lanspread/crates/lanspread-peer/src/stream_install.rs

use std::{
    future::Future,
    net::SocketAddr,
    path::{Path, PathBuf},
    pin::Pin,
    process::Stdio,
    sync::Arc,
    time::{Duration, Instant},
};

use bytes::Bytes;
use crc32fast::Hasher;
use futures::{SinkExt, StreamExt};
use lanspread_proto::{Message, Request, StreamInstallFrame};
use s2n_quic::stream::SendStream;
use tokio::{
    fs::File,
    io::{AsyncRead, AsyncReadExt, AsyncWriteExt},
    process::Command,
    sync::{mpsc, mpsc::UnboundedSender},
    time::{self, MissedTickBehavior},
};
use tokio_util::{
    codec::{FramedRead, FramedWrite, LengthDelimitedCodec},
    sync::CancellationToken,
};

use crate::{
    DownloadProgress,
    PeerEvent,
    install::root_eti_archives,
    network::connect_to_peer,
    path_validation::validate_game_file_path,
};

const FRAME_CHANNEL_DEPTH: usize = 16;
const STREAM_INSTALL_PROGRESS_UPDATE_INTERVAL: Duration = Duration::from_millis(500);
const STREAM_CHUNK_SIZE: usize = 256 * 1024;

/// Integrity metadata advertised by the sender's RAR archive.
///
/// This catches transport corruption, truncation, and provider bugs. It is not
/// a trusted-content guarantee because a malicious peer controls both the bytes
/// and the archive metadata. Trusted content would need catalog-owned hashes.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct SenderArchiveIntegrity {
    expected_size: u64,
    expected_crc32: u32,
}

impl SenderArchiveIntegrity {
    fn new(expected_size: u64, expected_crc32: u32) -> Self {
        Self {
            expected_size,
            expected_crc32,
        }
    }

    fn verify(self, relative_path: &str, received: u64, actual_crc32: u32) -> eyre::Result<()> {
        if received != self.expected_size {
            eyre::bail!(
                "streamed file {relative_path} size mismatch: got {received}, expected {}",
                self.expected_size
            );
        }

        if actual_crc32 != self.expected_crc32 {
            eyre::bail!(
                "streamed file {relative_path} sender RAR CRC32 mismatch: got {actual_crc32:08X}, expected {:08X}",
                self.expected_crc32
            );
        }

        Ok(())
    }
}

pub type StreamInstallFuture<'a> = Pin<Box<dyn Future<Output = eyre::Result<()>> + Send + 'a>>;

pub trait StreamInstallProvider: Send + Sync {
    fn stream_archive<'a>(
        &'a self,
        archive: &'a Path,
        frames: mpsc::Sender<StreamInstallFrame>,
        cancel_token: CancellationToken,
    ) -> StreamInstallFuture<'a>;
}

#[derive(Debug, Default)]
pub struct NoopStreamInstallProvider;

impl StreamInstallProvider for NoopStreamInstallProvider {
    fn stream_archive<'a>(
        &'a self,
        archive: &'a Path,
        _frames: mpsc::Sender<StreamInstallFrame>,
        _cancel_token: CancellationToken,
    ) -> StreamInstallFuture<'a> {
        Box::pin(async move {
            eyre::bail!(
                "streamed install provider is not configured for {}",
                archive.display()
            )
        })
    }
}

