//! The local control interface: a client asking a running agent for status.
//!
//! Uses a real Unix socket on a temporary path, the real agent and the real
//! WireGuard data plane, so what a `tsunagi status` client would see is what
//! is checked here.

#![allow(clippy::unwrap_used, clippy::expect_used, clippy::panic)]

mod common;

use std::sync::Arc;
use std::time::Duration;

use common::{config_with, network, wait_for_peers, wait_until};
use tempfile::TempDir;
use tsunagi::dataplane::IpPlugin;
use tsunagi::dataplane::wireguard::{MemoryTunFactory, WireguardConfig, WireguardPlugin};
use tsunagi::discovery::SharedMemoryDiscovery;
use tsunagi::ipc::unix::{ControlSocket, request_status};
use tsunagi::ipc::{StatusReport, control_socket_path};
use tsunagi::{Agent, BoxFuture};

/// Builds the report the way the binary does, from the agent plus the plugin.
fn source(agent: Agent, plugin: Arc<WireguardPlugin>) -> Arc<dyn tsunagi::ipc::unix::ReportSource> {
    Arc::new(move || -> BoxFuture<'static, StatusReport> {
        let agent = agent.clone();
        let plugin = Arc::clone(&plugin);
        Box::pin(async move {
            let status = agent.status().await.unwrap();
            let networks = status
                .networks
                .iter()
                .map(|net| tsunagi::ipc::NetworkReport {
                    name: net.name.to_string(),
                    network_id: net.network_id.to_string(),
                    active: true,
                    peers: net
                        .peers
                        .iter()
                        .map(|peer| tsunagi::ipc::PeerReport {
                            endpoint_id: peer.endpoint_id.to_string(),
                            hostname: peer.hostname.clone(),
                            transport: format!("{:?}", peer.transport),
                            rtt_ms: peer.rtt.map(|rtt| rtt.as_millis() as u64),
                        })
                        .collect(),
                    overlay: plugin.overview(net.network_id).map(|view| {
                        tsunagi::ipc::OverlayReport {
                            interface: view.interface.clone(),
                            mtu: view.mtu,
                            address: view.overlay_address.to_string(),
                            prefix: view.overlay_prefix.to_string(),
                            prefix_len: view.overlay_prefix_len,
                            peers: view
                                .peers
                                .iter()
                                .map(|peer| tsunagi::ipc::OverlayPeerReport {
                                    public_key: peer.public_key.to_string(),
                                    address: peer.overlay_address.to_string(),
                                    handshake_secs_ago: peer
                                        .tunnel
                                        .as_ref()
                                        .and_then(|t| t.health.since_handshake)
                                        .map(|since| since.as_secs()),
                                    ..Default::default()
                                })
                                .collect(),
                            ..Default::default()
                        }
                    }),
                    ..Default::default()
                })
                .collect();
            StatusReport {
                endpoint_id: status.endpoint_id.to_string(),
                hostname: status.hostname.clone(),
                bound_sockets: status
                    .bound_sockets
                    .iter()
                    .map(ToString::to_string)
                    .collect(),
                cache_healthy: status.cache_healthy,
                networks,
                dns: None,
            }
        })
    })
}

#[tokio::test]
async fn a_client_sees_the_agent_and_its_overlay() {
    let discovery = SharedMemoryDiscovery::new();
    let (name, secret) = network("control-socket");

    let dir_a = TempDir::new().unwrap();
    let tuns = MemoryTunFactory::new();
    let plugin = WireguardPlugin::open(
        WireguardConfig::new(dir_a.path().join("wg"))
            .with_interface_prefix("tca")
            .with_reconcile(Duration::from_millis(20), Duration::from_millis(250)),
        Arc::new(tuns),
    )
    .await
    .unwrap();
    let agent = Agent::spawn(
        config_with(dir_a.path(), &discovery).with_plugin(plugin.clone() as Arc<dyn IpPlugin>),
    )
    .await
    .unwrap();

    let dir_b = TempDir::new().unwrap();
    let plugin_b = WireguardPlugin::open(
        WireguardConfig::new(dir_b.path().join("wg"))
            .with_interface_prefix("tcb")
            .with_reconcile(Duration::from_millis(20), Duration::from_millis(250)),
        Arc::new(MemoryTunFactory::new()),
    )
    .await
    .unwrap();
    let agent_b = Agent::spawn(
        config_with(dir_b.path(), &discovery).with_plugin(plugin_b.clone() as Arc<dyn IpPlugin>),
    )
    .await
    .unwrap();

    let network_id = agent.join_network(&name, &secret).await.unwrap();
    agent_b.join_network(&name, &secret).await.unwrap();
    wait_for_peers(&agent, network_id, 1).await;

