// `mem::uninitialized` replaced with `mem::MaybeUninit`,
// can't upgrade yet
#![allow(deprecated)]

use std::fmt::{self, Write};
use std::mem;

use bytes::BytesMut;
use http::header::{self, Entry, HeaderName, HeaderValue};
use http::{HeaderMap, Method, StatusCode, Version};

use crate::error::Parse;
use crate::headers;
use crate::proto::h1::{
    date, Encode, Encoder, Http1Transaction, ParseContext, ParseResult, ParsedMessage,
};
use crate::proto::{BodyLength, DecodedLength, MessageHead, RequestHead, RequestLine};

const MAX_HEADERS: usize = 100;
const AVERAGE_HEADER_SIZE: usize = 30; // totally scientific

macro_rules! header_name {
    ($bytes:expr) => {{
        #[cfg(debug_assertions)]
        {
            match HeaderName::from_bytes($bytes) {
                Ok(name) => name,
                Err(_) => panic!(
                    "illegal header name from httparse: {:?}",
                    ::bytes::Bytes::copy_from_slice($bytes)
                ),
            }
        }

        #[cfg(not(debug_assertions))]
        {
            HeaderName::from_bytes($bytes).expect("header name validated by httparse")
        }
    }};
}

macro_rules! header_value {
    ($bytes:expr) => {{
        #[cfg(debug_assertions)]
        {
            let __hvb: ::bytes::Bytes = $bytes;
            match HeaderValue::from_maybe_shared(__hvb.clone()) {
                Ok(name) => name,
                Err(_) => panic!("illegal header value from httparse: {:?}", __hvb),
            }
        }

        #[cfg(not(debug_assertions))]
        {
            // Unsafe: httparse already validated header value
            unsafe { HeaderValue::from_maybe_shared_unchecked($bytes) }
        }
    }};
}

// There are 2 main roles, Client and Server.

pub(crate) enum Client {}

pub(crate) enum Server {}

impl Http1Transaction for Server {
    type Incoming = RequestLine;
    type Outgoing = StatusCode;
    const LOG: &'static str = "{role=server}";

    fn parse(buf: &mut BytesMut, ctx: ParseContext<'_>) -> ParseResult<RequestLine> {
        if buf.is_empty() {
            return Ok(None);
        }

        let mut keep_alive;
        let is_http_11;
        let subject;
        let version;
        let len;
        let headers_len;

        // Unsafe: both headers_indices and headers are using unitialized memory,
        // but we *never* read any of it until after httparse has assigned
        // values into it. By not zeroing out the stack memory, this saves
        // a good ~5% on pipeline benchmarks.
        let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
        {
            let mut headers: [httparse::Header<'_>; MAX_HEADERS] = unsafe { mem::uninitialized() };
            trace!(
                "Request.parse([Header; {}], [u8; {}])",
                headers.len(),
                buf.len()
            );
            let mut req = httparse::Request::new(&mut headers);
            let bytes = buf.as_ref();
            match req.parse(bytes) {
                Ok(httparse::Status::Complete(parsed_len)) => {
                    trace!("Request.parse Complete({})", parsed_len);
                    len = parsed_len;
                    subject = RequestLine(
                        Method::from_bytes(req.method.unwrap().as_bytes())?,
                        req.path.unwrap().parse()?,
                    );
                    version = if req.version.unwrap() == 1 {
                        keep_alive = true;
                        is_http_11 = true;
                        Version::HTTP_11
                    } else {
                        keep_alive = false;
                        is_http_11 = false;
                        Version::HTTP_10
                    };

                    record_header_indices(bytes, &req.headers, &mut headers_indices)?;
                    headers_len = req.headers.len();
                }
                Ok(httparse::Status::Partial) => return Ok(None),
                Err(err) => {
                    return Err(match err {
                        // if invalid Token, try to determine if for method or path
                        httparse::Error::Token => {
                            if req.method.is_none() {
                                Parse::Method
                            } else {
                                debug_assert!(req.path.is_none());
                                Parse::Uri
                            }
                        }
                        other => other.into(),
                    });
                }
            }
        };

        let slice = buf.split_to(len).freeze();

        // According to https://tools.ietf.org/html/rfc7230#section-3.3.3
        // 1. (irrelevant to Request)
        // 2. (irrelevant to Request)
        // 3. Transfer-Encoding: chunked has a chunked body.
        // 4. If multiple differing Content-Length headers or invalid, close connection.
        // 5. Content-Length header has a sized body.
        // 6. Length 0.
        // 7. (irrelevant to Request)

        let mut decoder = DecodedLength::ZERO;
        let mut expect_continue = false;
        let mut con_len = None;
        let mut is_te = false;
        let mut is_te_chunked = false;
        let mut wants_upgrade = subject.0 == Method::CONNECT;

        let mut headers = ctx.cached_headers.take().unwrap_or_else(HeaderMap::new);

        headers.reserve(headers_len);

        for header in &headers_indices[..headers_len] {
            let name = header_name!(&slice[header.name.0..header.name.1]);
            let value = header_value!(slice.slice(header.value.0..header.value.1));

            match name {
                header::TRANSFER_ENCODING => {
                    // https://tools.ietf.org/html/rfc7230#section-3.3.3
                    // If Transfer-Encoding header is present, and 'chunked' is
                    // not the final encoding, and this is a Request, then it is
                    // mal-formed. A server should respond with 400 Bad Request.
                    if !is_http_11 {
                        debug!("HTTP/1.0 cannot have Transfer-Encoding header");
                        return Err(Parse::Header);
                    }
                    is_te = true;
                    if headers::is_chunked_(&value) {
                        is_te_chunked = true;
                        decoder = DecodedLength::CHUNKED;
                    }
                }
                header::CONTENT_LENGTH => {
                    if is_te {
                        continue;
                    }
                    let len = value
                        .to_str()
                        .map_err(|_| Parse::Header)
                        .and_then(|s| s.parse().map_err(|_| Parse::Header))?;
                    if let Some(prev) = con_len {
                        if prev != len {
                            debug!(
                                "multiple Content-Length headers with different values: [{}, {}]",
                                prev, len,
                            );
                            return Err(Parse::Header);
                        }
                        // we don't need to append this secondary length
                        continue;
                    }
                    decoder = DecodedLength::checked_new(len)?;
                    con_len = Some(len);
                }
                header::CONNECTION => {
                    // keep_alive was previously set to default for Version
                    if keep_alive {
                        // HTTP/1.1
                        keep_alive = !headers::connection_close(&value);
                    } else {
                        // HTTP/1.0
                        keep_alive = headers::connection_keep_alive(&value);
                    }
                }
                header::EXPECT => {
                    expect_continue = value.as_bytes() == b"100-continue";
                }
                header::UPGRADE => {
                    // Upgrades are only allowed with HTTP/1.1
                    wants_upgrade = is_http_11;
                }

