use futures::{Async, Future, Poll};
use std::cell::UnsafeCell;
use std::marker::PhantomData;
use std::ops::{Deref, DerefMut};
use std::rc::Rc;

use error::Error;
use handler::{FromRequest, Handler, Reply, ReplyItem, Responder};
use httprequest::HttpRequest;
use httpresponse::HttpResponse;

pub struct ExtractorConfig<S: 'static, T: FromRequest<S>> {
    cfg: Rc<UnsafeCell<T::Config>>,
}

impl<S: 'static, T: FromRequest<S>> Default for ExtractorConfig<S, T> {
    fn default() -> Self {
        ExtractorConfig {
            cfg: Rc::new(UnsafeCell::new(T::Config::default())),
        }
    }
}

impl<S: 'static, T: FromRequest<S>> Clone for ExtractorConfig<S, T> {
    fn clone(&self) -> Self {
        ExtractorConfig {
            cfg: Rc::clone(&self.cfg),
        }
    }
}

impl<S: 'static, T: FromRequest<S>> AsRef<T::Config> for ExtractorConfig<S, T> {
    fn as_ref(&self) -> &T::Config {
        unsafe { &*self.cfg.get() }
    }
}

impl<S: 'static, T: FromRequest<S>> Deref for ExtractorConfig<S, T> {
    type Target = T::Config;

    fn deref(&self) -> &T::Config {
        unsafe { &*self.cfg.get() }
    }
}

impl<S: 'static, T: FromRequest<S>> DerefMut for ExtractorConfig<S, T> {
    fn deref_mut(&mut self) -> &mut T::Config {
        unsafe { &mut *self.cfg.get() }
    }
}

pub struct With<T, S, F, R>
where
    F: Fn(T) -> R,
    T: FromRequest<S>,
    S: 'static,
{
    hnd: Rc<UnsafeCell<F>>,
    cfg: ExtractorConfig<S, T>,
    _s: PhantomData<S>,
}

impl<T, S, F, R> With<T, S, F, R>
where
    F: Fn(T) -> R,
    T: FromRequest<S>,
    S: 'static,
{
    pub fn new(f: F, cfg: ExtractorConfig<S, T>) -> Self {
        With {
            cfg,
            hnd: Rc::new(UnsafeCell::new(f)),
            _s: PhantomData,
        }
    }
}

impl<T, S, F, R> Handler<S> for With<T, S, F, R>
where
    F: Fn(T) -> R + 'static,
    R: Responder + 'static,
    T: FromRequest<S> + 'static,
    S: 'static,
{
    type Result = Reply;

    fn handle(&mut self, req: HttpRequest<S>) -> Self::Result {
        let mut fut = WithHandlerFut {
            req,
            started: false,
            hnd: Rc::clone(&self.hnd),
            cfg: self.cfg.clone(),
            fut1: None,
            fut2: None,
        };

        match fut.poll() {
            Ok(Async::Ready(resp)) => Reply::response(resp),
            Ok(Async::NotReady) => Reply::async(fut),
            Err(e) => Reply::response(e),
        }
    }
}

struct WithHandlerFut<T, S, F, R>
where
    F: Fn(T) -> R,
    R: Responder,
    T: FromRequest<S> + 'static,
    S: 'static,
{
    started: bool,
    hnd: Rc<UnsafeCell<F>>,
    cfg: ExtractorConfig<S, T>,
    req: HttpRequest<S>,
    fut1: Option<Box<Future<Item = T, Error = Error>>>,
    fut2: Option<Box<Future<Item = HttpResponse, Error = Error>>>,
}

impl<T, S, F, R> Future for WithHandlerFut<T, S, F, R>
where
    F: Fn(T) -> R,
    R: Responder + 'static,
    T: FromRequest<S> + 'static,
    S: 'static,
{
    type Item = HttpResponse;
    type Error = Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        if let Some(ref mut fut) = self.fut2 {
            return fut.poll();
        }

