use std::sync::Arc;

use axum::{
    extract::{State, WebSocketUpgrade, ws::{Message, WebSocket}},
    response::Response,
    routing::get,
    Router,
};
use futures::{SinkExt, StreamExt};
use sqlx::sqlite::SqlitePool;
use tokio::sync::broadcast;

use crate::agent::WsMessage;
use crate::worker::{WorkerInfo, WorkerManager, WorkerToServer};

pub struct WsWorkerState {
    pub mgr: Arc<WorkerManager>,
    pub pool: SqlitePool,
    pub broadcast_fn: Arc<dyn Fn(&str) -> broadcast::Sender<WsMessage> + Send + Sync>,
}

pub fn router(mgr: Arc<WorkerManager>, pool: SqlitePool, broadcast_fn: Arc<dyn Fn(&str) -> broadcast::Sender<WsMessage> + Send + Sync>) -> Router {
    let state = Arc::new(WsWorkerState { mgr, pool, broadcast_fn });
    Router::new()
        .route("/", get(ws_handler))
        .with_state(state)
}

async fn ws_handler(
    ws: WebSocketUpgrade,
    State(state): State<Arc<WsWorkerState>>,
) -> Response {
    ws.on_upgrade(move |socket| handle_worker_socket(socket, state))
}

async fn handle_worker_socket(socket: WebSocket, state: Arc<WsWorkerState>) {
    let (mut sender, mut receiver) = socket.split();

    // First message must be registration
    let (name, mut msg_rx) = loop {
        match receiver.next().await {
            Some(Ok(Message::Text(text))) => {
                match serde_json::from_str::<serde_json::Value>(&text) {
                    Ok(v) if v["type"] == "register" => {
                        let info: WorkerInfo = match serde_json::from_value(v["info"].clone()) {
                            Ok(i) => i,
                            Err(_) => {
                                let _ = sender.send(Message::Text(
                                    r#"{"type":"error","message":"Invalid worker info"}"#.into(),
                                )).await;
                                return;
                            }
                        };
                        let name = info.name.clone();
                        let rx = state.mgr.register(name.clone(), info).await;
                        let ack = serde_json::json!({ "type": "registered", "name": &name });
                        let _ = sender.send(Message::Text(ack.to_string().into())).await;
                        break (name, rx);
                    }
                    _ => {
                        let _ = sender.send(Message::Text(
                            r#"{"type":"error","message":"First message must be register"}"#.into(),
                        )).await;
                        return;
                    }
                }
            }
            Some(Ok(Message::Close(_))) | None => return,
            _ => continue,
        }
    };

    let name_clone = name.clone();
    let mgr_for_cleanup = state.mgr.clone();

    // Task: send ServerToWorker messages from msg_rx to the WebSocket
    let send_task = tokio::spawn(async move {
        while let Some(msg) = msg_rx.recv().await {
            if let Ok(json) = serde_json::to_string(&msg) {
                if sender.send(Message::Text(json.into())).await.is_err() {
                    break;
                }
            }
        }
    });

    // Task: receive WorkerToServer messages from the WebSocket → process
    let state_clone = state.clone();
    let recv_task = tokio::spawn(async move {
        while let Some(Ok(msg)) = receiver.next().await {
            match msg {
                Message::Text(text) => {
                    if let Ok(worker_msg) = serde_json::from_str::<WorkerToServer>(&text) {
                        handle_worker_message(&state_clone, worker_msg).await;
                    }
                }
                Message::Close(_) => break,
                _ => {}
            }
        }
    });

    tokio::select! {
        _ = send_task => {},
        _ = recv_task => {},
    }

    mgr_for_cleanup.unregister(&name_clone).await;
}

async fn handle_worker_message(state: &WsWorkerState, msg: WorkerToServer) {
    match msg {
        WorkerToServer::Register { .. } => {
            // Already handled during initial handshake
        }
        WorkerToServer::Update { workflow_id, update } => {
            // Get project_id for broadcasting (look up from DB)
            let project_id: Option<String> = sqlx::query_scalar(
                "SELECT project_id FROM workflows WHERE id = ?"
            )
            .bind(&workflow_id)
            .fetch_optional(&state.pool)
            .await
            .ok()
            .flatten();

            let broadcast_tx = if let Some(ref pid) = project_id {
                Some((state.broadcast_fn)(pid))
            } else {
                None
            };

            // Check if this is a workflow completion
            if let crate::sink::AgentUpdate::WorkflowComplete { ref workflow_id, .. } = update {
                state.mgr.complete_workflow(workflow_id).await;
            }

            // Process the update: write to DB + broadcast
            crate::sink::handle_single_update(&update, &state.pool, broadcast_tx.as_ref()).await;
        }
    }
}