// Stolen from https://github.com/matrix-org/matrix-rust-sdk/blob/5ba90611b43915926a37be83f3de1d4d53bca6bd/examples/autojoin/src/main.rs
use tokio::time::{sleep, Duration};

use matrix_sdk::ruma::events::room::member::StrippedRoomMemberEvent;
use matrix_sdk::{Client, Room};

pub async fn on_stripped_state_member(
    room_member: StrippedRoomMemberEvent,
    client: Client,
    room: Room,
) {
    if room_member.state_key != client.user_id().unwrap() {
        return;
    }

    tokio::spawn(async move {
        let mut delay = 2;

        while let Err(err) = room.join().await {
            // retry autojoin due to synapse sending invites, before the
            // invited user can join for more information see
            // https://github.com/matrix-org/synapse/issues/4345
            eprintln!(
                "Failed to join room {} ({err:?}), retrying in {delay}s",
                room.room_id()
            );

            sleep(Duration::from_secs(delay)).await;
            delay *= 2;

            if delay > 3600 {
                eprintln!("Can't join room {} ({err:?})", room.room_id());
                break;
            }
        }
        println!("Successfully joined room {}", room.room_id());
    });
}