Don't view groups/rooms when possible, via MSC2409

Use the sidebar to sync non-DM messages, just like what's done for DM
messages.

However, since sidebar messages don't say who sent a message, this
requires scanning read receipts with MSC2409: when a non-DM sidebar
message is seen, the bridge bot sends that message. Only when that
placeholder is viewed in Matrix does Puppeteer actually view the non-DM
chat to find who really sent the message. Then the bridgebot redacts its
message, and the message gets re-sent by the puppet of the LINE user who
really sent it.

matrix_puppeteer_line/portal.py

@@ -190,10 +190,10 @@ class Portal(DBPortal, BasePortal):
                       f"cleaning up and deleting...")
         await self.cleanup_and_delete()
 
-    async def _bridge_own_message_pm(self, source: 'u.User', sender: Optional['p.Puppet'], mid: str,
+    async def _bridge_own_message_pm(self, source: 'u.User', puppet: Optional['p.Puppet'], mid: str,
                                      invite: bool = True) -> Optional[IntentAPI]:
-        intent = sender.intent if sender else (await source.get_own_puppet()).intent
-        if self.is_direct and (sender is None or sender.mid == source.mid and not sender.is_real_user):
+        intent = puppet.intent if puppet else (await source.get_own_puppet()).intent
+        if self.is_direct and (not puppet or puppet.mid == source.mid and not puppet.is_real_user):
             if self.invite_own_puppet_to_pm and invite:
                 try:
                     await intent.ensure_joined(self.mxid)
@@ -216,44 +216,54 @@ class Portal(DBPortal, BasePortal):
             self.log.debug(f"Ignoring duplicate message {evt.id}")
             return
 
-        is_preseen = evt.id != None and await DBMessage.get_num_noid_msgs(self.mxid) > 0
-
         if evt.is_outgoing:
             if source.intent:
-                sender = None
                 intent = source.intent
             else:
                 if not self.invite_own_puppet_to_pm:
                     self.log.warning(f"Ignoring message {evt.id}: double puppeting isn't enabled")
                     return
-                sender = await p.Puppet.get_by_mid(evt.sender.id) if evt.sender else None
-                intent = await self._bridge_own_message_pm(source, sender, f"message {evt.id}")
+                puppet = await p.Puppet.get_by_mid(evt.sender.id) if evt.sender else None
+                intent = await self._bridge_own_message_pm(source, puppet, f"message {evt.id}")
                 if not intent:
                     return
         else:
-            sender = await p.Puppet.get_by_mid(self.other_user if self.is_direct else evt.sender.id)
+            if self.is_direct:
                 # TODO Respond to name/avatar changes of users in a DM
-            if not self.is_direct:
-                if sender:
-                    await sender.update_info(evt.sender, source.client)
+                intent = (await p.Puppet.get_by_mid(self.other_user)).intent
+            elif evt.sender:
+                puppet = await p.Puppet.get_by_mid(evt.sender.id)
+                if puppet:
+                    await puppet.update_info(evt.sender, source.client)
                 else:
-                    self.log.warning(f"Could not find ID of LINE user who sent event {evt.id or 'with no ID'}")
-                    sender = await p.Puppet.get_by_profile(evt.sender, source.client)
-            intent = sender.intent
+                    self.log.warning(f"Could not find ID of LINE user who sent message {evt.id or 'with no ID'}")
+                    puppet = await p.Puppet.get_by_profile(evt.sender, source.client)
+                intent = puppet.intent
+            else:
+                self.log.info(f"Using bridgebot for unknown sender of message {evt.id or 'with no ID'}")
+                intent = self.az.intent
             await intent.ensure_joined(self.mxid)
 
-        if is_preseen:
+        if evt.id:
             msg = await DBMessage.get_next_noid_msg(self.mxid)
-            if msg:
-                self.log.debug(f"Found ID {evt.id} of preseen message in chat {self.mxid}: {msg.mxid}")
+            if not msg:
+                self.log.info(f"Handling new message {evt.id} in chat {self.mxid}")
+                prev_event_id = None
+            else:
+                self.log.info(f"Handling preseen message {evt.id} in chat {self.mxid}: {msg.mxid}")
+                if not self.is_direct:
+                    # Non-DM previews are always sent by bridgebot.
+                    # Must delete the bridgebot message and send a new message from the correct puppet.
+                    await self.az.intent.redact(self.mxid, msg.mxid, "Found actual sender")
+                    prev_event_id = None
+                else:
                     prev_event_id = msg.mxid
         else:
-                self.log.error(f"Could not find an existing event for a message with no ID in chat {self.mxid}")
-                return
-        else:
+            self.log.info(f"Handling new message with no ID in chat {self.mxid}")
+            msg = None
             prev_event_id = None
 
-        if is_preseen and evt.html:
+        if prev_event_id and evt.html:
             # No need to update a previewed text message, as their previews are accurate
             event_id = prev_event_id
         elif evt.image and evt.image.url:
@@ -364,7 +374,7 @@ class Portal(DBPortal, BasePortal):
         if evt.is_outgoing and evt.receipt_count:
             await self._handle_receipt(event_id, evt.receipt_count)
 
-        if not is_preseen:
+        if not msg:
             msg = DBMessage(mxid=event_id, mx_room=self.mxid, mid=evt.id, chat_id=self.chat_id)
             try:
                 await msg.insert()

puppet/src/puppet.js

@@ -771,18 +771,17 @@ export default class MessagesPuppeteer {
 		}
 
 		const mustSync =
-			// Can only use previews for DMs, because sender can't be found otherwise!
-			// TODO For non-DMs, send fake messages from bridgebot and delete them.
-			   chatListInfo.id.charAt(0) != 'u'
 			// If >1, a notification was missed. Only way to get them is to view the chat.
 			// If == 0, might be own message...or just a shuffled chat, or something else.
 			// To play it safe, just sync them. Should be no harm, as they're viewed already.
-			|| diffNumNotifications != 1
+			   diffNumNotifications != 1
 			// Without placeholders, some messages require visiting their chat to be synced.
 			|| !this.sendPlaceholders
 			&& (
+				// Can only use previews for DMs, because sender can't be found otherwise!
+				   chatListInfo.id.charAt(0) != 'u'
 				// Sync when lastMsg is a canned message for a non-previewable message type.
-				   chatListInfo.lastMsg.endsWith(" sent a photo.")
+				|| chatListInfo.lastMsg.endsWith(" sent a photo.")
 				|| chatListInfo.lastMsg.endsWith(" sent a sticker.")
 				|| chatListInfo.lastMsg.endsWith(" sent a location.")
 				// TODO More?
@@ -795,7 +794,7 @@ export default class MessagesPuppeteer {
 				id: null, // because sidebar messages have no ID
 				timestamp: null, // because this message was sent right now
 				is_outgoing: false, // because there's no reliable way to detect own messages...
-				sender: null, // because only DM messages are handled
+				sender: null, // because there's no way to tell who sent a message
 				html: chatListInfo.lastMsg,
 			}]
 			this.numChatNotifications.set(chatID, chatListInfo.notificationCount)