use std::{self, io, ptr};
use std::rc::Rc;
use std::cell::UnsafeCell;
use std::time::Duration;
use std::collections::VecDeque;

use actix::Arbiter;
use httparse;
use http::{Method, Version, HttpTryFrom, HeaderMap};
use http::header::{self, HeaderName, HeaderValue};
use bytes::{Bytes, BytesMut, BufMut};
use futures::{Future, Poll, Async};
use tokio_io::{AsyncRead, AsyncWrite};
use tokio_core::reactor::Timeout;
use percent_encoding;

use task::Task;
use channel::HttpHandler;
use error::ParseError;
use httpcodes::HTTPNotFound;
use httprequest::HttpRequest;
use payload::{Payload, PayloadError, PayloadSender};
use h1writer::H1Writer;

const KEEPALIVE_PERIOD: u64 = 15; // seconds
const INIT_BUFFER_SIZE: usize = 8192;
const MAX_BUFFER_SIZE: usize = 131_072;
const MAX_HEADERS: usize = 100;
const MAX_PIPELINED_MESSAGES: usize = 16;
const HTTP2_PREFACE: [u8; 14] = *b"PRI * HTTP/2.0";

pub(crate) enum Http1Result {
    Done,
    Switch,
}

pub(crate) struct Http1<T: AsyncWrite + 'static, A: 'static, H: 'static> {
    router: Rc<Vec<H>>,
    #[allow(dead_code)]
    addr: A,
    stream: H1Writer<T>,
    reader: Reader,
    read_buf: BytesMut,
    error: bool,
    tasks: VecDeque<Entry>,
    keepalive: bool,
    keepalive_timer: Option<Timeout>,
    h2: bool,
}

struct Entry {
    task: Task,
    req: UnsafeCell<HttpRequest>,
    eof: bool,
    error: bool,
    finished: bool,
}

impl<T, A, H> Http1<T, A, H>
    where T: AsyncRead + AsyncWrite + 'static,
          A: 'static,
          H: HttpHandler + 'static
{
    pub fn new(stream: T, addr: A, router: Rc<Vec<H>>) -> Self {
        Http1{ router: router,
               addr: addr,
               stream: H1Writer::new(stream),
               reader: Reader::new(),
               read_buf: BytesMut::new(),
               error: false,
               tasks: VecDeque::new(),
               keepalive: true,
               keepalive_timer: None,
               h2: false }
    }

    pub fn into_inner(mut self) -> (T, A, Rc<Vec<H>>, Bytes) {
        (self.stream.unwrap(), self.addr, self.router, self.read_buf.freeze())
    }

    pub fn poll(&mut self) -> Poll<Http1Result, ()> {
        // keep-alive timer
        if let Some(ref mut timeout) = self.keepalive_timer {
            match timeout.poll() {
                Ok(Async::Ready(_)) =>
                    return Ok(Async::Ready(Http1Result::Done)),
                Ok(Async::NotReady) => (),
                Err(_) => unreachable!(),
            }
        }

        loop {
            let mut not_ready = true;

            // check in-flight messages
            let mut io = false;
            let mut idx = 0;
            while idx < self.tasks.len() {
                let item = &mut self.tasks[idx];

                if !io && !item.eof {
                    if item.error {
                        return Err(())
                    }

                    // this is anoying
                    let req = unsafe {item.req.get().as_mut().unwrap()};
                    match item.task.poll_io(&mut self.stream, req)
                    {
                        Ok(Async::Ready(ready)) => {
                            not_ready = false;

                            // overide keep-alive state
                            if self.keepalive {
                                self.keepalive = self.stream.keepalive();
                            }
                            self.stream = H1Writer::new(self.stream.unwrap());

                            item.eof = true;
                            if ready {
                                item.finished = true;
                            }
                        },
                        Ok(Async::NotReady) => {
                            // no more IO for this iteration
                            io = true;
                        },
                        Err(_) => {
                            // it is not possible to recover from error
                            // during task handling, so just drop connection
                            return Err(())
                        }
                    }
                } else if !item.finished {
                    match item.task.poll() {
                        Ok(Async::NotReady) => (),
                        Ok(Async::Ready(_)) => {
                            not_ready = false;
                            item.finished = true;
                        },
                        Err(_) =>
                            item.error = true,
                    }
                }
                idx += 1;
            }

            // cleanup finished tasks
            while !self.tasks.is_empty() {
                if self.tasks[0].eof && self.tasks[0].finished {
                    self.tasks.pop_front();
                } else {
                    break
                }
            }

            // no keep-alive
            if !self.keepalive && self.tasks.is_empty() {
                if self.h2 {
                    return Ok(Async::Ready(Http1Result::Switch))
                } else {
                    return Ok(Async::Ready(Http1Result::Done))
                }
            }

            // read incoming data
            if !self.error && !self.h2 && self.tasks.len() < MAX_PIPELINED_MESSAGES {
                match self.reader.parse(self.stream.get_mut(), &mut self.read_buf) {
                    Ok(Async::Ready(Item::Http1(mut req, payload))) => {
                        not_ready = false;

