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#![feature(test)]

use std::marker::Unpin;

use base64::encode;
use futures::sink::SinkExt;
use http::HeaderValue;
use sha1::Sha1;
use tokio::io::{ AsyncRead, AsyncWrite, AsyncWriteExt };
use tokio::io::{ split, ReadHalf, WriteHalf };
use tokio::stream::StreamExt;
use tokio::sync::mpsc;
use tokio_util::codec::{ FramedRead, FramedWrite };
use tracing::trace;

pub mod error;
pub use error::{ WebsocketError, WebsocketResult };

pub mod codec;
pub use codec::WebsocketCodec;

pub mod opcode;
pub use opcode::Opcode;

pub mod message;
pub use message::Message;

#[derive(Debug)]
pub struct Websocket<S> {
    reader: FramedRead<ReadHalf<S>, WebsocketCodec>,
    tx: mpsc::Sender<Message>,
}

impl<S: 'static> Websocket<S>
where
    S: AsyncRead + AsyncWrite + Unpin + Send,
{
    pub async fn new(key: &HeaderValue, stream: S) -> WebsocketResult<Self> {
        let (reader, mut writer) = split(stream);
        Self::_send_handshake(key, &mut writer).await;

        let reader = FramedRead::new(reader, WebsocketCodec::default());
        let mut writer = FramedWrite::new(writer, WebsocketCodec::default());
        let (tx, mut rx) = mpsc::channel::<Message>(100);

        tokio::spawn(async move {
            while let Some(message) = rx.recv().await {
                if message.opcode == Opcode::Close { break }

                writer.send(message).await.unwrap();
            }

            trace!("Client disconnected");
        });

        return Ok(Self {
            reader,
            tx,
        })
    }

    async fn _send_handshake(key: &HeaderValue, writer: &mut WriteHalf<S>) {
        // TODO keep track of clients that already initiate a handshake
        let guid = [key.as_bytes(), b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"].concat();
        let sha1 = Sha1::from(guid).digest().bytes();
        let key = format!("Sec-WebSocket-Accept: {}", encode(sha1));

        let handshake = &[
            "HTTP/1.1 101 Switching Protocols",
            "Upgrade: websocket",
            "Connection: Upgrade",
            key.as_str(),
            "\r\n",
        ];

        let handshake = handshake.join("\r\n");

        writer.write_all(handshake.as_bytes()).await.unwrap()
    }

    pub async fn next(&mut self) -> Option<Message> {
        while let Some(Ok(msg)) = self.reader.next().await {
            if msg.opcode == Opcode::Text {
                return Some(msg)
            }

            if msg.opcode == Opcode::Close {
                self.tx.send(Message::close()).await.unwrap();
                return None
            }

            else if msg.opcode == Opcode::Ping {
                self.tx.send(Message::pong()).await.unwrap();
            }
        }

        None
    }

    pub async fn send_text<T: AsRef<str>>(&mut self, t: T) -> WebsocketResult<()> {
        Ok(self.tx.send(Message::text(t.as_ref())).await?)
    }
}