use crate::rpc::{RPCEvent, RPCMessage, Rpc};
use crate::NetworkConfig;
use futures::prelude::*;
use libp2p::{
    core::{
        swarm::{NetworkBehaviourAction, NetworkBehaviourEventProcess},
        PublicKey,
    },
    gossipsub::{Gossipsub, GossipsubEvent},
    identify::{protocol::IdentifyInfo, Identify, IdentifyEvent},
    ping::{Ping, PingEvent},
    tokio_io::{AsyncRead, AsyncWrite},
    NetworkBehaviour, PeerId,
};
use slog::{debug, o};
use types::Topic;

/// Builds the network behaviour for the libp2p Swarm.
/// Implements gossipsub message routing.
#[derive(NetworkBehaviour)]
#[behaviour(out_event = "BehaviourEvent", poll_method = "poll")]
pub struct Behaviour<TSubstream: AsyncRead + AsyncWrite> {
    /// The routing pub-sub mechanism for eth2.
    gossipsub: Gossipsub<TSubstream>,
    // TODO: Add Kademlia for peer discovery
    /// The events generated by this behaviour to be consumed in the swarm poll.
    serenity_rpc: Rpc<TSubstream>,
    /// Allows discovery of IP addresses for peers on the network.
    identify: Identify<TSubstream>,
    /// Keep regular connection to peers and disconnect if absent.
    // TODO: Keepalive, likely remove this later.
    // TODO: Make the ping time customizeable.
    ping: Ping<TSubstream>,
    #[behaviour(ignore)]
    events: Vec<BehaviourEvent>,
    /// Logger for behaviour actions.
    #[behaviour(ignore)]
    log: slog::Logger,
}

// Implement the NetworkBehaviourEventProcess trait so that we can derive NetworkBehaviour for Behaviour
impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<GossipsubEvent>
    for Behaviour<TSubstream>
{
    fn inject_event(&mut self, event: GossipsubEvent) {
        match event {
            GossipsubEvent::Message(message) => {
                let gs_message = String::from_utf8_lossy(&message.data);
                // TODO: Remove this type - debug only
                self.events
                    .push(BehaviourEvent::Message(gs_message.to_string()))
            }
            _ => {}
        }
    }
}

impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<RPCMessage>
    for Behaviour<TSubstream>
{
    fn inject_event(&mut self, event: RPCMessage) {
        match event {
            RPCMessage::PeerDialed(peer_id) => {
                self.events.push(BehaviourEvent::PeerDialed(peer_id))
            }
            RPCMessage::RPC(peer_id, rpc_event) => {
                self.events.push(BehaviourEvent::RPC(peer_id, rpc_event))
            }
        }
    }
}

impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<IdentifyEvent>
    for Behaviour<TSubstream>
{
    fn inject_event(&mut self, event: IdentifyEvent) {
        match event {
            IdentifyEvent::Identified {
                peer_id, mut info, ..
            } => {
                if info.listen_addrs.len() > 20 {
                    debug!(
                        self.log,
                        "More than 20 peers have been identified, truncating"
                    );
                    info.listen_addrs.truncate(20);
                }
                self.events.push(BehaviourEvent::Identified(peer_id, info));
            }
            IdentifyEvent::Error { .. } => {}
            IdentifyEvent::SendBack { .. } => {}
        }
    }
}

impl<TSubstream: AsyncRead + AsyncWrite> NetworkBehaviourEventProcess<PingEvent>
    for Behaviour<TSubstream>
{
    fn inject_event(&mut self, _event: PingEvent) {
        // not interested in ping responses at the moment.
    }
}

impl<TSubstream: AsyncRead + AsyncWrite> Behaviour<TSubstream> {
    pub fn new(local_public_key: PublicKey, net_conf: &NetworkConfig, log: &slog::Logger) -> Self {
        let local_peer_id = local_public_key.clone().into_peer_id();
        let identify_config = net_conf.identify_config.clone();
        let behaviour_log = log.new(o!());

        Behaviour {
            gossipsub: Gossipsub::new(local_peer_id, net_conf.gs_config.clone()),
            serenity_rpc: Rpc::new(log),
            identify: Identify::new(
                identify_config.version,
                identify_config.user_agent,
                local_public_key,
            ),
            ping: Ping::new(),
            events: Vec::new(),
            log: behaviour_log,
        }
    }

    /// Consumes the events list when polled.
    fn poll<TBehaviourIn>(
        &mut self,
    ) -> Async<NetworkBehaviourAction<TBehaviourIn, BehaviourEvent>> {
        if !self.events.is_empty() {
            return Async::Ready(NetworkBehaviourAction::GenerateEvent(self.events.remove(0)));
        }

        Async::NotReady
    }
}

/// Implements the combined behaviour for the libp2p service.
impl<TSubstream: AsyncRead + AsyncWrite> Behaviour<TSubstream> {
    /// Subscribes to a gossipsub topic.
    pub fn subscribe(&mut self, topic: Topic) -> bool {
        self.gossipsub.subscribe(topic)
    }

    /// Sends an RPC Request/Response via the RPC protocol.
    pub fn send_rpc(&mut self, peer_id: PeerId, rpc_event: RPCEvent) {
        self.serenity_rpc.send_rpc(peer_id, rpc_event);
    }
}

/// The types of events than can be obtained from polling the behaviour.
pub enum BehaviourEvent {
    RPC(PeerId, RPCEvent),
    PeerDialed(PeerId),
    Identified(PeerId, IdentifyInfo),
    // TODO: This is a stub at the moment
    Message(String),
}