                _ => (),
            }

            headers.append(name, value);
        }

        if is_te && !is_te_chunked {
            debug!("request with transfer-encoding header, but not chunked, bad request");
            return Err(Parse::Header);
        }

        *ctx.req_method = Some(subject.0.clone());

        Ok(Some(ParsedMessage {
            head: MessageHead {
                version,
                subject,
                headers,
            },
            decode: decoder,
            expect_continue,
            keep_alive,
            wants_upgrade,
        }))
    }

    fn encode(
        mut msg: Encode<'_, Self::Outgoing>,
        mut dst: &mut Vec<u8>,
    ) -> crate::Result<Encoder> {
        trace!(
            "Server::encode status={:?}, body={:?}, req_method={:?}",
            msg.head.subject,
            msg.body,
            msg.req_method
        );
        debug_assert!(
            !msg.title_case_headers,
            "no server config for title case headers"
        );

        let mut wrote_len = false;

        // hyper currently doesn't support returning 1xx status codes as a Response
        // This is because Service only allows returning a single Response, and
        // so if you try to reply with a e.g. 100 Continue, you have no way of
        // replying with the latter status code response.
        let (ret, mut is_last) = if msg.head.subject == StatusCode::SWITCHING_PROTOCOLS {
            (Ok(()), true)
        } else if msg.req_method == &Some(Method::CONNECT) && msg.head.subject.is_success() {
            // Sending content-length or transfer-encoding header on 2xx response
            // to CONNECT is forbidden in RFC 7231.
            wrote_len = true;
            (Ok(()), true)
        } else if msg.head.subject.is_informational() {
            warn!("response with 1xx status code not supported");
            *msg.head = MessageHead::default();
            msg.head.subject = StatusCode::INTERNAL_SERVER_ERROR;
            msg.body = None;
            (Err(crate::Error::new_user_unsupported_status_code()), true)
        } else {
            (Ok(()), !msg.keep_alive)
        };

        // In some error cases, we don't know about the invalid message until already
        // pushing some bytes onto the `dst`. In those cases, we don't want to send
        // the half-pushed message, so rewind to before.
        let orig_len = dst.len();
        let rewind = |dst: &mut Vec<u8>| {
            dst.truncate(orig_len);
        };

        let init_cap = 30 + msg.head.headers.len() * AVERAGE_HEADER_SIZE;
        dst.reserve(init_cap);
        if msg.head.version == Version::HTTP_11 && msg.head.subject == StatusCode::OK {
            extend(dst, b"HTTP/1.1 200 OK\r\n");
        } else {
            match msg.head.version {
                Version::HTTP_10 => extend(dst, b"HTTP/1.0 "),
                Version::HTTP_11 => extend(dst, b"HTTP/1.1 "),
                Version::HTTP_2 => {
                    warn!("response with HTTP2 version coerced to HTTP/1.1");
                    extend(dst, b"HTTP/1.1 ");
                }
                other => panic!("unexpected response version: {:?}", other),
            }

            extend(dst, msg.head.subject.as_str().as_bytes());
            extend(dst, b" ");
            // a reason MUST be written, as many parsers will expect it.
            extend(
                dst,
                msg.head
                    .subject
                    .canonical_reason()
                    .unwrap_or("<none>")
                    .as_bytes(),
            );
            extend(dst, b"\r\n");
        }

        let mut encoder = Encoder::length(0);
        let mut wrote_date = false;
        let mut cur_name = None;
        let mut is_name_written = false;
        let mut must_write_chunked = false;
        let mut prev_con_len = None;

        macro_rules! handle_is_name_written {
            () => {{
                if is_name_written {
                    // we need to clean up and write the newline
                    debug_assert_ne!(
                        &dst[dst.len() - 2..],
                        b"\r\n",
                        "previous header wrote newline but set is_name_written"
                    );

                    if must_write_chunked {
                        extend(dst, b", chunked\r\n");
                    } else {
                        extend(dst, b"\r\n");
                    }
                }
            }};
        }

        'headers: for (opt_name, value) in msg.head.headers.drain() {
            if let Some(n) = opt_name {
                cur_name = Some(n);
                handle_is_name_written!();
                is_name_written = false;
            }
            let name = cur_name.as_ref().expect("current header name");
            match *name {
                header::CONTENT_LENGTH => {
                    if wrote_len && !is_name_written {
                        warn!("unexpected content-length found, canceling");
                        rewind(dst);
                        return Err(crate::Error::new_user_header());
                    }
                    match msg.body {
                        Some(BodyLength::Known(known_len)) => {
                            // The Payload claims to know a length, and
                            // the headers are already set. For performance
                            // reasons, we are just going to trust that
                            // the values match.
                            //
                            // In debug builds, we'll assert they are the
                            // same to help developers find bugs.
                            #[cfg(debug_assertions)]
                            {
                                if let Some(len) = headers::content_length_parse(&value) {
                                    assert!(
                                        len == known_len,
                                        "payload claims content-length of {}, custom content-length header claims {}",
                                        known_len,
                                        len,
                                    );
                                }
                            }

                            if !is_name_written {
                                encoder = Encoder::length(known_len);
                                extend(dst, b"content-length: ");
                                extend(dst, value.as_bytes());
                                wrote_len = true;
                                is_name_written = true;
                            }
                            continue 'headers;
                        }
                        Some(BodyLength::Unknown) => {
                            // The Payload impl didn't know how long the
                            // body is, but a length header was included.
                            // We have to parse the value to return our
                            // Encoder...

