Download GMAILFS email attachments from Gmail

gmail.py

# NOTE: Gmail doesn't allow usage of service accounts for _personal GMail accounts_, you need OAuth client key

import base64
import json
import logging
import os.path

from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build


def get_attachments(service, msg_id):
    message = service.users().messages().get(userId='me', id=msg_id).execute()
    subject = [x['value'] for x in message['payload']['headers'] if x.get('name') == 'Subject'][0]
    if subject.startswith('GMAILFS:'):
        filepath = subject[10:subject[10:].find('[')+10-1]
        if os.path.isfile(filepath):
            print(f'Skip {filepath}, already there')
            return
        else:
            print(f'Analyzing {filepath}')
        d = os.path.dirname(filepath)
        file = os.path.basename(filepath)
        if d != '' and not os.path.isdir(d):
            try:
                os.makedirs(d, exist_ok=True)
            except:
                logging.exception("failed to create dir: " + d)
        if os.path.isfile(file):
            # peviously downoaded into root
            os.rename(file, filepath)
            return
        for part in message['payload']['parts']:
            if part['filename']:
                if 'data' in part['body']:
                    data = part['body']['data']
                else:
                    att_id = part['body']['attachmentId']
                    att = service.users().messages().attachments().get(userId='me', messageId=msg_id,
                                                                       id=att_id).execute()
                    data = att['data']
                file_data = base64.urlsafe_b64decode(data.encode('UTF-8'))
                try:
                    with open(filepath, 'wb') as f:
                        f.write(file_data)
                except:
                    logging.exception("failed to save an email with path: " + filepath + ", json:" + json.dumps(message))


def authenticate_and_get_service():
    # Set the scopes for Gmail API
    scopes = ['https://www.googleapis.com/auth/gmail.readonly']

    flow = InstalledAppFlow.from_client_secrets_file(
        'client_secret_....apps.googleusercontent.com.json',
        scopes=scopes
    )
    credentials = flow.run_local_server(port=0)

    # Save the credentials for the next run
    with open('token.json', 'w') as token:
        token.write(credentials.to_json())

    # Create a Gmail API service client
    service = build('gmail', 'v1', credentials=credentials)

    return service


if __name__ == '__main__':
    service = authenticate_and_get_service()
    pageToken = None
    while True:
        messages = service.users().messages().list(userId='me', maxResults=50, pageToken=pageToken).execute()
        print('Messages downloaded: ', len(messages['messages']))
        for msg in messages['messages']:
            get_attachments(service, msg['id'])
        if messages.get('nextPageToken', None) is None:
            break
        pageToken = messages['nextPageToken']
    service.close()

requirements.txt

google-api-python-client
google_auth_oauthlib