use http_body_util::Empty;
use hyper::body::Incoming;
use hyper::header::{
    CONNECTION, SEC_WEBSOCKET_ACCEPT, SEC_WEBSOCKET_KEY, SEC_WEBSOCKET_VERSION, UPGRADE,
};
use hyper::http::HeaderValue;
use hyper::upgrade::Upgraded;
use hyper::{body::Bytes, Request, Response};
use hyper::{StatusCode, Version};
use std::convert::Infallible;

use tokio_tungstenite::tungstenite::handshake::derive_accept_key;
use tokio_tungstenite::tungstenite::protocol::Role;
use tokio_tungstenite::tungstenite::Message;
use tokio_tungstenite::WebSocketStream;

use futures_util::sink::SinkExt;
use futures_util::stream::StreamExt;

use crate::chat::Chats;

async fn handle_connection(mut ws_stream: WebSocketStream<Upgraded>, chats: Chats) {
    tracing::info!("WebSocket connection established");

    let (sub_id, mut sub) = chats.new_sub();
    tracing::info!("New conn id: {sub_id}");

    let _ = chats.broadcast(format!("{sub_id} joined").as_str()).await;

    ws_stream
        .send(Message::Text("Started a connection!".into()))
        .await
        .unwrap();

    tracing::info!("Started stream for {sub_id}");
    loop {
        tokio::select! {
            biased;
            msg = ws_stream.next() => {
                match msg {
                    Some(msg) => {
                        let msg = msg.unwrap();
                        let txt = msg.to_text().unwrap().to_string();
                        tracing::info!("Received a message: {txt}, sub_id={sub_id}");
                        match chats.broadcast(format!("{sub_id}: {txt}").as_str()).await {
                            Ok(_) => {},
                            Err(err) => {
                                tracing::error!("Failed to broadcast a message from sub_id={sub_id}: {err}");
                            },
                        }
                    },
                    None => {
                        tracing::info!("Client {sub_id} closed the socket, stopping..");
                        break;
                    },
                }
            },
            msg = sub.recv() => {
                match msg {
                    Some(msg) => {
                        match ws_stream.send(Message::Text(msg)).await {
                            Ok(_) => {},
                            Err(err) => {
                                tracing::warn!("Failed to send msg, sub_id={sub_id}: {err}");
                                break;
                            },
                        }
                    },
                    None => {
                        break;
                    }
                }
            }
        }
    }
    tracing::info!("Ended stream for {sub_id}");
    chats.remove_sub(sub_id);
    let _ = chats.broadcast(format!("{sub_id} left").as_str()).await;
}

pub async fn handle_request(
    mut req: Request<Incoming>,
    chats: Chats,
) -> std::result::Result<Response<Empty<Bytes>>, Infallible> {
    tracing::info!("Received a new WS request");
    let upgrade = HeaderValue::from_static("Upgrade");
    let websocket = HeaderValue::from_static("websocket");
    let headers = req.headers();
    let key = headers.get(SEC_WEBSOCKET_KEY);
    let derived = key.map(|k| derive_accept_key(k.as_bytes()));
    if req.version() < Version::HTTP_11
        || !headers
            .get(CONNECTION)
            .and_then(|h| h.to_str().ok())
            .map(|h| {
                h.split(|c| c == ' ' || c == ',')
                    .any(|p| p.eq_ignore_ascii_case(upgrade.to_str().unwrap()))
            })
            .unwrap_or(false)
        || !headers
            .get(UPGRADE)
            .and_then(|h| h.to_str().ok())
            .map(|h| h.eq_ignore_ascii_case("websocket"))
            .unwrap_or(false)
        || !headers
            .get(SEC_WEBSOCKET_VERSION)
            .map(|h| h == "13")
            .unwrap_or(false)
        || key.is_none()
    {
        tracing::info!("Malformed request");
        let mut resp = Response::new(Empty::new());
        *resp.status_mut() = StatusCode::BAD_REQUEST;
        return Ok(resp);
    }
    let ver = req.version();

    let chats = chats.clone();
    tokio::task::spawn(async move {
        match hyper::upgrade::on(&mut req).await {
            Ok(upgraded) => {
                handle_connection(
                    WebSocketStream::from_raw_socket(upgraded, Role::Server, None).await,
                    chats,
                )
                .await;
            }
            Err(err) => tracing::error!("upgrade error: {err}"),
        }
    });
    let mut res = Response::new(Empty::new());
    *res.status_mut() = StatusCode::SWITCHING_PROTOCOLS;
    *res.version_mut() = ver;
    res.headers_mut().append(CONNECTION, upgrade);
    res.headers_mut().append(UPGRADE, websocket);
    res.headers_mut()
        .append(SEC_WEBSOCKET_ACCEPT, derived.unwrap().parse().unwrap());
    Ok(res)
}