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_tungstenite::tungstenite::Message;
use std::sync::Arc;
use tracing::{debug, error, 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>> {
        if !hyper_tungstenite::is_upgrade_request(&req) {
            return Ok(Response::builder()
                .status(StatusCode::BAD_REQUEST)
                .body(hyper::Body::from("Expected WebSocket upgrade"))?);
        }

        let (response, ws_fut) = hyper_tungstenite::upgrade(req, None)
            .map_err(|e| anyhow::anyhow!("WebSocket upgrade failed: {}", e))?;

        // Spawn a task to hold the connection open and avoid EPIPE when the UI connects
        tokio::spawn(async move {
            let mut ws_stream = match ws_fut.await {
                Ok(s) => s,
                Err(e) => {
                    error!("WebSocket handshake failed: {}", e);
                    return;
                }
            };
            info!("WebSocket /ws/db connected");
            // Keep connection open; UI may send/receive JSON patches. For now just accept and ignore.
            while let Some(msg) = ws_stream.next().await {
                match msg {
                    Ok(Message::Close(_)) => break,
                    Ok(Message::Ping(data)) => {
                        let _ = ws_stream.send(Message::Pong(data)).await;
                    }
                    Ok(_) => {}
                    Err(e) => {
                        debug!("WebSocket stream error: {}", e);
                        break;
                    }
                }
            }
        });

        Ok(response)
    }
}