        let item = if !self.started {
            self.started = true;
            let mut fut = T::from_request(&self.req, self.cfg.as_ref());
            match fut.poll() {
                Ok(Async::Ready(item)) => item,
                Ok(Async::NotReady) => {
                    self.fut1 = Some(Box::new(fut));
                    return Ok(Async::NotReady);
                }
                Err(e) => return Err(e),
            }
        } else {
            match self.fut1.as_mut().unwrap().poll()? {
                Async::Ready(item) => item,
                Async::NotReady => return Ok(Async::NotReady),
            }
        };

        let hnd: &mut F = unsafe { &mut *self.hnd.get() };
        let item = match (*hnd)(item).respond_to(self.req.drop_state()) {
            Ok(item) => item.into(),
            Err(e) => return Err(e.into()),
        };

        match item.into() {
            ReplyItem::Message(resp) => Ok(Async::Ready(resp)),
            ReplyItem::Future(fut) => {
                self.fut2 = Some(fut);
                self.poll()
            }
        }
    }
}

pub struct With2<T1, T2, S, F, R>
where
    F: Fn(T1, T2) -> R,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    S: 'static,
{
    hnd: Rc<UnsafeCell<F>>,
    cfg1: ExtractorConfig<S, T1>,
    cfg2: ExtractorConfig<S, T2>,
    _s: PhantomData<S>,
}

impl<T1, T2, S, F, R> With2<T1, T2, S, F, R>
where
    F: Fn(T1, T2) -> R,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    S: 'static,
{
    pub fn new(
        f: F, cfg1: ExtractorConfig<S, T1>, cfg2: ExtractorConfig<S, T2>
    ) -> Self {
        With2 {
            hnd: Rc::new(UnsafeCell::new(f)),
            cfg1,
            cfg2,
            _s: PhantomData,
        }
    }
}

impl<T1, T2, S, F, R> Handler<S> for With2<T1, T2, S, F, R>
where
    F: Fn(T1, T2) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    S: 'static,
{
    type Result = Reply;

    fn handle(&mut self, req: HttpRequest<S>) -> Self::Result {
        let mut fut = WithHandlerFut2 {
            req,
            started: false,
            hnd: Rc::clone(&self.hnd),
            cfg1: self.cfg1.clone(),
            cfg2: self.cfg2.clone(),
            item: None,
            fut1: None,
            fut2: None,
            fut3: None,
        };
        match fut.poll() {
            Ok(Async::Ready(resp)) => Reply::response(resp),
            Ok(Async::NotReady) => Reply::async(fut),
            Err(e) => Reply::response(e),
        }
    }
}

struct WithHandlerFut2<T1, T2, S, F, R>
where
    F: Fn(T1, T2) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    S: 'static,
{
    started: bool,
    hnd: Rc<UnsafeCell<F>>,
    cfg1: ExtractorConfig<S, T1>,
    cfg2: ExtractorConfig<S, T2>,
    req: HttpRequest<S>,
    item: Option<T1>,
    fut1: Option<Box<Future<Item = T1, Error = Error>>>,
    fut2: Option<Box<Future<Item = T2, Error = Error>>>,
    fut3: Option<Box<Future<Item = HttpResponse, Error = Error>>>,
}

impl<T1, T2, S, F, R> Future for WithHandlerFut2<T1, T2, S, F, R>
where
    F: Fn(T1, T2) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    S: 'static,
{
    type Item = HttpResponse;
    type Error = Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        if let Some(ref mut fut) = self.fut3 {
            return fut.poll();
        }

        if !self.started {
            self.started = true;
            let mut fut = T1::from_request(&self.req, self.cfg1.as_ref());
            match fut.poll() {
                Ok(Async::Ready(item1)) => {
                    let mut fut = T2::from_request(&self.req, self.cfg2.as_ref());
                    match fut.poll() {
                        Ok(Async::Ready(item2)) => {
                            let hnd: &mut F = unsafe { &mut *self.hnd.get() };
                            match (*hnd)(item1, item2).respond_to(self.req.drop_state())
                            {
                                Ok(item) => match item.into().into() {
                                    ReplyItem::Message(resp) => {
                                        return Ok(Async::Ready(resp))
                                    }
                                    ReplyItem::Future(fut) => {
                                        self.fut3 = Some(fut);
                                        return self.poll();
                                    }
                                },
                                Err(e) => return Err(e.into()),
                            }
                        }
                        Ok(Async::NotReady) => {
                            self.item = Some(item1);
                            self.fut2 = Some(Box::new(fut));
                            return Ok(Async::NotReady);
                        }
                        Err(e) => return Err(e),
                    }
                }
                Ok(Async::NotReady) => {
                    self.fut1 = Some(Box::new(fut));
                    return Ok(Async::NotReady);
                }
                Err(e) => return Err(e),
            }
        }