                            if let Some(len) = headers::content_length_parse(&value) {
                                if let Some(prev) = prev_con_len {
                                    if prev != len {
                                        warn!(
                                            "multiple Content-Length values found: [{}, {}]",
                                            prev, len
                                        );
                                        rewind(dst);
                                        return Err(crate::Error::new_user_header());
                                    }
                                    debug_assert!(is_name_written);
                                    continue 'headers;
                                } else {
                                    // we haven't written content-lenght yet!
                                    encoder = Encoder::length(len);
                                    extend(dst, b"content-length: ");
                                    extend(dst, value.as_bytes());
                                    wrote_len = true;
                                    is_name_written = true;
                                    prev_con_len = Some(len);
                                    continue 'headers;
                                }
                            } else {
                                warn!("illegal Content-Length value: {:?}", value);
                                rewind(dst);
                                return Err(crate::Error::new_user_header());
                            }
                        }
                        None => {
                            // We have no body to actually send,
                            // but the headers claim a content-length.
                            // There's only 2 ways this makes sense:
                            //
                            // - The header says the length is `0`.
                            // - This is a response to a `HEAD` request.
                            if msg.req_method == &Some(Method::HEAD) {
                                debug_assert_eq!(encoder, Encoder::length(0));
                            } else {
                                if value.as_bytes() != b"0" {
                                    warn!(
                                        "content-length value found, but empty body provided: {:?}",
                                        value
                                    );
                                }
                                continue 'headers;
                            }
                        }
                    }
                    wrote_len = true;
                }
                header::TRANSFER_ENCODING => {
                    if wrote_len && !is_name_written {
                        warn!("unexpected transfer-encoding found, canceling");
                        rewind(dst);
                        return Err(crate::Error::new_user_header());
                    }
                    // check that we actually can send a chunked body...
                    if msg.head.version == Version::HTTP_10
                        || !Server::can_chunked(msg.req_method, msg.head.subject)
                    {
                        continue;
                    }
                    wrote_len = true;
                    // Must check each value, because `chunked` needs to be the
                    // last encoding, or else we add it.
                    must_write_chunked = !headers::is_chunked_(&value);

                    if !is_name_written {
                        encoder = Encoder::chunked();
                        is_name_written = true;
                        extend(dst, b"transfer-encoding: ");
                        extend(dst, value.as_bytes());
                    } else {
                        extend(dst, b", ");
                        extend(dst, value.as_bytes());
                    }
                    continue 'headers;
                }
                header::CONNECTION => {
                    if !is_last {
                        if headers::connection_close(&value) {
                            is_last = true;
                        }
                    }
                    if !is_name_written {
                        is_name_written = true;
                        extend(dst, b"connection: ");
                        extend(dst, value.as_bytes());
                    } else {
                        extend(dst, b", ");
                        extend(dst, value.as_bytes());
                    }
                    continue 'headers;
                }
                header::DATE => {
                    wrote_date = true;
                }
                _ => (),
            }
            //TODO: this should perhaps instead combine them into
            //single lines, as RFC7230 suggests is preferable.

            // non-special write Name and Value
            debug_assert!(
                !is_name_written,
                "{:?} set is_name_written and didn't continue loop",
                name,
            );
            extend(dst, name.as_str().as_bytes());
            extend(dst, b": ");
            extend(dst, value.as_bytes());
            extend(dst, b"\r\n");
        }

        handle_is_name_written!();

        if !wrote_len {
            encoder = match msg.body {
                Some(BodyLength::Unknown) => {
                    if msg.head.version == Version::HTTP_10
                        || !Server::can_chunked(msg.req_method, msg.head.subject)
                    {
                        Encoder::close_delimited()
                    } else {
                        extend(dst, b"transfer-encoding: chunked\r\n");
                        Encoder::chunked()
                    }
                }
                None | Some(BodyLength::Known(0)) => {
                    if msg.head.subject != StatusCode::NOT_MODIFIED {
                        extend(dst, b"content-length: 0\r\n");
                    }
                    Encoder::length(0)
                }
                Some(BodyLength::Known(len)) => {
                    if msg.head.subject == StatusCode::NOT_MODIFIED {
                        Encoder::length(0)
                    } else {
                        extend(dst, b"content-length: ");
                        let _ = ::itoa::write(&mut dst, len);
                        extend(dst, b"\r\n");
                        Encoder::length(len)
                    }
                }
            };
        }

        if !Server::can_have_body(msg.req_method, msg.head.subject) {
            trace!(
                "server body forced to 0; method={:?}, status={:?}",
                msg.req_method,
                msg.head.subject
            );
            encoder = Encoder::length(0);
        }

        // cached date is much faster than formatting every request
        if !wrote_date {
            dst.reserve(date::DATE_VALUE_LENGTH + 8);
            extend(dst, b"date: ");
            date::extend(dst);
            extend(dst, b"\r\n\r\n");
        } else {
            extend(dst, b"\r\n");
        }

        ret.map(|()| encoder.set_last(is_last))
    }

    fn on_error(err: &crate::Error) -> Option<MessageHead<Self::Outgoing>> {
        use crate::error::Kind;
        let status = match *err.kind() {
            Kind::Parse(Parse::Method)
            | Kind::Parse(Parse::Header)
            | Kind::Parse(Parse::Uri)
            | Kind::Parse(Parse::Version) => StatusCode::BAD_REQUEST,
            Kind::Parse(Parse::TooLarge) => StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE,
            _ => return None,
        };

        debug!("sending automatic response ({}) for parse error", status);
        let mut msg = MessageHead::default();
        msg.subject = status;
        Some(msg)
    }

    fn is_server() -> bool {
        true
    }

    fn update_date() {
        date::update();
    }
}

impl Server {
    fn can_have_body(method: &Option<Method>, status: StatusCode) -> bool {
        Server::can_chunked(method, status)
    }

    fn can_chunked(method: &Option<Method>, status: StatusCode) -> bool {
        if method == &Some(Method::HEAD) {
            false
        } else if method == &Some(Method::CONNECT) && status.is_success() {
            false
        } else {
            match status {
                // TODO: support for 1xx codes needs improvement everywhere
                // would be 100...199 => false
                StatusCode::SWITCHING_PROTOCOLS
                | StatusCode::NO_CONTENT
                | StatusCode::NOT_MODIFIED => false,
                _ => true,
            }
        }
    }
}