                        // stop keepalive timer
                        self.keepalive_timer.take();

                        // start request processing
                        let mut task = None;
                        for h in self.router.iter() {
                            if req.path().starts_with(h.prefix()) {
                                task = Some(h.handle(&mut req, payload));
                                break
                            }
                        }

                        self.tasks.push_back(
                            Entry {task: task.unwrap_or_else(|| Task::reply(HTTPNotFound)),
                                   req: UnsafeCell::new(req),
                                   eof: false,
                                   error: false,
                                   finished: false});
                    }
                    Ok(Async::Ready(Item::Http2)) => {
                        self.h2 = true;
                    }
                    Err(ReaderError::Disconnect) => {
                        not_ready = false;
                        self.error = true;
                        self.stream.disconnected();
                        for entry in &mut self.tasks {
                            entry.task.disconnected()
                        }
                    },
                    Err(err) => {
                        // notify all tasks
                        not_ready = false;
                        self.stream.disconnected();
                        for entry in &mut self.tasks {
                            entry.task.disconnected()
                        }

                        // kill keepalive
                        self.keepalive = false;
                        self.keepalive_timer.take();

                        // on parse error, stop reading stream but
                        // tasks need to be completed
                        self.error = true;

                        if self.tasks.is_empty() {
                            if let ReaderError::Error(err) = err {
                                self.tasks.push_back(
                                    Entry {task: Task::reply(err),
                                           req: UnsafeCell::new(HttpRequest::for_error()),
                                           eof: false,
                                           error: false,
                                           finished: false});
                            }
                        }
                    }
                    Ok(Async::NotReady) => {
                        // start keep-alive timer, this is also slow request timeout
                        if self.tasks.is_empty() {
                            if self.keepalive {
                                if self.keepalive_timer.is_none() {
                                    trace!("Start keep-alive timer");
                                    let mut timeout = Timeout::new(
                                        Duration::new(KEEPALIVE_PERIOD, 0),
                                        Arbiter::handle()).unwrap();
                                    // register timeout
                                    let _ = timeout.poll();
                                    self.keepalive_timer = Some(timeout);
                                }
                            } else {
                                // keep-alive disable, drop connection
                                return Ok(Async::Ready(Http1Result::Done))
                            }
                        }
                        return Ok(Async::NotReady)
                    }
                }
            }

            // check for parse error
            if self.tasks.is_empty() {
                if self.h2 {
                    return Ok(Async::Ready(Http1Result::Switch))
                }
                if self.error || self.keepalive_timer.is_none() {
                    return Ok(Async::Ready(Http1Result::Done))
                }
            }

            if not_ready {
                return Ok(Async::NotReady)
            }
        }
    }
}

#[derive(Debug)]
enum Item {
    Http1(HttpRequest, Payload),
    Http2,
}

struct Reader {
    h1: bool,
    payload: Option<PayloadInfo>,
}

enum Decoding {
    Paused,
    Ready,
    NotReady,
}

struct PayloadInfo {
    tx: PayloadSender,
    decoder: Decoder,
}

#[derive(Debug)]
enum ReaderError {
    Disconnect,
    Payload,
    Error(ParseError),
}

#[derive(Debug)]
enum Message {
    Http1(HttpRequest, Option<Decoder>),
    Http2,
    NotReady,
}

impl Reader {
    pub fn new() -> Reader {
        Reader {
            h1: false,
            payload: None,
        }
    }

    fn decode(&mut self, buf: &mut BytesMut) -> std::result::Result<Decoding, ReaderError>
    {
        if let Some(ref mut payload) = self.payload {
            if payload.tx.maybe_paused() {
                return Ok(Decoding::Paused)
            }
            loop {
                match payload.decoder.decode(buf) {
                    Ok(Async::Ready(Some(bytes))) => {
                        payload.tx.feed_data(bytes)
                    },
                    Ok(Async::Ready(None)) => {
                        payload.tx.feed_eof();
                        return Ok(Decoding::Ready)
                    },
                    Ok(Async::NotReady) => return Ok(Decoding::NotReady),
                    Err(err) => {
                        payload.tx.set_error(err.into());
                        return Err(ReaderError::Payload)
                    }
                }
            }
        } else {
            return Ok(Decoding::Ready)
        }
    }
    
    pub fn parse<T>(&mut self, io: &mut T, buf: &mut BytesMut) -> Poll<Item, ReaderError>
        where T: AsyncRead
    {
        loop {
            match self.decode(buf)? {
                Decoding::Paused => return Ok(Async::NotReady),
                Decoding::Ready => {
                    self.payload = None;
                    break
                },
                Decoding::NotReady => {
                    match self.read_from_io(io, buf) {
                        Ok(Async::Ready(0)) => {
                            if let Some(ref mut payload) = self.payload {
                                payload.tx.set_error(PayloadError::Incomplete);
                            }
                            // http channel should not deal with payload errors
                            return Err(ReaderError::Payload)
                        }
                        Ok(Async::Ready(_)) => {
                            continue
                        }
                        Ok(Async::NotReady) => break,
                        Err(err) => {
                            if let Some(ref mut payload) = self.payload {
                                payload.tx.set_error(err.into());
                            }
                            // http channel should not deal with payload errors
                            return Err(ReaderError::Payload)
                        }
                    }
                }
            }
        }

        loop {
            match Reader::parse_message(buf).map_err(ReaderError::Error)? {
                Message::Http1(msg, decoder) => {
                    let payload = if let Some(decoder) = decoder {
                        let (tx, rx) = Payload::new(false);
                        let payload = PayloadInfo {
                            tx: tx,
                            decoder: decoder,
                        };
                        self.payload = Some(payload);

