use crossbeam_channel;
use eth2_libp2p::rpc::methods::BlockRootSlot;
use eth2_libp2p::PubsubMessage;
use futures::Future;
use grpcio::{RpcContext, UnarySink};
use network::NetworkMessage;
use protos::services::{
    BeaconBlock as BeaconBlockProto, ProduceBeaconBlockRequest, ProduceBeaconBlockResponse,
    PublishBeaconBlockRequest, PublishBeaconBlockResponse,
};
use protos::services_grpc::BeaconBlockService;
use slog::debug;
use slog::Logger;
use ssz::{Decodable, TreeHash};
use types::{BeaconBlock, Hash256, Slot};

#[derive(Clone)]
pub struct BeaconBlockServiceInstance {
    pub network_chan: crossbeam_channel::Sender<NetworkMessage>,
    pub log: Logger,
}

impl BeaconBlockService for BeaconBlockServiceInstance {
    /// Produce a `BeaconBlock` for signing by a validator.
    fn produce_beacon_block(
        &mut self,
        ctx: RpcContext,
        req: ProduceBeaconBlockRequest,
        sink: UnarySink<ProduceBeaconBlockResponse>,
    ) {
        println!("producing at slot {}", req.get_slot());

        // TODO: build a legit block.
        let mut block = BeaconBlockProto::new();
        block.set_ssz(b"cats".to_vec());

        let mut resp = ProduceBeaconBlockResponse::new();
        resp.set_block(block);

        let f = sink
            .success(resp)
            .map_err(move |e| println!("failed to reply {:?}: {:?}", req, e));
        ctx.spawn(f)
    }

    /// Accept some fully-formed `BeaconBlock`, process and publish it.
    fn publish_beacon_block(
        &mut self,
        ctx: RpcContext,
        req: PublishBeaconBlockRequest,
        sink: UnarySink<PublishBeaconBlockResponse>,
    ) {
        debug!(self.log, "PublishBeaconBlock");

        let block = req.get_block();

        match BeaconBlock::ssz_decode(block.get_ssz(), 0) {
            Ok((block, _i)) => {
                let block_root = Hash256::from_slice(&block.hash_tree_root()[..]);

                // TODO: Obtain topics from the network service properly.
                let topic = types::TopicBuilder::new("beacon_chain".to_string()).build();
                let message = PubsubMessage::Block(BlockRootSlot {
                    block_root,
                    slot: block.slot,
                });

                println!("Sending beacon block to gossipsub");
                self.network_chan.send(NetworkMessage::Publish {
                    topics: vec![topic],
                    message,
                });

                // TODO: actually process the block.
                let mut resp = PublishBeaconBlockResponse::new();
                resp.set_success(true);

                let f = sink
                    .success(resp)
                    .map_err(move |e| println!("failed to reply {:?}: {:?}", req, e));
                ctx.spawn(f)
            }
            Err(e) => {
                //
            }
        }
    }
}