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use std::pin::Pin;
use futures::stream::{self, Stream};
use crate::codec::{decode_tree_node, is_tree_node};
use crate::crypto::{decrypt_chk, EncryptionKey};
use crate::store::Store;
use crate::types::{to_hex, Cid, Hash};
use super::{HashTree, HashTreeError};
impl<S: Store> HashTree<S> {
/// Read content as a stream of chunks by Cid (handles decryption automatically)
///
/// Returns an async stream that yields chunks as they are read.
/// Useful for large files or when you want to process data incrementally.
pub fn get_stream(
&self,
cid: &Cid,
) -> Pin<Box<dyn Stream<Item = Result<Vec<u8>, HashTreeError>> + Send + '_>> {
let hash = cid.hash;
let key = cid.key;
if let Some(k) = key {
// Encrypted stream
Box::pin(self.read_file_stream_encrypted(hash, k))
} else {
// Unencrypted stream
self.read_file_stream(hash)
}
}
/// Read encrypted file as stream (internal)
fn read_file_stream_encrypted(
&self,
hash: Hash,
key: EncryptionKey,
) -> impl Stream<Item = Result<Vec<u8>, HashTreeError>> + Send + '_ {
stream::unfold(
EncryptedStreamState::Init {
hash,
key,
tree: self,
},
|state| async move {
match state {
EncryptedStreamState::Init { hash, key, tree } => {
let data = match tree.store.get(&hash).await {
Ok(Some(d)) => d,
Ok(None) => return None,
Err(e) => {
return Some((
Err(HashTreeError::Store(e.to_string())),
EncryptedStreamState::Done,
))
}
};
// Try to decrypt
let decrypted = match decrypt_chk(&data, &key) {
Ok(d) => d,
Err(e) => {
return Some((
Err(HashTreeError::Decryption(e.to_string())),
EncryptedStreamState::Done,
))
}
};
if !is_tree_node(&decrypted) {
// Single blob - yield decrypted data
return Some((Ok(decrypted), EncryptedStreamState::Done));
}
// Tree node - parse and traverse
let node = match decode_tree_node(&decrypted) {
Ok(n) => n,
Err(e) => {
return Some((
Err(HashTreeError::Codec(e)),
EncryptedStreamState::Done,
))
}
};
let mut stack: Vec<EncryptedStackItem> = Vec::new();
for link in node.links.into_iter().rev() {
stack.push(EncryptedStackItem {
hash: link.hash,
key: link.key,
});
}
tree.process_encrypted_stream_stack(&mut stack).await
}
EncryptedStreamState::Processing { mut stack, tree } => {
tree.process_encrypted_stream_stack(&mut stack).await
}
EncryptedStreamState::Done => None,
}
},
)
}
async fn process_encrypted_stream_stack<'a>(
&'a self,
stack: &mut Vec<EncryptedStackItem>,
) -> Option<(Result<Vec<u8>, HashTreeError>, EncryptedStreamState<'a, S>)> {
while let Some(item) = stack.pop() {
let data = match self.store.get(&item.hash).await {
Ok(Some(d)) => d,
Ok(None) => {
return Some((
Err(HashTreeError::MissingChunk(to_hex(&item.hash))),
EncryptedStreamState::Done,
))
}
Err(e) => {
return Some((
Err(HashTreeError::Store(e.to_string())),
EncryptedStreamState::Done,
))
}
};
// Decrypt if we have a key
let decrypted = if let Some(key) = item.key {
match decrypt_chk(&data, &key) {
Ok(d) => d,
Err(e) => {
return Some((
Err(HashTreeError::Decryption(e.to_string())),
EncryptedStreamState::Done,
))
}
}
} else {
data
};
if is_tree_node(&decrypted) {
// Nested tree node - add children to stack
let node = match decode_tree_node(&decrypted) {
Ok(n) => n,
Err(e) => {
return Some((Err(HashTreeError::Codec(e)), EncryptedStreamState::Done))
}
};
for link in node.links.into_iter().rev() {
stack.push(EncryptedStackItem {
hash: link.hash,
key: link.key,
});
}
} else {
// Leaf chunk - yield decrypted data
return Some((
Ok(decrypted),
EncryptedStreamState::Processing {
stack: std::mem::take(stack),
tree: self,
},
));
}
}
None
}
/// Read a file as stream of chunks
/// Returns an async stream that yields chunks as they are read
pub fn read_file_stream(
&self,
hash: Hash,
) -> Pin<Box<dyn Stream<Item = Result<Vec<u8>, HashTreeError>> + Send + '_>> {
Box::pin(stream::unfold(
ReadStreamState::Init { hash, tree: self },
|state| async move {
match state {
ReadStreamState::Init { hash, tree } => {
let data = match tree.store.get(&hash).await {
Ok(Some(d)) => d,
Ok(None) => return None,
Err(e) => {
return Some((
Err(HashTreeError::Store(e.to_string())),
ReadStreamState::Done,
))
}
};
if !is_tree_node(&data) {
// Single blob - yield it and finish
return Some((Ok(data), ReadStreamState::Done));
}
// Tree node - start streaming chunks
let node = match decode_tree_node(&data) {
Ok(n) => n,
Err(e) => {
return Some((Err(HashTreeError::Codec(e)), ReadStreamState::Done))
}
};
// Create stack with all links to process
let mut stack: Vec<StreamStackItem> = Vec::new();
for link in node.links.into_iter().rev() {
stack.push(StreamStackItem::Hash(link.hash));
}
// Process first item
tree.process_stream_stack(&mut stack).await
}
ReadStreamState::Processing { mut stack, tree } => {
tree.process_stream_stack(&mut stack).await
}
ReadStreamState::Done => None,
}
},
))
}
async fn process_stream_stack<'a>(
&'a self,
stack: &mut Vec<StreamStackItem>,
) -> Option<(Result<Vec<u8>, HashTreeError>, ReadStreamState<'a, S>)> {
while let Some(item) = stack.pop() {
match item {
StreamStackItem::Hash(hash) => {
let data = match self.store.get(&hash).await {
Ok(Some(d)) => d,
Ok(None) => {
return Some((
Err(HashTreeError::MissingChunk(to_hex(&hash))),
ReadStreamState::Done,
))
}
Err(e) => {
return Some((
Err(HashTreeError::Store(e.to_string())),
ReadStreamState::Done,
))
}
};
if is_tree_node(&data) {
// Nested tree - push its children to stack
let node = match decode_tree_node(&data) {
Ok(n) => n,
Err(e) => {
return Some((Err(HashTreeError::Codec(e)), ReadStreamState::Done))
}
};
for link in node.links.into_iter().rev() {
stack.push(StreamStackItem::Hash(link.hash));
}
} else {
// Leaf blob - yield it
return Some((
Ok(data),
ReadStreamState::Processing {
stack: std::mem::take(stack),
tree: self,
},
));
}
}
}
}
None
}
}
// Internal state types for streaming
enum StreamStackItem {
Hash(Hash),
}
enum ReadStreamState<'a, S: Store> {
Init {
hash: Hash,
tree: &'a HashTree<S>,
},
Processing {
stack: Vec<StreamStackItem>,
tree: &'a HashTree<S>,
},
Done,
}
// Encrypted stream state types
struct EncryptedStackItem {
hash: Hash,
key: Option<[u8; 32]>,
}
enum EncryptedStreamState<'a, S: Store> {
Init {
hash: Hash,
key: [u8; 32],
tree: &'a HashTree<S>,
},
Processing {
stack: Vec<EncryptedStackItem>,
tree: &'a HashTree<S>,
},
Done,
}