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

use std::{
    fs,
    net::{SocketAddr, UdpSocket},
    path::{Path, PathBuf},
    sync::{
        Arc,
        atomic::{AtomicBool, AtomicU64, Ordering},
    },
    thread::JoinHandle,
    time::{Duration, SystemTime, UNIX_EPOCH},
};

use pfs_tftp_sync::{Client, ClientConfig, Mode, Server, ServerConfig};

#[test]
fn octet_put_and_get_roundtrip() {
    let server_root = TempDir::new("pfs_tftp_server_root");
    let local_root = TempDir::new("pfs_tftp_local_root");

    let (addr, shutdown, handle) = start_server(server_root.path(), true);

    let client = Client::new(addr, test_client_config());

    let upload_local = local_root.path().join("upload.bin");
    let upload_remote = "upload.bin";
    let upload_data = vec![0xA5; 1500];
    fs::write(&upload_local, &upload_data).unwrap();
    client
        .put(&upload_local, upload_remote, Mode::Octet)
        .unwrap();
    assert_eq!(
        fs::read(server_root.path().join(upload_remote)).unwrap(),
        upload_data
    );

    let download_remote = "download.bin";
    let download_data = (0u8..=200).cycle().take(2048).collect::<Vec<u8>>();
    fs::write(server_root.path().join(download_remote), &download_data).unwrap();

    let download_local = local_root.path().join("download.bin");
    client
        .get(download_remote, &download_local, Mode::Octet)
        .unwrap();
    assert_eq!(fs::read(download_local).unwrap(), download_data);

    stop_server(&shutdown, handle);
}

#[test]
fn octet_exact_512_bytes_requires_final_empty_block() {
    let server_root = TempDir::new("pfs_tftp_server_root_512");
    let local_root = TempDir::new("pfs_tftp_local_root_512");

    let (addr, shutdown, handle) = start_server(server_root.path(), true);
    let client = Client::new(addr, test_client_config());

    let data = vec![0x11; 512];

    fs::write(server_root.path().join("exact512.bin"), &data).unwrap();
    let local = local_root.path().join("exact512.bin");
    client.get("exact512.bin", &local, Mode::Octet).unwrap();
    assert_eq!(fs::read(local).unwrap(), data);

    let local_up = local_root.path().join("exact512_upload.bin");
    fs::write(&local_up, &data).unwrap();
    client
        .put(&local_up, "exact512_upload.bin", Mode::Octet)
        .unwrap();
    assert_eq!(
        fs::read(server_root.path().join("exact512_upload.bin")).unwrap(),
        data
    );

    stop_server(&shutdown, handle);
}

#[test]
fn netascii_roundtrip_preserves_newlines_and_cr() {
    let server_root = TempDir::new("pfs_tftp_server_root_netascii");
    let local_root = TempDir::new("pfs_tftp_local_root_netascii");

    let (addr, shutdown, handle) = start_server(server_root.path(), true);
    let client = Client::new(addr, test_client_config());

    let data = b"line1\nline2\rline3\n".to_vec();

    let local_up = local_root.path().join("text.txt");
    fs::write(&local_up, &data).unwrap();
    client.put(&local_up, "text.txt", Mode::NetAscii).unwrap();
    assert_eq!(fs::read(server_root.path().join("text.txt")).unwrap(), data);

    let local_down = local_root.path().join("text_downloaded.txt");
    client.get("text.txt", &local_down, Mode::NetAscii).unwrap();
    assert_eq!(fs::read(local_down).unwrap(), data);

    stop_server(&shutdown, handle);
}

#[test]
fn missing_remote_file_does_not_create_local_file() {
    let server_root = TempDir::new("pfs_tftp_server_root_missing");
    let local_root = TempDir::new("pfs_tftp_local_root_missing");

    let (addr, shutdown, handle) = start_server(server_root.path(), true);
    let client = Client::new(addr, test_client_config());

    let out = local_root.path().join("should_not_exist.bin");
    assert!(!out.exists());

    let _err = client
        .get("does_not_exist.bin", &out, Mode::Octet)
        .unwrap_err();
    assert!(!out.exists());

    stop_server(&shutdown, handle);
}

fn test_client_config() -> ClientConfig {
    ClientConfig {
        timeout: Duration::from_millis(200),
        retries: 20,
        dally_timeout: Duration::from_millis(200),
        dally_retries: 2,
    }
}

fn start_server(root: &Path, allow_write: bool) -> (SocketAddr, Arc<AtomicBool>, JoinHandle<()>) {
    let addr = reserve_local_addr();

    let cfg = ServerConfig {
        bind: addr,
        root: root.to_path_buf(),
        allow_write,
        overwrite: true,
        timeout: Duration::from_millis(200),
        retries: 20,
        dally_timeout: Duration::from_millis(200),
        dally_retries: 2,
        ..ServerConfig::default()
    };

    let shutdown = Arc::new(AtomicBool::new(false));
    let shutdown_for_thread = Arc::clone(&shutdown);

    let handle = std::thread::spawn(move || {
        Server::new(cfg)
            .serve_until(shutdown_for_thread.as_ref())
            .unwrap();
    });

    std::thread::sleep(Duration::from_millis(50));
    (addr, shutdown, handle)
}

fn stop_server(shutdown: &Arc<AtomicBool>, handle: JoinHandle<()>) {
    shutdown.store(true, Ordering::Relaxed);
    handle.join().unwrap();
}

fn reserve_local_addr() -> SocketAddr {
    let sock = UdpSocket::bind(SocketAddr::from(([127, 0, 0, 1], 0))).unwrap();
    sock.local_addr().unwrap()
}

struct TempDir {
    path: PathBuf,
}

impl TempDir {
    fn new(prefix: &str) -> Self {
        static NEXT_ID: AtomicU64 = AtomicU64::new(0);

        let mut path = test_tmp_root();
        let now = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .map(|d| d.as_nanos())
            .unwrap_or(0);
        let id = NEXT_ID.fetch_add(1, Ordering::Relaxed);
        path.push(format!("{prefix}_{now}_{}_{}", std::process::id(), id));
        fs::create_dir_all(&path).unwrap();
        Self { path }
    }

    fn path(&self) -> &Path {
        &self.path
    }
}

impl Drop for TempDir {
    fn drop(&mut self) {
        let _ignored = fs::remove_dir_all(&self.path);
    }
}

fn test_tmp_root() -> PathBuf {
    // Keep temporary test artifacts inside the workspace, since the Codex CLI
    // sandbox does not allow writing to system temp directories.
    let manifest_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
    let workspace_root = manifest_dir
        .parent()
        .and_then(Path::parent)
        .unwrap_or(&manifest_dir);
    workspace_root
        .join("target")
        .join("tmp")
        .join("pfs-tftp-sync-tests")
}