        if self.fut1.is_some() {
            match self.fut1.as_mut().unwrap().poll()? {
                Async::Ready(item) => {
                    self.item = Some(item);
                    self.fut1.take();
                    self.fut2 = Some(Box::new(T2::from_request(
                        &self.req,
                        self.cfg2.as_ref(),
                    )));
                }
                Async::NotReady => return Ok(Async::NotReady),
            }
        }

        let item = match self.fut2.as_mut().unwrap().poll()? {
            Async::Ready(item) => item,
            Async::NotReady => return Ok(Async::NotReady),
        };

        let hnd: &mut F = unsafe { &mut *self.hnd.get() };
        let item = match (*hnd)(self.item.take().unwrap(), item)
            .respond_to(self.req.drop_state())
        {
            Ok(item) => item.into(),
            Err(err) => return Err(err.into()),
        };

        match item.into() {
            ReplyItem::Message(resp) => return Ok(Async::Ready(resp)),
            ReplyItem::Future(fut) => self.fut3 = Some(fut),
        }

        self.poll()
    }
}

pub struct With3<T1, T2, T3, S, F, R>
where
    F: Fn(T1, T2, T3) -> R,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    T3: FromRequest<S> + 'static,
    S: 'static,
{
    hnd: Rc<UnsafeCell<F>>,
    cfg1: ExtractorConfig<S, T1>,
    cfg2: ExtractorConfig<S, T2>,
    cfg3: ExtractorConfig<S, T3>,
    _s: PhantomData<S>,
}

impl<T1, T2, T3, S, F, R> With3<T1, T2, T3, S, F, R>
where
    F: Fn(T1, T2, T3) -> R,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    T3: FromRequest<S> + 'static,
    S: 'static,
{
    pub fn new(
        f: F, cfg1: ExtractorConfig<S, T1>, cfg2: ExtractorConfig<S, T2>,
        cfg3: ExtractorConfig<S, T3>,
    ) -> Self {
        With3 {
            hnd: Rc::new(UnsafeCell::new(f)),
            cfg1,
            cfg2,
            cfg3,
            _s: PhantomData,
        }
    }
}

impl<T1, T2, T3, S, F, R> Handler<S> for With3<T1, T2, T3, S, F, R>
where
    F: Fn(T1, T2, T3) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S>,
    T2: FromRequest<S>,
    T3: FromRequest<S>,
    T1: 'static,
    T2: 'static,
    T3: 'static,
    S: 'static,
{
    type Result = Reply;

    fn handle(&mut self, req: HttpRequest<S>) -> Self::Result {
        let mut fut = WithHandlerFut3 {
            req,
            hnd: Rc::clone(&self.hnd),
            cfg1: self.cfg1.clone(),
            cfg2: self.cfg2.clone(),
            cfg3: self.cfg3.clone(),
            started: false,
            item1: None,
            item2: None,
            fut1: None,
            fut2: None,
            fut3: None,
            fut4: None,
        };
        match fut.poll() {
            Ok(Async::Ready(resp)) => Reply::response(resp),
            Ok(Async::NotReady) => Reply::async(fut),
            Err(e) => Reply::response(e),
        }
    }
}

struct WithHandlerFut3<T1, T2, T3, S, F, R>
where
    F: Fn(T1, T2, T3) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    T3: FromRequest<S> + 'static,
    S: 'static,
{
    hnd: Rc<UnsafeCell<F>>,
    req: HttpRequest<S>,
    cfg1: ExtractorConfig<S, T1>,
    cfg2: ExtractorConfig<S, T2>,
    cfg3: ExtractorConfig<S, T3>,
    started: bool,
    item1: Option<T1>,
    item2: Option<T2>,
    fut1: Option<Box<Future<Item = T1, Error = Error>>>,
    fut2: Option<Box<Future<Item = T2, Error = Error>>>,
    fut3: Option<Box<Future<Item = T3, Error = Error>>>,
    fut4: Option<Box<Future<Item = HttpResponse, Error = Error>>>,
}