                        loop {
                            match self.decode(buf)? {
                                Decoding::Paused =>
                                    break,
                                Decoding::Ready => {
                                    self.payload = None;
                                    break
                                },
                                Decoding::NotReady => {
                                    match self.read_from_io(io, buf) {
                                        Ok(Async::Ready(0)) => {
                                            trace!("parse eof");
                                            if let Some(ref mut payload) = self.payload {
                                                payload.tx.set_error(PayloadError::Incomplete);
                                            }
                                            // http channel should deal with payload errors
                                            return Err(ReaderError::Payload)
                                        }
                                        Ok(Async::Ready(_)) => {
                                            continue
                                        }
                                        Ok(Async::NotReady) => break,
                                        Err(err) => {
                                            if let Some(ref mut payload) = self.payload {
                                                payload.tx.set_error(err.into());
                                            }
                                            // http channel should deal with payload errors
                                            return Err(ReaderError::Payload)
                                        }
                                    }
                                }
                            }
                        }
                        rx
                    } else {
                        let (_, rx) = Payload::new(true);
                        rx
                    };
                    self.h1 = true;
                    return Ok(Async::Ready(Item::Http1(msg, payload)));
                },
                Message::Http2 => {
                    if self.h1 {
                        return Err(ReaderError::Error(ParseError::Version))
                    }
                    return Ok(Async::Ready(Item::Http2));
                },
                Message::NotReady => {
                    if buf.capacity() >= MAX_BUFFER_SIZE {
                        debug!("MAX_BUFFER_SIZE reached, closing");
                        return Err(ReaderError::Error(ParseError::TooLarge));
                    }
                },
            }
            match self.read_from_io(io, buf) {
                Ok(Async::Ready(0)) => {
                    debug!("Ignored premature client disconnection");
                    return Err(ReaderError::Disconnect);
                },
                Ok(Async::Ready(_)) => (),
                Ok(Async::NotReady) =>
                    return Ok(Async::NotReady),
                Err(err) =>
                    return Err(ReaderError::Error(err.into()))
            }
        }
    }

    fn read_from_io<T: AsyncRead>(&mut self, io: &mut T, buf: &mut BytesMut)
                                  -> Poll<usize, io::Error>
    {
        if buf.remaining_mut() < INIT_BUFFER_SIZE {
            buf.reserve(INIT_BUFFER_SIZE);
            unsafe { // Zero out unused memory
                let b = buf.bytes_mut();
                let len = b.len();
                ptr::write_bytes(b.as_mut_ptr(), 0, len);
            }
        }
        unsafe {
            let n = match io.read(buf.bytes_mut()) {
                Ok(n) => n,
                Err(e) => {
                    if e.kind() == io::ErrorKind::WouldBlock {
                        return Ok(Async::NotReady);
                    }
                    return Err(e)
                }
            };
            buf.advance_mut(n);
            Ok(Async::Ready(n))
        }
    }

    fn parse_message(buf: &mut BytesMut) -> Result<Message, ParseError>
    {
        if buf.is_empty() {
            return Ok(Message::NotReady);
        }
        if buf.len() >= 14 && buf[..14] == HTTP2_PREFACE[..] {
            return Ok(Message::Http2)
        }

        // Parse http message
        let mut headers_indices = [HeaderIndices {
            name: (0, 0),
            value: (0, 0)
        }; MAX_HEADERS];

        let (len, method, path, version, headers_len) = {
            let mut headers = [httparse::EMPTY_HEADER; MAX_HEADERS];
            trace!("Request.parse([Header; {}], [u8; {}])", headers.len(), buf.len());
            let mut req = httparse::Request::new(&mut headers);
            match try!(req.parse(buf)) {
                httparse::Status::Complete(len) => {
                    trace!("Request.parse Complete({})", len);
                    let method = Method::try_from(req.method.unwrap())
                        .map_err(|_| ParseError::Method)?;
                    let path = req.path.unwrap();
                    let bytes_ptr = buf.as_ref().as_ptr() as usize;
                    let path_start = path.as_ptr() as usize - bytes_ptr;
                    let path_end = path_start + path.len();
                    let path = (path_start, path_end);

                    let version = if req.version.unwrap() == 1 {
                        Version::HTTP_11
                    } else {
                        Version::HTTP_10
                    };

                    record_header_indices(buf.as_ref(), req.headers, &mut headers_indices);
                    let headers_len = req.headers.len();
                    (len, method, path, version, headers_len)
                }
                httparse::Status::Partial => return Ok(Message::NotReady),
            }
        };

        let slice = buf.split_to(len).freeze();
        let path = slice.slice(path.0, path.1);

