// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the MIT License, <LICENSE or http://opensource.org/licenses/MIT>.
// This file may not be copied, modified, or distributed except according to those terms.

use {Reactor, WireError};
use bincode;
#[cfg(feature = "tls")]
use self::tls::*;
use tokio_core::reactor;

type WireResponse<Resp, E> = Result<Result<Resp, WireError<E>>, bincode::Error>;

/// TLS-specific functionality
#[cfg(feature = "tls")]
pub mod tls {
    use native_tls::{Error, TlsConnector};

    /// TLS context for client
    pub struct Context {
        /// Domain to connect to
        pub domain: String,
        /// TLS connector
        pub tls_connector: TlsConnector,
    }

    impl Context {
        /// Try to construct a new `Context`.
        ///
        /// The provided domain will be used for both
        /// [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication) and certificate hostname
        /// validation.
        pub fn new<S: Into<String>>(domain: S) -> Result<Self, Error> {
            Ok(Context {
                domain: domain.into(),
                tls_connector: TlsConnector::builder()?.build()?,
            })
        }

        /// Construct a new `Context` using the provided domain and `TlsConnector`
        ///
        /// The domain will be used for both
        /// [SNI](https://en.wikipedia.org/wiki/Server_Name_Indication) and certificate hostname
        /// validation.
        pub fn from_connector<S: Into<String>>(domain: S, tls_connector: TlsConnector) -> Self {
            Context {
                domain: domain.into(),
                tls_connector: tls_connector,
            }
        }
    }
}

/// Additional options to configure how the client connects and operates.
#[derive(Default)]
pub struct Options {
    reactor: Option<Reactor>,
    #[cfg(feature = "tls")]
    tls_ctx: Option<Context>,
}

impl Options {
    /// Connect using the given reactor handle.
    pub fn handle(mut self, handle: reactor::Handle) -> Self {
        self.reactor = Some(Reactor::Handle(handle));
        self
    }

    /// Connect using the given reactor remote.
    pub fn remote(mut self, remote: reactor::Remote) -> Self {
        self.reactor = Some(Reactor::Remote(remote));
        self
    }

    /// Connect using the given `Context`
    #[cfg(feature = "tls")]
    pub fn tls(mut self, tls_ctx: Context) -> Self {
        self.tls_ctx = Some(tls_ctx);
        self
    }
}

/// Exposes a trait for connecting asynchronously to servers.
pub mod future {
    use {REMOTE, Reactor, WireError};
    use futures::{self, Future, future};
    use protocol::Proto;
    use serde::{Deserialize, Serialize};
    use std::fmt;
    use std::io;
    use std::net::SocketAddr;
    use stream_type::StreamType;
    use super::{Options, WireResponse};
    use tokio_core::net::TcpStream;
    use tokio_core::reactor;
    use tokio_proto::BindClient as ProtoBindClient;
    use tokio_proto::multiplex::Multiplex;
    use tokio_service::Service;
    #[cfg(feature = "tls")]
    use tokio_tls::TlsConnectorExt;
    #[cfg(feature = "tls")]
    use errors::native_to_io;

    /// A client that impls `tokio_service::Service` that writes and reads bytes.
    #[doc(hidden)]
    pub struct Client<Req, Resp, E>
        where Req: Serialize + 'static,
              Resp: Deserialize + 'static,
              E: Deserialize + 'static
    {
        inner: BindClient<Req, Resp, E>,
    }

    impl<Req, Resp, E> Clone for Client<Req, Resp, E>
        where Req: Serialize + 'static,
              Resp: Deserialize + 'static,
              E: Deserialize + 'static
    {
        fn clone(&self) -> Self {
            Client { inner: self.inner.clone() }
        }
    }

    impl<Req, Resp, E> Service for Client<Req, Resp, E>
        where Req: Serialize + Sync + Send + 'static,
              Resp: Deserialize + Sync + Send + 'static,
              E: Deserialize + Sync + Send + 'static
    {
        type Request = Req;
        type Response = Resp;
        type Error =  ::Error<E>;
        type Future = ResponseFuture<Req, Resp, E>;

        fn call(&self, request: Self::Request) -> Self::Future {
            fn identity<T>(t: T) -> T { t }
            self.inner.call(request)
                .map(Self::map_err as _)
                .map_err(::Error::from as _)
                .and_then(identity as _)
        }
    }

    impl<Req, Resp, E> Client<Req, Resp, E>
        where Req: Serialize + 'static,
              Resp: Deserialize + 'static,
              E: Deserialize + 'static
    {
        fn new(inner: BindClient<Req, Resp, E>) -> Self
            where Req: Serialize + Sync + Send + 'static,
                  Resp: Deserialize + Sync + Send + 'static,
                  E: Deserialize + Sync + Send + 'static
        {
            Client { inner: inner }
        }

        fn map_err(resp: WireResponse<Resp, E>) -> Result<Resp, ::Error<E>> {
            resp.map(|r| r.map_err(::Error::from))
                .map_err(::Error::ClientSerialize)
                .and_then(|r| r)
        }
    }

    impl<Req, Resp, E> fmt::Debug for Client<Req, Resp, E>
        where Req: Serialize + 'static,
              Resp: Deserialize + 'static,
              E: Deserialize + 'static
    {
        fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
            write!(f, "Client {{ .. }}")
        }
    }

