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use super::common::{BaseHandler_, LoadBalance_};
use crate::config::{LoadBalancer, RouteAddr};
use gateway_common::{
    error::{BoxError, HttpError},
    FusenFuture,
};
use futures::{SinkExt, StreamExt};
use http::{
    header::{CONNECTION, UPGRADE},
    Request, Response, StatusCode, Uri,
};
use http_body_util::{combinators::BoxBody, BodyExt};
use hyper::upgrade::OnUpgrade;
use hyper_util::{
    client::legacy::{connect::HttpConnector, Client},
    rt::TokioIo,
};
use std::{convert::Infallible, sync::Arc};
use tokio::net::TcpStream;
use tokio_tungstenite::{tungstenite::protocol::Role, WebSocketStream};
use tracing::{debug, error, info};

pub struct DefaultBaseHandler {
    load_balance: Box<dyn LoadBalance_>,
    client: Client<HttpConnector, BoxBody<bytes::Bytes, Infallible>>,
}

impl Default for DefaultBaseHandler {
    fn default() -> Self {
        let mut http_connector = HttpConnector::new();
        http_connector.set_nodelay(true);
        Self {
            load_balance: Box::new(DefaultLoadBalance),
            client: Client::builder(hyper_util::rt::TokioExecutor::new()).build_http(),
        }
    }
}

impl BaseHandler_ for DefaultBaseHandler {
    fn handler_(
        &'static self,
        mut context: crate::support::Context,
        _config: Option<String>,
    ) -> gateway_common::FusenFuture<crate::support::Context> {
        Box::pin(async move {
            info!("DefaultBaseHandler : {:?}", context);
            let path_config = context.get_path_config();
            let route_addr = path_config.load_balancer.clone();
            let addr = self.load_balance.select_(route_addr).await;
            let Some(addr) = addr else {
                info!("route addrs is empty : {:?}", context);
                context.response_error(HttpError::Error("not find route".to_owned()));
                return context;
            };
            if is_upgrade_request(context.get_request().get_org_request()) {
                let (request, mut org_request) = context.into_request();
                let Ok(mut response) = send_http1_request(&addr, request.unwrap()).await else {
                    context.response_error(HttpError::Error("websocket conn is err".to_owned()));
                    return context;
                };
                if is_upgrade_response(&response) {
                    context.insert_response(&mut response).await;
                    tokio::spawn(async move {
                        let request_upgrade = hyper::upgrade::on(&mut org_request);
                        let response_upgrade = hyper::upgrade::on(&mut response);
                        let result = connect(request_upgrade, response_upgrade).await;
                        debug!("websocket close{:?}", result);
                    });
                } else {
                    context.response_error(HttpError::Error(
                        "websocket conn response is err".to_owned(),
                    ));
                }
                context.disruption(crate::support::DisruptionStatus::Flush);
                context
            } else {
                let (request, _org_request) = context.into_request();
                match send_http_request_poll(&self.client, &addr, request.unwrap()).await {
                    Ok(mut response) => {
                        context.insert_response(&mut response).await;
                    }
                    Err(error) => {
                        error!("send_http1_request error : {:?}", addr);
                        context.response_error(HttpError::Error(format!(
                            "http1 conn response is err : {}",
                            error
                        )));
                    }
                }
                context
            }
        })
    }
}

#[derive(Default)]
pub struct DefaultLoadBalance;

impl LoadBalance_ for DefaultLoadBalance {
    fn select_(
        &'static self,
        load_balancer: Arc<LoadBalancer>,
    ) -> FusenFuture<Option<Arc<RouteAddr>>> {
        Box::pin(async move { load_balancer.select() })
    }
}

async fn send_http_request_poll(
    client: &Client<HttpConnector, BoxBody<bytes::Bytes, Infallible>>,
    addr: &RouteAddr,
    mut request: Request<BoxBody<bytes::Bytes, Infallible>>,
) -> Result<Response<BoxBody<bytes::Bytes, hyper::Error>>, BoxError> {
    let org: &Uri = request.uri();
    let new_uri = Uri::builder()
        .scheme(org.scheme_str().unwrap_or("http"))
        .authority(addr.get_addr())
        .path_and_query(org.path_and_query().map_or("", |e| e.as_str()))
        .build()?;
    *request.uri_mut() = new_uri;
    let response = client.request(request).await.map_err(|e| {
        error!("error : {:?}", e);
        BoxError::from(e.to_string())
    })?;
    Ok(response.map(|e| e.boxed()))
}

async fn send_http1_request(
    addr: &RouteAddr,
    request: Request<BoxBody<bytes::Bytes, Infallible>>,
) -> Result<Response<BoxBody<bytes::Bytes, hyper::Error>>, BoxError> {
    let io = get_tcp_stream(addr).await.map_err(BoxError::from)?;
    let (mut sender, conn) = hyper::client::conn::http1::Builder::new()
        .handshake(io)
        .await
        .map_err(|e| BoxError::from(e.to_string()))?;
    tokio::spawn(async move {
        if let Err(err) = conn.with_upgrades().await {
            error!("conn err : {}", err);
        }
    });
    let response = sender.send_request(request).await.map_err(|e| {
        error!("error : {:?}", e);
        BoxError::from(e.to_string())
    })?;
    Ok(response.map(|e| e.boxed()))
}

async fn get_tcp_stream(addr: &RouteAddr) -> Result<TokioIo<TcpStream>, BoxError> {
    let url = addr
        .get_addr()
        .parse::<hyper::Uri>()
        .map_err(|e| BoxError::from(e.to_string()))?;
    let host = url.host().expect("uri has no host");
    let port = url.port_u16().unwrap_or(80);
    let addr = format!("{}:{}", host, port);
    TcpStream::connect(addr)
        .await
        .map(TokioIo::new)
        .map_err(|e| BoxError::from(e.to_string()))
}

fn is_upgrade_request(request: &Request<BoxBody<bytes::Bytes, hyper::Error>>) -> bool {
    request
        .headers()
        .get(UPGRADE)
        .map_or(false, |h| h.as_bytes().eq_ignore_ascii_case(b"websocket"))
        && request
            .headers()
            .get(CONNECTION)
            .map(|h| h.as_bytes())
            .unwrap_or(&[])
            .windows(b"upgrade".len())
            .any(|window| window.eq_ignore_ascii_case(b"upgrade"))
}

fn is_upgrade_response(request: &Response<BoxBody<bytes::Bytes, hyper::Error>>) -> bool {
    request.status() == StatusCode::SWITCHING_PROTOCOLS
}

async fn connect(request_conn: OnUpgrade, response_conn: OnUpgrade) -> Result<(), BoxError> {
    let tokio1 = TokioIo::new(request_conn.await?);
    let tokio2 = TokioIo::new(response_conn.await?);
    let (mut outgoing1, mut incoming1) =
        WebSocketStream::from_raw_socket(tokio1, Role::Server, None)
            .await
            .split();
    let (mut outgoing2, mut incoming2) =
        WebSocketStream::from_raw_socket(tokio2, Role::Client, None)
            .await
            .split();
    tokio::spawn(async move {
        while let Some(msg) = incoming1.next().await {
            let msg = msg.unwrap();
            let _ = outgoing2.send(msg.clone()).await;
        }
    });
    while let Some(msg) = incoming2.next().await {
        let msg = msg.unwrap();
        let _ = outgoing1.send(msg.clone()).await;
    }
    Ok(())
}