impl<T1, T2, T3, S, F, R> Future for WithHandlerFut3<T1, T2, T3, S, F, R>
where
    F: Fn(T1, T2, T3) -> R + 'static,
    R: Responder + 'static,
    T1: FromRequest<S> + 'static,
    T2: FromRequest<S> + 'static,
    T3: FromRequest<S> + 'static,
    S: 'static,
{
    type Item = HttpResponse;
    type Error = Error;

    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
        if let Some(ref mut fut) = self.fut4 {
            return fut.poll();
        }

        if !self.started {
            self.started = true;
            let mut fut = T1::from_request(&self.req, self.cfg1.as_ref());
            match fut.poll() {
                Ok(Async::Ready(item1)) => {
                    let mut fut = T2::from_request(&self.req, self.cfg2.as_ref());
                    match fut.poll() {
                        Ok(Async::Ready(item2)) => {
                            let mut fut =
                                T3::from_request(&self.req, self.cfg3.as_ref());
                            match fut.poll() {
                                Ok(Async::Ready(item3)) => {
                                    let hnd: &mut F = unsafe { &mut *self.hnd.get() };
                                    match (*hnd)(item1, item2, item3)
                                        .respond_to(self.req.drop_state())
                                    {
                                        Ok(item) => match item.into().into() {
                                            ReplyItem::Message(resp) => {
                                                return Ok(Async::Ready(resp))
                                            }
                                            ReplyItem::Future(fut) => {
                                                self.fut4 = Some(fut);
                                                return self.poll();
                                            }
                                        },
                                        Err(e) => return Err(e.into()),
                                    }
                                }
                                Ok(Async::NotReady) => {
                                    self.item1 = Some(item1);
                                    self.item2 = Some(item2);
                                    self.fut3 = Some(Box::new(fut));
                                    return Ok(Async::NotReady);
                                }
                                Err(e) => return Err(e),
                            }
                        }
                        Ok(Async::NotReady) => {
                            self.item1 = Some(item1);
                            self.fut2 = Some(Box::new(fut));
                            return Ok(Async::NotReady);
                        }
                        Err(e) => return Err(e),
                    }
                }
                Ok(Async::NotReady) => {
                    self.fut1 = Some(Box::new(fut));
                    return Ok(Async::NotReady);
                }
                Err(e) => return Err(e),
            }
        }

        if self.fut1.is_some() {
            match self.fut1.as_mut().unwrap().poll()? {
                Async::Ready(item) => {
                    self.item1 = Some(item);
                    self.fut1.take();
                    self.fut2 = Some(Box::new(T2::from_request(
                        &self.req,
                        self.cfg2.as_ref(),
                    )));
                }
                Async::NotReady => return Ok(Async::NotReady),
            }
        }

        if self.fut2.is_some() {
            match self.fut2.as_mut().unwrap().poll()? {
                Async::Ready(item) => {
                    self.item2 = Some(item);
                    self.fut2.take();
                    self.fut3 = Some(Box::new(T3::from_request(
                        &self.req,
                        self.cfg3.as_ref(),
                    )));
                }
                Async::NotReady => return Ok(Async::NotReady),
            }
        }

        let item = match self.fut3.as_mut().unwrap().poll()? {
            Async::Ready(item) => item,
            Async::NotReady => return Ok(Async::NotReady),
        };

        let hnd: &mut F = unsafe { &mut *self.hnd.get() };
        let item = match (*hnd)(
            self.item1.take().unwrap(),
            self.item2.take().unwrap(),
            item,
        ).respond_to(self.req.drop_state())
        {
            Ok(item) => item.into(),
            Err(err) => return Err(err.into()),
        };

        match item.into() {
            ReplyItem::Message(resp) => return Ok(Async::Ready(resp)),
            ReplyItem::Future(fut) => self.fut4 = Some(fut),
        }

        self.poll()
    }
}