        // manually split path, path was found to be utf8 by httparse
        let uri = {
            if let Ok(path) = percent_encoding::percent_decode(&path).decode_utf8() {
                let parts: Vec<&str> = path.splitn(2, '?').collect();
                if parts.len() == 2 {
                    Some((parts[0].to_owned(), parts[1].to_owned()))
                } else {
                    Some((parts[0].to_owned(), String::new()))
                }
            } else {
                None
            }
        };
        let (path, query) = if let Some(uri) = uri {
            uri
        } else {
            let parts: Vec<&str> = unsafe{
                std::str::from_utf8_unchecked(&path)}.splitn(2, '?').collect();
            if parts.len() == 2 {
                (parts[0].to_owned(), parts[1][1..].to_owned())
            } else {
                (parts[0].to_owned(), String::new())
            }
        };

        // convert headers
        let mut headers = HeaderMap::with_capacity(headers_len);
        for header in headers_indices[..headers_len].iter() {
            if let Ok(name) = HeaderName::try_from(slice.slice(header.name.0, header.name.1)) {
                if let Ok(value) = HeaderValue::try_from(
                    slice.slice(header.value.0, header.value.1))
                {
                    headers.append(name, value);
                } else {
                    return Err(ParseError::Header)
                }
            } else {
                return Err(ParseError::Header)
            }
        }

        let msg = HttpRequest::new(method, path, version, headers, query);

        let decoder = if msg.upgrade() {
            Some(Decoder::eof())
        } else {
            let chunked = msg.chunked()?;

            // Content-Length
            if let Some(len) = msg.headers().get(header::CONTENT_LENGTH) {
                if chunked {
                    return Err(ParseError::Header)
                }
                if let Ok(s) = len.to_str() {
                    if let Ok(len) = s.parse::<u64>() {
                        Some(Decoder::length(len))
                    } else {
                        debug!("illegal Content-Length: {:?}", len);
                        return Err(ParseError::Header)
                    }
                } else {
                    debug!("illegal Content-Length: {:?}", len);
                    return Err(ParseError::Header)
                }
            } else if chunked {
                Some(Decoder::chunked())
            } else {
                None
            }
        };
        Ok(Message::Http1(msg, decoder))
    }
}

#[derive(Clone, Copy)]
struct HeaderIndices {
    name: (usize, usize),
    value: (usize, usize),
}

fn record_header_indices(bytes: &[u8],
                         headers: &[httparse::Header],
                         indices: &mut [HeaderIndices])
{
    let bytes_ptr = bytes.as_ptr() as usize;
    for (header, indices) in headers.iter().zip(indices.iter_mut()) {
        let name_start = header.name.as_ptr() as usize - bytes_ptr;
        let name_end = name_start + header.name.len();
        indices.name = (name_start, name_end);
        let value_start = header.value.as_ptr() as usize - bytes_ptr;
        let value_end = value_start + header.value.len();
        indices.value = (value_start, value_end);
    }
}

/// Decoders to handle different Transfer-Encodings.
///
/// If a message body does not include a Transfer-Encoding, it *should*
/// include a Content-Length header.
#[derive(Debug, Clone, PartialEq)]
struct Decoder {
    kind: Kind,
}

impl Decoder {
    pub fn length(x: u64) -> Decoder {
        Decoder { kind: Kind::Length(x) }
    }

    pub fn chunked() -> Decoder {
        Decoder { kind: Kind::Chunked(ChunkedState::Size, 0) }
    }

    pub fn eof() -> Decoder {
        Decoder { kind: Kind::Eof(false) }
    }
}

#[derive(Debug, Clone, PartialEq)]
enum Kind {
    /// A Reader used when a Content-Length header is passed with a positive integer.
    Length(u64),
    /// A Reader used when Transfer-Encoding is `chunked`.
    Chunked(ChunkedState, u64),
    /// A Reader used for responses that don't indicate a length or chunked.
    ///
    /// Note: This should only used for `Response`s. It is illegal for a
    /// `Request` to be made with both `Content-Length` and
    /// `Transfer-Encoding: chunked` missing, as explained from the spec:
    ///
    /// > If a Transfer-Encoding header field is present in a response and
    /// > the chunked transfer coding is not the final encoding, the
    /// > message body length is determined by reading the connection until
    /// > it is closed by the server.  If a Transfer-Encoding header field
    /// > is present in a request and the chunked transfer coding is not
    /// > the final encoding, the message body length cannot be determined
    /// > reliably; the server MUST respond with the 400 (Bad Request)
    /// > status code and then close the connection.
    Eof(bool),
}