impl Http1Transaction for Client {
    type Incoming = StatusCode;
    type Outgoing = RequestLine;
    const LOG: &'static str = "{role=client}";

    fn parse(buf: &mut BytesMut, ctx: ParseContext<'_>) -> ParseResult<StatusCode> {
        // Loop to skip information status code headers (100 Continue, etc).
        loop {
            if buf.is_empty() {
                return Ok(None);
            }
            // Unsafe: see comment in Server Http1Transaction, above.
            let mut headers_indices: [HeaderIndices; MAX_HEADERS] = unsafe { mem::uninitialized() };
            let (len, status, version, headers_len) = {
                let mut headers: [httparse::Header<'_>; MAX_HEADERS] =
                    unsafe { mem::uninitialized() };
                trace!(
                    "Response.parse([Header; {}], [u8; {}])",
                    headers.len(),
                    buf.len()
                );
                let mut res = httparse::Response::new(&mut headers);
                let bytes = buf.as_ref();
                match res.parse(bytes)? {
                    httparse::Status::Complete(len) => {
                        trace!("Response.parse Complete({})", len);
                        let status = StatusCode::from_u16(res.code.unwrap())?;
                        let version = if res.version.unwrap() == 1 {
                            Version::HTTP_11
                        } else {
                            Version::HTTP_10
                        };
                        record_header_indices(bytes, &res.headers, &mut headers_indices)?;
                        let headers_len = res.headers.len();
                        (len, status, version, headers_len)
                    }
                    httparse::Status::Partial => return Ok(None),
                }
            };

            let slice = buf.split_to(len).freeze();

            let mut headers = ctx.cached_headers.take().unwrap_or_else(HeaderMap::new);

            let mut keep_alive = version == Version::HTTP_11;

            headers.reserve(headers_len);
            for header in &headers_indices[..headers_len] {
                let name = header_name!(&slice[header.name.0..header.name.1]);
                let value = header_value!(slice.slice(header.value.0..header.value.1));

                if let header::CONNECTION = name {
                    // keep_alive was previously set to default for Version
                    if keep_alive {
                        // HTTP/1.1
                        keep_alive = !headers::connection_close(&value);
                    } else {
                        // HTTP/1.0
                        keep_alive = headers::connection_keep_alive(&value);
                    }
                }
                headers.append(name, value);
            }

            let head = MessageHead {
                version,
                subject: status,
                headers,
            };
            if let Some((decode, is_upgrade)) = Client::decoder(&head, ctx.req_method)? {
                return Ok(Some(ParsedMessage {
                    head,
                    decode,
                    expect_continue: false,
                    // a client upgrade means the connection can't be used
                    // again, as it is definitely upgrading.
                    keep_alive: keep_alive && !is_upgrade,
                    wants_upgrade: is_upgrade,
                }));
            }
        }
    }

    fn encode(msg: Encode<'_, Self::Outgoing>, dst: &mut Vec<u8>) -> crate::Result<Encoder> {
        trace!(
            "Client::encode method={:?}, body={:?}",
            msg.head.subject.0,
            msg.body
        );

        *msg.req_method = Some(msg.head.subject.0.clone());

        let body = Client::set_length(msg.head, msg.body);

        let init_cap = 30 + msg.head.headers.len() * AVERAGE_HEADER_SIZE;
        dst.reserve(init_cap);

        extend(dst, msg.head.subject.0.as_str().as_bytes());
        extend(dst, b" ");
        //TODO: add API to http::Uri to encode without std::fmt
        let _ = write!(FastWrite(dst), "{} ", msg.head.subject.1);

        match msg.head.version {
            Version::HTTP_10 => extend(dst, b"HTTP/1.0"),
            Version::HTTP_11 => extend(dst, b"HTTP/1.1"),
            Version::HTTP_2 => {
                warn!("request with HTTP2 version coerced to HTTP/1.1");
                extend(dst, b"HTTP/1.1");
            }
            other => panic!("unexpected request version: {:?}", other),
        }
        extend(dst, b"\r\n");

        if msg.title_case_headers {
            write_headers_title_case(&msg.head.headers, dst);
        } else {
            write_headers(&msg.head.headers, dst);
        }
        extend(dst, b"\r\n");
        msg.head.headers.clear(); //TODO: remove when switching to drain()

        Ok(body)
    }

    fn on_error(_err: &crate::Error) -> Option<MessageHead<Self::Outgoing>> {
        // we can't tell the server about any errors it creates
        None
    }

    fn is_client() -> bool {
        true
    }
}

impl Client {
    /// Returns Some(length, wants_upgrade) if successful.
    ///
    /// Returns None if this message head should be skipped (like a 100 status).
    fn decoder(
        inc: &MessageHead<StatusCode>,
        method: &mut Option<Method>,
    ) -> Result<Option<(DecodedLength, bool)>, Parse> {
        // According to https://tools.ietf.org/html/rfc7230#section-3.3.3
        // 1. HEAD responses, and Status 1xx, 204, and 304 cannot have a body.
        // 2. Status 2xx to a CONNECT cannot have a body.
        // 3. Transfer-Encoding: chunked has a chunked body.
        // 4. If multiple differing Content-Length headers or invalid, close connection.
        // 5. Content-Length header has a sized body.
        // 6. (irrelevant to Response)
        // 7. Read till EOF.

