How to use the granary.facebook.Facebook function in granary

user = addr.split('@')[0]
    source = FacebookEmailAccount.query(FacebookEmailAccount.email_user == user).get()
    logging.info('Source for %s is %s', user, source)

    htmls = list(body.decode() for _, body in email.bodies('text/html'))
    fbe = FacebookEmail.get_or_insert(
      message_id, source=source.key if source else None, htmls=htmls)
    logging.info('FacebookEmail created %s: %s', fbe.created, fbe.key.urlsafe())

    if not source:
      self.response.status_code = 404
      self.response.write('No Facebook email user found with address %s' % addr)
      return

    for html in htmls:
      obj = gr_facebook.Facebook().email_to_object(html)
      if obj:
        break
    else:
      self.response.status_code = 400
      self.response.write('No HTML body could be parsed')
      return
    logging.info('Converted to AS1: %s', json_dumps(obj, indent=2))

    base_obj = source.gr_source.base_object(obj)
    # note that this ignores the id query param (the post's user id) and uses
    # the source object's user id instead.
    base_obj['url'] = source.canonicalize_url(base_obj['url'])
    # also note that base_obj['id'] is not a tag URI, it's the raw Facebook post
    # id, eg '104790764108207'. we don't use it from activities_json much,
    # though, just in PropagateResponse.source_url(), which handles this fine.

def get_comment(self, id, **kwargs):
    resp = ndb.Key('Response', self.gr_source.tag_uri(id))
    email = FacebookEmail.query(FacebookEmail.response == resp).get()
    if email:
      return gr_facebook.Facebook().email_to_object(email.htmls[0])

MAX_RESOLVED_OBJECT_IDS = 200
MAX_POST_PUBLICS = 200

# empirically we've seen global user ids as high as 407874323168, and app scoped
# ids as low as 527127880724, so there's probably not a single cutoff like this.
# but it's ok as an approximation.
MIN_APP_SCOPED_ID = 500000000000


class FacebookPage(models.Source):
  """A Facebook profile or page.

  The key name is the Facebook id.
  """
  GR_CLASS = gr_facebook.Facebook
  OAUTH_START_HANDLER = oauth_facebook.StartHandler
  SHORT_NAME = 'facebook'

  URL_CANONICALIZER = util.UrlCanonicalizer(
    domain=GR_CLASS.DOMAIN,
    subdomain='www',
    query=True,
    approve=r'https://www\.facebook\.com/[^/?]+/posts/[^/?]+$',
    headers=util.REQUEST_HEADERS)
    # no reject regexp; non-private FB post URLs just 404

  # unique name used in FB URLs, e.g. facebook.com/[username]
  username = ndb.StringProperty()
  # inferred from syndication URLs if username isn't available
  inferred_username = ndb.StringProperty()
  # inferred application-specific user IDs (from other applications)

"""Returns the 'base' silo object that an object operates on.

    This is mostly a big bag of heuristics for reverse engineering and
    parsing Facebook URLs. Whee.

    Args:
      obj: ActivityStreams object
      verb: string, optional
      resolve_numeric_id: if True, tries harder to populate the numeric_id field
        by making an additional API call to look up the object if necessary.

    Returns:
      dict, minimal ActivityStreams object. Usually has at least id,
      numeric_id, and url fields; may also have author.
    """
    base_obj = super(Facebook, self).base_object(obj)

    url = base_obj.get('url')
    if not url:
      return base_obj

    author = base_obj.setdefault('author', {})
    base_id = base_obj.get('id')
    if base_id and not base_obj.get('numeric_id'):
      if util.is_int(base_id):
        base_obj['numeric_id'] = base_id
      elif resolve_numeric_id:
        base_obj = self.user_to_actor(self.urlopen(base_id))

    try:
      parsed = urllib.parse.urlparse(url)
      params = urllib.parse.parse_qs(parsed.query)

def base_object(self, obj, verb=None, resolve_numeric_id=False):
    """Returns the 'base' silo object that an object operates on.

