use futures::{Async, Future, Poll};
use h2;
use http;
use hyper;
use tokio_connect::Connect;
use tokio_core::reactor::Handle;
use tower::{Service, NewService};
use tower_h2;

use bind;
use super::glue::{BodyStream, HttpBody, HyperConnect};

/// A `NewService` that can speak either HTTP/1 or HTTP/2.
pub struct Client<C, B>
where
    B: tower_h2::Body,
{
    inner: ClientInner<C, B>,
}

enum ClientInner<C, B>
where
    B: tower_h2::Body,
{
    Http1(hyper::Client<HyperConnect<C>, BodyStream<B>>),
    Http2(tower_h2::client::Client<C, Handle, B>),
}

/// A `Future` returned from `Client::new_service()`.
pub struct ClientNewServiceFuture<C, B>
where
    B: tower_h2::Body + 'static,
    C: Connect + 'static,
{
    inner: ClientNewServiceFutureInner<C, B>,
}

enum ClientNewServiceFutureInner<C, B>
where
    B: tower_h2::Body + 'static,
    C: Connect + 'static,
{
    Http1(Option<hyper::Client<HyperConnect<C>, BodyStream<B>>>),
    Http2(tower_h2::client::ConnectFuture<C, Handle, B>),
}

/// The `Service` yielded by `Client::new_service()`.
pub struct ClientService<C, B>
where
    B: tower_h2::Body,
{
    inner: ClientServiceInner<C, B>,
}

enum ClientServiceInner<C, B>
where
    B: tower_h2::Body,
{
    Http1(hyper::Client<HyperConnect<C>, BodyStream<B>>),
    Http2(tower_h2::client::Service<C, Handle, B>),
}

impl<C, B> Client<C, B>
where
    C: Connect + Clone + 'static,
    C::Future: 'static,
    B: tower_h2::Body + 'static,
{
    /// Create a new `Client`, bound to a specific protocol (HTTP/1 or HTTP/2).
    pub fn new(protocol: bind::Protocol, connect: C, executor: Handle) -> Self {
        match protocol {
            bind::Protocol::Http1 => {
                let h1 = hyper::Client::configure()
                    .connector(HyperConnect::new(connect))
                    .body()
                    .build(&executor);
                Client {
                    inner: ClientInner::Http1(h1),
                }
            },
            bind::Protocol::Http2 => {
                let mut h2_builder = h2::client::Builder::default();
                // h2 currently doesn't handle PUSH_PROMISE that well, so we just
                // disable it for now.
                h2_builder.enable_push(false);
                let h2 = tower_h2::client::Client::new(connect, h2_builder, executor);

                Client {
                    inner: ClientInner::Http2(h2),
                }
            }
        }
    }
}

impl<C, B> NewService for Client<C, B>
where
    C: Connect + Clone + 'static,
    C::Future: 'static,
    B: tower_h2::Body + 'static,
{
    type Request = http::Request<B>;
    type Response = http::Response<HttpBody>;
    type Error = tower_h2::client::Error;
    type InitError = tower_h2::client::ConnectError<C::Error>;
    type Service = ClientService<C, B>;
    type Future = ClientNewServiceFuture<C, B>;

    fn new_service(&self) -> Self::Future {
        let inner = match self.inner {
            ClientInner::Http1(ref h1) => {
                ClientNewServiceFutureInner::Http1(Some(h1.clone()))
            },
            ClientInner::Http2(ref h2) => {
                ClientNewServiceFutureInner::Http2(h2.new_service())                        },
        };
        ClientNewServiceFuture {
            inner,
        }
    }
}

impl<C, B> Future for ClientNewServiceFuture<C, B>
where
    C: Connect + 'static,
    B: tower_h2::Body + 'static,
{
    type Item = ClientService<C, B>;
    type Error = tower_h2::client::ConnectError<C::Error>;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        let inner = match self.inner {
            ClientNewServiceFutureInner::Http1(ref mut h1) => {
                ClientServiceInner::Http1(h1.take().expect("poll more than once"))
            },
            ClientNewServiceFutureInner::Http2(ref mut h2) => {
                let s = try_ready!(h2.poll());
                ClientServiceInner::Http2(s)
            },
        };
        Ok(Async::Ready(ClientService {
            inner,
        }))
    }
}

impl<C, B> Service for ClientService<C, B>
where
    C: Connect + 'static,
    C::Future: 'static,
    B: tower_h2::Body + 'static,
{
    type Request = http::Request<B>;
    type Response = http::Response<HttpBody>;
    type Error = tower_h2::client::Error;
    type Future = ClientServiceFuture;

    fn poll_ready(&mut self) -> Poll<(), Self::Error> {
        match self.inner {
            ClientServiceInner::Http1(_) => Ok(Async::Ready(())),
            ClientServiceInner::Http2(ref mut h2) => h2.poll_ready(),
        }
    }

    fn call(&mut self, req: Self::Request) -> Self::Future {
        match self.inner {
            ClientServiceInner::Http1(ref h1) => {
                let is_body_empty = req.body().is_end_stream();
                let mut req = hyper::Request::from(req.map(BodyStream));
                if is_body_empty {
                    req.headers_mut().set(hyper::header::ContentLength(0));
                }
                ClientServiceFuture::Http1(h1.request(req))
            },
            ClientServiceInner::Http2(ref mut h2) => {
                ClientServiceFuture::Http2(h2.call(req))
            },
        }
    }
}

pub enum ClientServiceFuture {
    Http1(hyper::client::FutureResponse),
    Http2(tower_h2::client::ResponseFuture),
}

impl Future for ClientServiceFuture {
    type Item = http::Response<HttpBody>;
    type Error = tower_h2::client::Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        match *self {
            ClientServiceFuture::Http1(ref mut f) => {
                match f.poll() {
                    Ok(Async::Ready(res)) => {
                        let res = http::Response::from(res);
                        let res = res.map(HttpBody::Http1);
                        Ok(Async::Ready(res))
                    },
                    Ok(Async::NotReady) => Ok(Async::NotReady),
                    Err(e) => {
                        debug!("http/1 client error: {}", e);
                        Err(h2::Reason::INTERNAL_ERROR.into())
                    }
                }
            },
            ClientServiceFuture::Http2(ref mut f) => {
                let res = try_ready!(f.poll());
                let res = res.map(HttpBody::Http2);
                Ok(Async::Ready(res))
            }
        }
    }
}