        match inc.subject.as_u16() {
            101 => {
                return Ok(Some((DecodedLength::ZERO, true)));
            }
            100..=199 => {
                trace!("ignoring informational response: {}", inc.subject.as_u16());
                return Ok(None);
            }
            204 | 304 => return Ok(Some((DecodedLength::ZERO, false))),
            _ => (),
        }
        match *method {
            Some(Method::HEAD) => {
                return Ok(Some((DecodedLength::ZERO, false)));
            }
            Some(Method::CONNECT) => {
                if let 200..=299 = inc.subject.as_u16() {
                    return Ok(Some((DecodedLength::ZERO, true)));
                }
            }
            Some(_) => {}
            None => {
                trace!("Client::decoder is missing the Method");
            }
        }

        if inc.headers.contains_key(header::TRANSFER_ENCODING) {
            // https://tools.ietf.org/html/rfc7230#section-3.3.3
            // If Transfer-Encoding header is present, and 'chunked' is
            // not the final encoding, and this is a Request, then it is
            // mal-formed. A server should respond with 400 Bad Request.
            if inc.version == Version::HTTP_10 {
                debug!("HTTP/1.0 cannot have Transfer-Encoding header");
                Err(Parse::Header)
            } else if headers::transfer_encoding_is_chunked(&inc.headers) {
                Ok(Some((DecodedLength::CHUNKED, false)))
            } else {
                trace!("not chunked, read till eof");
                Ok(Some((DecodedLength::CLOSE_DELIMITED, false)))
            }
        } else if let Some(len) = headers::content_length_parse_all(&inc.headers) {
            Ok(Some((DecodedLength::checked_new(len)?, false)))
        } else if inc.headers.contains_key(header::CONTENT_LENGTH) {
            debug!("illegal Content-Length header");
            Err(Parse::Header)
        } else {
            trace!("neither Transfer-Encoding nor Content-Length");
            Ok(Some((DecodedLength::CLOSE_DELIMITED, false)))
        }
    }
}

impl Client {
    fn set_length(head: &mut RequestHead, body: Option<BodyLength>) -> Encoder {
        let body = if let Some(body) = body {
            body
        } else {
            head.headers.remove(header::TRANSFER_ENCODING);
            return Encoder::length(0);
        };

        // HTTP/1.0 doesn't know about chunked
        let can_chunked = head.version == Version::HTTP_11;
        let headers = &mut head.headers;

        // If the user already set specific headers, we should respect them, regardless
        // of what the Payload knows about itself. They set them for a reason.

        // Because of the borrow checker, we can't check the for an existing
        // Content-Length header while holding an `Entry` for the Transfer-Encoding
        // header, so unfortunately, we must do the check here, first.

        let existing_con_len = headers::content_length_parse_all(headers);
        let mut should_remove_con_len = false;

        if !can_chunked {
            // Chunked isn't legal, so if it is set, we need to remove it.
            if headers.remove(header::TRANSFER_ENCODING).is_some() {
                trace!("removing illegal transfer-encoding header");
            }

            return if let Some(len) = existing_con_len {
                Encoder::length(len)
            } else if let BodyLength::Known(len) = body {
                set_content_length(headers, len)
            } else {
                // HTTP/1.0 client requests without a content-length
                // cannot have any body at all.
                Encoder::length(0)
            };
        }

        // If the user set a transfer-encoding, respect that. Let's just
        // make sure `chunked` is the final encoding.
        let encoder = match headers.entry(header::TRANSFER_ENCODING) {
            Entry::Occupied(te) => {
                should_remove_con_len = true;
                if headers::is_chunked(te.iter()) {
                    Some(Encoder::chunked())
                } else {
                    warn!("user provided transfer-encoding does not end in 'chunked'");

                    // There's a Transfer-Encoding, but it doesn't end in 'chunked'!
                    // An example that could trigger this:
                    //
                    //     Transfer-Encoding: gzip
                    //
                    // This can be bad, depending on if this is a request or a
                    // response.
                    //
                    // - A request is illegal if there is a `Transfer-Encoding`
                    //   but it doesn't end in `chunked`.
                    // - A response that has `Transfer-Encoding` but doesn't
                    //   end in `chunked` isn't illegal, it just forces this
                    //   to be close-delimited.
                    //
                    // We can try to repair this, by adding `chunked` ourselves.

                    headers::add_chunked(te);
                    Some(Encoder::chunked())
                }
            }
            Entry::Vacant(te) => {
                if let Some(len) = existing_con_len {
                    Some(Encoder::length(len))
                } else if let BodyLength::Unknown = body {
                    // GET, HEAD, and CONNECT almost never have bodies.
                    //
                    // So instead of sending a "chunked" body with a 0-chunk,
                    // assume no body here. If you *must* send a body,
                    // set the headers explicitly.
                    match head.subject.0 {
                        Method::GET | Method::HEAD | Method::CONNECT => Some(Encoder::length(0)),
                        _ => {
                            te.insert(HeaderValue::from_static("chunked"));
                            Some(Encoder::chunked())
                        }
                    }
                } else {
                    None
                }
            }
        };

        // This is because we need a second mutable borrow to remove
        // content-length header.
        if let Some(encoder) = encoder {
            if should_remove_con_len && existing_con_len.is_some() {
                headers.remove(header::CONTENT_LENGTH);
            }
            return encoder;
        }

        // User didn't set transfer-encoding, AND we know body length,
        // so we can just set the Content-Length automatically.

        let len = if let BodyLength::Known(len) = body {
            len
        } else {
            unreachable!("BodyLength::Unknown would set chunked");
        };

        set_content_length(headers, len)
    }
}

fn set_content_length(headers: &mut HeaderMap, len: u64) -> Encoder {
    // At this point, there should not be a valid Content-Length
    // header. However, since we'll be indexing in anyways, we can
    // warn the user if there was an existing illegal header.
    //
    // Or at least, we can in theory. It's actually a little bit slower,
    // so perhaps only do that while the user is developing/testing.

    if cfg!(debug_assertions) {
        match headers.entry(header::CONTENT_LENGTH) {
            Entry::Occupied(mut cl) => {
                // Internal sanity check, we should have already determined
                // that the header was illegal before calling this function.
                debug_assert!(headers::content_length_parse_all_values(cl.iter()).is_none());
                // Uh oh, the user set `Content-Length` headers, but set bad ones.
                // This would be an illegal message anyways, so let's try to repair
                // with our known good length.
                error!("user provided content-length header was invalid");

                cl.insert(HeaderValue::from(len));
                Encoder::length(len)
            }
            Entry::Vacant(cl) => {
                cl.insert(HeaderValue::from(len));
                Encoder::length(len)
            }
        }
    } else {
        headers.insert(header::CONTENT_LENGTH, HeaderValue::from(len));
        Encoder::length(len)
    }
}

