use async_std::{
    net::{TcpListener, TcpStream},
    sync::{Arc, Mutex},
};
use std::{net::SocketAddr, sync::atomic::Ordering};

use async_channel::Receiver;
use async_executor::Executor;

use futures::{io::BufReader, AsyncBufReadExt, AsyncReadExt, FutureExt};
use fxhash::FxHashMap;
use log::{debug, error, info, warn};
use rand::rngs::OsRng;
use ringbuffer::RingBufferWrite;
use smol::future;
use structopt_toml::StructOptToml;

use darkfi::{
    async_daemonize, net,
    rpc::server::listen_and_serve,
    util::{
        cli::{get_log_config, get_log_level, spawn_config},
        path::get_config_path,
    },
    Error, Result,
};

pub mod crypto;
pub mod privmsg;
pub mod protocol_privmsg;
pub mod rpc;
pub mod server;
pub mod settings;

use crate::{
    crypto::try_decrypt_message,
    privmsg::{Privmsg, PrivmsgsBuffer, SeenMsgIds},
    protocol_privmsg::ProtocolPrivmsg,
    rpc::JsonRpcInterface,
    server::IrcServerConnection,
    settings::{parse_configured_channels, Args, ChannelInfo, CONFIG_FILE, CONFIG_FILE_CONTENTS},
};

const SIZE_OF_MSGS_BUFFER: usize = 4096;

fn clean_input(mut line: String, peer_addr: &SocketAddr) -> Result<String> {
    if line.is_empty() {
        warn!("Received empty line from {}. ", peer_addr);
        warn!("Closing connection.");
        return Err(Error::ChannelStopped)
    }

    if &line[(line.len() - 2)..] != "\r\n" {
        warn!("Closing connection.");
        return Err(Error::ChannelStopped)
    }

    // Remove CRLF
    line.pop();
    line.pop();

    Ok(line)
}

struct Ircd {
    // msgs
    seen_msg_ids: SeenMsgIds,
    privmsgs_buffer: PrivmsgsBuffer,
    // channels
    autojoin_chans: Vec<String>,
    configured_chans: FxHashMap<String, ChannelInfo>,
    // p2p
    p2p: net::P2pPtr,
    p2p_receiver: Receiver<Privmsg>,
}

impl Ircd {
    fn new(
        seen_msg_ids: SeenMsgIds,
        autojoin_chans: Vec<String>,
        configured_chans: FxHashMap<String, ChannelInfo>,
        p2p: net::P2pPtr,
        p2p_receiver: Receiver<Privmsg>,
    ) -> Self {
        let privmsgs_buffer: PrivmsgsBuffer =
            Arc::new(Mutex::new(ringbuffer::AllocRingBuffer::with_capacity(SIZE_OF_MSGS_BUFFER)));

        Self { seen_msg_ids, privmsgs_buffer, autojoin_chans, configured_chans, p2p, p2p_receiver }
    }

    async fn process(
        &self,
        executor: Arc<Executor<'_>>,
        stream: TcpStream,
        peer_addr: SocketAddr,
    ) -> Result<()> {
        let (reader, writer) = stream.split();

        let mut reader = BufReader::new(reader);
        let mut conn = IrcServerConnection::new(
            writer,
            self.seen_msg_ids.clone(),
            self.privmsgs_buffer.clone(),
            self.autojoin_chans.clone(),
            self.configured_chans.clone(),
            self.p2p.clone(),
        );

        let p2p_receiver = self.p2p_receiver.clone();
        let privmsgs_buffer = self.privmsgs_buffer.clone();

        executor.spawn(async move {
            loop {
                let mut line = String::new();
                futures::select! {
                    privmsg = p2p_receiver.recv().fuse() => {
                        let mut msg = privmsg?;
                        info!("Received msg from P2p network: {:?}", msg);

                        // Try to potentially decrypt the incoming message.
                        if conn.configured_chans.contains_key(&msg.channel) {
                            let chan_info = conn.configured_chans.get(&msg.channel).unwrap();
                            if !chan_info.joined.load(Ordering::Relaxed) {
                                continue
                            }
                            if let Some(salt_box) = &chan_info.salt_box {
                                if let Some(decrypted_msg) = try_decrypt_message(salt_box, &msg.message) {
                                    msg.message = decrypted_msg;
                                    info!("Decrypted received message: {:?}", msg);
                                }
                            }
                        }

