use std::sync::atomic::Ordering;
use std::time::Duration;
use std::io::ErrorKind;

use hashbrown::HashMap;
use mio::{net::TcpStream, Events, Poll, Interest, Token};
use rand::{rngs::SmallRng, prelude::*};
use tungstenite::{WebSocket, HandshakeError, ClientHandshake, handshake::MidHandshake};

use crate::common::*;
use crate::config::*;
use crate::utils::create_random_request;


pub enum ConnectionState {
    TcpStream(TcpStream),
    WebSocket(WebSocket<TcpStream>),
    MidHandshake(MidHandshake<ClientHandshake<TcpStream>>)
}


impl ConnectionState {
    fn advance(self, config: &Config) -> Option<Self> {
        match self {
            Self::TcpStream(stream) => {
                let req = format!(
                    "ws://{}:{}",
                    config.server_address.ip(),
                    config.server_address.port()
                );

                match ::tungstenite::client(req, stream){
                    Ok((ws, _)) => {
                        Some(ConnectionState::WebSocket(ws))
                    },
                    Err(HandshakeError::Interrupted(handshake)) => {
                        Some(ConnectionState::MidHandshake(handshake))
                    },
                    Err(HandshakeError::Failure(err)) => {
                        eprintln!("handshake error: {:?}", err);

                        None
                    }
                }
            },
            Self::MidHandshake(handshake) => {
                match handshake.handshake() {
                    Ok((ws, _)) => {
                        Some(ConnectionState::WebSocket(ws))
                    },
                    Err(HandshakeError::Interrupted(handshake)) => {
                        Some(ConnectionState::MidHandshake(handshake))
                    },
                    Err(HandshakeError::Failure(err)) => {
                        eprintln!("handshake error: {:?}", err);

                        None
                    }
                }
            },
            Self::WebSocket(ws) => Some(Self::WebSocket(ws)),
        }
    }

}


pub struct Connection {
    stream: ConnectionState,
    can_send_initial: bool,
    marked_as_complete: bool
}


impl Connection {
    pub fn create_and_register(
        config: &Config,
        connections: &mut ConnectionMap,
        poll: &mut Poll,
        token_counter: &mut usize,
    ) -> anyhow::Result<()> {
        let mut stream = TcpStream::connect(config.server_address)?;
    
        poll.registry()
            .register(&mut stream, Token(*token_counter), Interest::READABLE)
            .unwrap();

        let connection  = Connection {
            stream: ConnectionState::TcpStream(stream),
            can_send_initial: false,
            marked_as_complete: false,
        };
    
        connections.insert(*token_counter, connection);

        *token_counter = *token_counter + 1;
    
        Ok(())
    }

    pub fn advance(self, config: &Config) -> Option<Self> {
        if let Some(stream) = self.stream.advance(config){
            Some(Self {
                stream,
                can_send_initial: self.can_send_initial,
                marked_as_complete: false,
            })
        } else {
            None
        }
    }

    pub fn read_response_and_send_request(
        &mut self,
        config: &Config,
        state: &LoadTestState,
        rng: &mut impl Rng,
    ){
        if let ConnectionState::WebSocket(ref mut ws) = self.stream {
            let mut send_request = false;

            loop {
                match ws.read_message(){
                    Ok(message) => {
                        send_request |= Self::register_response_type(state, message);
                    },
                    Err(tungstenite::Error::Io(err)) if err.kind() == ErrorKind::WouldBlock => {
                        self.can_send_initial = false;

                        break;
                    },
                    Err(err) => {
                        eprintln!("handle_read_event error: {}", err);

