Refactor email summary generation. (#9260)

* Fixes a case where no summary text was returned.
* The use of messages_from_person vs. messages_from_person_and_others
  was tweaked to depend on whether there was 1 sender or multiple senders,
  not based on if there was 1 room or multiple rooms.

changelog.d/9260.misc

@@ -0,0 +1 @@
+Refactor the generation of summary text for email notifications.

synapse/push/mailer.py

@@ -267,8 +267,20 @@ class Mailer:
             fallback_to_members=True,
         )
 
+        if len(notifs_by_room) == 1:
+            # Only one room has new stuff
+            room_id = list(notifs_by_room.keys())[0]
+
+            summary_text = await self.make_summary_text_single_room(
+                room_id,
+                notifs_by_room[room_id],
+                state_by_room[room_id],
+                notif_events,
+                user_id,
+            )
+        else:
             summary_text = await self.make_summary_text(
-            notifs_by_room, state_by_room, notif_events, user_id, reason
+                notifs_by_room, state_by_room, notif_events, reason
             )
 
         template_vars = {
@@ -492,28 +504,37 @@ class Mailer:
         if "url" in event.content:
             messagevars["image_url"] = event.content["url"]
 
-    async def make_summary_text(
+    async def make_summary_text_single_room(
         self,
-        notifs_by_room: Dict[str, List[Dict[str, Any]]],
+        room_id: str,
-        room_state_ids: Dict[str, StateMap[str]],
+        notifs: List[Dict[str, Any]],
+        room_state_ids: StateMap[str],
         notif_events: Dict[str, EventBase],
         user_id: str,
-        reason: Dict[str, Any],
+    ) -> str:
-    ):
+        """
-        if len(notifs_by_room) == 1:
+        Make a summary text for the email when only a single room has notifications.
-            # Only one room has new stuff
-            room_id = list(notifs_by_room.keys())[0]
 
+        Args:
+            room_id: The ID of the room.
+            notifs: The notifications for this room.
+            room_state_ids: The state map for the room.
+            notif_events: A map of event ID -> notification event.
+            user_id: The user receiving the notification.
+
+        Returns:
+            The summary text.
+        """
         # If the room has some kind of name, use it, but we don't
         # want the generated-from-names one here otherwise we'll
         # end up with, "new message from Bob in the Bob room"
         room_name = await calculate_room_name(
-                self.store, room_state_ids[room_id], user_id, fallback_to_members=False
+            self.store, room_state_ids, user_id, fallback_to_members=False
         )
 
         # See if one of the notifs is an invite event for the user
         invite_event = None
-            for n in notifs_by_room[room_id]:
+        for n in notifs:
             ev = notif_events[n["event_id"]]
             if ev.type == EventTypes.Member and ev.state_key == user_id:
                 if ev.content.get("membership") == Membership.INVITE:
@@ -521,7 +542,7 @@ class Mailer:
                     break
 
         if invite_event:
-                inviter_member_event_id = room_state_ids[room_id].get(
+            inviter_member_event_id = room_state_ids.get(
                 ("m.room.member", invite_event.sender)
             )
             inviter_name = invite_event.sender
@@ -537,21 +558,19 @@ class Mailer:
                     "person": inviter_name,
                     "app": self.app_name,
                 }
-                else:
+
             return self.email_subjects.invite_from_person_to_room % {
                 "person": inviter_name,
                 "room": room_name,
                 "app": self.app_name,
             }
 
-            sender_name = None
+        if len(notifs) == 1:
-            if len(notifs_by_room[room_id]) == 1:
             # There is just the one notification, so give some detail
-                event = notif_events[notifs_by_room[room_id][0]["event_id"]]
+            sender_name = None
-                if ("m.room.member", event.sender) in room_state_ids[room_id]:
+            event = notif_events[notifs[0]["event_id"]]
-                    state_event_id = room_state_ids[room_id][
+            if ("m.room.member", event.sender) in room_state_ids:
-                        ("m.room.member", event.sender)
+                state_event_id = room_state_ids[("m.room.member", event.sender)]
-                    ]
                 state_event = await self.store.get_event(state_event_id)
                 sender_name = name_from_member_event(state_event)
 
@@ -566,6 +585,12 @@ class Mailer:
                     "person": sender_name,
                     "app": self.app_name,
                 }
+
+            # The sender is unknown, just use the room name (or ID).
+            return self.email_subjects.messages_in_room % {
+                "room": room_name or room_id,
+                "app": self.app_name,
+            }
         else:
             # There's more than one notification for this room, so just
             # say there are several
@@ -574,57 +599,83 @@ class Mailer:
                     "room": room_name,
                     "app": self.app_name,
                 }
-                else:
+
-                    # If the room doesn't have a name, say who the messages
+            return await self.make_summary_text_from_member_events(
-                    # are from explicitly to avoid, "messages in the Bob room"
+                room_id, notifs, room_state_ids, notif_events
-                    sender_ids = list(
-                        {
-                            notif_events[n["event_id"]].sender
-                            for n in notifs_by_room[room_id]
-                        }
             )
 
-                    member_events = await self.store.get_events(
+    async def make_summary_text(
-                        [
+        self,
-                            room_state_ids[room_id][("m.room.member", s)]
+        notifs_by_room: Dict[str, List[Dict[str, Any]]],
-                            for s in sender_ids
+        room_state_ids: Dict[str, StateMap[str]],
-                        ]
+        notif_events: Dict[str, EventBase],
-                    )
+        reason: Dict[str, Any],
+    ) -> str:
+        """
+        Make a summary text for the email when multiple rooms have notifications.
 