#[derive(Debug)]
pub struct ExternalUnrarStreamProvider {
    program: PathBuf,
}

impl ExternalUnrarStreamProvider {
    #[must_use]
    pub fn new(program: PathBuf) -> Self {
        Self { program }
    }
}

impl StreamInstallProvider for ExternalUnrarStreamProvider {
    fn stream_archive<'a>(
        &'a self,
        archive: &'a Path,
        frames: mpsc::Sender<StreamInstallFrame>,
        cancel_token: CancellationToken,
    ) -> StreamInstallFuture<'a> {
        Box::pin(async move {
            let listing = unrar_listing(&self.program, archive).await?;
            let archive_name = archive
                .file_name()
                .and_then(|name| name.to_str())
                .unwrap_or("archive.eti")
                .to_string();

            send_stream_frame(
                &frames,
                StreamInstallFrame::ArchiveBegin {
                    archive_name: archive_name.clone(),
                    solid: listing.solid,
                    unpacked_size: listing.unpacked_size(),
                },
            )
            .await?;

            stream_unrar_entries(
                &self.program,
                archive,
                &listing.entries,
                &frames,
                cancel_token.clone(),
            )
            .await?;

            send_stream_frame(&frames, StreamInstallFrame::ArchiveEnd { archive_name }).await
        })
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct RarListing {
    solid: bool,
    entries: Vec<RarEntry>,
}

impl RarListing {
    fn unpacked_size(&self) -> u64 {
        self.entries
            .iter()
            .filter(|entry| entry.kind == RarEntryKind::File)
            .map(|entry| entry.size)
            .sum()
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct RarEntry {
    relative_path: String,
    kind: RarEntryKind,
    size: u64,
    crc32: Option<u32>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum RarEntryKind {
    File,
    Directory,
}

#[derive(Default)]
struct RarEntryDraft {
    relative_path: Option<String>,
    kind: Option<RarEntryKind>,
    size: Option<u64>,
    crc32: Option<u32>,
}

async fn unrar_listing(program: &Path, archive: &Path) -> eyre::Result<RarListing> {
    let output = Command::new(program)
        .arg("lt")
        .arg("-cfg-")
        .arg(archive)
        .output()
        .await?;
    if !output.status.success() {
        eyre::bail!(
            "unrar lt failed for {} with status {}: {}",
            archive.display(),
            output.status,
            String::from_utf8_lossy(&output.stderr)
        );
    }

    parse_unrar_listing(&String::from_utf8_lossy(&output.stdout))
}

fn parse_unrar_listing(output: &str) -> eyre::Result<RarListing> {
    let mut solid = false;
    let mut entries = Vec::new();
    let mut current = RarEntryDraft::default();

    for line in output.lines() {
        let trimmed = line.trim();
        if let Some(details) = trimmed.strip_prefix("Details:") {
            solid = details.to_ascii_lowercase().contains("solid");
            continue;
        }

        if let Some(name) = trimmed.strip_prefix("Name:") {
            push_rar_entry(&mut entries, std::mem::take(&mut current))?;
            current.relative_path = Some(name.trim().to_string());
            continue;
        }

        if let Some(kind) = trimmed.strip_prefix("Type:") {
            current.kind = match kind.trim() {
                "File" => Some(RarEntryKind::File),
                "Directory" => Some(RarEntryKind::Directory),
                _ => None,
            };
            continue;
        }

        if let Some(size) = trimmed.strip_prefix("Size:") {
            current.size = Some(size.trim().parse()?);
            continue;
        }

        if let Some(crc) = trimmed.strip_prefix("CRC32:") {
            current.crc32 = Some(u32::from_str_radix(crc.trim(), 16)?);
        }
    }

    push_rar_entry(&mut entries, current)?;
    Ok(RarListing { solid, entries })
}

fn push_rar_entry(entries: &mut Vec<RarEntry>, draft: RarEntryDraft) -> eyre::Result<()> {
    let Some(relative_path) = draft.relative_path else {
        return Ok(());
    };

    let Some(kind) = draft.kind else {
        return Ok(());
    };

    let (size, crc32) = match kind {
        RarEntryKind::File => {
            let size = draft
                .size
                .ok_or_else(|| eyre::eyre!("RAR file entry {relative_path} has no Size"))?;
            let crc32 = draft
                .crc32
                .ok_or_else(|| eyre::eyre!("RAR file entry {relative_path} has no CRC32"))?;
            (size, Some(crc32))
        }
        RarEntryKind::Directory => (0, None),
    };