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

fn record_header_indices(
    bytes: &[u8],
    headers: &[httparse::Header<'_>],
    indices: &mut [HeaderIndices],
) -> Result<(), crate::error::Parse> {
    let bytes_ptr = bytes.as_ptr() as usize;

    for (header, indices) in headers.iter().zip(indices.iter_mut()) {
        if header.name.len() >= (1 << 16) {
            debug!("header name larger than 64kb: {:?}", header.name);
            return Err(crate::error::Parse::TooLarge);
        }
        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);
    }

    Ok(())
}

// Write header names as title case. The header name is assumed to be ASCII,
// therefore it is trivial to convert an ASCII character from lowercase to
// uppercase. It is as simple as XORing the lowercase character byte with
// space.
fn title_case(dst: &mut Vec<u8>, name: &[u8]) {
    dst.reserve(name.len());

    let mut iter = name.iter();

    // Uppercase the first character
    if let Some(c) = iter.next() {
        if *c >= b'a' && *c <= b'z' {
            dst.push(*c ^ b' ');
        } else {
            dst.push(*c);
        }
    }

    while let Some(c) = iter.next() {
        dst.push(*c);

        if *c == b'-' {
            if let Some(c) = iter.next() {
                if *c >= b'a' && *c <= b'z' {
                    dst.push(*c ^ b' ');
                } else {
                    dst.push(*c);
                }
            }
        }
    }
}

fn write_headers_title_case(headers: &HeaderMap, dst: &mut Vec<u8>) {
    for (name, value) in headers {
        title_case(dst, name.as_str().as_bytes());
        extend(dst, b": ");
        extend(dst, value.as_bytes());
        extend(dst, b"\r\n");
    }
}

fn write_headers(headers: &HeaderMap, dst: &mut Vec<u8>) {
    for (name, value) in headers {
        extend(dst, name.as_str().as_bytes());
        extend(dst, b": ");
        extend(dst, value.as_bytes());
        extend(dst, b"\r\n");
    }
}

struct FastWrite<'a>(&'a mut Vec<u8>);

impl<'a> fmt::Write for FastWrite<'a> {
    #[inline]
    fn write_str(&mut self, s: &str) -> fmt::Result {
        extend(self.0, s.as_bytes());
        Ok(())
    }

    #[inline]
    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> fmt::Result {
        fmt::write(self, args)
    }
}

#[inline]
fn extend(dst: &mut Vec<u8>, data: &[u8]) {
    dst.extend_from_slice(data);
}

#[cfg(test)]
mod tests {
    use bytes::BytesMut;

    use super::*;

    #[test]
    fn test_parse_request() {
        let _ = pretty_env_logger::try_init();
        let mut raw = BytesMut::from("GET /echo HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
        let mut method = None;
        let msg = Server::parse(
            &mut raw,
            ParseContext {
                cached_headers: &mut None,
                req_method: &mut method,
            },
        )
        .unwrap()
        .unwrap();
        assert_eq!(raw.len(), 0);
        assert_eq!(msg.head.subject.0, crate::Method::GET);
        assert_eq!(msg.head.subject.1, "/echo");
        assert_eq!(msg.head.version, crate::Version::HTTP_11);
        assert_eq!(msg.head.headers.len(), 1);
        assert_eq!(msg.head.headers["Host"], "hyper.rs");
        assert_eq!(method, Some(crate::Method::GET));
    }

    #[test]
    fn test_parse_response() {
        let _ = pretty_env_logger::try_init();
        let mut raw = BytesMut::from("HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n");
        let ctx = ParseContext {
            cached_headers: &mut None,
            req_method: &mut Some(crate::Method::GET),
        };
        let msg = Client::parse(&mut raw, ctx).unwrap().unwrap();
        assert_eq!(raw.len(), 0);
        assert_eq!(msg.head.subject, crate::StatusCode::OK);
        assert_eq!(msg.head.version, crate::Version::HTTP_11);
        assert_eq!(msg.head.headers.len(), 1);
        assert_eq!(msg.head.headers["Content-Length"], "0");
    }

    #[test]
    fn test_parse_request_errors() {
        let mut raw = BytesMut::from("GET htt:p// HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
        let ctx = ParseContext {
            cached_headers: &mut None,
            req_method: &mut None,
        };
        Server::parse(&mut raw, ctx).unwrap_err();
    }

    #[test]
    fn test_decoder_request() {
        fn parse(s: &str) -> ParsedMessage<RequestLine> {
            let mut bytes = BytesMut::from(s);
            Server::parse(
                &mut bytes,
                ParseContext {
                    cached_headers: &mut None,
                    req_method: &mut None,
                },
            )
            .expect("parse ok")
            .expect("parse complete")
        }

        fn parse_err(s: &str, comment: &str) -> crate::error::Parse {
            let mut bytes = BytesMut::from(s);
            Server::parse(
                &mut bytes,
                ParseContext {
                    cached_headers: &mut None,
                    req_method: &mut None,
                },
            )
            .expect_err(comment)
        }

        // no length or transfer-encoding means 0-length body
        assert_eq!(
            parse(
                "\
                 GET / HTTP/1.1\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::ZERO
        );

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::ZERO
        );

        // transfer-encoding: chunked
        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 transfer-encoding: gzip, chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 transfer-encoding: gzip\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        // content-length
        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 content-length: 10\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::new(10)
        );

        // transfer-encoding and content-length = chunked
        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 content-length: 10\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 transfer-encoding: chunked\r\n\
                 content-length: 10\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 transfer-encoding: gzip\r\n\
                 content-length: 10\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        // multiple content-lengths of same value are fine
        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.1\r\n\
                 content-length: 10\r\n\
                 content-length: 10\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::new(10)
        );

        // multiple content-lengths with different values is an error
        parse_err(
            "\
             POST / HTTP/1.1\r\n\
             content-length: 10\r\n\
             content-length: 11\r\n\
             \r\n\
             ",
            "multiple content-lengths",
        );

