medium.py

"""Medium hosted blog implementation.

Medium's API is unsupported and degrading. We should probably sunset this.

Only supports outbound webmentions right now, not inbound, since Medium's API
doesn't support creating responses or recommendations yet.

* https://github.com/Medium/medium-api-docs/issues/71
* https://github.com/Medium/medium-api-docs/issues/72

API docs:

* https://github.com/Medium/medium-api-docs#contents
* https://medium.com/developers/welcome-to-the-medium-api-3418f956552
"""
import collections
import logging

from flask import render_template, request
from google.cloud import ndb
from oauth_dropins import medium as oauth_medium
from oauth_dropins.webutil.util import json_dumps, json_loads

from flask_app import app
import models
import superfeedr
import util

logger = logging.getLogger(__name__)


class Medium(models.Source):
  """A Medium publication or user blog.

  The key name is the username (with ``@`` prefix) or publication name.
  """
  GR_CLASS = collections.namedtuple('FakeGrClass', ('NAME',))(NAME='Medium')
  OAUTH_START = oauth_medium.Start
  SHORT_NAME = 'medium'
  USERNAME_KEY_ID = True

  def is_publication(self):
    return not self.key_id().startswith('@')

  def feed_url(self):
    # https://help.medium.com/hc/en-us/articles/214874118-RSS-Feeds-of-publications-and-profiles
    return self.url.replace('medium.com/', 'medium.com/feed/')

  def silo_url(self):
    return self.url

  @staticmethod
  def new(auth_entity=None, username=None, **kwargs):
    """Creates and returns a Medium for the logged in user.

    Args:
      auth_entity (oauth_dropins.medium.MediumAuth):
      username (str): either username (starting with ``@``) or publication id
    """
    assert username
    assert 'id' not in kwargs
    medium = Medium(username=username,
                    auth_entity=auth_entity.key,
                    superfeedr_secret=util.generate_secret(),
                    **kwargs)

    data = medium._data(auth_entity)
    medium.name = data.get('name') or data.get('username')
    medium.picture = data.get('imageUrl')
    medium.url = data.get('url')
    return medium

  def verified(self):
    return False

  def verify(self, force=False):
    """No incoming webmention support yet."""
    pass

  def has_bridgy_webmention_endpoint(self):
    return True

  def _data(self, auth_entity):
    """Returns the Medium API object for this user or publication.

    https://github.com/Medium/medium-api-docs/#user-content-getting-the-authenticated-users-details

    Example user::

        {
          'imageUrl': 'https://cdn-images-1.medium.com/fit/c/200/200/0*4dsrv3pwIJfFraSz.jpeg',
          'url': 'https://medium.com/@snarfed',
          'name': 'Ryan Barrett',
          'username': 'snarfed',
          'id': '113863a5ca2ab60671e8c9fe089e59c07acbf8137c51523605dc55528516c0d7e'
        }

    Example publication::

        {
          'id': 'b45573563f5a',
          'name': 'Developers',
          'description': "Medium's Developer resources",
          'url': 'https://medium.com/developers',
          'imageUrl': 'https://cdn-images-1.medium.com/fit/c/200/200/1*ccokMT4VXmDDO1EoQQHkzg@2x.png'
        }
    """
    id = self.username.lstrip('@')

    user = json_loads(auth_entity.user_json).get('data')
    if user.get('username').lstrip('@') == id:
      return user

    for pub in json_loads(auth_entity.publications_json).get('data', []):
      if pub.get('id') == id:
        return pub

  def urls_and_domains(self, auth_entity, user_url):
    if self.url:
      return [self.url], [util.domain_from_link(self.url)]

    return [], []


@app.route('/medium/add', methods=['POST'])
def medium_add():
  auth_entity = ndb.Key(urlsafe=request.values['auth_entity_key']).get()
  util.maybe_add_or_delete_source(Medium, auth_entity, request.values['state'],
                                  username=request.values['blog'])


class ChooseBlog(oauth_medium.Callback):
  def finish(self, auth_entity, state=None):
    if not auth_entity:
      util.maybe_add_or_delete_source(Medium, auth_entity, state)
      return

    user = json_loads(auth_entity.user_json)['data']
    username = user['username']
    if not username.startswith('@'):
      username = '@' + username

    # fetch publications this user contributes or subscribes to.
    # (sadly medium's API doesn't tell us the difference unless we fetch each
    # pub's metadata separately.)
    # https://github.com/Medium/medium-api-docs/#user-content-listing-the-users-publications
    auth_entity.publications_json = auth_entity.get(
      oauth_medium.API_BASE + f'users/{user["id"]}/publications').text
    auth_entity.put()
    pubs = json_loads(auth_entity.publications_json).get('data')
    if not pubs:
      util.maybe_add_or_delete_source(Medium, auth_entity, state,
                                      username=username)
      return

    # add user profile to start of pubs list
    user['id'] = username
    pubs.insert(0, user)

    vars = {
      'action': '/medium/add',
      'state': state,
      'auth_entity_key': auth_entity.key.urlsafe().decode(),
      'blogs': [{
        'id': p['id'],
        'title': p.get('name', ''),
        'url': p.get('url', ''),
        'pretty_url': util.pretty_link(str(p.get('url', ''))),
        'image': p.get('imageUrl', ''),
      } for p in pubs if p.get('id')],
    }
    logger.info(f'Rendering choose_blog.html with {vars}')
    return render_template('choose_blog.html', **vars)


class SuperfeedrNotify(superfeedr.Notify):
  SOURCE_CLS = Medium


# https://github.com/Medium/medium-api-docs#user-content-21-browser-based-authentication
start = util.oauth_starter(oauth_medium.Start).as_view(
  'medium_start', '/medium/choose_blog', scopes=('basicProfile', 'listPublications'))
app.add_url_rule('/medium/start', view_func=start, methods=['POST'])
app.add_url_rule('/medium/choose_blog', view_func=ChooseBlog.as_view(
  'medium_choose_blog', 'unused to_path'), methods=['GET'])
app.add_url_rule('/medium/delete/finish', view_func=oauth_medium.Callback.as_view(
  'medium_delete', '/delete/finish')),
app.add_url_rule('/medium/notify/<id>', view_func=SuperfeedrNotify.as_view('medium_notify'), methods=['POST'])