use std::{
    future::Future,
    pin::Pin,
    task::{Context, Poll},
};

use actix_rt::net::TcpStream;
use actix_service::{Service, ServiceFactory};
use futures_core::{future::LocalBoxFuture, ready};

use super::connect::{Address, Connect, Connection};
use super::connector::{TcpConnector, TcpConnectorFactory};
use super::error::ConnectError;
use super::resolve::{Resolver, ResolverFactory};

pub struct ConnectServiceFactory {
    tcp: TcpConnectorFactory,
    resolver: ResolverFactory,
}

impl ConnectServiceFactory {
    /// Construct new ConnectService factory
    pub fn new(resolver: Resolver) -> Self {
        ConnectServiceFactory {
            tcp: TcpConnectorFactory,
            resolver: ResolverFactory::new(resolver),
        }
    }

    /// Construct new service
    pub fn service(&self) -> ConnectService {
        ConnectService {
            tcp: self.tcp.service(),
            resolver: self.resolver.service(),
        }
    }

    /// Construct new tcp stream service
    pub fn tcp_service(&self) -> TcpConnectService {
        TcpConnectService {
            tcp: self.tcp.service(),
            resolver: self.resolver.service(),
        }
    }
}

impl Clone for ConnectServiceFactory {
    fn clone(&self) -> Self {
        ConnectServiceFactory {
            tcp: self.tcp,
            resolver: self.resolver.clone(),
        }
    }
}

impl<T: Address> ServiceFactory<Connect<T>> for ConnectServiceFactory {
    type Response = Connection<T, TcpStream>;
    type Error = ConnectError;
    type Config = ();
    type Service = ConnectService;
    type InitError = ();
    type Future = LocalBoxFuture<'static, Result<Self::Service, Self::InitError>>;

    fn new_service(&self, _: ()) -> Self::Future {
        let service = self.service();
        Box::pin(async move { Ok(service) })
    }
}

#[derive(Clone)]
pub struct ConnectService {
    tcp: TcpConnector,
    resolver: Resolver,
}

impl<T: Address> Service<Connect<T>> for ConnectService {
    type Response = Connection<T, TcpStream>;
    type Error = ConnectError;
    type Future = ConnectServiceResponse<T>;

    actix_service::always_ready!();

    fn call(&mut self, req: Connect<T>) -> Self::Future {
        ConnectServiceResponse {
            fut: ConnectFuture::Resolve(self.resolver.call(req)),
            tcp: self.tcp,
        }
    }
}

// helper enum to generic over futures of resolve and connect phase.
pub(crate) enum ConnectFuture<T: Address> {
    Resolve(<Resolver as Service<Connect<T>>>::Future),
    Connect(<TcpConnector as Service<Connect<T>>>::Future),
}

// helper enum to contain the future output of ConnectFuture
pub(crate) enum ConnectOutput<T: Address> {
    Resolved(Connect<T>),
    Connected(Connection<T, TcpStream>),
}

impl<T: Address> ConnectFuture<T> {
    fn poll_connect(
        &mut self,
        cx: &mut Context<'_>,
    ) -> Poll<Result<ConnectOutput<T>, ConnectError>> {
        match self {
            ConnectFuture::Resolve(ref mut fut) => {
                Pin::new(fut).poll(cx).map_ok(ConnectOutput::Resolved)
            }
            ConnectFuture::Connect(ref mut fut) => {
                Pin::new(fut).poll(cx).map_ok(ConnectOutput::Connected)
            }
        }
    }
}

pub struct ConnectServiceResponse<T: Address> {
    fut: ConnectFuture<T>,
    tcp: TcpConnector,
}

impl<T: Address> Future for ConnectServiceResponse<T> {
    type Output = Result<Connection<T, TcpStream>, ConnectError>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {
            match ready!(self.fut.poll_connect(cx))? {
                ConnectOutput::Resolved(res) => {
                    self.fut = ConnectFuture::Connect(self.tcp.call(res));
                }
                ConnectOutput::Connected(res) => return Poll::Ready(Ok(res)),
            }
        }
    }
}

#[derive(Clone)]
pub struct TcpConnectService {
    tcp: TcpConnector,
    resolver: Resolver,
}

impl<T: Address> Service<Connect<T>> for TcpConnectService {
    type Response = TcpStream;
    type Error = ConnectError;
    type Future = TcpConnectServiceResponse<T>;

    actix_service::always_ready!();

    fn call(&mut self, req: Connect<T>) -> Self::Future {
        TcpConnectServiceResponse {
            fut: ConnectFuture::Resolve(self.resolver.call(req)),
            tcp: self.tcp,
        }
    }
}

pub struct TcpConnectServiceResponse<T: Address> {
    fut: ConnectFuture<T>,
    tcp: TcpConnector,
}

impl<T: Address> Future for TcpConnectServiceResponse<T> {
    type Output = Result<TcpStream, ConnectError>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        loop {
            match ready!(self.fut.poll_connect(cx))? {
                ConnectOutput::Resolved(res) => {
                    self.fut = ConnectFuture::Connect(self.tcp.call(res));
                }
                ConnectOutput::Connected(conn) => return Poll::Ready(Ok(conn.into_parts().0)),
            }
        }
    }
}