use crate::api::rpc::RpcHandler;
use crate::config::Config;
use anyhow::Result;
use futures_util::{SinkExt, StreamExt};
use hyper::{Method, Request, Response, StatusCode};
use hyper_ws_listener::WsStream;
use std::sync::Arc;
use tokio_tungstenite::tungstenite::Message;
use tracing::{debug, info};

pub struct ApiHandler {
    _config: Config,
    rpc_handler: Arc<RpcHandler>,
}

impl ApiHandler {
    pub async fn new(config: Config) -> Result<Self> {
        let rpc_handler = Arc::new(RpcHandler::new(config.clone()).await?);

        Ok(Self {
            _config: config,
            rpc_handler,
        })
    }

    pub async fn handle_request(
        &self,
        req: Request<hyper::Body>,
    ) -> Result<Response<hyper::Body>> {
        let path = req.uri().path().to_string();
        let method = req.method().clone();

        // WebSocket upgrade must be handled before consuming the body
        if method == Method::GET && path == "/ws/db" {
            return Self::handle_websocket(req).await;
        }

        // Convert body to bytes for non-WS routes
        let (parts, body) = req.into_parts();
        let body_bytes = hyper::body::to_bytes(body).await
            .map_err(|e| anyhow::anyhow!("Failed to read body: {}", e))?;
        let req_with_bytes = Request::from_parts(parts, hyper::Body::from(body_bytes));

        debug!("{} {}", method, path);

        match (method, path.as_str()) {
            (Method::POST, "/rpc/v1") => self.rpc_handler.handle(req_with_bytes).await,
            (Method::GET, "/health") => Ok(Response::builder()
                .status(StatusCode::OK)
                .body(hyper::Body::from("OK"))
                .unwrap()),
            _ => Ok(Response::builder()
                .status(StatusCode::NOT_FOUND)
                .body(hyper::Body::from("Not Found"))
                .unwrap()),
        }
    }

    async fn handle_websocket(
        req: Request<hyper::Body>,
    ) -> Result<Response<hyper::Body>> {
        let (response, ws_fut_opt) = hyper_ws_listener::create_ws(req)
            .map_err(|e| anyhow::anyhow!("WebSocket upgrade failed: {}", e))?;

        // Spawn a task to hold the connection open if upgrade future exists
        if let Some(ws_fut) = ws_fut_opt {
            tokio::spawn(async move {
                let ws_stream: WsStream = match ws_fut.await {
                    Ok(Ok(s)) => s,
                    Ok(Err(e)) => {
                        debug!("WebSocket handshake failed (hyper): {}", e);
                        return;
                    }
                    Err(e) => {
                        debug!("WebSocket task join failed: {}", e);
                        return;
                    }
                };
                info!("WebSocket /ws/db connected");
                
                let (mut tx, mut rx) = ws_stream.split();
                
                // Send periodic pings to keep connection alive
                let ping_interval = tokio::time::interval(tokio::time::Duration::from_secs(30));
                tokio::pin!(ping_interval);
                
                // Keep connection open; UI may send/receive JSON patches. For now just accept and ignore.
                loop {
                    tokio::select! {
                        _ = ping_interval.tick() => {
                            if tx.send(Message::Ping(vec![])).await.is_err() {
                                debug!("Failed to send ping, connection likely closed");
                                break;
                            }
                        }
                        msg = rx.next() => {
                            match msg {
                                Some(Ok(Message::Close(_))) => break,
                                Some(Ok(Message::Pong(_))) => {
                                    debug!("Received pong");
                                }
                                Some(Ok(Message::Ping(data))) => {
                                    let _ = tx.send(Message::Pong(data)).await;
                                }
                                Some(Ok(_)) => {}
                                Some(Err(e)) => {
                                    debug!("WebSocket stream error: {}", e);
                                    break;
                                }
                                None => break,
                            }
                        }
                    }
                }
                info!("WebSocket /ws/db disconnected");
            });
        }

        Ok(response)
    }
}