//! Milestone 5: systemd socket activation, readiness notification, and
//! metered behavior.

mod support;

use std::os::fd::AsRawFd;
use std::os::unix::process::CommandExt;
use std::path::Path;
use std::process::Command;
use std::time::{Duration, Instant};

use varde_proto::{PinPolicy, Request, ResponseData};

extern "C" {
    fn dup2(oldfd: i32, newfd: i32) -> i32;
    fn fcntl(fd: i32, cmd: i32, arg: i32) -> i32;
}

const F_SETFD: i32 = 2;

/// Spawn the daemon with an activation socket on fd 3, the LISTEN_FDS
/// protocol systemd uses.
#[test]
fn systemd_socket_activation() {
    let dir = tempfile::tempdir().unwrap();
    let socket_path = dir.path().join("activated.sock");
    let listener = std::os::unix::net::UnixListener::bind(&socket_path).unwrap();
    let fd = listener.as_raw_fd();

    std::fs::write(dir.path().join("no-config.toml"), "").unwrap();
    let mut command = Command::new(env!("CARGO_BIN_EXE_varde-daemon"));
    command
        .arg("--user")
        .arg("--store")
        .arg(dir.path().join("store"))
        // Deliberately point --socket elsewhere: the activation fd must
        // win over self-binding.
        .arg("--socket")
        .arg(dir.path().join("ignored.sock"))
        .env("VARDE_CONFIG", dir.path().join("no-config.toml"))
        .env("VARDE_DISCOVERY", "false")
        .env("LISTEN_FDS", "1")
        .env_remove("LISTEN_PID");
    // SAFETY: dup2/fcntl are async-signal-safe; we place the listener on
    // fd 3 in the child. dup2 clears CLOEXEC on the duplicate, but when
    // the listener already *is* fd 3, dup2(3,3) is a no-op that leaves
    // CLOEXEC set and exec would close the socket — clear it explicitly.
    unsafe {
        command.pre_exec(move || {
            let rc = if fd == 3 {
                fcntl(3, F_SETFD, 0)
            } else {
                dup2(fd, 3)
            };
            if rc < 0 {
                return Err(std::io::Error::last_os_error());
            }
            Ok(())
        });
    }
    let mut child = command.spawn().expect("spawning daemon");
    // Drop our copy of the listener: if the daemon dies, connects must
    // fail (and this test fail cleanly) rather than queue in the backlog
    // of a socket nobody accepts on.
    drop(listener);

    // The daemon must answer on the activation socket.
    let deadline = Instant::now() + Duration::from_secs(10);
    let mut answered = false;
    while Instant::now() < deadline {
        if std::os::unix::net::UnixStream::connect(&socket_path).is_ok() {
            let mut client = support::Client::connect(&socket_path);
            client.set_read_timeout(Duration::from_secs(5));
            let reply = client.request(&Request::Status { hash: None });
            if reply.ok {
                answered = true;
                break;
            }
        }
        std::thread::sleep(Duration::from_millis(50));
    }
    let _ = child.kill();
    let _ = child.wait();
    assert!(answered, "daemon did not serve on the activation socket");
    assert!(
        !dir.path().join("ignored.sock").exists(),
        "daemon bound its own socket despite activation"
    );
}

/// With NOTIFY_SOCKET set, the daemon reports READY=1 once serving.
#[test]
fn sd_notify_ready_is_sent() {
    let dir = tempfile::tempdir().unwrap();
    let notify_path = dir.path().join("notify.sock");
    let notify = std::os::unix::net::UnixDatagram::bind(&notify_path).unwrap();
    notify
        .set_read_timeout(Some(Duration::from_secs(10)))
        .unwrap();

    std::fs::write(dir.path().join("no-config.toml"), "").unwrap();
    let mut child = Command::new(env!("CARGO_BIN_EXE_varde-daemon"))
        .arg("--user")
        .arg("--store")
        .arg(dir.path().join("store"))
        .arg("--socket")
        .arg(dir.path().join("varde.sock"))
        .env("VARDE_CONFIG", dir.path().join("no-config.toml"))
        .env("VARDE_DISCOVERY", "false")
        .env("NOTIFY_SOCKET", &notify_path)
        .spawn()
        .expect("spawning daemon");