        // transfer-encoding that isn't chunked is an error
        parse_err(
            "\
             POST / HTTP/1.1\r\n\
             transfer-encoding: gzip\r\n\
             \r\n\
             ",
            "transfer-encoding but not chunked",
        );

        parse_err(
            "\
             POST / HTTP/1.1\r\n\
             transfer-encoding: chunked, gzip\r\n\
             \r\n\
             ",
            "transfer-encoding doesn't end in chunked",
        );

        // http/1.0

        assert_eq!(
            parse(
                "\
                 POST / HTTP/1.0\r\n\
                 content-length: 10\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::new(10)
        );

        // 1.0 doesn't understand chunked, so its an error
        parse_err(
            "\
             POST / HTTP/1.0\r\n\
             transfer-encoding: chunked\r\n\
             \r\n\
             ",
            "1.0 chunked",
        );
    }

    #[test]
    fn test_decoder_response() {
        fn parse(s: &str) -> ParsedMessage<StatusCode> {
            parse_with_method(s, Method::GET)
        }

        fn parse_ignores(s: &str) {
            let mut bytes = BytesMut::from(s);
            assert!(Client::parse(
                &mut bytes,
                ParseContext {
                    cached_headers: &mut None,
                    req_method: &mut Some(Method::GET),
                }
            )
            .expect("parse ok")
            .is_none())
        }

        fn parse_with_method(s: &str, m: Method) -> ParsedMessage<StatusCode> {
            let mut bytes = BytesMut::from(s);
            Client::parse(
                &mut bytes,
                ParseContext {
                    cached_headers: &mut None,
                    req_method: &mut Some(m),
                },
            )
            .expect("parse ok")
            .expect("parse complete")
        }

        fn parse_err(s: &str) -> crate::error::Parse {
            let mut bytes = BytesMut::from(s);
            Client::parse(
                &mut bytes,
                ParseContext {
                    cached_headers: &mut None,
                    req_method: &mut Some(Method::GET),
                },
            )
            .expect_err("parse should err")
        }

        // no content-length or transfer-encoding means close-delimited
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CLOSE_DELIMITED
        );

        // 204 and 304 never have a body
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 204 No Content\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::ZERO
        );

        assert_eq!(
            parse(
                "\
                 HTTP/1.1 304 Not Modified\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::ZERO
        );

        // content-length
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 8\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::new(8)
        );

        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 8\r\n\
                 content-length: 8\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::new(8)
        );

        parse_err(
            "\
             HTTP/1.1 200 OK\r\n\
             content-length: 8\r\n\
             content-length: 9\r\n\
             \r\n\
             ",
        );

        // transfer-encoding: chunked
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        // transfer-encoding not-chunked is close-delimited
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 transfer-encoding: yolo\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CLOSE_DELIMITED
        );

        // transfer-encoding and content-length = chunked
        assert_eq!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 10\r\n\
                 transfer-encoding: chunked\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CHUNKED
        );

        // HEAD can have content-length, but not body
        assert_eq!(
            parse_with_method(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 8\r\n\
                 \r\n\
                 ",
                Method::HEAD
            )
            .decode,
            DecodedLength::ZERO
        );

        // CONNECT with 200 never has body
        {
            let msg = parse_with_method(
                "\
                 HTTP/1.1 200 OK\r\n\
                 \r\n\
                 ",
                Method::CONNECT,
            );
            assert_eq!(msg.decode, DecodedLength::ZERO);
            assert!(!msg.keep_alive, "should be upgrade");
            assert!(msg.wants_upgrade, "should be upgrade");
        }

        // CONNECT receiving non 200 can have a body
        assert_eq!(
            parse_with_method(
                "\
                 HTTP/1.1 400 Bad Request\r\n\
                 \r\n\
                 ",
                Method::CONNECT
            )
            .decode,
            DecodedLength::CLOSE_DELIMITED
        );

        // 1xx status codes
        parse_ignores(
            "\
             HTTP/1.1 100 Continue\r\n\
             \r\n\
             ",
        );

        parse_ignores(
            "\
             HTTP/1.1 103 Early Hints\r\n\
             \r\n\
             ",
        );

        // 101 upgrade not supported yet
        {
            let msg = parse(
                "\
                 HTTP/1.1 101 Switching Protocols\r\n\
                 \r\n\
                 ",
            );
            assert_eq!(msg.decode, DecodedLength::ZERO);
            assert!(!msg.keep_alive, "should be last");
            assert!(msg.wants_upgrade, "should be upgrade");
        }

        // http/1.0
        assert_eq!(
            parse(
                "\
                 HTTP/1.0 200 OK\r\n\
                 \r\n\
                 "
            )
            .decode,
            DecodedLength::CLOSE_DELIMITED
        );

        // 1.0 doesn't understand chunked
        parse_err(
            "\
             HTTP/1.0 200 OK\r\n\
             transfer-encoding: chunked\r\n\
             \r\n\
             ",
        );

        // keep-alive
        assert!(
            parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 0\r\n\
                 \r\n\
                 "
            )
            .keep_alive,
            "HTTP/1.1 keep-alive is default"
        );

        assert!(
            !parse(
                "\
                 HTTP/1.1 200 OK\r\n\
                 content-length: 0\r\n\
                 connection: foo, close, bar\r\n\
                 \r\n\
                 "
            )
            .keep_alive,
            "connection close is always close"
        );

        assert!(
            !parse(
                "\
                 HTTP/1.0 200 OK\r\n\
                 content-length: 0\r\n\
                 \r\n\
                 "
            )
            .keep_alive,
            "HTTP/1.0 close is default"
        );

        assert!(
            parse(
                "\
                 HTTP/1.0 200 OK\r\n\
                 content-length: 0\r\n\
                 connection: foo, keep-alive, bar\r\n\
                 \r\n\
                 "
            )
            .keep_alive,
            "connection keep-alive is always keep-alive"
        );
    }