-                    return self.email_subjects.messages_from_person % {
+        Args:
-                        "person": descriptor_from_member_events(member_events.values()),
+            notifs_by_room: A map of room ID to the notifications for that room.
-                        "app": self.app_name,
+            room_state_ids: A map of room ID to the state map for that room.
-                    }
+            notif_events: A map of event ID -> notification event.
-        else:
+            reason: The reason this notification is being sent.
+
+        Returns:
+            The summary text.
+        """
         # Stuff's happened in multiple different rooms
-
         # ...but we still refer to the 'reason' room which triggered the mail
         if reason["room_name"] is not None:
             return self.email_subjects.messages_in_room_and_others % {
                 "room": reason["room_name"],
                 "app": self.app_name,
             }
-            else:
-                # If the reason room doesn't have a name, say who the messages
-                # are from explicitly to avoid, "messages in the Bob room"
-                room_id = reason["room_id"]
 
-                sender_ids = list(
+        room_id = reason["room_id"]
-                    {
+        return await self.make_summary_text_from_member_events(
-                        notif_events[n["event_id"]].sender
+            room_id, notifs_by_room[room_id], room_state_ids[room_id], notif_events
-                        for n in notifs_by_room[room_id]
-                    }
         )
 
+    async def make_summary_text_from_member_events(
+        self,
+        room_id: str,
+        notifs: List[Dict[str, Any]],
+        room_state_ids: StateMap[str],
+        notif_events: Dict[str, EventBase],
+    ) -> str:
+        """
+        Make a summary text for the email when only a single room has notifications.
+
+        Args:
+            room_id: The ID of the room.
+            notifs: The notifications for this room.
+            room_state_ids: The state map for the room.
+            notif_events: A map of event ID -> notification event.
+
+        Returns:
+            The summary text.
+        """
+        # If the room doesn't have a name, say who the messages
+        # are from explicitly to avoid, "messages in the Bob room"
+        sender_ids = {notif_events[n["event_id"]].sender for n in notifs}
+
         member_events = await self.store.get_events(
-                    [room_state_ids[room_id][("m.room.member", s)] for s in sender_ids]
+            [room_state_ids[("m.room.member", s)] for s in sender_ids]
         )
 
-                return self.email_subjects.messages_from_person_and_others % {
+        # There was a single sender.
+        if len(sender_ids) == 1:
+            return self.email_subjects.messages_from_person % {
                 "person": descriptor_from_member_events(member_events.values()),
                 "app": self.app_name,
             }
 
+        # There was more than one sender, use the first one and a tweaked template.
+        return self.email_subjects.messages_from_person_and_others % {
+            "person": descriptor_from_member_events(list(member_events.values())[:1]),
+            "app": self.app_name,
+        }
+
     def make_room_link(self, room_id: str) -> str:
         if self.hs.config.email_riot_base_url:
             base_url = "%s/#/room" % (self.hs.config.email_riot_base_url)

tests/push/test_email.py

@@ -187,6 +187,36 @@ class EmailPusherTests(HomeserverTestCase):
         # We should get emailed about those messages
         self._check_for_mail()
 
+    def test_multiple_rooms(self):
+        # We want to test multiple notifications from multiple rooms, so we pause
+        # processing of push while we send messages.
+        self.pusher._pause_processing()
+
+        # Create a simple room with multiple other users
+        rooms = [
+            self.helper.create_room_as(self.user_id, tok=self.access_token),
+            self.helper.create_room_as(self.user_id, tok=self.access_token),
+        ]
+
+        for r, other in zip(rooms, self.others):
+            self.helper.invite(
+                room=r, src=self.user_id, tok=self.access_token, targ=other.id
+            )
+            self.helper.join(room=r, user=other.id, tok=other.token)
+
+        # The other users send some messages
+        self.helper.send(rooms[0], body="Hi!", tok=self.others[0].token)
+        self.helper.send(rooms[1], body="There!", tok=self.others[1].token)
+        self.helper.send(rooms[1], body="There!", tok=self.others[1].token)
+
+        # Nothing should have happened yet, as we're paused.
+        assert not self.email_attempts
+
+        self.pusher._resume_processing()
+
+        # We should get emailed about those messages
+        self._check_for_mail()
+
     def test_encrypted_message(self):
         room = self.helper.create_room_as(self.user_id, tok=self.access_token)
         self.helper.invite(