Webhooks: smarter way to find the user the webhook applies to.

We now also match on Blender ID (through the 'auth' section of the user
document), so that even when we have missed an email change we can still
apply the changes from the webhook.

cloud/webhooks.py

@@ -1,9 +1,11 @@
 """Blender ID webhooks."""
 
+import functools
 import hashlib
 import hmac
 import json
 import logging
+import typing
 
 from flask_login import request
 from flask import Blueprint
@@ -53,6 +55,66 @@ def webhook_payload(hmac_secret: str) -> dict:
         raise wz_exceptions.BadRequest('Bad JSON')
 
 
+def score(wh_payload: dict, user: dict) -> int:
+    """Determine how likely it is that this is the correct user to modify.
+
+    :param wh_payload: the info we received from Blender ID;
+        see user_modified()
+    :param user: the user in our database
+    :return: the score for this user
+    """
+
+    bid_str = str(wh_payload['id'])
+    try:
+        match_on_bid = any((auth['provider'] == 'blender-id' and auth['user_id'] == bid_str)
+                           for auth in user['auth'])
+    except KeyError:
+        match_on_bid = False
+
+    match_on_old_email = user.get('email', 'none') == wh_payload.get('old_email', 'nothere')
+    match_on_new_email = user.get('email', 'none') == wh_payload.get('email', 'nothere')
+    return match_on_bid * 10 + match_on_old_email + match_on_new_email * 2
+
+
+def fetch_user(wh_payload: dict) -> typing.Optional[dict]:
+    """Fetch the user from the DB
+
+    :returns the user document, or None when not found.
+    """
+
+    users_coll = current_app.db('users')
+    my_log = log.getChild('insert_or_fetch_user')
+
+    # Find the user by their Blender ID, or any of their email addresses.
+    # We use one query to find all matching users. This is done as a
+    # consistency check; if more than one user is returned, we know the
+    # database is inconsistent with Blender ID and can emit a warning
+    # about this.
+    bid_str = str(wh_payload['id'])
+    query = {'$or': [
+        {'auth.provider': 'blender-id', 'auth.user_id': bid_str},
+        {'email': {'$in': [wh_payload['old_email'], wh_payload['email']]}},
+    ]}
+    db_users = users_coll.find(query)
+    user_count = db_users.count()
+    if user_count > 1:
+        # Now we have to pay the price for finding users in one query; we
+        # have to prioritise them and return the one we think is most reliable.
+        calc_score = functools.partial(score, wh_payload)
+        best_score = max(db_users, key=calc_score)
+
+        my_log.warning('%d users found for query %s, picking %s',
+                       user_count, query, best_score['email'])
+        return best_score
+    if user_count:
+        db_user = db_users[0]
+        my_log.debug('found user %s', db_user['email'])
+        return db_user
+
+    my_log.info('Received update for unknown user %r', wh_payload['old_email'])
+    return None
+
+
 @blueprint.route('/user-modified', methods=['POST'])
 def user_modified():
     """Updates the local user based on the info from Blender ID.
@@ -73,17 +135,14 @@ def user_modified():
     my_log.info('payload: %s', payload)
 
     # Update the user
-    users_coll = current_app.db('users')
-    db_user = users_coll.find_one({'email': payload['old_email']})
+    db_user = fetch_user(payload)
     if not db_user:
-        db_user = users_coll.find_one({'email': payload['email']})
-        if not db_user:
-            my_log.info('Received update for unknown user %r', payload['old_email'])
-            return '', 204
+        my_log.info('Received update for unknown user %r', payload['old_email'])
+        return '', 204
 
     # Use direct database updates to change the email and full name.
     updates = {}
-    if payload['old_email'] != payload['email']:
+    if db_user['email'] != payload['email']:
         my_log.info('User changed email from %s to %s', payload['old_email'], payload['email'])
         updates['email'] = payload['email']
 
@@ -97,6 +156,7 @@ def user_modified():
             updates['full_name'] = db_user['username']
 
     if updates:
+        users_coll = current_app.db('users')
         update_res = users_coll.update_one({'_id': db_user['_id']},
                                            {'$set': updates})
         if update_res.matched_count != 1: