// Copyright 2018 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

#![doc = include_str!("../README.md")]

use std::num::NonZeroUsize;
use std::ops::Add;
use std::time::{Duration, Instant};

use anyhow::{bail, Result};
use clap::Parser;
use futures::StreamExt;
use libp2p::swarm::{StreamProtocol, SwarmEvent};
use libp2p::{bytes::BufMut, identity, kad, noise, tcp, yamux, PeerId};
use tracing_subscriber::EnvFilter;

const BOOTNODES: [&str; 4] = [
    "QmNnooDu7bfjPFoTZYxMNLWUQJyrVwtbZg5gBMjTezGAJN",
    "QmQCU2EcMqAqQPR2i9bChDtGNJchTbq5TbXJJ16u19uLTa",
    "QmbLHAnMoJPWSCR5Zhtx6BHJX9KiKNN6tpvbUcqanj75Nb",
    "QmcZf59bWwK5XFi76CZX8cbJ4BhTzzA3gU1ZjYZcYW3dwt",
];

const IPFS_PROTO_NAME: StreamProtocol = StreamProtocol::new("/ipfs/kad/1.0.0");

#[tokio::main]
async fn main() -> Result<()> {
    let _ = tracing_subscriber::fmt()
        .with_env_filter(EnvFilter::from_default_env())
        .try_init();

    // Create a random key for ourselves.
    let local_key = identity::Keypair::generate_ed25519();

    let mut swarm = libp2p::SwarmBuilder::with_existing_identity(local_key.clone())
        .with_tokio()
        .with_tcp(
            tcp::Config::default(),
            noise::Config::new,
            yamux::Config::default,
        )?
        .with_dns()?
        .with_behaviour(|key| {
            // Create a Kademlia behaviour.
            let mut cfg = kad::Config::new(IPFS_PROTO_NAME);
            cfg.set_query_timeout(Duration::from_secs(5 * 60));
            let store = kad::store::MemoryStore::new(key.public().to_peer_id());
            kad::Behaviour::with_config(key.public().to_peer_id(), store, cfg)
        })?
        .with_swarm_config(|c| c.with_idle_connection_timeout(Duration::from_secs(5)))
        .build();

    // Add the bootnodes to the local routing table. `libp2p-dns` built
    // into the `transport` resolves the `dnsaddr` when Kademlia tries
    // to dial these nodes.
    for peer in &BOOTNODES {
        swarm
            .behaviour_mut()
            .add_address(&peer.parse()?, "/dnsaddr/bootstrap.libp2p.io".parse()?);
    }

    let cli_opt = Opt::parse();

    match cli_opt.argument {
        CliArgument::GetPeers { peer_id } => {
            let peer_id = peer_id.unwrap_or(PeerId::random());
            println!("Searching for the closest peers to {peer_id}");
            swarm.behaviour_mut().get_closest_peers(peer_id);
        }
        CliArgument::PutPkRecord {} => {
            println!("Putting PK record into the DHT");

            let mut pk_record_key = vec![];
            pk_record_key.put_slice("/pk/".as_bytes());
            pk_record_key.put_slice(swarm.local_peer_id().to_bytes().as_slice());

            let mut pk_record =
                kad::Record::new(pk_record_key, local_key.public().encode_protobuf());
            pk_record.publisher = Some(*swarm.local_peer_id());
            pk_record.expires = Some(Instant::now().add(Duration::from_secs(60)));

            swarm
                .behaviour_mut()
                .put_record(pk_record, kad::Quorum::N(NonZeroUsize::new(3).unwrap()))?;
        }
    }

    loop {
        let event = swarm.select_next_some().await;

        match event {
            SwarmEvent::Behaviour(kad::Event::OutboundQueryProgressed {
                result: kad::QueryResult::GetClosestPeers(Ok(ok)),
                ..
            }) => {
                // The example is considered failed as there
                // should always be at least 1 reachable peer.
                if ok.peers.is_empty() {
                    bail!("Query finished with no closest peers.")
                }

                println!("Query finished with closest peers: {:#?}", ok.peers);

                return Ok(());
            }
            SwarmEvent::Behaviour(kad::Event::OutboundQueryProgressed {
                result:
                    kad::QueryResult::GetClosestPeers(Err(kad::GetClosestPeersError::Timeout {
                        ..
                    })),
                ..
            }) => {
                bail!("Query for closest peers timed out")
            }
            SwarmEvent::Behaviour(kad::Event::OutboundQueryProgressed {
                result: kad::QueryResult::PutRecord(Ok(_)),
                ..
            }) => {
                println!("Successfully inserted the PK record");

                return Ok(());
            }
            SwarmEvent::Behaviour(kad::Event::OutboundQueryProgressed {
                result: kad::QueryResult::PutRecord(Err(err)),
                ..
            }) => {
                bail!(anyhow::Error::new(err).context("Failed to insert the PK record"));
            }
            _ => {}
        }
    }
}

#[derive(Parser, Debug)]
#[clap(name = "libp2p Kademlia DHT example")]
struct Opt {
    #[clap(subcommand)]
    argument: CliArgument,
}

#[derive(Debug, Parser)]
enum CliArgument {
    GetPeers {
        #[clap(long)]
        peer_id: Option<PeerId>,
    },
    PutPkRecord {},
}