use futures::{sink, Async, Future, Poll, Sink, Stream};
use xmpp_parsers::{Jid, Element};
use std::mem::replace;
use tokio_codec::Framed;
use tokio_io::{AsyncRead, AsyncWrite};

use crate::xmpp_codec::{Packet, XMPPCodec};
use crate::xmpp_stream::XMPPStream;
use crate::{Error, ProtocolError};

const NS_XMPP_STREAM: &str = "http://etherx.jabber.org/streams";

pub struct StreamStart<S: AsyncWrite> {
    state: StreamStartState<S>,
    jid: Jid,
    ns: String,
}

enum StreamStartState<S: AsyncWrite> {
    SendStart(sink::Send<Framed<S, XMPPCodec>>),
    RecvStart(Framed<S, XMPPCodec>),
    RecvFeatures(Framed<S, XMPPCodec>, String),
    Invalid,
}

impl<S: AsyncWrite> StreamStart<S> {
    pub fn from_stream(stream: Framed<S, XMPPCodec>, jid: Jid, ns: String) -> Self {
        let attrs = [
            ("to".to_owned(), jid.domain.clone()),
            ("version".to_owned(), "1.0".to_owned()),
            ("xmlns".to_owned(), ns.clone()),
            ("xmlns:stream".to_owned(), NS_XMPP_STREAM.to_owned()),
        ]
        .iter()
        .cloned()
        .collect();
        let send = stream.send(Packet::StreamStart(attrs));

        StreamStart {
            state: StreamStartState::SendStart(send),
            jid,
            ns,
        }
    }
}

impl<S: AsyncRead + AsyncWrite> Future for StreamStart<S> {
    type Item = XMPPStream<S>;
    type Error = Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        let old_state = replace(&mut self.state, StreamStartState::Invalid);
        let mut retry = false;

        let (new_state, result) = match old_state {
            StreamStartState::SendStart(mut send) => match send.poll() {
                Ok(Async::Ready(stream)) => {
                    retry = true;
                    (StreamStartState::RecvStart(stream), Ok(Async::NotReady))
                }
                Ok(Async::NotReady) => (StreamStartState::SendStart(send), Ok(Async::NotReady)),
                Err(e) => (StreamStartState::Invalid, Err(e.into())),
            },
            StreamStartState::RecvStart(mut stream) => match stream.poll() {
                Ok(Async::Ready(Some(Packet::StreamStart(stream_attrs)))) => {
                    let stream_ns = stream_attrs
                        .get("xmlns")
                        .ok_or(ProtocolError::NoStreamNamespace)?
                        .clone();
                    if self.ns == "jabber:client" {
                        retry = true;
                        // TODO: skip RecvFeatures for version < 1.0
                        (
                            StreamStartState::RecvFeatures(stream, stream_ns),
                            Ok(Async::NotReady),
                        )
                    } else {
                        let id = stream_attrs
                            .get("id")
                            .ok_or(ProtocolError::NoStreamId)?
                            .clone();
                        // FIXME: huge hack, shouldn’t be an element!
                        let stream = XMPPStream::new(
                            self.jid.clone(),
                            stream,
                            self.ns.clone(),
                            Element::builder(id).build(),
                        );
                        (StreamStartState::Invalid, Ok(Async::Ready(stream)))
                    }
                }
                Ok(Async::Ready(_)) => return Err(ProtocolError::InvalidToken.into()),
                Ok(Async::NotReady) => (StreamStartState::RecvStart(stream), Ok(Async::NotReady)),
                Err(e) => return Err(ProtocolError::from(e).into()),
            },
            StreamStartState::RecvFeatures(mut stream, stream_ns) => match stream.poll() {
                Ok(Async::Ready(Some(Packet::Stanza(stanza)))) => {
                    if stanza.is("features", NS_XMPP_STREAM) {
                        let stream =
                            XMPPStream::new(self.jid.clone(), stream, self.ns.clone(), stanza);
                        (StreamStartState::Invalid, Ok(Async::Ready(stream)))
                    } else {
                        (
                            StreamStartState::RecvFeatures(stream, stream_ns),
                            Ok(Async::NotReady),
                        )
                    }
                }
                Ok(Async::Ready(_)) | Ok(Async::NotReady) => (
                    StreamStartState::RecvFeatures(stream, stream_ns),
                    Ok(Async::NotReady),
                ),
                Err(e) => return Err(ProtocolError::from(e).into()),
            },
            StreamStartState::Invalid => unreachable!(),
        };

        self.state = new_state;
        if retry {
            self.poll()
        } else {
            result
        }
    }
}