Hack in autojoin invite example

src/main.rs

@@ -1,13 +1,18 @@
 use matrix_sdk::{
     room::Room,
     ruma::{
-        events::room::message::{
-            MessageType, OriginalSyncRoomMessageEvent, Relation, RoomMessageEvent,
+        events::room::{
+            message::{
+                MessageType, OriginalSyncRoomMessageEvent, Relation, RoomMessageEvent,
+            },
+            member::StrippedRoomMemberEvent
         },
         OwnedRoomId,
     },
+    Client,
     Error, LoopCtrl,
 };
+use tokio::time::{sleep, Duration};
 use std::path::PathBuf;
 use once_cell::sync::Lazy;
 
@@ -24,6 +29,30 @@ static ROOMS_CONFIG_FILE: Lazy<PathBuf> = Lazy::new(|| DATA_DIR.join("rooms_conf
 
 static CONFIG: Lazy<config::Config> = Lazy::new(|| config::Config::load());
 
+// Autojoin rooms the bot is invited to
+async fn on_stripped_state_member(room_member: StrippedRoomMemberEvent, client: Client, room: Room) {
+    if room_member.state_key != client.user_id().unwrap() {
+        return;
+    }
+
+    if let Room::Invited(room) = room {
+        tokio::spawn(async move {
+            let mut delay = 2;
+
+            while let Err(err) = room.accept_invitation().await {
+                eprintln!("Warn: {} ({err:?}), retrying in {delay}s", room.room_id());
+
+                sleep(Duration::from_secs(delay)).await;
+                delay *= 2;
+
+                if delay > 3600 {
+                    eprintln!("Warn: {} ({err:?})", room.room_id());
+                    break;
+                }
+            }
+        });
+    }
+}
 
 async fn on_room_message(event: OriginalSyncRoomMessageEvent, room: Room) -> anyhow::Result<()> {
     if let Room::Joined(room) = room {
@@ -187,6 +216,7 @@ async fn main() -> anyhow::Result<()> {
     };
 
     client.add_event_handler(on_room_message);
+    client.add_event_handler(on_stripped_state_member);
 
     client
         .sync_with_result_callback(sync_settings, |sync_result| async move {