//! Fixed test vectors for the address book.

use std::time::Instant;

use chrono::Utc;
use tracing::Span;

use zebra_chain::{
    parameters::Network::*,
    serialization::{DateTime32, Duration32},
};

use crate::{
    constants::{DEFAULT_MAX_CONNS_PER_IP, MAX_ADDRS_IN_ADDRESS_BOOK},
    meta_addr::MetaAddr,
    protocol::external::types::PeerServices,
    AddressBook,
};

/// Make sure an empty address book is actually empty.
#[test]
fn address_book_empty() {
    let address_book = AddressBook::new(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        Span::current(),
    );

    assert_eq!(
        address_book
            .reconnection_peers(Instant::now(), Utc::now())
            .next(),
        None
    );
    assert_eq!(address_book.len(), 0);
}

/// Make sure peers are attempted in priority order.
#[test]
fn address_book_peer_order() {
    let addr1 = "127.0.0.1:1".parse().unwrap();
    let addr2 = "127.0.0.2:2".parse().unwrap();

    let mut meta_addr1 =
        MetaAddr::new_gossiped_meta_addr(addr1, PeerServices::NODE_NETWORK, DateTime32::MIN);
    let mut meta_addr2 = MetaAddr::new_gossiped_meta_addr(
        addr2,
        PeerServices::NODE_NETWORK,
        DateTime32::MIN.saturating_add(Duration32::from_seconds(1)),
    );

    // Regardless of the order of insertion, the most recent address should be chosen first
    let addrs = vec![meta_addr1, meta_addr2];
    let address_book = AddressBook::new_with_addrs(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        MAX_ADDRS_IN_ADDRESS_BOOK,
        Span::current(),
        addrs,
    );
    assert_eq!(
        address_book
            .reconnection_peers(Instant::now(), Utc::now())
            .next(),
        Some(meta_addr2),
    );

    // Reverse the order, check that we get the same result
    let addrs = vec![meta_addr2, meta_addr1];
    let address_book = AddressBook::new_with_addrs(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        MAX_ADDRS_IN_ADDRESS_BOOK,
        Span::current(),
        addrs,
    );
    assert_eq!(
        address_book
            .reconnection_peers(Instant::now(), Utc::now())
            .next(),
        Some(meta_addr2),
    );

    // Now check that the order depends on the time, not the address
    meta_addr1.addr = addr2;
    meta_addr2.addr = addr1;

    let addrs = vec![meta_addr1, meta_addr2];
    let address_book = AddressBook::new_with_addrs(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        MAX_ADDRS_IN_ADDRESS_BOOK,
        Span::current(),
        addrs,
    );
    assert_eq!(
        address_book
            .reconnection_peers(Instant::now(), Utc::now())
            .next(),
        Some(meta_addr2),
    );

    // Reverse the order, check that we get the same result
    let addrs = vec![meta_addr2, meta_addr1];
    let address_book = AddressBook::new_with_addrs(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        MAX_ADDRS_IN_ADDRESS_BOOK,
        Span::current(),
        addrs,
    );
    assert_eq!(
        address_book
            .reconnection_peers(Instant::now(), Utc::now())
            .next(),
        Some(meta_addr2),
    );
}

/// Check that `reconnection_peers` skips addresses with IPs for which
/// Zebra already has recently updated outbound peers.
#[test]
fn reconnection_peers_skips_recently_updated_ip() {
    // tests that reconnection_peers() skips addresses where there's a connection at that IP with a recent:
    // - `last_response`
    test_reconnection_peers_skips_recently_updated_ip(true, MetaAddr::new_responded);

    // tests that reconnection_peers() *does not* skip addresses where there's a connection at that IP with a recent:
    // - `last_attempt`
    test_reconnection_peers_skips_recently_updated_ip(false, MetaAddr::new_reconnect);
    // - `last_failure`
    test_reconnection_peers_skips_recently_updated_ip(false, |addr| {
        MetaAddr::new_errored(addr, PeerServices::NODE_NETWORK)
    });
}

fn test_reconnection_peers_skips_recently_updated_ip<
    M: Fn(crate::PeerSocketAddr) -> crate::meta_addr::MetaAddrChange,
>(
    should_skip_ip: bool,
    make_meta_addr_change: M,
) {
    let addr1 = "127.0.0.1:1".parse().unwrap();
    let addr2 = "127.0.0.1:2".parse().unwrap();

    let meta_addr1 = make_meta_addr_change(addr1).into_new_meta_addr(
        Instant::now(),
        Utc::now().try_into().expect("will succeed until 2038"),
    );
    let meta_addr2 = MetaAddr::new_gossiped_meta_addr(
        addr2,
        PeerServices::NODE_NETWORK,
        DateTime32::MIN.saturating_add(Duration32::from_seconds(1)),
    );

    // The second address should be skipped because the first address has a
    // recent `last_response` time and the two addresses have the same IP.
    let addrs = vec![meta_addr1, meta_addr2];
    let address_book = AddressBook::new_with_addrs(
        "0.0.0.0:0".parse().unwrap(),
        &Mainnet,
        DEFAULT_MAX_CONNS_PER_IP,
        MAX_ADDRS_IN_ADDRESS_BOOK,
        Span::current(),
        addrs,
    );

    let next_reconnection_peer = address_book
        .reconnection_peers(Instant::now(), Utc::now())
        .next();

    if should_skip_ip {
        assert_eq!(next_reconnection_peer, None,);
    } else {
        assert_ne!(next_reconnection_peer, None,);
    }
}