    // A short path: a Unix socket address is limited to about 100 bytes.
    let socket_path = dir_a.path().join("agent.sock");
    let control = ControlSocket::bind(&socket_path, source(agent.clone(), plugin.clone()))
        .await
        .unwrap();

    let report = wait_until("the overlay is reported as up", || {
        let socket_path = socket_path.clone();
        async move {
            let report = request_status(&socket_path).await.ok()?;
            let overlay = report.networks.first()?.overlay.as_ref()?;
            overlay
                .peers
                .iter()
                .any(|peer| peer.is_up())
                .then_some(report)
        }
    })
    .await;

    assert_eq!(report.endpoint_id, agent.endpoint_id().to_string());
    assert_eq!(report.networks.len(), 1);
    let net = &report.networks[0];
    assert_eq!(net.network_id, network_id.to_string());
    assert_eq!(net.peers.len(), 1);
    assert_eq!(net.peers[0].endpoint_id, agent_b.endpoint_id().to_string());

    let overlay = net.overlay.as_ref().unwrap();
    assert!(overlay.interface.starts_with("tca"));
    assert_eq!(overlay.mtu, 1280);
    assert_eq!(overlay.peers.len(), 1);

    // The report carries what a reader needs, in structured form: how it is
    // laid out is the CLI's business and is tested there.
    assert_eq!(report.endpoint_id, agent.endpoint_id().to_string());
    assert_eq!(
        overlay.peers.iter().filter(|peer| peer.is_up()).count(),
        1,
        "the tunnel is up: {:?}",
        overlay.peers
    );
    assert!(!overlay.address.is_empty());

    control.shutdown().await;
    assert!(!socket_path.exists(), "the socket is removed on shutdown");

    // With nothing listening, a client gets an error rather than hanging.
    assert!(request_status(&socket_path).await.is_err());

    agent.shutdown().await;
    agent_b.shutdown().await;
}

#[tokio::test]
async fn a_leftover_socket_file_is_replaced_but_a_live_one_is_not() {
    let dir = TempDir::new().unwrap();
    let path = dir.path().join("agent.sock");

    let empty: Arc<dyn tsunagi::ipc::unix::ReportSource> =
        Arc::new(|| -> BoxFuture<'static, StatusReport> {
            Box::pin(async { StatusReport::default() })
        });

    // A file with nobody listening is a leftover from a crash.
    std::fs::write(&path, b"stale").unwrap();
    let first = ControlSocket::bind(&path, Arc::clone(&empty))
        .await
        .unwrap();
    assert!(request_status(&path).await.is_ok());

    // A live socket is not stolen from the agent that owns it.
    let second = ControlSocket::bind(&path, Arc::clone(&empty)).await;
    assert!(
        matches!(second, Err(tsunagi::Error::StateLocked { .. })),
        "a second agent must not take over a live control socket"
    );

    first.shutdown().await;
}

#[test]
fn the_socket_path_is_derived_and_short_enough() {
    let deep = std::path::PathBuf::from(
        "/home/someone/.local/share/with/a/very/deeply/nested/directory/that/goes/on/and/on/and/on/tsunagi/state",
    );
    let path = control_socket_path(&deep);

    // A Unix socket address is limited to roughly 100 bytes, so a deep state
    // directory must not produce a path that cannot be bound.
    if std::env::var_os("XDG_RUNTIME_DIR").is_some() {
        assert!(
            path.as_os_str().len() < 100,
            "derived path is {} bytes: {}",
            path.as_os_str().len(),
            path.display()
        );
    }

    // Deterministic, and different state directories never share a socket.
    assert_eq!(path, control_socket_path(&deep));
    assert_ne!(
        path,
        control_socket_path(&std::path::PathBuf::from("/somewhere/else"))
    );
}

/// Asking who this device is must not need the directory lock.
///
/// The lock belongs to the one agent allowed to *write* the state. `id` only
/// reads, so making it take the lock would mean the question could never be
/// answered while an agent was running — which is exactly when you want to
/// ask it.
#[cfg(feature = "cli")]
#[tokio::test]
async fn identity_can_be_read_while_an_agent_holds_the_directory() {
    let dir = TempDir::new().unwrap();
    let discovery = SharedMemoryDiscovery::new();

    // Hold the directory the way a running agent does.
    let agent = Agent::spawn(config_with(dir.path(), &discovery))
        .await
        .unwrap();
    let expected = agent.endpoint_id().to_string();

    let output = tokio::process::Command::new(env!("CARGO_BIN_EXE_tsunagi"))
        .arg("id")
        // The same layout `StoragePaths::under` gives the agent above.
        .arg("--state-dir")
        .arg(dir.path().join("state"))
        .arg("--cache-dir")
        .arg(dir.path().join("cache"))
        .output()
        .await
        .unwrap();

    let stdout = String::from_utf8_lossy(&output.stdout);
    let stderr = String::from_utf8_lossy(&output.stderr);
    assert!(
        output.status.success(),
        "`id` failed while an agent was running:\n{stderr}"
    );
    assert!(
        stdout.contains(&expected),
        "expected {expected} in:\n{stdout}"
    );

    agent.shutdown().await;
}