#[derive(Debug, PartialEq, Clone)]
enum ChunkedState {
    Size,
    SizeLws,
    Extension,
    SizeLf,
    Body,
    BodyCr,
    BodyLf,
    EndCr,
    EndLf,
    End,
}

impl Decoder {
    /*pub fn is_eof(&self) -> bool {
        trace!("is_eof? {:?}", self);
        match self.kind {
            Kind::Length(0) |
            Kind::Chunked(ChunkedState::End, _) |
            Kind::Eof(true) => true,
            _ => false,
        }
    }*/
}

impl Decoder {
    pub fn decode(&mut self, body: &mut BytesMut) -> Poll<Option<Bytes>, io::Error> {
        match self.kind {
            Kind::Length(ref mut remaining) => {
                trace!("Sized read, remaining={:?}", remaining);
                if *remaining == 0 {
                    Ok(Async::Ready(None))
                } else {
                    if body.is_empty() {
                        return Ok(Async::NotReady)
                    }
                    let len = body.len() as u64;
                    let buf;
                    if *remaining > len {
                        buf = body.take().freeze();
                        *remaining -= len;
                    } else {
                        buf = body.split_to(*remaining as usize).freeze();
                        *remaining = 0;
                    }
                    trace!("Length read: {}", buf.len());
                    Ok(Async::Ready(Some(buf)))
                }
            }
            Kind::Chunked(ref mut state, ref mut size) => {
                loop {
                    let mut buf = None;
                    // advances the chunked state
                    *state = try_ready!(state.step(body, size, &mut buf));
                    if *state == ChunkedState::End {
                        trace!("End of chunked stream");
                        return Ok(Async::Ready(None));
                    }
                    if let Some(buf) = buf {
                        return Ok(Async::Ready(Some(buf)));
                    }
                    if body.is_empty() {
                        return Ok(Async::NotReady);
                    }
                }
            }
            Kind::Eof(ref mut is_eof) => {
                if *is_eof {
                    Ok(Async::Ready(None))
                } else if !body.is_empty() {
                    Ok(Async::Ready(Some(body.take().freeze())))
                } else {
                    Ok(Async::NotReady)
                }
            }
        }
    }
}

macro_rules! byte (
    ($rdr:ident) => ({
        if $rdr.len() > 0 {
            let b = $rdr[0];
            $rdr.split_to(1);
            b
        } else {
            return Ok(Async::NotReady)
        }
    })
);

impl ChunkedState {
    fn step(&self, body: &mut BytesMut, size: &mut u64, buf: &mut Option<Bytes>)
            -> Poll<ChunkedState, io::Error>
    {
        use self::ChunkedState::*;
        match *self {
            Size => ChunkedState::read_size(body, size),
            SizeLws => ChunkedState::read_size_lws(body),
            Extension => ChunkedState::read_extension(body),
            SizeLf => ChunkedState::read_size_lf(body, size),
            Body => ChunkedState::read_body(body, size, buf),
            BodyCr => ChunkedState::read_body_cr(body),
            BodyLf => ChunkedState::read_body_lf(body),
            EndCr => ChunkedState::read_end_cr(body),
            EndLf => ChunkedState::read_end_lf(body),
            End => Ok(Async::Ready(ChunkedState::End)),
        }
    }
    fn read_size(rdr: &mut BytesMut, size: &mut u64) -> Poll<ChunkedState, io::Error> {
        trace!("Read chunk hex size");
        let radix = 16;
        match byte!(rdr) {
            b @ b'0'...b'9' => {
                *size *= radix;
                *size += u64::from(b - b'0');
            }
            b @ b'a'...b'f' => {
                *size *= radix;
                *size += u64::from(b + 10 - b'a');
            }
            b @ b'A'...b'F' => {
                *size *= radix;
                *size += u64::from(b + 10 - b'A');
            }
            b'\t' | b' ' => return Ok(Async::Ready(ChunkedState::SizeLws)),
            b';' => return Ok(Async::Ready(ChunkedState::Extension)),
            b'\r' => return Ok(Async::Ready(ChunkedState::SizeLf)),
            _ => {
                return Err(io::Error::new(io::ErrorKind::InvalidInput,
                                          "Invalid chunk size line: Invalid Size"));
            }
        }
        Ok(Async::Ready(ChunkedState::Size))
    }
    fn read_size_lws(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        trace!("read_size_lws");
        match byte!(rdr) {
            // LWS can follow the chunk size, but no more digits can come
            b'\t' | b' ' => Ok(Async::Ready(ChunkedState::SizeLws)),
            b';' => Ok(Async::Ready(ChunkedState::Extension)),
            b'\r' => Ok(Async::Ready(ChunkedState::SizeLf)),
            _ => {
                Err(io::Error::new(io::ErrorKind::InvalidInput,
                                   "Invalid chunk size linear white space"))
            }
        }
    }
    fn read_extension(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        trace!("read_extension");
        match byte!(rdr) {
            b'\r' => Ok(Async::Ready(ChunkedState::SizeLf)),
            _ => Ok(Async::Ready(ChunkedState::Extension)), // no supported extensions
        }
    }
    fn read_size_lf(rdr: &mut BytesMut, size: &mut u64) -> Poll<ChunkedState, io::Error> {
        trace!("Chunk size is {:?}", size);
        match byte!(rdr) {
            b'\n' if *size > 0 => Ok(Async::Ready(ChunkedState::Body)),
            b'\n' if *size == 0 => Ok(Async::Ready(ChunkedState::EndCr)),
            _ => Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid chunk size LF")),
        }
    }