    /// Types that can connect to a server asynchronously.
    pub trait Connect: Sized {
        /// The type of the future returned when calling `connect`.
        type ConnectFut: Future<Item = Self, Error = io::Error>;

        /// Connects to a server located at the given address, using the given options.
        fn connect(addr: SocketAddr, options: Options) -> Self::ConnectFut;
    }

    /// A future that resolves to a `Client` or an `io::Error`.
    pub type ConnectFuture<Req, Resp, E> = futures::Flatten<
        futures::MapErr<futures::Oneshot<io::Result<Client<Req, Resp, E>>>,
        fn(futures::Canceled) -> io::Error>>;

    impl<Req, Resp, E> Connect for Client<Req, Resp, E>
        where Req: Serialize + Sync + Send + 'static,
              Resp: Deserialize + Sync + Send + 'static,
              E: Deserialize + Sync + Send + 'static
    {
        type ConnectFut = ConnectFuture<Req, Resp, E>;

        fn connect(addr: SocketAddr, options: Options) -> Self::ConnectFut {
            // we need to do this for tls because we need to avoid moving the entire `Options`
            // struct into the `setup` closure, since `Reactor` is not `Send`.
            #[cfg(feature = "tls")]
            let mut options = options;
            #[cfg(feature = "tls")]
            let tls_ctx = options.tls_ctx.take();

            let connect = move |handle: &reactor::Handle| {
                let handle2 = handle.clone();
                TcpStream::connect(&addr, handle)
                    .and_then(move |socket| {
                        #[cfg(feature = "tls")]
                        match tls_ctx {
                            Some(tls_ctx) => {
                                future::Either::A(tls_ctx.tls_connector
                                    .connect_async(&tls_ctx.domain, socket)
                                    .map(StreamType::Tls)
                                    .map_err(native_to_io))
                            }
                            None => future::Either::B(future::ok(StreamType::Tcp(socket))),
                        }
                        #[cfg(not(feature = "tls"))]
                        future::ok(StreamType::Tcp(socket))
                    })
                    .map(move |tcp| Client::new(Proto::new().bind_client(&handle2, tcp)))
            };
            let setup = move |tx: futures::sync::oneshot::Sender<_>| {
                move |handle: &reactor::Handle| {
                    connect(handle).then(move |result| {
                        tx.complete(result);
                        Ok(())
                    })
                }
            };

            let rx = match options.reactor {
                Some(Reactor::Handle(handle)) => {
                    let (tx, rx) = futures::oneshot();
                    handle.spawn(setup(tx)(&handle));
                    rx
                }
                Some(Reactor::Remote(remote)) => {
                    let (tx, rx) = futures::oneshot();
                    remote.spawn(setup(tx));
                    rx
                }
                None => {
                    let (tx, rx) = futures::oneshot();
                    REMOTE.spawn(setup(tx));
                    rx
                }
            };
            fn panic(canceled: futures::Canceled) -> io::Error {
                unreachable!(canceled)
            }
            rx.map_err(panic as _).flatten()
        }
    }

    type ResponseFuture<Req, Resp, E> =
        futures::AndThen<futures::MapErr<
        futures::Map<<BindClient<Req, Resp, E> as Service>::Future,
                     fn(WireResponse<Resp, E>) -> Result<Resp, ::Error<E>>>,
            fn(io::Error) -> ::Error<E>>,
                     Result<Resp, ::Error<E>>,
                     fn(Result<Resp, ::Error<E>>) -> Result<Resp, ::Error<E>>>;
    type BindClient<Req, Resp, E> =
        <Proto<Req, Result<Resp, WireError<E>>>
            as ProtoBindClient<Multiplex, StreamType>>::BindClient;
}

/// Exposes a trait for connecting synchronously to servers.
pub mod sync {
    use std::io;
    use std::net::ToSocketAddrs;
    use super::Options;

    /// Types that can connect to a server synchronously.
    pub trait Connect: Sized {
        /// Connects to a server located at the given address.
        fn connect<A>(addr: A, options: Options) -> Result<Self, io::Error> where A: ToSocketAddrs;
    }
}