# Copyright 2011 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Helper routines to facilitate use of oauth2_client in gsutil."""

import sys
import time
import webbrowser

import oauth2_client

GSUTIL_CLIENT_ID = '909320924072.apps.googleusercontent.com'
# Google OAuth2 clients always have a secret, even if the client is an installed
# application/utility such as gsutil.  Of course, in such cases the "secret" is
# actually publicly known; security depends entirly on the secrecy of refresh
# tokens, which effectively become bearer tokens.
GSUTIL_CLIENT_NOTSOSECRET = 'p3RlpR10xMFh9ZXBS/ZNLYUu'

GOOGLE_OAUTH2_PROVIDER_LABEL = 'Google'
GOOGLE_OAUTH2_PROVIDER_AUTHORIZATION_URI = (
    'https://accounts.google.com/o/oauth2/auth')
GOOGLE_OAUTH2_PROVIDER_TOKEN_URI = (
    'https://accounts.google.com/o/oauth2/token')

OOB_REDIRECT_URI = 'urn:ietf:wg:oauth:2.0:oob'

def OAuth2ClientFromBotoConfig(config):
  token_cache = None
  token_cache_type = config.get('OAuth2', 'token_cache', 'file_system')

  if token_cache_type == 'file_system':
    if config.has_option('OAuth2', 'token_cache_path_pattern'):
      token_cache = oauth2_client.FileSystemTokenCache(
          path_pattern=config.get('OAuth2', 'token_cache_path_pattern'))
    else:
      token_cache = oauth2_client.FileSystemTokenCache()
  elif token_cache_type == 'in_memory':
    token_cache = oauth2_client.InMemoryTokenCache()
  else:
    raise Exception(
        "Invalid value for config option OAuth2/token_cache: %s" %
        token_cache_type)

  proxy = None
  if (config.has_option('Boto', 'proxy')
      and config.has_option('Boto', 'proxy_port')):
    proxy = "%s:%s" % (config.get('Boto', 'proxy'),
        config.get('Boto', 'proxy_port'))

  provider_label = config.get(
      'OAuth2', 'provider_label', GOOGLE_OAUTH2_PROVIDER_LABEL)
  provider_authorization_uri = config.get(
      'OAuth2', 'provider_authorization_uri',
      GOOGLE_OAUTH2_PROVIDER_AUTHORIZATION_URI)
  provider_token_uri = config.get(
      'OAuth2', 'provider_token_uri', GOOGLE_OAUTH2_PROVIDER_TOKEN_URI)

  client_id = config.get('OAuth2', 'client_id', GSUTIL_CLIENT_ID)
  client_secret = config.get(
      'OAuth2', 'client_secret', GSUTIL_CLIENT_NOTSOSECRET)

  return oauth2_client.OAuth2Client(
      oauth2_client.OAuth2Provider(
          provider_label, provider_authorization_uri, provider_token_uri),
      client_id, client_secret,
      proxy=proxy, access_token_cache=token_cache)

def OAuth2ApprovalFlow(oauth2_client, scopes, launch_browser=False):
  approval_url = oauth2_client.GetAuthorizationUri(OOB_REDIRECT_URI, scopes)
  if launch_browser:
    sys.stdout.write(
        'Attempting to launch a browser with the OAuth2 approval dialog at '
        'URL: %s\n\n'
        '[Note: due to a Python bug, you may see a spurious error message "object is not\n'
        'callable [...] in [...] Popen.__del__" which can be ignored.]\n\n' % approval_url)
  else:
    sys.stdout.write(
        'Please navigate your browser to the following URL:\n%s\n\n' %
        approval_url)

  if (launch_browser and
      not webbrowser.open(approval_url, new=1, autoraise=True)):
    sys.stdout.write(
        'Launching browser appears to have failed; please navigate a browser '
        'to the following URL:\n%s\n' % approval_url)
  code = raw_input('Enter the authorization code: ')

  refresh_token, access_token = oauth2_client.ExchangeAuthorizationCode(
      code, OOB_REDIRECT_URI, scopes)

  return refresh_token