//FIXME: we disallow warnings for the HTTP/2 module temporarily
#![allow(warnings)]
use std::{cell::RefCell, net::SocketAddr, rc::Weak};

use mio::{net::TcpStream, *};
use rusty_ulid::Ulid;

use crate::{
    Protocol, Readiness, SessionMetrics, StateResult,
    pool::{Checkout, Pool},
    socket::{SocketHandler, SocketResult},
    sozu_command::{buffer::fixed::Buffer, ready::Ready},
};

mod parser;
mod serializer;
mod state;
mod stream;

type BackendToken = Token;

#[derive(PartialEq)]
pub enum SessionStatus {
    Normal,
    DefaultAnswer,
}

pub struct Http2<Front: SocketHandler> {
    pub frontend: Connection<Front>,
    backend: Option<TcpStream>,
    frontend_token: Token,
    backend_token: Option<Token>,
    back_buf: Option<Checkout>,
    pub cluster_id: Option<String>,
    pub request_id: Ulid,
    pub back_readiness: Readiness,
    pub log_ctx: String,
    public_address: Option<SocketAddr>,
    pub state: Option<state::State>,
    pool: Weak<RefCell<Pool>>,
}

impl<Front: SocketHandler> Http2<Front> {
    pub fn new(
        frontend: Front,
        frontend_token: Token,
        pool: Weak<RefCell<Pool>>,
        public_address: Option<SocketAddr>,
        client_address: Option<SocketAddr>,
        sticky_name: String,
    ) -> Http2<Front> {
        let request_id = Ulid::generate();
        let log_ctx = format!("{}\tunknown\t", &request_id);
        let (read, write) = {
            let p0 = pool.upgrade().unwrap();
            let mut p = p0.borrow_mut();
            let res = (p.checkout().unwrap(), p.checkout().unwrap());
            res
        };
        let session = Http2 {
            frontend: Connection::new(frontend, read, write),
            frontend_token,
            backend: None,
            backend_token: None,
            back_buf: None,
            cluster_id: None,
            state: Some(state::State::new()),
            request_id,
            back_readiness: Readiness {
                interest: Ready::READABLE | Ready::WRITABLE | Ready::HUP | Ready::ERROR,
                event: Ready::EMPTY,
            },
            log_ctx,
            public_address,
            pool,
        };

        trace!("created http2");
        session
    }

    pub fn front_socket(&self) -> &TcpStream {
        self.frontend.socket.socket_ref()
    }

    pub fn front_socket_mut(&mut self) -> &mut TcpStream {
        self.frontend.socket.socket_mut()
    }

    pub fn back_socket(&self) -> Option<&TcpStream> {
        self.backend.as_ref()
    }

    pub fn back_socket_mut(&mut self) -> Option<&mut TcpStream> {
        self.backend.as_mut()
    }

    pub fn set_back_socket(&mut self, socket: TcpStream) {
        self.backend = Some(socket);
    }

    pub fn back_token(&self) -> Option<Token> {
        self.backend_token
    }

    pub fn log_context(&self) -> String {
        if let Some(ref cluster_id) = self.cluster_id {
            format!("{}\t{}\t", self.request_id, cluster_id)
        } else {
            format!("{}\tunknown\t", self.request_id)
        }
    }

    pub fn set_back_token(&mut self, token: Token) {
        self.backend_token = Some(token);
    }

    pub fn front_hup(&mut self) -> StateResult {
        StateResult::CloseSession
    }

    pub fn back_hup(&mut self) -> StateResult {
        error!("todo[{}:{}]: back_hup", file!(), line!());
        StateResult::CloseSession
        /*
        if self.back_buf.output_data_size() == 0 || self.back_buf.next_output_data().len() == 0 {
          if self.back_readiness.event.is_readable() {
            self.back_readiness().interest.insert(Ready::READABLE);
            error!("Http2::back_hup: backend connection closed but the kernel still holds some data. readiness: {:?} -> {:?}", self.frontend.readiness, self.back_readiness);
            SessionResult::Continue
          } else {
            SessionResult::CloseSession
          }
        } else {
          self.frontend.readiness().interest.insert(Ready::WRITABLE);
          if self.back_readiness.event.is_readable() {
            self.back_readiness.interest.insert(Ready::READABLE);
          }
          SessionResult::Continue
        }
        */
    }

    // Read content from the session
    pub fn readable(&mut self, metrics: &mut SessionMetrics) -> StateResult {
        trace!("http2 readable");
        error!("todo[{}:{}]: readable", file!(), line!());