    entries.push(RarEntry {
        relative_path,
        kind,
        size,
        crc32,
    });
    Ok(())
}

async fn stream_unrar_entries(
    program: &Path,
    archive: &Path,
    entries: &[RarEntry],
    frames: &mpsc::Sender<StreamInstallFrame>,
    cancel_token: CancellationToken,
) -> eyre::Result<()> {
    let mut child = Command::new(program)
        .arg("p")
        .arg("-inul")
        .arg("-cfg-")
        .arg(archive)
        .stdout(Stdio::piped())
        .stderr(Stdio::null())
        .spawn()?;

    let result = async {
        let mut stdout = child
            .stdout
            .take()
            .ok_or_else(|| eyre::eyre!("unrar stdout was not captured"))?;
        let mut buffer = vec![0_u8; STREAM_CHUNK_SIZE];

        for entry in entries {
            if cancel_token.is_cancelled() {
                eyre::bail!("streamed archive {} was cancelled", archive.display());
            }

            match entry.kind {
                RarEntryKind::Directory => {
                    send_stream_frame(
                        frames,
                        StreamInstallFrame::Directory {
                            relative_path: entry.relative_path.clone(),
                        },
                    )
                    .await?;
                }
                RarEntryKind::File => {
                    let Some(crc32) = entry.crc32 else {
                        eyre::bail!("RAR file entry {} has no CRC32", entry.relative_path);
                    };
                    send_stream_frame(
                        frames,
                        StreamInstallFrame::FileBegin {
                            relative_path: entry.relative_path.clone(),
                            size: entry.size,
                            crc32,
                        },
                    )
                    .await?;
                    stream_unrar_file_from_stdout(
                        &mut stdout,
                        archive,
                        entry,
                        frames,
                        &mut buffer,
                        &cancel_token,
                    )
                    .await?;
                    send_stream_frame(
                        frames,
                        StreamInstallFrame::FileEnd {
                            relative_path: entry.relative_path.clone(),
                        },
                    )
                    .await?;
                }
            }
        }

        let extra =
            read_unrar_stdout(&mut stdout, &mut buffer[..1], &cancel_token, archive).await?;
        if extra != 0 {
            eyre::bail!(
                "unrar produced bytes after listed entries for {}",
                archive.display()
            );
        }

        let status = wait_unrar_child(&mut child, &cancel_token, archive).await?;
        if !status.success() {
            eyre::bail!(
                "unrar p failed for {} with status {status}",
                archive.display()
            );
        }

        Ok(())
    }
    .await;

    if result.is_err() {
        let _ = child.kill().await;
    }

    result
}

async fn stream_unrar_file_from_stdout(
    stdout: &mut (impl AsyncRead + Unpin),
    archive: &Path,
    entry: &RarEntry,
    frames: &mpsc::Sender<StreamInstallFrame>,
    buffer: &mut [u8],
    cancel_token: &CancellationToken,
) -> eyre::Result<()> {
    let mut remaining = entry.size;
    while remaining > 0 {
        let read_len = usize::try_from(remaining.min(u64::try_from(buffer.len())?))?;
        let read =
            read_unrar_stdout(stdout, &mut buffer[..read_len], cancel_token, archive).await?;
        if read == 0 {
            eyre::bail!(
                "unrar ended while streaming {} from {}; {remaining} bytes missing",
                entry.relative_path,
                archive.display()
            );
        }

        send_stream_frame(
            frames,
            StreamInstallFrame::FileChunk {
                bytes: Bytes::copy_from_slice(&buffer[..read]),
            },
        )
        .await?;
        remaining = remaining.saturating_sub(u64::try_from(read)?);
    }

