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use tokio::io::AsyncWriteExt;
use crate::client::{Session, TransferProgress};
use crate::error::{ClientError, Result, TransportError};
use crate::transport::transfer::{TransferFrame, read_next_frame, write_get_request};
use crate::client::transfer::store::{persist_temp_file, temp_transfer_path};
impl Session {
/// Downloads one remote file or directory to a local path.
///
/// If `remote` is a directory, it will be downloaded recursively.
pub async fn get(
&mut self,
remote: impl AsRef<std::path::Path>,
local: impl AsRef<std::path::Path>,
recursive: bool,
) -> Result<()> {
self.get_with_progress(remote, local, recursive, |_| {})
.await
}
/// Downloads one remote file or directory with progress reporting.
///
/// This method manages the entire download lifecycle:
/// 1. Connects a dedicated P2P side-stream for the transfer.
/// 2. Performs a handshake and determines the expected size and mode.
/// 3. Streams the remote data (recursively if `recursive` is true).
/// 4. Atomic persistence: Data is written to a temporary file first and
/// only moved to the final destination upon successful completion.
///
/// The `on_progress` closure is invoked periodically as bytes are read
/// from the transport stream.
///
/// # Errors
///
/// Returns an error if the connection fails, the remote path is not found,
/// or if the local filesystem prevents writing the data.
pub async fn get_with_progress<F>(
&mut self,
remote: impl AsRef<std::path::Path>,
local: impl AsRef<std::path::Path>,
recursive: bool,
on_progress: F,
) -> Result<()>
where
F: FnMut(TransferProgress) + Clone + Send + 'static,
{
let remote = remote.as_ref();
let local = local.as_ref();
// Check if remote is a directory.
let is_dir = self.is_remote_dir(remote).await?;
if is_dir {
if !recursive {
return Err(ClientError::TransferTargetInvalid {
reason: "remote is a directory, but recursive flag not set",
}
.into());
}
self.get_dir_with_progress(remote, local, on_progress).await
} else {
self.get_file_with_progress(remote, local, on_progress)
.await
}
}
/// Downloads one remote file to a local path on a separate authenticated stream.
pub async fn get_file(
&mut self,
remote: impl AsRef<std::path::Path>,
local: impl AsRef<std::path::Path>,
) -> Result<()> {
self.get_file_with_progress(remote, local, |_| {}).await
}
/// Downloads one remote file and reports progress synchronously through the callback.
pub async fn get_file_with_progress<F>(
&mut self,
remote: impl AsRef<std::path::Path>,
local: impl AsRef<std::path::Path>,
mut on_progress: F,
) -> Result<()>
where
F: FnMut(TransferProgress),
{
let remote = remote.as_ref();
let local = local.as_ref();
if remote.as_os_str().is_empty() {
return Err(ClientError::TransferTargetInvalid {
reason: "remote path is empty",
}
.into());
}
if local.as_os_str().is_empty() {
return Err(ClientError::TransferTargetInvalid {
reason: "local path is empty",
}
.into());
}
let mut stream = self.open_transfer_stream("download unavailable").await?;
write_get_request(
&mut stream,
&crate::transport::transfer::GetRequest {
path: remote.display().to_string(),
recursive: false,
},
)
.await
.map_err(TransportError::from)?;
let (expected_size, expected_mode) = match read_next_frame(&mut stream)
.await
.map_err(TransportError::from)?
{
TransferFrame::GetReady(ready) => (ready.size, ready.mode),
TransferFrame::Error(details) => {
return Err(ClientError::TransferRejected {
details: format!("remote rejected file {:?}: {}", remote, details),
}
.into());
}
other => {
return Err(ClientError::DownloadFailed {
details: format!("unexpected preflight frame for {:?}: {:?}", remote, other),
}
.into());
}
};
on_progress(TransferProgress::new(0, expected_size));
let temp_path = temp_transfer_path(local);
// Ensure parent directory exists for local path
if let Some(parent) = local.parent() {
let _ = tokio::fs::create_dir_all(parent).await;
}
let mut dest = tokio::fs::File::create(&temp_path)
.await
.map_err(|source| ClientError::FileIo {
operation: "create temp download file",
path: temp_path.clone(),
source,
})?;
let mut received = 0u64;
loop {
match read_next_frame(&mut stream)
.await
.map_err(TransportError::from)?
{
TransferFrame::GetChunk(chunk) => {
received += chunk.len() as u64;
dest.write_all(&chunk)
.await
.map_err(|source| ClientError::FileIo {
operation: "write to temp download file",
path: temp_path.clone(),
source,
})?;
on_progress(TransferProgress::new(received, expected_size));
}
TransferFrame::GetComplete(complete) => {
if complete.size != expected_size || received != expected_size {
let _ = tokio::fs::remove_file(&temp_path).await;
return Err(ClientError::DownloadFailed {
details: format!(
"expected {expected_size} bytes, received {received}, completion reported {}",
complete.size
),
}
.into());
}
break;
}
TransferFrame::Error(details) => {
let _ = tokio::fs::remove_file(&temp_path).await;
return Err(ClientError::TransferRejected {
details: format!(
"remote error during data stream for {:?}: {}",
remote, details
),
}
.into());
}
other => {
let _ = tokio::fs::remove_file(&temp_path).await;
return Err(ClientError::DownloadFailed {
details: format!(
"unexpected data stream frame for {:?}: {:?}",
remote, other
),
}
.into());
}
}
}
dest.flush().await.map_err(|source| ClientError::FileIo {
operation: "flush temp download file",
path: temp_path.clone(),
source,
})?;
drop(dest);
persist_temp_file(&temp_path, local).await?;
if let Some(_mode) = expected_mode {
#[cfg(unix)]
{
use std::os::unix::fs::PermissionsExt;
let _ =
tokio::fs::set_permissions(local, std::fs::Permissions::from_mode(_mode)).await;
}
}
Ok(())
}
/// Downloads a remote directory recursively.