    #[test]
    fn test_client_request_encode_title_case() {
        use crate::proto::BodyLength;
        use http::header::HeaderValue;

        let mut head = MessageHead::default();
        head.headers
            .insert("content-length", HeaderValue::from_static("10"));
        head.headers
            .insert("content-type", HeaderValue::from_static("application/json"));
        head.headers.insert("*-*", HeaderValue::from_static("o_o"));

        let mut vec = Vec::new();
        Client::encode(
            Encode {
                head: &mut head,
                body: Some(BodyLength::Known(10)),
                keep_alive: true,
                req_method: &mut None,
                title_case_headers: true,
            },
            &mut vec,
        )
        .unwrap();

        assert_eq!(vec, b"GET / HTTP/1.1\r\nContent-Length: 10\r\nContent-Type: application/json\r\n*-*: o_o\r\n\r\n".to_vec());
    }

    #[test]
    fn test_server_encode_connect_method() {
        let mut head = MessageHead::default();

        let mut vec = Vec::new();
        let encoder = Server::encode(
            Encode {
                head: &mut head,
                body: None,
                keep_alive: true,
                req_method: &mut Some(Method::CONNECT),
                title_case_headers: false,
            },
            &mut vec,
        )
        .unwrap();

        assert!(encoder.is_last());
    }

    #[test]
    fn parse_header_htabs() {
        let mut bytes = BytesMut::from("HTTP/1.1 200 OK\r\nserver: hello\tworld\r\n\r\n");
        let parsed = Client::parse(
            &mut bytes,
            ParseContext {
                cached_headers: &mut None,
                req_method: &mut Some(Method::GET),
            },
        )
        .expect("parse ok")
        .expect("parse complete");

        assert_eq!(parsed.head.headers["server"], "hello\tworld");
    }

    #[cfg(feature = "nightly")]
    use test::Bencher;

    #[cfg(feature = "nightly")]
    #[bench]
    fn bench_parse_incoming(b: &mut Bencher) {
        let mut raw = BytesMut::from(
            &b"GET /super_long_uri/and_whatever?what_should_we_talk_about/\
            I_wonder/Hard_to_write_in_an_uri_after_all/you_have_to_make\
            _up_the_punctuation_yourself/how_fun_is_that?test=foo&test1=\
            foo1&test2=foo2&test3=foo3&test4=foo4 HTTP/1.1\r\nHost: \
            hyper.rs\r\nAccept: a lot of things\r\nAccept-Charset: \
            utf8\r\nAccept-Encoding: *\r\nAccess-Control-Allow-\
            Credentials: None\r\nAccess-Control-Allow-Origin: None\r\n\
            Access-Control-Allow-Methods: None\r\nAccess-Control-Allow-\
            Headers: None\r\nContent-Encoding: utf8\r\nContent-Security-\
            Policy: None\r\nContent-Type: text/html\r\nOrigin: hyper\
            \r\nSec-Websocket-Extensions: It looks super important!\r\n\
            Sec-Websocket-Origin: hyper\r\nSec-Websocket-Version: 4.3\r\
            \nStrict-Transport-Security: None\r\nUser-Agent: hyper\r\n\
            X-Content-Duration: None\r\nX-Content-Security-Policy: None\
            \r\nX-DNSPrefetch-Control: None\r\nX-Frame-Options: \
            Something important obviously\r\nX-Requested-With: Nothing\
            \r\n\r\n"[..],
        );
        let len = raw.len();
        let mut headers = Some(HeaderMap::new());

        b.bytes = len as u64;
        b.iter(|| {
            let mut msg = Server::parse(
                &mut raw,
                ParseContext {
                    cached_headers: &mut headers,
                    req_method: &mut None,
                },
            )
            .unwrap()
            .unwrap();
            ::test::black_box(&msg);
            msg.head.headers.clear();
            headers = Some(msg.head.headers);
            restart(&mut raw, len);
        });

        fn restart(b: &mut BytesMut, len: usize) {
            b.reserve(1);
            unsafe {
                b.set_len(len);
            }
        }
    }

    #[cfg(feature = "nightly")]
    #[bench]
    fn bench_parse_short(b: &mut Bencher) {
        let s = &b"GET / HTTP/1.1\r\nHost: localhost:8080\r\n\r\n"[..];
        let mut raw = BytesMut::from(s);
        let len = raw.len();
        let mut headers = Some(HeaderMap::new());

        b.bytes = len as u64;
        b.iter(|| {
            let mut msg = Server::parse(
                &mut raw,
                ParseContext {
                    cached_headers: &mut headers,
                    req_method: &mut None,
                },
            )
            .unwrap()
            .unwrap();
            ::test::black_box(&msg);
            msg.head.headers.clear();
            headers = Some(msg.head.headers);
            restart(&mut raw, len);
        });

        fn restart(b: &mut BytesMut, len: usize) {
            b.reserve(1);
            unsafe {
                b.set_len(len);
            }
        }
    }

    #[cfg(feature = "nightly")]
    #[bench]
    fn bench_server_encode_headers_preset(b: &mut Bencher) {
        use crate::proto::BodyLength;
        use http::header::HeaderValue;

        let len = 108;
        b.bytes = len as u64;

        let mut head = MessageHead::default();
        let mut headers = HeaderMap::new();
        headers.insert("content-length", HeaderValue::from_static("10"));
        headers.insert("content-type", HeaderValue::from_static("application/json"));

        b.iter(|| {
            let mut vec = Vec::new();
            head.headers = headers.clone();
            Server::encode(
                Encode {
                    head: &mut head,
                    body: Some(BodyLength::Known(10)),
                    keep_alive: true,
                    req_method: &mut Some(Method::GET),
                    title_case_headers: false,
                },
                &mut vec,
            )
            .unwrap();
            assert_eq!(vec.len(), len);
            ::test::black_box(vec);
        })
    }

    #[cfg(feature = "nightly")]
    #[bench]
    fn bench_server_encode_no_headers(b: &mut Bencher) {
        use crate::proto::BodyLength;

        let len = 76;
        b.bytes = len as u64;

        let mut head = MessageHead::default();
        let mut vec = Vec::with_capacity(128);

        b.iter(|| {
            Server::encode(
                Encode {
                    head: &mut head,
                    body: Some(BodyLength::Known(10)),
                    keep_alive: true,
                    req_method: &mut Some(Method::GET),
                    title_case_headers: false,
                },
                &mut vec,
            )
            .unwrap();
            assert_eq!(vec.len(), len);
            ::test::black_box(&vec);

            vec.clear();
        })
    }
}
