bgneal@451: """
bgneal@451: This module handles the OAuth integration with Google.
bgneal@451: 
bgneal@451: """
bgneal@451: from __future__ import with_statement
bgneal@451: import logging
bgneal@451: 
bgneal@451: import gdata.gauth
bgneal@451: from gdata.calendar_resource.client import CalendarResourceClient
bgneal@451: 
bgneal@451: from django.conf import settings
bgneal@451: 
bgneal@451: 
bgneal@451: logger = logging.getLogger(__name__)
bgneal@451: USER_AGENT = 'surfguitar101-gcalendar-v1'
bgneal@451: REQ_TOKEN_SESSION_KEY = 'gcalendar oauth request token'
bgneal@451: 
bgneal@451: 
bgneal@451: def fetch_auth(request, scopes, callback_url):
bgneal@451:     """
bgneal@451:     This function fetches a request token from Google and stores it in the
bgneal@451:     session. It then returns the authorization URL as a string.
bgneal@451: 
bgneal@451:     request - the HttpRequest object for the user requesting the token. The
bgneal@451:     token is stored in the session object attached to this request.
bgneal@451: 
bgneal@451:     scopes - a list of scope strings that the request token is for. See
bgneal@451:     http://code.google.com/apis/gdata/faq.html#AuthScopes
bgneal@451: 
bgneal@451:     callback_url - a string that is the URL that Google should redirect the user
bgneal@451:     to after the user has authorized our application access to their data.
bgneal@451: 
bgneal@451:     This function only supports RSA-SHA1 authentication. Settings in the Django
bgneal@451:     settings module determine the consumer key and path to the RSA private key.
bgneal@451:     """
bgneal@453:     logger.info("fetch_auth started; callback url='%s'", callback_url)
bgneal@451:     client = CalendarResourceClient(None, source=USER_AGENT)
bgneal@451: 
bgneal@451:     with open(settings.GOOGLE_OAUTH_PRIVATE_KEY_PATH, 'r') as f:
bgneal@451:         rsa_key = f.read()
bgneal@451:     logger.info("read RSA key; now getting request token")
bgneal@451: 
bgneal@451:     request_token = client.GetOAuthToken(
bgneal@451:             scopes,
bgneal@451:             callback_url,
bgneal@451:             settings.GOOGLE_OAUTH_CONSUMER_KEY,
bgneal@451:             rsa_private_key=rsa_key)
bgneal@451: 
bgneal@451:     logger.info("received token")
bgneal@451:     request.session[REQ_TOKEN_SESSION_KEY] = request_token
bgneal@451: 
bgneal@452:     auth_url = request_token.generate_authorization_url()
bgneal@451:     logger.info("generated auth url '%s'", str(auth_url))
bgneal@451: 
bgneal@451:     return str(auth_url)
bgneal@451: 
bgneal@451: 
bgneal@451: def get_access_token(request):
bgneal@451:     """
bgneal@451:     This function should be called after Google has sent the user back to us
bgneal@451:     after the user authorized us. We retrieve the oauth token from the request
bgneal@451:     URL and then upgrade it to an access token. We then return the access token.
bgneal@451: 
bgneal@451:     """
bgneal@451:     logger.info("get_access_token started; retrieving saved request_token...")
bgneal@451: 
bgneal@451:     saved_token = request.session.get(REQ_TOKEN_SESSION_KEY)
bgneal@451:     if saved_token is None:
bgneal@451:         logger.error("saved request token not found in session!")
bgneal@451:         return None
bgneal@451: 
bgneal@451:     logger.info("extracting token...")
bgneal@451:     request_token = gdata.gauth.AuthorizeRequestToken(saved_token,
bgneal@451:                         request.build_absolute_uri())
bgneal@451: 
bgneal@451:     logger.info("upgrading to access token...")
bgneal@451: 
bgneal@451:     client = CalendarResourceClient(None, source=USER_AGENT)
bgneal@451:     access_token = client.GetAccessToken(request_token)
bgneal@451: 
bgneal@451:     logger.info("upgraded to access token...")
bgneal@451:     return access_token