// Copyright 2018 Parity Technologies (UK) Ltd.
//
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//
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//! Demonstrates how to perform Kademlia queries on the IPFS network.
//!
//! You can pass as parameter a base58 peer ID to search for. If you don't pass any parameter, a
//! peer ID will be generated randomly.

use async_std::task;
use futures::StreamExt;
use libp2p::{
    Multiaddr,
    swarm::{Swarm, SwarmEvent},
    PeerId,
    identity,
    development_transport
};
use libp2p::kad::{
    Kademlia,
    KademliaConfig,
    KademliaEvent,
    GetClosestPeersError,
    QueryResult,
};
use libp2p::kad::record::store::MemoryStore;
use std::{env, error::Error, str::FromStr, time::Duration};

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

#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    env_logger::init();

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

    // Set up a an encrypted DNS-enabled TCP Transport over the Mplex protocol
    let transport = development_transport(local_key).await?;

    // Create a swarm to manage peers and events.
    let mut swarm = {
        // Create a Kademlia behaviour.
        let mut cfg = KademliaConfig::default();
        cfg.set_query_timeout(Duration::from_secs(5 * 60));
        let store = MemoryStore::new(local_peer_id);
        let mut behaviour = Kademlia::with_config(local_peer_id, store, cfg);

        // Add the bootnodes to the local routing table. `libp2p-dns` built
        // into the `transport` resolves the `dnsaddr` when Kademlia tries
        // to dial these nodes.
        let bootaddr = Multiaddr::from_str("/dnsaddr/bootstrap.libp2p.io")?;
        for peer in &BOOTNODES {
            behaviour.add_address(&PeerId::from_str(peer)?, bootaddr.clone());
        }

        Swarm::new(transport, behaviour, local_peer_id)
    };

    // Order Kademlia to search for a peer.
    let to_search: PeerId = if let Some(peer_id) = env::args().nth(1) {
        peer_id.parse()?
    } else {
        identity::Keypair::generate_ed25519().public().into()
    };

    println!("Searching for the closest peers to {:?}", to_search);
    swarm.behaviour_mut().get_closest_peers(to_search);

    // Kick it off!
    task::block_on(async move {
        loop {
            let event = swarm.select_next_some().await;
            if let SwarmEvent::Behaviour(KademliaEvent::OutboundQueryCompleted {
                result: QueryResult::GetClosestPeers(result),
                ..
            }) = event {
                match result {
                    Ok(ok) =>
                        if !ok.peers.is_empty() {
                            println!("Query finished with closest peers: {:#?}", ok.peers)
                        } else {
                            // The example is considered failed as there
                            // should always be at least 1 reachable peer.
                            println!("Query finished with no closest peers.")
                        }
                    Err(GetClosestPeersError::Timeout { peers, .. }) =>
                        if !peers.is_empty() {
                            println!("Query timed out with closest peers: {:#?}", peers)
                        } else {
                            // The example is considered failed as there
                            // should always be at least 1 reachable peer.
                            println!("Query timed out with no closest peers.");
                        }
                };

                break;
            }
        }

        Ok(())
    })
}