    This is mostly a big bag of heuristics for reverse engineering and
    parsing Facebook URLs. Whee.

    Args:
      obj: ActivityStreams object
      verb: string, optional
      resolve_numeric_id: if True, tries harder to populate the numeric_id field
        by making an additional API call to look up the object if necessary.

    Returns: dict, minimal ActivityStreams object. Usually has at least id,
      numeric_id, and url fields; may also have author.
    """
    base_obj = super(Facebook, self).base_object(obj)

    url = base_obj.get('url')
    if not url:
      return base_obj

    author = base_obj.setdefault('author', {})
    base_id = base_obj.get('id')
    if base_id and not base_obj.get('numeric_id'):
      if util.is_int(base_id):
        base_obj['numeric_id'] = base_id
      elif resolve_numeric_id:
        base_obj = self.user_to_actor(self.urlopen(base_id))

    try:
      parsed = urlparse.urlparse(url)
      params = urlparse.parse_qs(parsed.query)

def parsed_post_id(id):
      parsed = gr_facebook.Facebook.parse_id(id)
      return parsed.post if parsed.post else id

The key id is the Message-ID header.
  """
  source = ndb.KeyProperty()
  htmls = ndb.TextProperty(repeated=True)
  created = ndb.DateTimeProperty(auto_now_add=True, required=True)
  response = ndb.KeyProperty()


class FacebookEmailAccount(FacebookPage):
  """A Facebook profile or page.

  The key name is the Facebook user id.
  """

  GR_CLASS = gr_facebook.Facebook
  SHORT_NAME = 'facebook-email'

  # username for the inbound email address that users forward notification
  # emails to. the address will be [email_user]@brid-gy.appspotmail.com.
  # https://cloud.google.com/appengine/docs/standard/python/mail/receiving-mail-with-mail-api
  email_user = ndb.StringProperty()

  def get_activities_response(self, **kwargs):
    activities = []

    activity_id = kwargs.get('activity_id')
    if activity_id:
      activities = [{
        'id': activity_id,
        'url': 'https://www.facebook.com/%s/posts/%s' % (self.key.id(), activity_id),
      }]

def new(handler, auth_entity=None, **kwargs):
    """Creates and returns a :class:`FacebookPage` for the logged in user.

    Args:
      handler: the current :class:`webapp2.RequestHandler`
      auth_entity: :class:`oauth_dropins.facebook.FacebookAuth`
      kwargs: property values
    """
    user = json_loads(auth_entity.user_json)
    gr_source = gr_facebook.Facebook(access_token=auth_entity.access_token())
    actor = gr_source.user_to_actor(user)
    return FacebookPage(id=user['id'],
                        auth_entity=auth_entity.key,
                        name=actor.get('displayName'),
                        username=actor.get('username'),
                        picture=actor.get('image', {}).get('url'),
                        url=actor.get('url'),
                        **kwargs)

'jsonfeed',
  'mf2-json',
)
SILOS = (
  'flickr',
  'github',
  'instagram',
  'mastodon',
  'twitter',
)
OAUTHS = {  # maps oauth-dropins module name to module
  name: importlib.import_module('oauth_dropins.%s' % name)
  for name in SILOS
}
SILO_DOMAINS = {cls.DOMAIN for cls in (
  Facebook,
  Flickr,
  GitHub,
  Instagram,
  Twitter,
)}
SCOPE_OVERRIDES = {
  # https://developers.facebook.com/docs/reference/login/
  'facebook': 'user_status,user_posts,user_photos,user_events',
  # https://developer.github.com/apps/building-oauth-apps/scopes-for-oauth-apps/
  'github': 'notifications,public_repo',
  # https://docs.joinmastodon.org/api/permissions/
  'mastodon': 'read',
}


class FrontPageHandler(handlers.TemplateHandler):