Transfer local user's push rules on room upgrade (#4838)

Transfer push rules (notifications) on room upgrade

changelog.d/4838.bugfix

+Transfer a user's notification settings (push rules) on room upgrade.
\ No newline at end of file

synapse/handlers/room_member.py

@@ -232,6 +232,10 @@ class RoomMemberHandler(object):
                 self.copy_room_tags_and_direct_to_room(
                     predecessor["room_id"], room_id, user_id,
                 )
+                # Move over old push rules
+                self.store.move_push_rules_from_room_to_room_for_user(
+                    predecessor["room_id"], room_id, user_id,
+                )
         elif event.membership == Membership.LEAVE:
             if prev_member_event_id:
                 prev_member_event = yield self.store.get_event(prev_member_event_id)

synapse/storage/push_rule.py

@@ -185,6 +185,63 @@ class PushRulesWorkerStore(ApplicationServiceWorkerStore,
 
         defer.returnValue(results)
 
+    @defer.inlineCallbacks
+    def move_push_rule_from_room_to_room(
+        self, new_room_id, user_id, rule,
+    ):
+        """Move a single push rule from one room to another for a specific user.
+
+        Args:
+            new_room_id (str): ID of the new room.
+            user_id (str): ID of user the push rule belongs to.
+            rule (Dict): A push rule.
+        """
+        # Create new rule id
+        rule_id_scope = '/'.join(rule["rule_id"].split('/')[:-1])
+        new_rule_id = rule_id_scope + "/" + new_room_id
+
+        # Change room id in each condition
+        for condition in rule.get("conditions", []):
+            if condition.get("key") == "room_id":
+                condition["pattern"] = new_room_id
+
+        # Add the rule for the new room
+        yield self.add_push_rule(
+            user_id=user_id,
+            rule_id=new_rule_id,
+            priority_class=rule["priority_class"],
+            conditions=rule["conditions"],
+            actions=rule["actions"],
+        )
+
+        # Delete push rule for the old room
+        yield self.delete_push_rule(user_id, rule["rule_id"])
+
+    @defer.inlineCallbacks
+    def move_push_rules_from_room_to_room_for_user(
+        self, old_room_id, new_room_id, user_id,
+    ):
+        """Move all of the push rules from one room to another for a specific
+        user.
+
+        Args:
+            old_room_id (str): ID of the old room.
+            new_room_id (str): ID of the new room.
+            user_id (str): ID of user to copy push rules for.
+        """
+        # Retrieve push rules for this user
+        user_push_rules = yield self.get_push_rules_for_user(user_id)
+
+        # Get rules relating to the old room, move them to the new room, then
+        # delete them from the old room
+        for rule in user_push_rules:
+            conditions = rule.get("conditions", [])
+            if any((c.get("key") == "room_id" and
+                    c.get("pattern") == old_room_id) for c in conditions):
+                self.move_push_rule_from_room_to_room(
+                    new_room_id, user_id, rule,
+                )
+
     @defer.inlineCallbacks
     def bulk_get_push_rules_for_room(self, event, context):
         state_group = context.state_group