plugin XEP-0045: add set_room_configuration and is_jid_in_room methods:

The `set_room_configuration` allow to update configuration with well-known options.
The `is_jid_in_room` check if an entity with the given real JID is in the room.

libervia/backend/plugins/plugin_xep_0045.py

@@ -743,6 +743,46 @@ class XEP_0045:
         del self._sessions[raw_data["session_id"]]
         return d
 
+    async def set_room_configuration(
+        self, client: SatXMPPEntity, room_jid: jid.JID, options: dict
+    ) -> None:
+        """Set MUC configuration.
+
+        Values from ``options`` are set if the corresponding field exists in the room's
+        configuration form, otherwise they are ignored; a ``None`` value removes the
+        field's value. Other fields are not modified.
+
+        @param client: The client instance.
+        @param options: option name -> value.
+        """
+        muc_client = client.get_plugin_data(IMPORT_NAME, MUCClientData).muc_client
+        form = await muc_client.getConfiguration(room_jid)
+        if form is None:
+            log.warning(
+                f"[{client.profile}] can't get the configuration form of "
+                f"{room_jid}, not applying {options}"
+            )
+            return
+        config: dict = {}
+        for field in form.fields.values():
+            if field.values:
+                # DataForm values are always lists (even single-valued fields
+                # have one element); `configure()` accepts a list for any field
+                config[field.var] = field.values
+        for var, value in options.items():
+            if var in form.fields:
+                config[var] = value
+            else:
+                log.warning(
+                    f"[{client.profile}] config field {var} not present in the form of "
+                    f"{room_jid}, ignoring it"
+                )
+        await muc_client.configure(room_jid, config)
+        log.info(
+            f"[{client.profile}] room {room_jid.userhost()} configuration updated with "
+            f"{options}"
+        )
+
     def is_nick_in_room(
         self, client: SatXMPPEntity, room_jid: jid.JID, nick: str
     ) -> bool:
@@ -754,6 +794,28 @@ class XEP_0045:
             .inRoster(muc.User(nick))
         )
 
+    def is_jid_in_room(
+        self, client: SatXMPPEntity, room_jid: jid.JID, user_jid: jid.JID
+    ) -> bool:
+        """Tell if a read JIDcurrently present in a room.
+
+        Only the bare JID will be checked. This can work only if profile can access real
+        JIDs in the room (owner of the room, or the room is not anonymous).
+
+        @param room_jid: JID of the room to check.
+        @param user_jid: JID of the entity to check.
+
+        """
+        try:
+            room = self.get_room(client, room_jid)
+        except exceptions.NotFound:
+            return False
+        bare_jid = user_jid.userhost()
+        return any(
+            user.entity is not None and user.entity.userhost() == bare_jid
+            for user in room.roster.values()
+        )
+
     # Text commands
 
     def _get_muc_service(