Baby's first Rust Matrix Bot

async fn main() -> anyhow::Result<()> {
    tracing_subscriber::fmt::init();

    let (homeserver_url, username, password) =
        match (env::args().nth(1), env::args().nth(2), env::args().nth(3)) {
            (Some(a), Some(b), Some(c)) => (a, b, c),
            _ => {
                eprintln!(
                    "Usage: {} <homeserver_url> <username> <password>",
                    env::args().next().unwrap()
                );
                exit(1)
            }
        };

    login_and_sync(homeserver_url, &username, &password).await?;
    Ok(())
}

async fn login_and_sync(
    homeserver_url: String,
    username: &str,
    password: &str,
) -> anyhow::Result<()> {
    // first, we set up the client. We use the convenient client builder to set our
    // custom homeserver URL on it
    #[allow(unused_mut)]
    let mut client_builder = Client::builder().homeserver_url(homeserver_url);

    // Matrix-SDK has support for pluggable, configurable state and crypto-store
    // support we use the default sled-store (enabled by default on native
    // architectures), to configure a local cache and store for our crypto keys
    let home = dirs::data_dir().expect("no home directory found").join("getting_started");
    client_builder = client_builder.sled_store(home, None)?;

    // alright, let's make that into a client
    let client = client_builder.build().await?;

    // then let's log that client in
    client
        .login_username(username, password)
        .initial_device_display_name("getting started bot")
        .send()
        .await?;

    // it worked!
    println!("logged in as {username}");

    client.add_event_handler(on_stripped_state_member).await;

    client.sync_once(SyncSettings::default()).await.unwrap();

    client.add_event_handler(on_room_message).await;

    let settings = SyncSettings::default().token(client.sync_token().await.unwrap());
    client.sync(settings).await; // this essentially loops until we kill the bot

    Ok(())
}

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 {
        println!("Autojoining room {}", room.room_id());
        let mut delay = 2;

        while let Err(err) = room.accept_invitation().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());
    }
}

async fn on_room_message(event: OriginalSyncRoomMessageEvent, room: Room) {
    if let Room::Joined(room) = room {
        let msg_body = match event.content.msgtype {
            MessageType::Text(TextMessageEventContent { body, .. }) => body,
            _ => return,
        };

        if msg_body.contains("!party") {
            let content = RoomMessageEventContent::text_plain("🎉🎊🥳 let's PARTY!! 🥳🎊🎉");

            println!("sending");
            room.send(content, None).await.unwrap();

            println!("message sent");
        }
    }
}