                        // add the msg to buffer
                        {
                            (*privmsgs_buffer.lock().await).push(msg.clone());
                        }

                        conn.reply(&msg.to_irc_msg()).await?;
                    }
                    err = reader.read_line(&mut line).fuse() => {
                        if let Err(e) = err {
                            warn!("Read line error. Closing stream for {}: {}", peer_addr, e);
                            return Ok(())
                        }
                        info!("Received msg from IRC client: {:?}", line);
                        let irc_msg = match clean_input(line, &peer_addr) {
                            Ok(m) => m,
                            Err(e) => return Err(e)
                        };

                        info!("Send msg to IRC client '{}' from {}", irc_msg, peer_addr);

                        if let Err(e) = conn.update(irc_msg).await {
                            warn!("Connection error: {} for {}", e, peer_addr);
                            return Err(Error::ChannelStopped)
                        }
                    }
                };
            }
        }).detach();

        Ok(())
    }
}

async_daemonize!(realmain);
async fn realmain(settings: Args, executor: Arc<Executor<'_>>) -> Result<()> {
    let seen_msg_ids = Arc::new(Mutex::new(vec![]));

    if settings.gen_secret {
        let secret_key = crypto_box::SecretKey::generate(&mut OsRng);
        let encoded = bs58::encode(secret_key.as_bytes());
        println!("{}", encoded.into_string());
        return Ok(())
    }

    // Pick up channel settings from the TOML configuration
    let cfg_path = get_config_path(settings.config, CONFIG_FILE)?;
    let configured_chans = parse_configured_channels(&cfg_path)?;

    //
    // P2p setup
    //
    let net_settings = settings.net;
    let (p2p_send_channel, p2p_recv_channel) = async_channel::unbounded::<Privmsg>();

    let p2p = net::P2p::new(net_settings.into()).await;
    let p2p = p2p.clone();

    let registry = p2p.protocol_registry();

    let seen_msg_ids_cloned = seen_msg_ids.clone();
    registry
        .register(net::SESSION_ALL, move |channel, p2p| {
            let sender = p2p_send_channel.clone();
            let seen_msg_ids_cloned = seen_msg_ids_cloned.clone();
            async move { ProtocolPrivmsg::init(channel, sender, p2p, seen_msg_ids_cloned).await }
        })
        .await;

    p2p.clone().start(executor.clone()).await?;

    let executor_cloned = executor.clone();
    executor_cloned.spawn(p2p.clone().run(executor.clone())).detach();

    //
    // RPC interface
    //
    let rpc_listen_addr = settings.rpc_listen.clone();
    let rpc_interface =
        Arc::new(JsonRpcInterface { addr: rpc_listen_addr.clone(), p2p: p2p.clone() });
    executor.spawn(async move { listen_and_serve(rpc_listen_addr, rpc_interface).await }).detach();

    //
    // IRC instance
    //
    let irc_listen_addr = settings.irc_listen.socket_addrs(|| None)?[0];
    let listener = TcpListener::bind(irc_listen_addr).await?;
    let local_addr = listener.local_addr()?;
    info!("IRC listening on {}", local_addr);

    let executor_cloned = executor.clone();
    executor
        .spawn(async move {
            let ircd = Ircd::new(
                seen_msg_ids.clone(),
                settings.autojoin.clone(),
                configured_chans.clone(),
                p2p.clone(),
                p2p_recv_channel.clone(),
            );

            loop {
                let (stream, peer_addr) = match listener.accept().await {
                    Ok((s, a)) => (s, a),
                    Err(e) => {
                        error!("failed accepting new connections: {}", e);
                        continue
                    }
                };

                let result = ircd.process(executor_cloned.clone(), stream, peer_addr).await;

                if let Err(e) = result {
                    error!("failed process the {} connections: {}", peer_addr, e);
                    continue
                };

                info!("IRC Accepted new client: {}", peer_addr);
            }
        })
        .detach();

    // Run once receive exit signal
    let (signal, shutdown) = async_channel::bounded::<()>(1);
    ctrlc_async::set_async_handler(async move {
        warn!(target: "ircd", "ircd start Exit Signal");
        // cleaning up tasks running in the background
        signal.send(()).await.unwrap();
    })
    .unwrap();

    // Wait for SIGINT
    shutdown.recv().await?;
    print!("\r");
    info!("Caught termination signal, cleaning up and exiting...");

    Ok(())
}