use std::marker::PhantomData;

use futures::future::{ok, Future, FutureResult};
use futures::{try_ready, Async, IntoFuture, Poll};

use crate::{IntoNewService, IntoService, NewService, Service};

/// Create `NewService` for function that can act as a Service
pub fn service_fn<F, Req, Out, Cfg>(f: F) -> NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    NewServiceFn::new(f)
}

/// Create `NewService` for function that can produce services
pub fn new_service_fn<F, C, R, S, E>(f: F) -> FnNewServiceNoConfig<F, C, R, S, E>
where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    FnNewServiceNoConfig::new(f)
}

/// Create `NewService` for function that can produce services with configuration
pub fn new_service_cfg<F, C, R, S, E>(f: F) -> FnNewServiceConfig<F, C, R, S, E>
where
    F: Fn(&C) -> R,
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    FnNewServiceConfig::new(f)
}

pub struct ServiceFn<F, Req, Out>
where
    F: FnMut(Req) -> Out,
    Out: IntoFuture,
{
    f: F,
    _t: PhantomData<Req>,
}

impl<F, Req, Out> ServiceFn<F, Req, Out>
where
    F: FnMut(Req) -> Out,
    Out: IntoFuture,
{
    pub(crate) fn new(f: F) -> Self {
        ServiceFn { f, _t: PhantomData }
    }
}

impl<F, Req, Out> Clone for ServiceFn<F, Req, Out>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    fn clone(&self) -> Self {
        ServiceFn::new(self.f.clone())
    }
}

impl<F, Req, Out> Service for ServiceFn<F, Req, Out>
where
    F: FnMut(Req) -> Out,
    Out: IntoFuture,
{
    type Request = Req;
    type Response = Out::Item;
    type Error = Out::Error;
    type Future = Out::Future;

    fn poll_ready(&mut self) -> Poll<(), Self::Error> {
        Ok(Async::Ready(()))
    }

    fn call(&mut self, req: Req) -> Self::Future {
        (self.f)(req).into_future()
    }
}

impl<F, Req, Out> IntoService<ServiceFn<F, Req, Out>> for F
where
    F: FnMut(Req) -> Out,
    Out: IntoFuture,
{
    fn into_service(self) -> ServiceFn<F, Req, Out> {
        ServiceFn::new(self)
    }
}

pub struct NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out,
    Out: IntoFuture,
{
    f: F,
    _t: PhantomData<(Req, Cfg)>,
}

impl<F, Req, Out, Cfg> NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    pub(crate) fn new(f: F) -> Self {
        NewServiceFn { f, _t: PhantomData }
    }
}

impl<F, Req, Out, Cfg> Clone for NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    fn clone(&self) -> Self {
        NewServiceFn::new(self.f.clone())
    }
}

impl<F, Req, Out, Cfg> NewService for NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    type Request = Req;
    type Response = Out::Item;
    type Error = Out::Error;

    type Config = Cfg;
    type Service = ServiceFn<F, Req, Out>;
    type InitError = ();
    type Future = FutureResult<Self::Service, Self::InitError>;

    fn new_service(&self, _: &Cfg) -> Self::Future {
        ok(ServiceFn::new(self.f.clone()))
    }
}

impl<F, Req, Out, Cfg> IntoService<ServiceFn<F, Req, Out>> for NewServiceFn<F, Req, Out, Cfg>
where
    F: FnMut(Req) -> Out + Clone,
    Out: IntoFuture,
{
    fn into_service(self) -> ServiceFn<F, Req, Out> {
        ServiceFn::new(self.f.clone())
    }
}

impl<F, Req, Out, Cfg> IntoNewService<NewServiceFn<F, Req, Out, Cfg>> for F
where
    F: Fn(Req) -> Out + Clone,
    Out: IntoFuture,
{
    fn into_new_service(self) -> NewServiceFn<F, Req, Out, Cfg> {
        NewServiceFn::new(self)
    }
}

/// Convert `Fn(&Config) -> Future<Service>` fn to NewService
pub struct FnNewServiceConfig<F, C, R, S, E>
where
    F: Fn(&C) -> R,
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    f: F,
    _t: PhantomData<(C, R, S, E)>,
}

impl<F, C, R, S, E> FnNewServiceConfig<F, C, R, S, E>
where
    F: Fn(&C) -> R,
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    pub fn new(f: F) -> Self {
        FnNewServiceConfig { f, _t: PhantomData }
    }
}

impl<F, C, R, S, E> NewService for FnNewServiceConfig<F, C, R, S, E>
where
    F: Fn(&C) -> R,
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    type Request = S::Request;
    type Response = S::Response;
    type Error = S::Error;

    type Config = C;
    type Service = S;
    type InitError = E;
    type Future = FnNewServiceConfigFut<R, S, E>;

    fn new_service(&self, cfg: &C) -> Self::Future {
        FnNewServiceConfigFut {
            fut: (self.f)(cfg).into_future(),
            _t: PhantomData,
        }
    }
}

pub struct FnNewServiceConfigFut<R, S, E>
where
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    fut: R::Future,
    _t: PhantomData<(S,)>,
}

impl<R, S, E> Future for FnNewServiceConfigFut<R, S, E>
where
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    type Item = S;
    type Error = R::Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        Ok(Async::Ready(try_ready!(self.fut.poll()).into_service()))
    }
}

impl<F, C, R, S, E> Clone for FnNewServiceConfig<F, C, R, S, E>
where
    F: Fn(&C) -> R + Clone,
    R: IntoFuture<Error = E>,
    R::Item: IntoService<S>,
    S: Service,
{
    fn clone(&self) -> Self {
        Self::new(self.f.clone())
    }
}

/// Converter for `Fn() -> Future<Service>` fn
pub struct FnNewServiceNoConfig<F, C, R, S, E>
where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    S: Service,
{
    f: F,
    _t: PhantomData<C>,
}

impl<F, C, R, S, E> FnNewServiceNoConfig<F, C, R, S, E>
where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    S: Service,
{
    pub fn new(f: F) -> Self {
        FnNewServiceNoConfig { f, _t: PhantomData }
    }
}

impl<F, C, R, S, E> NewService for FnNewServiceNoConfig<F, C, R, S, E>
where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    S: Service,
{
    type Request = S::Request;
    type Response = S::Response;
    type Error = S::Error;
    type Service = S;
    type Config = C;
    type InitError = E;
    type Future = R::Future;

    fn new_service(&self, _: &C) -> Self::Future {
        (self.f)().into_future()
    }
}

impl<F, C, R, S, E> Clone for FnNewServiceNoConfig<F, C, R, S, E>
where
    F: Fn() -> R + Clone,
    R: IntoFuture<Item = S, Error = E>,
    S: Service,
{
    fn clone(&self) -> Self {
        Self::new(self.f.clone())
    }
}

impl<F, C, R, S, E> IntoNewService<FnNewServiceNoConfig<F, C, R, S, E>> for F
where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    S: Service,
{
    fn into_new_service(self) -> FnNewServiceNoConfig<F, C, R, S, E> {
        FnNewServiceNoConfig::new(self)
    }
}