    Ok(())
}

async fn read_unrar_stdout(
    stdout: &mut (impl AsyncRead + Unpin),
    buffer: &mut [u8],
    cancel_token: &CancellationToken,
    archive: &Path,
) -> eyre::Result<usize> {
    tokio::select! {
        () = cancel_token.cancelled() => {
            eyre::bail!("streamed archive {} was cancelled", archive.display());
        }
        read = stdout.read(buffer) => Ok(read?),
    }
}

async fn wait_unrar_child(
    child: &mut tokio::process::Child,
    cancel_token: &CancellationToken,
    archive: &Path,
) -> eyre::Result<std::process::ExitStatus> {
    tokio::select! {
        () = cancel_token.cancelled() => {
            let _ = child.kill().await;
            eyre::bail!("streamed archive {} was cancelled", archive.display());
        }
        status = child.wait() => Ok(status?),
    }
}

async fn send_stream_frame(
    frames: &mpsc::Sender<StreamInstallFrame>,
    frame: StreamInstallFrame,
) -> eyre::Result<()> {
    frames
        .send(frame)
        .await
        .map_err(|_| eyre::eyre!("streamed install frame receiver closed"))
}

pub(crate) async fn send_stream_install_error(
    tx: SendStream,
    message: impl Into<String>,
) -> SendStream {
    let mut framed_tx = FramedWrite::new(tx, LengthDelimitedCodec::new());
    if let Err(err) = framed_tx
        .send(
            StreamInstallFrame::Error {
                message: message.into(),
            }
            .encode(),
        )
        .await
    {
        log::warn!("Failed to send streamed install error frame: {err}");
    }
    if let Err(err) = framed_tx.close().await {
        log::debug!("Failed to close streamed install error response: {err}");
    }
    framed_tx.into_inner()
}

pub(crate) async fn send_game_install_stream(
    provider: Arc<dyn StreamInstallProvider>,
    tx: SendStream,
    game_root: &Path,
    game_id: &str,
    cancel_token: CancellationToken,
) -> (SendStream, eyre::Result<()>) {
    let archives = match root_eti_archives(game_root).await {
        Ok(archives) => archives,
        Err(err) => {
            let message = err.to_string();
            let tx = send_stream_install_error(tx, message.clone()).await;
            return (tx, Err(eyre::eyre!(message)));
        }
    };
    if archives.is_empty() {
        let message = format!("no .eti archives found for {game_id}");
        let tx = send_stream_install_error(tx, message.clone()).await;
        return (tx, Err(eyre::eyre!(message)));
    }

    let (frame_tx, mut frame_rx) = mpsc::channel(FRAME_CHANNEL_DEPTH);
    let producer_cancel = cancel_token.child_token();
    let game_id_for_producer = game_id.to_string();
    let producer = tokio::spawn({
        let provider = provider.clone();
        let producer_cancel = producer_cancel.clone();
        async move {
            for archive in archives {
                if producer_cancel.is_cancelled() {
                    eyre::bail!("streamed install for {game_id_for_producer} was cancelled");
                }

                if let Err(err) = provider
                    .stream_archive(&archive, frame_tx.clone(), producer_cancel.clone())
                    .await
                {
                    let message = err.to_string();
                    let _ = frame_tx.send(StreamInstallFrame::Error { message }).await;
                    return Err(err);
                }
            }

            let _ = frame_tx.send(StreamInstallFrame::Complete).await;
            Ok(())
        }
    });

    let mut framed_tx = FramedWrite::new(tx, LengthDelimitedCodec::new());
    let mut send_result = Ok(());

    while let Some(frame) = frame_rx.recv().await {
        if let Err(err) = framed_tx.send(frame.encode()).await {
            producer_cancel.cancel();
            send_result = Err(eyre::eyre!("failed to send streamed install frame: {err}"));
            break;
        }
    }

    let close_result = framed_tx
        .close()
        .await
        .map_err(|err| eyre::eyre!("failed to close streamed install stream: {err}"));
    let tx = framed_tx.into_inner();
    let producer_result = match producer.await {
        Ok(result) => result,
        Err(err) => Err(eyre::eyre!("streamed install producer task failed: {err}")),
    };
    let result = send_result.and(producer_result).and(close_result);