                        break;
                    }
                }
            };

            if send_request {
                self.send_request(
                    config,
                    state,
                    rng,
                );
            }
        }
    }

    fn register_response_type(
        state: &LoadTestState,
        message: ::tungstenite::Message,
    ) -> bool {
        if let ::tungstenite::Message::Text(text) = message {
            if text.contains("offer"){
                state.statistics.responses_offer
                    .fetch_add(1, Ordering::SeqCst);
                
                return false;
            } else if text.contains("announce"){
                state.statistics.responses_announce
                    .fetch_add(1, Ordering::SeqCst);
            } else if text.contains("scrape"){
                state.statistics.responses_scrape
                    .fetch_add(1, Ordering::SeqCst);
            }
        }

        true
    }

    pub fn send_request(
        &mut self,
        config: &Config,
        state: &LoadTestState,
        rng: &mut impl Rng,
    ){
        if let ConnectionState::WebSocket(ref mut ws) = self.stream {
            let request = create_random_request(
                &config,
                &state,
                rng
            );

            let message = request.to_ws_message();

            match ws.write_message(message){
                Ok(_) => {
                    state.statistics.requests.fetch_add(1, Ordering::SeqCst);
                },
                Err(err) => {
                    eprintln!("send request error: {}", err);
                }
            }

            self.can_send_initial = false;
        } else {
            println!("send request can't send to non-ws stream");
        }
    }
}


pub type ConnectionMap = HashMap<usize, Connection>;


const NUM_CONNECTIONS: usize = 5;
const CREATE_CONN_INTERVAL: usize = 2 ^ 30;


pub fn run_socket_thread(
    config: &Config,
    state: LoadTestState,
    num_initial_requests: usize,
) {
    let timeout = Duration::from_micros(config.network.poll_timeout_microseconds);

    let mut connections: ConnectionMap = HashMap::with_capacity(NUM_CONNECTIONS);
    let mut poll = Poll::new().expect("create poll");
    let mut events = Events::with_capacity(config.network.poll_event_capacity);
    let mut rng = SmallRng::from_entropy();

    let mut token_counter = 0usize;

    for _ in 0..num_initial_requests {
        Connection::create_and_register(
            config,
            &mut connections,
            &mut poll,
            &mut token_counter,
        ).unwrap();
    }

    println!("num connections in map: {}", connections.len());

    let mut initial_sent = false;
    let mut iter_counter = 0usize;

    let mut num_completed = 0usize;

    loop {
        poll.poll(&mut events, Some(timeout))
            .expect("failed polling");

        for event in events.iter(){
            if event.is_readable(){
                let token = event.token();

                let mut run_advance = false;

                if let Some(connection) = connections.get_mut(&token.0){
                    if let ConnectionState::WebSocket(_) = connection.stream {
                        connection.read_response_and_send_request(
                            config,
                            &state,
                            &mut rng,
                        );
                    } else {
                        run_advance = true;

                        println!("set run_advance=true");
                    }
                } else {
                    eprintln!("connection not found: {:?}", token);
                }

                if run_advance {
                    let connection = connections.remove(&token.0).unwrap();

                    if let Some(connection) = connection.advance(config){
                        println!("advanced connection");
                        connections.insert(token.0, connection);
                    }
                }
            }
        }

        if num_completed != token_counter {
            for k in 0..token_counter {
                if let Some(mut connection) = connections.remove(&k){
                    if let ConnectionState::WebSocket(_) = connection.stream {
                        if !connection.marked_as_complete {
                            connection.can_send_initial = true;
                            connection.marked_as_complete = true;
                            initial_sent = false;
                            num_completed += 1;
                        }

                        connections.insert(k, connection);

                    } else {
                        if let Some(connection) = connection.advance(config){
                            connections.insert(k, connection);
                        }
                    }
                } else {
                    // println!("connection not found for token {}", k);
                }
            }
        }

        if !initial_sent {
            for (_, connection) in connections.iter_mut(){
                if connection.can_send_initial {

                    connection.send_request(
                        config,
                        &state,
                        &mut rng,
                    );

                    initial_sent = true;
                }
            }
        }

        // Slowly create new connections
        if token_counter < NUM_CONNECTIONS && iter_counter % CREATE_CONN_INTERVAL == 0 {
            let res = Connection::create_and_register(
                config,
                &mut connections,
                &mut poll,
                &mut token_counter,
            );

            if let Err(err) = res {
                eprintln!("create connection error: {}", err);
            }

            // initial_sent = false;
        }

        iter_counter = iter_counter.wrapping_add(1);
    }
}