    let mut buf = [0u8; 64];
    let result = notify.recv(&mut buf);
    let _ = child.kill();
    let _ = child.wait();
    let n = result.expect("no readiness notification received");
    let message = std::str::from_utf8(&buf[..n]).unwrap();
    assert!(
        message.contains("READY=1"),
        "unexpected notify payload: {message}"
    );
}

fn wait_complete(socket: &Path, hash: &str, timeout: Duration) -> bool {
    let deadline = Instant::now() + timeout;
    while Instant::now() < deadline {
        let mut client = support::Client::connect(socket);
        let reply = client.request(&Request::Status {
            hash: Some(hash.to_string()),
        });
        if let Some(ResponseData::HashStatus(s)) = reply.data {
            if s.complete {
                return true;
            }
        }
        std::thread::sleep(Duration::from_millis(100));
    }
    false
}

/// A metered daemon serves nothing, even openly exported content.
#[test]
fn metered_daemon_stops_serving() {
    let provider_dir = tempfile::tempdir().unwrap();
    let provider =
        support::spawn_daemon_with_env(provider_dir.path(), &[("VARDE_FORCE_METERED", "true")]);
    let fetcher = support::spawn_daemon();
    let mut provider_client = support::Client::connect(&provider.socket);
    let mut fetcher_client = support::Client::connect(&fetcher.socket);

    let dir = tempfile::tempdir().unwrap();
    let src = dir.path().join("f.bin");
    std::fs::write(&src, vec![4u8; 200_000]).unwrap();
    let reply = provider_client.request(&Request::Add {
        path: src.display().to_string(),
        recursive: false,
    });
    let hash = match reply.data {
        Some(ResponseData::Added { hash, .. }) => hash,
        other => panic!("unexpected add reply: {other:?}"),
    };
    let reply = provider_client.request(&Request::Pin {
        hash: hash.clone(),
        policy: PinPolicy::default(),
    });
    assert!(reply.ok);
    let reply = provider_client.request(&Request::TicketExport { hash: hash.clone() });
    let ticket = match reply.data {
        Some(ResponseData::Ticket { ticket }) => ticket,
        other => panic!("unexpected ticket reply: {other:?}"),
    };

    let reply = fetcher_client.request(&Request::TicketImport {
        ticket,
        pin_policy: PinPolicy::default(),
    });
    assert!(reply.ok, "import should be accepted (pin recorded)");
    assert!(
        !wait_complete(&fetcher.socket, &hash, Duration::from_secs(8)),
        "metered provider must not serve"
    );
}

/// A metered daemon defers its own fetches too.
#[test]
fn metered_daemon_defers_fetching() {
    let provider = support::spawn_daemon();
    let fetcher_dir = tempfile::tempdir().unwrap();
    let fetcher =
        support::spawn_daemon_with_env(fetcher_dir.path(), &[("VARDE_FORCE_METERED", "true")]);
    let mut provider_client = support::Client::connect(&provider.socket);
    let mut fetcher_client = support::Client::connect(&fetcher.socket);

    let dir = tempfile::tempdir().unwrap();
    let src = dir.path().join("f.bin");
    std::fs::write(&src, vec![6u8; 200_000]).unwrap();
    let reply = provider_client.request(&Request::Add {
        path: src.display().to_string(),
        recursive: false,
    });
    let hash = match reply.data {
        Some(ResponseData::Added { hash, .. }) => hash,
        other => panic!("unexpected add reply: {other:?}"),
    };
    assert!(
        provider_client
            .request(&Request::Pin {
                hash: hash.clone(),
                policy: PinPolicy::default(),
            })
            .ok
    );
    let reply = provider_client.request(&Request::TicketExport { hash: hash.clone() });
    let ticket = match reply.data {
        Some(ResponseData::Ticket { ticket }) => ticket,
        other => panic!("unexpected ticket reply: {other:?}"),
    };

    let reply = fetcher_client.request(&Request::TicketImport {
        ticket,
        pin_policy: PinPolicy::default(),
    });
    assert!(reply.ok, "import records the pin even while metered");
    assert!(
        !wait_complete(&fetcher.socket, &hash, Duration::from_secs(8)),
        "metered fetcher must not download"
    );
}