    (tx, result)
}

pub(crate) async fn receive_streamed_install(
    peer_addr: SocketAddr,
    game_id: &str,
    staging_dir: &Path,
    tx_notify_ui: UnboundedSender<PeerEvent>,
    cancel_token: CancellationToken,
) -> eyre::Result<()> {
    let staging_dir = tokio::fs::canonicalize(staging_dir)
        .await
        .unwrap_or_else(|_| staging_dir.to_path_buf());
    let mut conn = connect_to_peer(peer_addr).await?;
    let stream = conn.open_bidirectional_stream().await?;
    let (rx, tx) = stream.split();
    let mut framed_tx = FramedWrite::new(tx, LengthDelimitedCodec::new());

    framed_tx
        .send(
            Request::StreamInstall {
                game_id: game_id.to_string(),
            }
            .encode(),
        )
        .await?;
    framed_tx.close().await?;

    let mut framed_rx = FramedRead::new(rx, LengthDelimitedCodec::new());
    let mut current_file: Option<IncomingFile> = None;
    let mut progress = StreamInstallProgress::new(game_id.to_string());
    let mut progress_interval = time::interval(STREAM_INSTALL_PROGRESS_UPDATE_INTERVAL);
    progress_interval.set_missed_tick_behavior(MissedTickBehavior::Skip);
    progress_interval.tick().await;

    loop {
        let next = tokio::select! {
            () = cancel_token.cancelled() => eyre::bail!("streamed install for {game_id} was cancelled"),
            _ = progress_interval.tick() => {
                progress.emit_current(&tx_notify_ui);
                continue;
            }
            next = framed_rx.next() => next,
        };

        let Some(frame) = next else {
            eyre::bail!("streamed install ended before Complete");
        };
        let frame = frame?.freeze();
        let frame = StreamInstallFrame::decode(frame);

        match frame {
            StreamInstallFrame::ArchiveBegin {
                archive_name,
                solid,
                unpacked_size,
            } => {
                progress.add_total(unpacked_size);
                progress.emit_snapshot(&tx_notify_ui, 0);
                log::info!(
                    "Receiving streamed install archive {archive_name} for {game_id} \
                     (solid={solid}, unpacked_size={unpacked_size})"
                );
            }
            StreamInstallFrame::Directory { relative_path } => {
                let path = resolve_stream_path(&staging_dir, &relative_path)?;
                tokio::fs::create_dir_all(path).await?;
            }
            StreamInstallFrame::FileBegin {
                relative_path,
                size,
                crc32,
            } => {
                if current_file.is_some() {
                    eyre::bail!("received FileBegin for {relative_path} before previous FileEnd");
                }
                let path = resolve_stream_path(&staging_dir, &relative_path)?;
                if let Some(parent) = path.parent() {
                    tokio::fs::create_dir_all(parent).await?;
                }
                let file = File::create(&path).await?;
                current_file = Some(IncomingFile::new(relative_path, path, size, crc32, file));
            }
            StreamInstallFrame::FileChunk { bytes } => {
                let Some(file) = current_file.as_mut() else {
                    eyre::bail!("received FileChunk without FileBegin");
                };
                let length = file
                    .write_chunk(game_id, peer_addr, &tx_notify_ui, bytes)
                    .await?;
                progress.record_bytes(length);
            }
            StreamInstallFrame::FileEnd { relative_path } => {
                let Some(file) = current_file.take() else {
                    eyre::bail!("received FileEnd for {relative_path} without FileBegin");
                };
                file.finish(&relative_path).await?;
            }
            StreamInstallFrame::ArchiveEnd { archive_name } => {
                log::info!("Finished streamed install archive {archive_name} for {game_id}");
            }
            StreamInstallFrame::Complete => {
                if current_file.is_some() {
                    eyre::bail!("streamed install completed with an open file");
                }
                progress.emit_snapshot(&tx_notify_ui, 0);
                return Ok(());
            }
            StreamInstallFrame::Error { message } => {
                eyre::bail!("streamed install sender failed: {message}");
            }
        }
    }
}

