//! Changes passed on in a full mesh (`swarm::relay`) to the members the writer can't
//! reach: those on none of its transports, or behind a link that fails.

use std::time::Duration;

use serde_json::json;

use super::{SYNC_REPLY_TIMEOUT, Sim, read, write};
use crate::state::Timing;
use crate::swarm::bootstrap::Start;
use crate::swarm::topology;
use crate::transport::sim::DELIVERY_LIMIT;

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

/// a on `sim` alone, c on `sim2` alone, b on both; a full mesh at each (every member
/// it reaches is its neighbour), so a pushes its write to b alone, and b, which only
/// received it, must pass it on to c: along a's tree at once (b is c's parent), else by
/// announcement 200 to 400 ms later and a pull. With a long keepalive, the regular
/// STATUS (every third keepalive, 15 s) can't be what brings it: c has it within a
/// second. Without either, a STATUS that happens to fall into that second would pass it
/// too, once in about 15 runs.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn changes_reach_members_the_writer_cant_reach_at_once() {
    let keepalive = Duration::from_secs(5);
    let slow = move |config: &mut crate::node::NodeConfig| {
        config.timing = Timing::new(keepalive, SYNC_REPLY_TIMEOUT, DELIVERY_LIMIT);
    };
    let sim = Sim::with_identity(62);
    let a = sim.start_on_with("a", &["sim"], &[], Start::Genesis, slow);
    let b = sim.start_on_with("b", &["sim", "sim2"], &["a"], Start::Join, slow);
    let c = sim.start_on_with("c", &["sim2"], &["b"], Start::Join, slow);
    sim.wait_ready(&[&a, &b, &c], SOON).await;
    let c_id = c.local_id().to_owned();
    {
        let (a, b, c_id) = (&a, &b, c_id.clone());
        sim.wait_until(
            "a and b know their neighbours, a full mesh, c beyond a's reach",
            SOON,
            move || {
                let c_id = c_id.clone();
                async move {
                    topology::view_known(a)
                        && topology::view_known(b)
                        && topology::is_full_mesh(a)
                        && topology::is_full_mesh(b)
                        && topology::is_neighbour(b, &c_id)
                        && topology::transports_of(a, &c_id).contains("sim2")
                        && !a.transport.can_reach(&c_id)
                }
            },
        )
        .await;
    }
    sim.wait_converged(&[&a, &b, &c], SOON).await;

    write(&a, "x", json!(1)).await;
    {
        let c = &c;
        sim.wait_until(
            "c has a's write within a second",
            Duration::from_secs(1),
            move || async move { read(c, "x").await == Some(json!(1)) },
        )
        .await;
    }
}

/// One transport, a full mesh by the member list, but the writer x reaches b alone (as
/// one behind NAT may): what x writes reaches c through b, at once, though the member
/// list makes c x's neighbour too.
#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn changes_reach_members_the_writer_fails_to_reach_at_once() {
    let keepalive = Duration::from_secs(5);
    let slow = move |config: &mut crate::node::NodeConfig| {
        config.timing = Timing::new(keepalive, SYNC_REPLY_TIMEOUT, DELIVERY_LIMIT);
    };
    let sim = Sim::with_identity(63);
    // Nothing between x and c, either way.
    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_with("b", &["sim"], &[], Start::Genesis, slow);
    let c = sim.start_on_with("c", &["sim"], &["b"], Start::Join, slow);
    let x = sim.start_on_with("x", &["sim"], &["b"], Start::Join, slow);
    sim.wait_ready(&[&b, &c, &x], SOON).await;
    let (c_id, x_id) = (c.local_id().to_owned(), x.local_id().to_owned());
    {
        let (b, c_id, x_id) = (&b, c_id.clone(), x_id.clone());
        sim.wait_until(
            "b knows its neighbours, a full mesh, x and c among them",
            SOON,
            move || {
                let (c_id, x_id) = (c_id.clone(), x_id.clone());
                async move {
                    topology::view_known(b)
                        && topology::is_full_mesh(b)
                        && topology::is_neighbour(b, &c_id)
                        && topology::is_neighbour(b, &x_id)
                }
            },
        )
        .await;
    }
    sim.wait_converged(&[&b, &c, &x], SOON).await;

    write(&x, "y", json!(1)).await;
    {
        let c = &c;
        sim.wait_until(
            "c has x's write within a second",
            Duration::from_secs(1),
            move || async move { read(c, "y").await == Some(json!(1)) },
        )
        .await;
    }
}