    fn read_body(rdr: &mut BytesMut, rem: &mut u64, buf: &mut Option<Bytes>)
                 -> Poll<ChunkedState, io::Error>
    {
        trace!("Chunked read, remaining={:?}", rem);

        let len = rdr.len() as u64;
        if len == 0 {
            Ok(Async::Ready(ChunkedState::Body))
        } else {
            let slice;
            if *rem > len {
                slice = rdr.take().freeze();
                *rem -= len;
            } else {
                slice = rdr.split_to(*rem as usize).freeze();
                *rem = 0;
            }
            *buf = Some(slice);
            if *rem > 0 {
                Ok(Async::Ready(ChunkedState::Body))
            } else {
                Ok(Async::Ready(ChunkedState::BodyCr))
            }
        }
    }

    fn read_body_cr(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        match byte!(rdr) {
            b'\r' => Ok(Async::Ready(ChunkedState::BodyLf)),
            _ => Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid chunk body CR")),
        }
    }
    fn read_body_lf(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        match byte!(rdr) {
            b'\n' => Ok(Async::Ready(ChunkedState::Size)),
            _ => Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid chunk body LF")),
        }
    }
    fn read_end_cr(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        match byte!(rdr) {
            b'\r' => Ok(Async::Ready(ChunkedState::EndLf)),
            _ => Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid chunk end CR")),
        }
    }
    fn read_end_lf(rdr: &mut BytesMut) -> Poll<ChunkedState, io::Error> {
        match byte!(rdr) {
            b'\n' => Ok(Async::Ready(ChunkedState::End)),
            _ => Err(io::Error::new(io::ErrorKind::InvalidInput, "Invalid chunk end LF")),
        }
    }
}

#[cfg(test)]
mod tests {
    use std::{io, cmp};
    use bytes::{Bytes, BytesMut};
    use futures::{Async};
    use tokio_io::AsyncRead;
    use http::{Version, Method};
    use super::*;

    struct Buffer {
        buf: Bytes,
        err: Option<io::Error>,
    }

    impl Buffer {
        fn new(data: &'static str) -> Buffer {
            Buffer {
                buf: Bytes::from(data),
                err: None,
            }
        }
        fn feed_data(&mut self, data: &'static str) {
            let mut b = BytesMut::from(self.buf.as_ref());
            b.extend(data.as_bytes());
            self.buf = b.take().freeze();
        }
    }
    
    impl AsyncRead for Buffer {}
    impl io::Read for Buffer {
        fn read(&mut self, dst: &mut [u8]) -> Result<usize, io::Error> {
            if self.buf.is_empty() {
                if self.err.is_some() {
                    Err(self.err.take().unwrap())
                } else {
                    Err(io::Error::new(io::ErrorKind::WouldBlock, ""))
                }
            } else {
                let size = cmp::min(self.buf.len(), dst.len());
                let b = self.buf.split_to(size);
                dst[..size].copy_from_slice(&b);
                Ok(size)
            }
        }
    }

    macro_rules! not_ready {
        ($e:expr) => (match $e {
            Ok(Async::NotReady) => (),
            Err(err) => panic!("Unexpected error: {:?}", err),
            _ => panic!("Should not be ready"),
        })
    }

    macro_rules! parse_ready {
        ($e:expr) => (
            match Reader::new().parse($e, &mut BytesMut::new()) {
                Ok(Async::Ready(Item::Http1(req, payload))) => (req, payload),
                Ok(_) => panic!("Eof during parsing http request"),
                Err(err) => panic!("Error during parsing http request: {:?}", err),
            }
        )
    }

    macro_rules! reader_parse_ready {
        ($e:expr) => (
            match $e {
                Ok(Async::Ready(Item::Http1(req, payload))) => (req, payload),
                Ok(_) => panic!("Eof during parsing http request"),
                Err(err) => panic!("Error during parsing http request: {:?}", err),
            }
        )
    }

    macro_rules! expect_parse_err {
        ($e:expr) => ({
            let mut buf = BytesMut::new();
            match Reader::new().parse($e, &mut buf) {
                Err(err) => match err {
                    ReaderError::Error(_) => (),
                    _ => panic!("Parse error expected"),
                },
                val => {
                    panic!("Error expected")
                }
            }}
        )
    }