struct StreamInstallProgress {
    id: String,
    total_bytes: u64,
    downloaded_bytes: u64,
    last_downloaded_bytes: u64,
    last_at: Instant,
}

impl StreamInstallProgress {
    fn new(id: String) -> Self {
        Self {
            id,
            total_bytes: 0,
            downloaded_bytes: 0,
            last_downloaded_bytes: 0,
            last_at: Instant::now(),
        }
    }

    fn add_total(&mut self, bytes: u64) {
        self.total_bytes = self.total_bytes.saturating_add(bytes);
    }

    fn record_bytes(&mut self, bytes: u64) {
        self.downloaded_bytes = self.downloaded_bytes.saturating_add(bytes);
    }

    fn emit_current(&mut self, tx_notify_ui: &UnboundedSender<PeerEvent>) {
        let now = Instant::now();
        let speed = bytes_per_second(
            self.downloaded_bytes
                .saturating_sub(self.last_downloaded_bytes),
            now.duration_since(self.last_at),
        );

        self.last_downloaded_bytes = self.downloaded_bytes;
        self.last_at = now;
        self.emit_snapshot(tx_notify_ui, speed);
    }

    fn emit_snapshot(&self, tx_notify_ui: &UnboundedSender<PeerEvent>, bytes_per_second: u64) {
        let _ = tx_notify_ui.send(PeerEvent::DownloadGameFilesProgress(DownloadProgress {
            id: self.id.clone(),
            downloaded_bytes: self.downloaded_bytes,
            total_bytes: self.total_bytes,
            bytes_per_second,
            active_peer_count: 1,
        }));
    }
}

fn bytes_per_second(bytes: u64, elapsed: Duration) -> u64 {
    let millis = elapsed.as_millis().max(1);
    let rate = u128::from(bytes).saturating_mul(1_000) / millis;
    u64::try_from(rate).unwrap_or(u64::MAX)
}

struct IncomingFile {
    relative_path: String,
    path: PathBuf,
    integrity: SenderArchiveIntegrity,
    received: u64,
    crc32: Hasher,
    file: File,
}

impl IncomingFile {
    fn new(
        relative_path: String,
        path: PathBuf,
        expected_size: u64,
        expected_crc32: u32,
        file: File,
    ) -> Self {
        Self {
            relative_path,
            path,
            integrity: SenderArchiveIntegrity::new(expected_size, expected_crc32),
            received: 0,
            crc32: Hasher::new(),
            file,
        }
    }

    async fn write_chunk(
        &mut self,
        game_id: &str,
        peer_addr: SocketAddr,
        tx_notify_ui: &UnboundedSender<PeerEvent>,
        bytes: Bytes,
    ) -> eyre::Result<u64> {
        let offset = self.received;
        let length = u64::try_from(bytes.len())?;
        if offset.saturating_add(length) > self.integrity.expected_size {
            eyre::bail!(
                "streamed file {} exceeded expected size {}",
                self.relative_path,
                self.integrity.expected_size
            );
        }
        self.file.write_all(&bytes).await?;
        self.crc32.update(&bytes);
        self.received = self.received.saturating_add(length);

        let _ = tx_notify_ui.send(PeerEvent::DownloadGameFileChunkFinished {
            id: game_id.to_string(),
            peer_addr,
            relative_path: format!("{game_id}/.local.installing/{}", self.relative_path),
            offset,
            length,
        });
        Ok(length)
    }