        /* do not handle buffer pooling for now
        if self.front_buf.is_none() {
          if let Some(p) = self.pool.upgrade() {
            if let Some(buf) = p.borrow_mut().checkout() {
              self.front_buf = Some(buf);
            } else {
              error!("cannot get front buffer from pool, closing");
              return SessionResult::CloseSession;
            }
          }
        }
        */

        if self.frontend.read_buffer.available_space() == 0 {
            if self.backend_token == None {
                //let answer_413 = "HTTP/1.1 413 Payload Too Large\r\nContent-Length: 0\r\n\r\n";
                //self.set_answer(DefaultAnswerStatus::Answer413, Rc::new(Vec::from(answer_413.as_bytes())));
                self.frontend.readiness.interest.remove(Ready::READABLE);
                self.frontend.readiness.interest.insert(Ready::WRITABLE);
            } else {
                self.frontend.readiness.interest.remove(Ready::READABLE);
                self.back_readiness.interest.insert(Ready::WRITABLE);
            }
            return StateResult::Continue;
        }

        let res = self.frontend.read(metrics);

        match res {
            SocketResult::Error => {
                let front_readiness = self.frontend.readiness.clone();
                let back_readiness = self.back_readiness.clone();
                error!(
                    "front socket error, closing the connection. Readiness: {:?} -> {:?}",
                    front_readiness, back_readiness
                );
                return StateResult::CloseSession;
            }
            SocketResult::Closed => {
                return StateResult::CloseSession;
            }
            SocketResult::WouldBlock => {}
            SocketResult::Continue => {}
        };

        self.readable_parse(metrics)
    }

    pub fn readable_parse(&mut self, metrics: &mut SessionMetrics) -> StateResult {
        let mut state = self.state.take().unwrap();
        let (sz, cont) = { state.parse_and_handle(self.frontend.read_buffer.data()) };
        self.frontend.read_buffer.consume(sz);
        self.frontend.readiness.interest = state.interest;
        self.state = Some(state);

        match cont {
            state::FrameResult::Close => StateResult::CloseSession,
            state::FrameResult::Continue => StateResult::Continue,
            state::FrameResult::ConnectBackend(id) => StateResult::ConnectBackend,
        }

        /*let is_initial = unwrap_msg!(self.state.as_ref()).request == Some(RequestState::Initial);
        // if there's no host, continue parsing until we find it
        let has_host = unwrap_msg!(self.state.as_ref()).has_host();
        if !has_host {
          self.state = Some(parse_request_until_stop(unwrap_msg!(self.state.take()), &self.request_id,
            &mut self.front_buf.as_mut().unwrap(), &self.sticky_name));
          if unwrap_msg!(self.state.as_ref()).is_front_error() {
            self.log_request_error(metrics, "front parsing error, closing the connection");
            incr!("http.front_parse_errors");

            // increment active requests here because it will be decremented right away
            // when closing the connection. It's slightly easier than decrementing it
            // at every place we return SessionResult::CloseSession
            gauge_add!("http.active_requests", 1);

            return SessionResult::CloseSession;
          }
        }
        */
    }

    // Forward content to session
    pub fn writable(&mut self, metrics: &mut SessionMetrics) -> StateResult {
        trace!("http2 writable");
        error!("todo[{}:{}]: writable", file!(), line!());

        let mut state = self.state.take().unwrap();
        //FIXME: do that in a loop until no more frames or WouldBlock
        match state.r#gen(self.frontend.write_buffer.space()) {
            Ok(sz) => {
                self.frontend.write_buffer.fill(sz);
                //FIXME: use real condition here to indicate there was nothing to write
                if sz == 0 {}
            }
            Err(e) => {
                self.state = Some(state);
                error!("error serializing to front write buffer: {:?}", e);
                return StateResult::CloseSession;
            }
        }

        self.frontend.readiness.interest = state.interest;

        let res = self.frontend.write(metrics);
        match res {
            SocketResult::Error | SocketResult::Closed => {
                error!(
                    "{}\t[{:?}] error writing to front socket, closing",
                    self.log_ctx, self.frontend_token
                );
                incr!("http2.errors");
                metrics.service_stop();
                self.frontend.readiness.reset();
                self.back_readiness.reset();
                self.state = Some(state);
                return StateResult::CloseSession;
            }
            SocketResult::WouldBlock => {}
            SocketResult::Continue => {}
        }

        self.state = Some(state);
        StateResult::Continue
    }

    // Forward content to cluster
    pub fn back_writable(&mut self, metrics: &mut SessionMetrics) -> StateResult {
        trace!("http2 back_writable");
        error!("todo[{}:{}]: back_writable", file!(), line!());
        StateResult::CloseSession
        /*
        if self.front_buf.output_data_size() == 0 || self.front_buf.next_output_data().len() == 0 {
          self.frontend.readiness.interest.insert(Ready::READABLE);
          self.back_readiness.interest.remove(Ready::WRITABLE);
          return SessionResult::Continue;
        }

        let tokens = self.tokens().clone();
        let output_size = self.front_buf.output_data_size();

        let mut sz = 0usize;
        let mut socket_res = SocketResult::Continue;

        if let Some(ref mut backend) = self.backend {
          while socket_res == SocketResult::Continue && self.front_buf.output_data_size() > 0 {
            // no more data in buffer, stop here
            if self.front_buf.next_output_data().len() == 0 {
              self.frontend.readiness.interest.insert(Ready::READABLE);
              self.back_readiness.interest.remove(Ready::WRITABLE);
              return SessionResult::Continue;
            }

