Error on gmail access, trying to login again.")
                return gmail_auth()
            time.sleep(5)
            continue


def email_check():
    print("Starting e-mail checker.")
    imap_conn = gmail_auth()
    while True:
        try:
            check_email(imap_conn)
            time.sleep(60)
            imap_conn = gmail_keepalive(imap_conn)
        except Exception as err:
            if "state NONAUTH" in str(err):
                imap_conn = gmail_auth()
                time.sleep(10)
                continue
            exit()


if __name__ == '__main__':
    email_check()