    async fn finish(mut self, relative_path: &str) -> eyre::Result<()> {
        if self.relative_path != relative_path {
            eyre::bail!(
                "streamed file end mismatch: began {}, ended {relative_path}",
                self.relative_path
            );
        }
        self.file.flush().await?;

        let actual_crc32 = self.crc32.finalize();
        self.integrity
            .verify(&self.relative_path, self.received, actual_crc32)?;

        log::debug!(
            "Received streamed file {} -> {}",
            self.relative_path,
            self.path.display()
        );
        Ok(())
    }
}

fn resolve_stream_path(staging_dir: &Path, relative_path: &str) -> eyre::Result<PathBuf> {
    validate_game_file_path(staging_dir, relative_path)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_support::TempDir;

    #[test]
    fn stream_paths_stay_inside_staging_dir() {
        let temp = TempDir::new("lanspread-stream-install-path");
        let staging = temp.path().join("staging");
        std::fs::create_dir_all(&staging).expect("staging should be created");
        let staging = std::fs::canonicalize(staging).expect("staging should canonicalize");

        assert!(resolve_stream_path(&staging, "bin/game.exe").is_ok());
        assert!(resolve_stream_path(&staging, "../outside").is_err());
        assert!(resolve_stream_path(&staging, "/absolute").is_err());
        assert!(resolve_stream_path(&staging, "C:/windows").is_err());
    }

    #[test]
    fn parses_unrar_technical_listing() {
        let listing = parse_unrar_listing(
            r#"
Archive: game.eti
Details: RAR 5, solid

        Name: bin/payload.bin
        Type: File
        Size: 123
       CRC32: 38B488A7

        Name: bin
        Type: Directory
"#,
        )
        .expect("listing should parse");

        assert!(listing.solid);
        assert_eq!(
            listing.entries,
            vec![
                RarEntry {
                    relative_path: "bin/payload.bin".to_string(),
                    kind: RarEntryKind::File,
                    size: 123,
                    crc32: Some(0x38B4_88A7),
                },
                RarEntry {
                    relative_path: "bin".to_string(),
                    kind: RarEntryKind::Directory,
                    size: 0,
                    crc32: None,
                },
            ]
        );
    }

    #[test]
    fn rejects_unrar_file_entries_without_crc32() {
        let err = parse_unrar_listing(
            r#"
Archive: game.eti
Details: RAR 5

        Name: bin/payload.bin
        Type: File
        Size: 123
"#,
        )
        .expect_err("file entries without CRC32 should be rejected");

        assert!(err.to_string().contains("has no CRC32"));
    }

    #[test]
    fn sender_archive_integrity_accepts_matching_size_and_crc32() {
        let bytes = b"payload";
        let integrity =
            SenderArchiveIntegrity::new(u64::try_from(bytes.len()).unwrap(), crc32_of(bytes));

        integrity
            .verify(
                "bin/payload.bin",
                u64::try_from(bytes.len()).unwrap(),
                crc32_of(bytes),
            )
            .expect("matching sender archive metadata should verify");
    }

    #[test]
    fn sender_archive_integrity_rejects_size_mismatch() {
        let integrity = SenderArchiveIntegrity::new(7, crc32_of(b"payload"));
        let err = integrity
            .verify("bin/payload.bin", 6, crc32_of(b"payload"))
            .expect_err("truncated file should fail sender archive integrity");

        assert!(err.to_string().contains("size mismatch"));
    }

    #[test]
    fn sender_archive_integrity_rejects_crc32_mismatch() {
        let integrity = SenderArchiveIntegrity::new(7, crc32_of(b"payload"));
        let err = integrity
            .verify("bin/payload.bin", 7, crc32_of(b"paylord"))
            .expect_err("mutated file should fail sender archive integrity");

        assert!(err.to_string().contains("sender RAR CRC32 mismatch"));
    }

    fn crc32_of(bytes: &[u8]) -> u32 {
        let mut hasher = Hasher::new();
        hasher.update(bytes);
        hasher.finalize()
    }
}