            let (current_sz, current_res) = backend.socket_write(self.front_buf.next_output_data());
            socket_res = current_res;
            self.front_buf.consume_output_data(current_sz);
            self.front_buf_position += current_sz;
            sz += current_sz;
          }
        }

        metrics.backend_bout += sz;

        if let Some((front,back)) = tokens {
          debug!("{}\tBACK [{}->{}]: wrote {} bytes of {}", self.log_ctx, front.0, back.0, sz, output_size);
        }
        match socket_res {
          SocketResult::Error | SocketResult::Closed => {
            error!("{}\tback socket write error, closing connection", self.log_ctx);
            metrics.service_stop();
            incr!("http2.errors");
            self.frontend.readiness.reset();
            self.back_readiness.reset();
            return SessionResult::CloseSession;
          },
          SocketResult::WouldBlock => {
            self.back_readiness.event.remove(Ready::WRITABLE);

          },
          SocketResult::Continue => {}
        }
        SessionResult::Continue
        */
    }

    // Read content from cluster
    pub fn back_readable(&mut self, metrics: &mut SessionMetrics) -> StateResult {
        trace!("http2 back_readable");
        error!("todo[{}:{}]: back_readable", file!(), line!());
        StateResult::CloseSession
        /*
        if self.back_buf.buffer.available_space() == 0 {
          self.back_readiness.interest.remove(Ready::READABLE);
          return SessionResult::Continue;
        }

        let tokens     = self.tokens().clone();

        if let Some(ref mut backend) = self.backend {
          let (sz, r) = backend.socket_read(&mut self.back_buf.buffer.space());
          self.back_buf.buffer.fill(sz);
          self.back_buf.sliced_input(sz);
          self.back_buf.consume_parsed_data(sz);
          self.back_buf.slice_output(sz);

          if let Some((front,back)) = tokens {
            debug!("{}\tBACK  [{}<-{}]: read {} bytes", self.log_ctx, front.0, back.0, sz);
          }

          if r != SocketResult::Continue || sz == 0 {
            self.back_readiness.event.remove(Ready::READABLE);
          }
          if sz > 0 {
            self.frontend.readiness.interest.insert(Ready::WRITABLE);
            metrics.backend_bin += sz;
          }

          match r {
            SocketResult::Error => {
              error!("{}\tback socket read error, closing connection", self.log_ctx);
              metrics.service_stop();
              incr!("http2.errors");
              self.frontend.readiness.reset();
              self.back_readiness.reset();
              return SessionResult::CloseSession;
            },
            SocketResult::Closed => {
              metrics.service_stop();
              self.frontend.readiness.reset();
              self.back_readiness.reset();
              return SessionResult::CloseSession;
            },
            SocketResult::WouldBlock => {
              self.back_readiness.event.remove(Ready::READABLE);
            },
            SocketResult::Continue => {}
          }
        }

        SessionResult::Continue
        */
    }
}

pub struct Connection<Socket: SocketHandler> {
    pub socket: Socket,
    pub readiness: Readiness,
    pub read_buffer: Checkout,
    pub write_buffer: Checkout,
}

impl<Socket: SocketHandler> Connection<Socket> {
    pub fn new(socket: Socket, read_buffer: Checkout, write_buffer: Checkout) -> Self {
        Connection {
            socket,
            readiness: Readiness {
                interest: Ready::READABLE | Ready::WRITABLE | Ready::HUP | Ready::ERROR,
                event: Ready::EMPTY,
            },
            //FIXME: capacity can be configured
            read_buffer,
            //FIXME: capacity can be configured
            write_buffer,
        }
    }

    pub fn read(&mut self, metrics: &mut SessionMetrics) -> SocketResult {
        let (sz, res) = self.socket.socket_read(self.read_buffer.space());

        if sz > 0 {
            count!("bytes_in", sz as i64);
            metrics.bin += sz;

            self.read_buffer.fill(sz);

            if self.read_buffer.available_space() == 0 {
                self.readiness.interest.remove(Ready::READABLE);
            }
        } else {
            self.readiness.event.remove(Ready::READABLE);
        }

        if res == SocketResult::WouldBlock {
            self.readiness.event.remove(Ready::READABLE);
        }

        res
    }

    pub fn write(&mut self, metrics: &mut SessionMetrics) -> SocketResult {
        let mut sz = 0usize;
        let mut res = SocketResult::Continue;
        while res == SocketResult::Continue && self.write_buffer.available_data() > 0 {
            let (current_sz, current_res) = self.socket.socket_write(self.write_buffer.data());
            res = current_res;
            self.write_buffer.consume(current_sz);
            sz += current_sz;
        }

        if sz > 0 {
            count!("bytes_out", sz as i64);
            metrics.bout += sz;
        }

        if res == SocketResult::WouldBlock {
            self.readiness.event.remove(Ready::WRITABLE);
        }

        res
    }
}
