#
# Import an mbox file into Google Groups using the Groups Migration API
#
# To run this script, you will need to:
#     1. Be an admin on your domain
#     2. Enable API access in your domain
#     3. Create a project on the developer console
#     4. Activate the Groups Migration API for the project
#     5. Create an OAuth Client ID and Secret for the project
#     6. Install the google-api-python-client and google-auth-oauthlib 
#        packages into your python environment (tested in python 3)
#
# Messy Details (recorded 2018-07-02):
# 2. See https://developers.google.com/admin-sdk/groups-migration/v1/guides/prerequisites
# 3. Go to https://console.developers.google.com
#       Create a new project
#           Pick a meaningful name and set the Organization and Location to your domain name
# 4. Select your project in the developer console (https://console.developers.google.com)
#        Go the the dashboard page and click "Enable APIs and Servces"
#        Find the Groups Migration API and click it
#        Click the "Enable" button
# 5. Select your project in the developer console (https://console.developers.google.com)
#        Go to the credentials page/tab and click "Create Credentials"
#        Choose OAuth Client ID
#        Click "Configure Consent Screen"
#        Set a product name. (This will appear in an authorization prompt when you attempt to run the script.)
#        Click "Save"
#        Choose "Other" for the application type and choose a name (e.g. "mbox2gg") for the OAuth client ID
#        Click "Create"
#        Your OAuth Client ID should now be listed on the Credentials page/tab. Click the download link
#            to save the json file.
#
# References:
#    Groups Migration API:
#        https://developers.google.com/admin-sdk/groups-migration/v1/get-start/getting-started
#    Python API Client:
#        https://developers.google.com/api-client-library/python/
#    Google Auth / OAuth:
#        http://google-auth-oauthlib.readthedocs.io/en/latest/
#

import mailbox
import time
from io import StringIO
import apiclient                              # pip install --upgrade google-api-python-client
from google_auth_oauthlib.flow import Flow    # pip install --upgrade google-auth-oauthlib


# File containing the OAuth Client ID / Secret
client_secret_file = 'client_secret.json'

# The email address of the group to import to (e.g. "groupname@example.com")
groupId = input('Enter groupId: ')

# The mbox file you want to import
mbox_path = input('Enter mbox_path: ')


# Scope for the Groups Migration API
# See https://developers.google.com/admin-sdk/groups-migration/v1/guides/authorizing
scope = 'https://www.googleapis.com/auth/apps.groups.migration'

# 
# The next few lines to handle authentication are taken almost verbatim from
# http://google-auth-oauthlib.readthedocs.io/en/latest/reference/google_auth_oauthlib.flow.html
#
# The original version of this script used the oauth2client library (which is now [2018-07-02]
# deprecated) for authentication and included a feature for reading saved credentials from a 
# file. The google_auth_oauthlib library doesn't have comparable functionality (and I haven't
# spent the time to figure out how to do it) so this script will prompt for authorization every
# time it runs.
#

# Create the flow using the client secrets file from the Google API Console.
flow = Flow.from_client_secrets_file(
    client_secret_file,
    scopes=[scope],
    redirect_uri='urn:ietf:wg:oauth:2.0:oob')

# Tell the user to go to the authorization URL.
auth_url, _ = flow.authorization_url(prompt='consent')

print('Please go to this URL: {}'.format(auth_url))

# The user will get an authorization code. This code is used to get the
# access token.
code = input('Enter the authorization code: ')
flow.fetch_token(code=code)



# Can now get the credentials after the call to fetch_token()
credentials = flow.credentials

# Create an object for interacting with the Groups Migration API
#service = discovery.build('groupsmigration', 'v1', credentials=credentials)
service = apiclient.discovery.build('groupsmigration', 'v1', credentials=credentials)

# Open the mbox file
mb = mailbox.mbox(mbox_path)  # The path of the mbox file to import

# Create a counter variable and find the total number of messages
# Use this for status updates as messages are uploaded
i = 1
total_messages = len(mb)

# Process messages from the mbox file one-at-a-time
for msg in mb:
    # Read the rfc822 text (i.e. the message) as a stream object
    stream = StringIO()
    stream.write(msg.as_string())
    
    # Create an object/description suitable for uploading
    media = apiclient.http.MediaIoBaseUpload(stream, mimetype='message/rfc822')
    
    # Upload message to the group archive and get the response
    response = service.archive().insert(groupId=groupId, media_body=media).execute()

    # Show a status message
    print('Message {} of {}: {}'.format(
        i,
        total_messages,
        response['responseCode'])
    )

    i = i + 1

    # Limit to no more than 10 messages per second to avoid exceeding API quota
    # https://developers.google.com/admin-sdk/groups-migration/v1/limits
    time.sleep(0.1)

print('Done.')