pub async fn get_dir_with_progress<F>(
&mut self,
remote: impl AsRef<std::path::Path>,
local: impl AsRef<std::path::Path>,
mut on_progress: F,
) -> Result<()>
where
F: FnMut(TransferProgress) + Clone + Send + 'static,
{
let remote_root = remote.as_ref();
let local_root = local.as_ref();
let mut stream = self
.open_transfer_stream("recursive download unavailable")
.await?;
// 1. Send recursive GetRequest
crate::transport::transfer::write_get_request(
&mut stream,
&crate::transport::transfer::GetRequest {
path: remote_root.display().to_string(),
recursive: true,
},
)
.await
.map_err(TransportError::from)?;
// 2. Expect GetReady
match read_next_frame(&mut stream)
.await
.map_err(TransportError::from)?
{
TransferFrame::GetReady(_) => {}
TransferFrame::Error(details) => {
return Err(ClientError::TransferRejected {
details: details.to_string(),
}
.into());
}
other => {
return Err(ClientError::DownloadFailed {
details: format!("unexpected preflight frame: {other:?}"),
}
.into());
}
}
let mut total_received = 0u64;
loop {
match read_next_frame(&mut stream)
.await
.map_err(TransportError::from)?
{
TransferFrame::NewEntry(header) => {
let sanitized_rel =
crate::transport::transfer::sanitize_remote_path(&header.path)?;
let local_path = local_root.join(sanitized_rel);
if header.is_dir {
tokio::fs::create_dir_all(&local_path).await.map_err(|e| {
ClientError::FileIo {
operation: "create local directory",
path: local_path.clone(),
source: e,
}
})?;
} else {
if let Some(parent) = local_path.parent() {
let _ = tokio::fs::create_dir_all(parent).await;
}
let temp_path = temp_transfer_path(&local_path);
let mut dest = tokio::fs::File::create(&temp_path).await.map_err(|e| {
ClientError::FileIo {
operation: "create temp download file",
path: temp_path.clone(),
source: e,
}
})?;
loop {
match read_next_frame(&mut stream)
.await
.map_err(TransportError::from)?
{
TransferFrame::GetChunk(chunk) => {
dest.write_all(&chunk).await.map_err(|e| {
ClientError::FileIo {
operation: "write to temp download file",
path: temp_path.clone(),
source: e,
}
})?;
total_received += chunk.len() as u64;
on_progress(TransferProgress::new(total_received, 0));
}
TransferFrame::EntryComplete(_) => break,
other => {
let _ = tokio::fs::remove_file(&temp_path).await;
return Err(ClientError::DownloadFailed {
details: format!(
"unexpected frame during recursive download stream: {other:?}"
),
}
.into());
}
}
}
dest.flush().await.ok();
drop(dest);
persist_temp_file(&temp_path, &local_path).await?;
if let Some(_mode) = header.mode {
#[cfg(unix)]
{
use std::os::unix::fs::PermissionsExt;
let _ = tokio::fs::set_permissions(
&local_path,
std::fs::Permissions::from_mode(_mode),
)
.await;
}
}
}
}
TransferFrame::GetComplete(complete) => {
let _ = complete;
return Ok(());
}
TransferFrame::Error(details) => {
return Err(ClientError::TransferRejected {
details: details.to_string(),
}
.into());
}
other => {
return Err(ClientError::DownloadFailed {
details: format!("unexpected frame during recursive download: {other:?}"),
}
.into());
}
}
}
}
/// Best-effort check if a remote path is a directory.
async fn is_remote_dir(&mut self, path: impl AsRef<std::path::Path>) -> Result<bool> {
let path_str = path.as_ref().display().to_string();
let mut stream = self
.open_transfer_stream("directory check unavailable")
.await?;
crate::transport::transfer::write_exists_request(
&mut stream,
&crate::transport::transfer::ExistsRequest { path: path_str },
)
.await
.map_err(crate::error::TransportError::from)?;
match crate::transport::transfer::read_next_frame(&mut stream)
.await
.map_err(crate::error::TransportError::from)?
{
crate::transport::transfer::TransferFrame::ExistsResponse(res) => Ok(res.is_dir),
crate::transport::transfer::TransferFrame::Error(e) => {
Err(crate::error::ClientError::TransferRejected {
details: e.to_string(),
}
.into())
}
other => Err(crate::error::ClientError::DownloadFailed {
details: format!("unexpected frame during is_dir check: {:?}", other),
}
.into()),
}
}
}