Test tool to print labels (aka mailboxes) for a Gmail account using Google Gmail APIs

gmail-label.py

#!/usr/bin/env python

"""Test tool to print labels (aka mailboxes) for a Gmail account using Google Gmail APIs    # NOQA

When this tool starts, it reads a local file, called CLIENT_SECRET_FILE,
containing the Cline ID / Client Secret any existing credentials.
If the credentials don't exits, it then prompts you, via the web browser,
to authenticate to get them.  It the credentials exist, but need to be renewed,
it will do that.

Credentials are place within the directory DIR_HOME/CREDENTIAL_DIR and
the credentials file is called CREDENTIAL_FILE. It contains
the Client ID, Client Secret, Access Token, Refresh Token, etc.

Based on: https://developers.google.com/gmail/api/quickstart/python
"""

# for support of both Python 2 and Python 3
from __future__ import print_function

SCOPES = ['https://www.googleapis.com/auth/gmail.readonly',
          'https://www.googleapis.com/auth/gmail.compose', ]
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Gmail API Python Quickstart'
CREDENTIALS_FILE = 'gmail-python-quickstart.json'
CREDENTIALS_DIR = '.credentials'
DIR_HOME = '~'

import httplib2   # comprehensive HTTP client library
import os         # miscellaneous operating system interfaces

# library for accessing resources protected by OAuth 2.0
import oauth2client
from oauth2client import client
from oauth2client import tools

try:
    import argparse   # command-line parsing module
    flags = argparse.ArgumentParser(parents=[tools.argparser]).parse_args()
except ImportError:
    flags = None


def get_credentials():
    """Gets valid user credentials from storage or request new ones.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """

    # location where credentials are stored
    home_dir = os.path.expanduser(DIR_HOME)
    credential_dir = os.path.join(home_dir, CREDENTIALS_DIR)

    # if credential store doesn't exist, create it
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)

    credential_path = os.path.join(credential_dir, CREDENTIALS_FILE)
    store = oauth2client.file.Storage(credential_path)
    credentials = store.get()

    # if the credentials don't exist/invalid, get new credentials and store them
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = tools.run_flow(flow, store, flags)
        else:                    # needed only for compatibility with Python 2.6
            credentials = tools.run(flow, store)
        print('\nStoring credentials to ' + credential_path)

    return credentials


def main():
    """Shows basic OArth functionality of the Gmail API

    Creates a Gmail API service object  and outputs a list of label
    (aka mailebox) names of the user's Gmail account.
    """
    from apiclient import discovery

    # get the credentials
    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('gmail', 'v1', http=http)

    results = service.users().labels().list(userId='me').execute()
    labels = results.get('labels', [])

    # print out the labels (aka mailboxes)
    if not labels:
        print('\nNo labels found.')
    else:
        print('\nLabels:')
        for label in labels:
            print(label['name'])


if __name__ == '__main__':
    main()