//! Whom neighbours reach (`swarm::reach`): told in STATUSes, as measured; and the
//! writers' trees built on it (`swarm::tree`).

use std::time::Duration;

use super::Sim;
use crate::state::AppState;
use crate::swarm::bootstrap::Start;
use crate::swarm::{reach, topology, tree};

const SOON: Duration = Duration::from_secs(30);

/// Whether `node` reaches `member`, as `node` measured and told it.
fn reaches(node: &AppState, member: &AppState) -> bool {
    reach::published(node).contains(&topology::pair_key(member.local_id()))
}

/// Whether `node` heard from `neighbour` that it reaches `member`.
async fn heard(node: &AppState, neighbour: &AppState, member: &AppState) -> bool {
    let Some(peer_state) = node.get_peer_state(neighbour.local_id()).await else {
        return false;
    };
    let said = peer_state.lock().await.reaches.clone();
    reach::of(node, said.as_ref())
        .is_some_and(|keys| keys.contains(&topology::pair_key(member.local_id())))
}

/// x, b and c on one net, all members of one full mesh, but nothing passes between x
/// and c: b reaches both and says so; c learns from b that b reaches x, which c itself
/// doesn't.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn neighbours_tell_whom_they_reach() {
    let sim = Sim::with_identity(66);
    let cut = crate::transport::sim::LinkParams {
        loss: 1.0,
        ..Default::default()
    };
    sim.net.set_link("x", "c", cut.clone());
    sim.net.set_link("c", "x", cut);
    let b = sim.start_on("b", &["sim"], &[], Start::Genesis);
    let c = sim.start_on("c", &["sim"], &["b"], Start::Join);
    let x = sim.start_on("x", &["sim"], &["b"], Start::Join);
    sim.wait_ready(&[&b, &c, &x], SOON).await;
    let (b, c, x) = (&b, &c, &x);
    sim.wait_until(
        "c heard from b that b reaches x, and c doesn't reach x",
        SOON,
        move || async move {
            reaches(b, x) && reaches(b, c) && !reaches(c, x) && heard(c, b, x).await
        },
    )
    .await;
}

/// The same three: in x's tree (`swarm::tree`), c can't take x as its parent (it
/// doesn't reach it), so it takes b, which comes before it if c comes later by pair
/// key; else c has no parent and gets x's changes from announcements. Either way x's
/// only child is b, and nobody but b passes x's changes to c.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn writer_trees_go_around_links_down() {
    let sim = Sim::with_identity(67);
    let cut = crate::transport::sim::LinkParams {
        loss: 1.0,
        ..Default::default()
    };
    sim.net.set_link("x", "c", cut.clone());
    sim.net.set_link("c", "x", cut);
    let b = sim.start_on("b", &["sim"], &[], Start::Genesis);
    let c = sim.start_on("c", &["sim"], &["b"], Start::Join);
    let x = sim.start_on("x", &["sim"], &["b"], Start::Join);
    sim.wait_ready(&[&b, &c, &x], SOON).await;
    let (b, c, x) = (&b, &c, &x);
    let writer = topology::pair_key(x.local_id());
    let c_after_b = topology::pair_key(c.local_id()) > topology::pair_key(b.local_id());
    sim.wait_until(
        "x's tree: b under x, and c under b if c comes after it",
        SOON,
        move || async move {
            let of_x = tree::children(x, writer).await;
            let of_b = tree::children(b, writer).await;
            heard(c, b, x).await
                && of_x == [b.local_id().to_owned()]
                && of_b
                    == if c_after_b {
                        vec![c.local_id().to_owned()]
                    } else {
                        Vec::new()
                    }
        },
    )
    .await;
}