#![allow(unused_imports, unused_variables, dead_code)]
use std::fmt;
use std::io::{self, Write};

use actix_codec::{Decoder, Encoder};
use bitflags::bitflags;
use bytes::{BufMut, Bytes, BytesMut};
use http::header::{HeaderValue, CONNECTION, CONTENT_LENGTH, DATE, TRANSFER_ENCODING};
use http::{Method, StatusCode, Version};

use super::decoder::{PayloadDecoder, PayloadItem, PayloadType};
use super::{decoder, encoder};
use super::{Message, MessageType};
use crate::body::BodySize;
use crate::config::ServiceConfig;
use crate::error::ParseError;
use crate::helpers;
use crate::message::{ConnectionType, Head, ResponseHead};
use crate::request::Request;
use crate::response::Response;

bitflags! {
    struct Flags: u8 {
        const HEAD              = 0b0000_0001;
        const KEEPALIVE_ENABLED = 0b0000_1000;
        const STREAM            = 0b0001_0000;
    }
}

const AVERAGE_HEADER_SIZE: usize = 30;

/// HTTP/1 Codec
pub struct Codec {
    pub(crate) config: ServiceConfig,
    decoder: decoder::MessageDecoder<Request>,
    payload: Option<PayloadDecoder>,
    version: Version,
    ctype: ConnectionType,

    // encoder part
    flags: Flags,
    headers_size: u32,
    encoder: encoder::MessageEncoder<Response<()>>,
}

impl Default for Codec {
    fn default() -> Self {
        Codec::new(ServiceConfig::default())
    }
}

impl fmt::Debug for Codec {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "h1::Codec({:?})", self.flags)
    }
}

impl Codec {
    /// Create HTTP/1 codec.
    ///
    /// `keepalive_enabled` how response `connection` header get generated.
    pub fn new(config: ServiceConfig) -> Self {
        let flags = if config.keep_alive_enabled() {
            Flags::KEEPALIVE_ENABLED
        } else {
            Flags::empty()
        };
        Codec {
            config,
            decoder: decoder::MessageDecoder::default(),
            payload: None,
            version: Version::HTTP_11,
            ctype: ConnectionType::Close,

            flags,
            headers_size: 0,
            encoder: encoder::MessageEncoder::default(),
        }
    }

    #[inline]
    /// Check if request is upgrade
    pub fn upgrade(&self) -> bool {
        self.ctype == ConnectionType::Upgrade
    }

    #[inline]
    /// Check if last response is keep-alive
    pub fn keepalive(&self) -> bool {
        self.ctype == ConnectionType::KeepAlive
    }

    #[inline]
    /// Check if keep-alive enabled on server level
    pub fn keepalive_enabled(&self) -> bool {
        self.flags.contains(Flags::KEEPALIVE_ENABLED)
    }

    #[inline]
    /// Check last request's message type
    pub fn message_type(&self) -> MessageType {
        if self.flags.contains(Flags::STREAM) {
            MessageType::Stream
        } else if self.payload.is_none() {
            MessageType::None
        } else {
            MessageType::Payload
        }
    }
}

impl Decoder for Codec {
    type Item = Message<Request>;
    type Error = ParseError;

    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
        if self.payload.is_some() {
            Ok(match self.payload.as_mut().unwrap().decode(src)? {
                Some(PayloadItem::Chunk(chunk)) => Some(Message::Chunk(Some(chunk))),
                Some(PayloadItem::Eof) => {
                    self.payload.take();
                    Some(Message::Chunk(None))
                }
                None => None,
            })
        } else if let Some((req, payload)) = self.decoder.decode(src)? {
            let head = req.head();
            self.flags.set(Flags::HEAD, head.method == Method::HEAD);
            self.version = head.version;
            self.ctype = head.connection_type();
            if self.ctype == ConnectionType::KeepAlive
                && !self.flags.contains(Flags::KEEPALIVE_ENABLED)
            {
                self.ctype = ConnectionType::Close
            }
            match payload {
                PayloadType::None => self.payload = None,
                PayloadType::Payload(pl) => self.payload = Some(pl),
                PayloadType::Stream(pl) => {
                    self.payload = Some(pl);
                    self.flags.insert(Flags::STREAM);
                }
            }
            Ok(Some(Message::Item(req)))
        } else {
            Ok(None)
        }
    }
}

impl Encoder for Codec {
    type Item = Message<(Response<()>, BodySize)>;
    type Error = io::Error;

    fn encode(
        &mut self,
        item: Self::Item,
        dst: &mut BytesMut,
    ) -> Result<(), Self::Error> {
        match item {
            Message::Item((mut res, length)) => {
                if res.head().status == StatusCode::CONTINUE {
                    dst.extend_from_slice(b"HTTP/1.1 100 Continue\r\n\r\n");
                } else {
                    // set response version
                    res.head_mut().version = self.version;

                    // connection status
                    self.ctype = if let Some(ct) = res.head().ctype() {
                        if ct == ConnectionType::KeepAlive {
                            self.ctype
                        } else {
                            ct
                        }
                    } else {
                        self.ctype
                    };

                    // encode message
                    let len = dst.len();
                    self.encoder.encode(
                        dst,
                        &mut res,
                        self.flags.contains(Flags::HEAD),
                        self.flags.contains(Flags::STREAM),
                        self.version,
                        length,
                        self.ctype,
                        &self.config,
                    )?;
                    self.headers_size = (dst.len() - len) as u32;
                }
            }
            Message::Chunk(Some(bytes)) => {
                self.encoder.encode_chunk(bytes.as_ref(), dst)?;
            }
            Message::Chunk(None) => {
                self.encoder.encode_eof(dst)?;
            }
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::{cmp, io};

    use actix_codec::{AsyncRead, AsyncWrite};
    use bytes::{Buf, Bytes, BytesMut};
    use http::{Method, Version};

    use super::*;
    use crate::error::ParseError;
    use crate::h1::Message;
    use crate::httpmessage::HttpMessage;
    use crate::request::Request;

    #[test]
    fn test_http_request_chunked_payload_and_next_message() {
        let mut codec = Codec::default();

        let mut buf = BytesMut::from(
            "GET /test HTTP/1.1\r\n\
             transfer-encoding: chunked\r\n\r\n",
        );
        let item = codec.decode(&mut buf).unwrap().unwrap();
        let req = item.message();

        assert_eq!(req.method(), Method::GET);
        assert!(req.chunked().unwrap());

        buf.extend(
            b"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"
                .iter(),
        );

        let msg = codec.decode(&mut buf).unwrap().unwrap();
        assert_eq!(msg.chunk().as_ref(), b"data");

        let msg = codec.decode(&mut buf).unwrap().unwrap();
        assert_eq!(msg.chunk().as_ref(), b"line");

        let msg = codec.decode(&mut buf).unwrap().unwrap();
        assert!(msg.eof());

        // decode next message
        let item = codec.decode(&mut buf).unwrap().unwrap();
        let req = item.message();
        assert_eq!(*req.method(), Method::POST);
        assert!(req.chunked().unwrap());
    }
}