    #[test]
    fn test_parse() {
        let mut buf = Buffer::new("GET /test HTTP/1.1\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::GET);
                assert_eq!(req.path(), "/test");
                assert!(payload.eof());
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_parse_partial() {
        let mut buf = Buffer::new("PUT /test HTTP/1");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::NotReady) => (),
            _ => panic!("Error"),
        }

        buf.feed_data(".1\r\n\r\n");
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::PUT);
                assert_eq!(req.path(), "/test");
                assert!(payload.eof());
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_parse_post() {
        let mut buf = Buffer::new("POST /test2 HTTP/1.0\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, payload))) => {
                assert_eq!(req.version(), Version::HTTP_10);
                assert_eq!(*req.method(), Method::POST);
                assert_eq!(req.path(), "/test2");
                assert!(payload.eof());
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_parse_body() {
        let mut buf = Buffer::new("GET /test HTTP/1.1\r\nContent-Length: 4\r\n\r\nbody");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, mut payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::GET);
                assert_eq!(req.path(), "/test");
                assert_eq!(payload.readall().unwrap().as_ref(), b"body");
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_parse_body_crlf() {
        let mut buf = Buffer::new(
            "\r\nGET /test HTTP/1.1\r\nContent-Length: 4\r\n\r\nbody");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, mut payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::GET);
                assert_eq!(req.path(), "/test");
                assert_eq!(payload.readall().unwrap().as_ref(), b"body");
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_parse_partial_eof() {
        let mut buf = Buffer::new("GET /test HTTP/1.1\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        not_ready!{ reader.parse(&mut buf, &mut readbuf) }

        buf.feed_data("\r\n");
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::GET);
                assert_eq!(req.path(), "/test");
                assert!(payload.eof());
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_headers_split_field() {
        let mut buf = Buffer::new("GET /test HTTP/1.1\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        not_ready!{ reader.parse(&mut buf, &mut readbuf) }

        buf.feed_data("t");
        not_ready!{ reader.parse(&mut buf, &mut readbuf) }

        buf.feed_data("es");
        not_ready!{ reader.parse(&mut buf, &mut readbuf) }

        buf.feed_data("t: value\r\n\r\n");
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, payload))) => {
                assert_eq!(req.version(), Version::HTTP_11);
                assert_eq!(*req.method(), Method::GET);
                assert_eq!(req.path(), "/test");
                assert_eq!(req.headers().get("test").unwrap().as_bytes(), b"value");
                assert!(payload.eof());
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_headers_multi_value() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             Set-Cookie: c1=cookie1\r\n\
             Set-Cookie: c2=cookie2\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http1(req, _))) => {
                let val: Vec<_> = req.headers().get_all("Set-Cookie")
                    .iter().map(|v| v.to_str().unwrap().to_owned()).collect();
                assert_eq!(val[0], "c1=cookie1");
                assert_eq!(val[1], "c2=cookie2");
            }
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }

    #[test]
    fn test_conn_default_1_0() {
        let mut buf = Buffer::new("GET /test HTTP/1.0\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(!req.keep_alive());
    }

    #[test]
    fn test_conn_default_1_1() {
        let mut buf = Buffer::new("GET /test HTTP/1.1\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(req.keep_alive());
    }

    #[test]
    fn test_conn_close() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             connection: close\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(!req.keep_alive());
    }

    #[test]
    fn test_conn_close_1_0() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.0\r\n\
             connection: close\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(!req.keep_alive());
    }

    #[test]
    fn test_conn_keep_alive_1_0() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.0\r\n\
             connection: keep-alive\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(req.keep_alive());
    }

    #[test]
    fn test_conn_keep_alive_1_1() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             connection: keep-alive\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(req.keep_alive());
    }

    #[test]
    fn test_conn_other_1_0() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.0\r\n\
             connection: other\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(!req.keep_alive());
    }

    #[test]
    fn test_conn_other_1_1() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             connection: other\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert!(req.keep_alive());
    }

    #[test]
    fn test_conn_upgrade() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             connection: upgrade\r\n\r\n");
        let (req, payload) = parse_ready!(&mut buf);

        assert!(!payload.eof());
        assert!(req.upgrade());
    }

    #[test]
    fn test_conn_upgrade_connect_method() {
        let mut buf = Buffer::new(
            "CONNECT /test HTTP/1.1\r\n\
             content-length: 0\r\n\r\n");
        let (req, payload) = parse_ready!(&mut buf);

        assert!(req.upgrade());
        assert!(!payload.eof());
    }

    #[test]
    fn test_request_chunked() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");
        let (req, payload) = parse_ready!(&mut buf);

        assert!(!payload.eof());
        if let Ok(val) = req.chunked() {
            assert!(val);
        } else {
            panic!("Error");
        }

        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chnked\r\n\r\n");
        let (req, payload) = parse_ready!(&mut buf);

        assert!(payload.eof());
        if let Ok(val) = req.chunked() {
            assert!(!val);
        } else {
            panic!("Error");
        }
    }

    #[test]
    fn test_headers_content_length_err_1() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             content-length: line\r\n\r\n");

        expect_parse_err!(&mut buf)
    }

    #[test]
    fn test_headers_content_length_err_2() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             content-length: -1\r\n\r\n");

        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_invalid_header() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             test line\r\n\r\n");

