#![cfg(feature = "servo-embed")]

use std::sync::mpsc;

pub enum AppdCmd {
    Launch { session_id: u64, app_id: String },
    Stop { session_id: u64 },
}

pub fn spawn_appd_listener(
    ws_port: u16,
    tx: mpsc::SyncSender<AppdCmd>,
    wake: Box<dyn Fn() + Send>,
) {
    std::thread::Builder::new()
        .name("appd-ws".into())
        .spawn(move || run_listener(ws_port, tx, wake))
        .ok();
}

fn run_listener(ws_port: u16, tx: mpsc::SyncSender<AppdCmd>, wake: Box<dyn Fn() + Send>) {
    let url = format!("ws://127.0.0.1:{ws_port}");
    let mut backoff = std::time::Duration::from_millis(500);
    const MAX_BACKOFF: std::time::Duration = std::time::Duration::from_secs(16);

    loop {
        match tungstenite::connect(&url) {
            Err(e) => {
                tracing::debug!("appd WebSocket connect failed: {e}; retry in {backoff:?}");
                std::thread::sleep(backoff);
                backoff = (backoff * 2).min(MAX_BACKOFF);
                continue;
            }
            Ok((mut ws, _)) => {
                backoff = std::time::Duration::from_millis(500);
                let _ = ws.send(tungstenite::Message::Text(
                    r#"{"type":"QUERY_RUNNING"}"#.into(),
                ));
                loop {
                    match ws.read() {
                        Ok(tungstenite::Message::Text(text)) => {
                            process_message(&text, &tx, &*wake);
                        }
                        Ok(_) => {}
                        Err(e) => {
                            tracing::debug!("appd WebSocket read error: {e}; reconnecting");
                            break;
                        }
                    }
                }
            }
        }
        std::thread::sleep(backoff);
        backoff = (backoff * 2).min(MAX_BACKOFF);
    }
}

fn process_message(text: &str, tx: &mpsc::SyncSender<AppdCmd>, wake: &dyn Fn()) {
    let Ok(v) = serde_json::from_str::<serde_json::Value>(text) else {
        return;
    };

    match v["type"].as_str() {
        Some("LAUNCH_ACK") => {
            let Some(session_id) = v["session_id"].as_u64() else {
                return;
            };
            let Some(app_id) = v["app_id"].as_str().map(str::to_string) else {
                return;
            };
            if tx.try_send(AppdCmd::Launch { session_id, app_id }).is_ok() {
                wake();
            }
        }
        Some("RUNNING_APPS") => {
            let Some(sessions) = v["sessions"].as_array() else {
                return;
            };
            for s in sessions {
                let Some(session_id) = s["session_id"].as_u64() else {
                    continue;
                };
                let Some(app_id) = s["app_id"].as_str().map(str::to_string) else {
                    continue;
                };
                let _ = tx.try_send(AppdCmd::Launch { session_id, app_id });
            }
            wake();
        }
        Some("APP_STATE") if v["state"].as_str() == Some("stopped") => {
            let Some(session_id) = v["session_id"].as_u64() else {
                return;
            };
            if tx.try_send(AppdCmd::Stop { session_id }).is_ok() {
                wake();
            }
        }
        _ => {}
    }
}