text: # The MIT License (MIT)
  # 
  # Copyright (c) 2018 stanwood GmbH
  # 
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  # 
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  # 
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  # THE SOFTWARE.
  import json
  import logging
  
  from google.appengine.api import urlfetch, app_identity
  
  
  class FcmClientError(Exception):
      pass
  
  
  class FcmClient(object):
  
      def __init__(self, project_id):
          self._project_id = project_id
  
      @property
      def access_token(self):
          return app_identity.get_access_token(
              scopes=[
                  'https://www.googleapis.com/auth/firebase.messaging'
              ]
          )[0]
  
      def push(self, payload):
          payload = json.dumps(payload, indent=2)
          logging.debug(payload)
          url = 'https://fcm.googleapis.com/v1/projects/{}/messages:send'.format(self._project_id)
          logging.debug(u'POST {} \n {}'.format(url, json.dumps(payload, indent=2)))
          result = urlfetch.fetch(
              url=url,
              method='POST',
              headers={
                  'Content-Type': 'application/json',
                  'Authorization': 'Bearer {}'.format(self.access_token)
              },
              payload=payload
          )
  
          if result.status_code / 400:
              raise FcmClientError('Failed to send push: {} {}'.format(result.status_code, result.content))
  
          return json.loads(result.content)
  