        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_invalid_name() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             test[]: line\r\n\r\n");

        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_http_request_bad_status_line() {
        let mut buf = Buffer::new("getpath \r\n\r\n");
        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_http_request_upgrade() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             connection: upgrade\r\n\
             upgrade: websocket\r\n\r\n\
             some raw data");
        let (req, mut payload) = parse_ready!(&mut buf);
        assert!(!req.keep_alive());
        assert!(req.upgrade());
        assert_eq!(payload.readall().unwrap().as_ref(), b"some raw data");
    }

    #[test]
    fn test_http_request_parser_utf8() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             x-test: тест\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert_eq!(req.headers().get("x-test").unwrap().as_bytes(),
                   "тест".as_bytes());
    }

    #[test]
    fn test_http_request_parser_two_slashes() {
        let mut buf = Buffer::new(
            "GET //path HTTP/1.1\r\n\r\n");
        let (req, _) = parse_ready!(&mut buf);

        assert_eq!(req.path(), "//path");
    }

    #[test]
    fn test_http_request_parser_bad_method() {
        let mut buf = Buffer::new(
            "!12%()+=~$ /get HTTP/1.1\r\n\r\n");

        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_http_request_parser_bad_version() {
        let mut buf = Buffer::new("GET //get HT/11\r\n\r\n");

        expect_parse_err!(&mut buf);
    }

    #[test]
    fn test_http_request_chunked_payload() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        let (req, mut payload) = reader_parse_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(req.chunked().unwrap());
        assert!(!payload.eof());

        buf.feed_data("4\r\ndata\r\n4\r\nline\r\n0\r\n\r\n");
        not_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(!payload.eof());
        assert_eq!(payload.readall().unwrap().as_ref(), b"dataline");
        assert!(payload.eof());
    }

    #[test]
    fn test_http_request_chunked_payload_and_next_message() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();

        let (req, mut payload) = reader_parse_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(req.chunked().unwrap());
        assert!(!payload.eof());

        buf.feed_data(
            "4\r\ndata\r\n4\r\nline\r\n0\r\n\r\n\
             POST /test2 HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");

        let (req2, payload2) = reader_parse_ready!(reader.parse(&mut buf, &mut readbuf));
        assert_eq!(*req2.method(), Method::POST);
        assert!(req2.chunked().unwrap());
        assert!(!payload2.eof());

        assert_eq!(payload.readall().unwrap().as_ref(), b"dataline");
        assert!(payload.eof());
    }

    #[test]
    fn test_http_request_chunked_payload_chunks() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        let (req, mut payload) = reader_parse_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(req.chunked().unwrap());
        assert!(!payload.eof());

        buf.feed_data("4\r\ndata\r");
        not_ready!(reader.parse(&mut buf, &mut readbuf));

        buf.feed_data("\n4");
        not_ready!(reader.parse(&mut buf, &mut readbuf));

        buf.feed_data("\r");
        not_ready!(reader.parse(&mut buf, &mut readbuf));
        buf.feed_data("\n");
        not_ready!(reader.parse(&mut buf, &mut readbuf));

        buf.feed_data("li");
        not_ready!(reader.parse(&mut buf, &mut readbuf));

        buf.feed_data("ne\r\n0\r\n");
        not_ready!(reader.parse(&mut buf, &mut readbuf));

        //buf.feed_data("test: test\r\n");
        //not_ready!(reader.parse(&mut buf, &mut readbuf));

        assert_eq!(payload.readall().unwrap().as_ref(), b"dataline");
        assert!(!payload.eof());

        buf.feed_data("\r\n");
        not_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(payload.eof());
    }

    #[test]
    fn test_parse_chunked_payload_chunk_extension() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        let (req, mut payload) = reader_parse_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(req.chunked().unwrap());
        assert!(!payload.eof());

        buf.feed_data("4;test\r\ndata\r\n4\r\nline\r\n0\r\n\r\n"); // test: test\r\n\r\n")
        not_ready!(reader.parse(&mut buf, &mut readbuf));
        assert!(!payload.eof());
        assert_eq!(payload.readall().unwrap().as_ref(), b"dataline");
        assert!(payload.eof());
    }

    /*#[test]
    #[should_panic]
    fn test_parse_multiline() {
        let mut buf = Buffer::new(
            "GET /test HTTP/1.1\r\n\
             test: line\r\n \
               continue\r\n\
             test2: data\r\n\
             \r\n", false);

        let mut reader = Reader::new();
        match reader.parse(&mut buf) {
            Ok(res) => (),
            Err(err) => panic!("{:?}", err),
        }
    }*/

    #[test]
    fn test_http2_prefix() {
        let mut buf = Buffer::new("PRI * HTTP/2.0\r\n\r\n");
        let mut readbuf = BytesMut::new();

        let mut reader = Reader::new();
        match reader.parse(&mut buf, &mut readbuf) {
            Ok(Async::Ready(Item::Http2)) => (),
            Ok(_) | Err(_) => panic!("Error during parsing http request"),
        }
    }
}