use super::{catch_error, ToolCall};
use crate::utils::AbortSignal;
use anyhow::{anyhow, bail, Context, Result};
use futures_util::{Stream, StreamExt};
use reqwest::RequestBuilder;
use reqwest_eventsource::{Error as EventSourceError, Event, RequestBuilderExt};
use serde_json::Value;
use tokio::sync::mpsc::UnboundedSender;
pub struct SseHandler {
sender: UnboundedSender<SseEvent>,
abort_signal: AbortSignal,
buffer: String,
tool_calls: Vec<ToolCall>,
}
impl SseHandler {
pub fn new(sender: UnboundedSender<SseEvent>, abort_signal: AbortSignal) -> Self {
Self {
sender,
abort_signal,
buffer: String::new(),
tool_calls: Vec::new(),
}
}
pub fn text(&mut self, text: &str) -> Result<()> {
if text.is_empty() {
return Ok(());
}
self.buffer.push_str(text);
let ret = self
.sender
.send(SseEvent::Text(text.to_string()))
.with_context(|| "Failed to send SseEvent:Text");
if let Err(err) = ret {
if self.abort_signal.aborted() {
return Ok(());
}
return Err(err);
}
Ok(())
}
pub fn done(&mut self) {
let ret = self.sender.send(SseEvent::Done);
if ret.is_err() {
if self.abort_signal.aborted() {
return;
}
warn!("Failed to send SseEvent:Done");
}
}
pub fn tool_call(&mut self, call: ToolCall) -> Result<()> {
self.tool_calls.push(call);
Ok(())
}
pub fn abort(&self) -> AbortSignal {
self.abort_signal.clone()
}
pub fn tool_calls(&self) -> &[ToolCall] {
&self.tool_calls
}
pub fn take(self) -> (String, Vec<ToolCall>) {
let Self {
buffer, tool_calls, ..
} = self;
(buffer, tool_calls)
}
}
#[derive(Debug)]
pub enum SseEvent {
Text(String),
Done,
}
#[derive(Debug)]
pub struct SseMmessage {
#[allow(unused)]
pub event: String,
pub data: String,
}
pub async fn sse_stream<F>(builder: RequestBuilder, mut handle: F) -> Result<()>
where
F: FnMut(SseMmessage) -> Result<bool>,
{
let mut es = builder.eventsource()?;
while let Some(event) = es.next().await {
match event {
Ok(Event::Open) => {}
Ok(Event::Message(message)) => {
let message = SseMmessage {
event: message.event,
data: message.data,
};
if handle(message)? {
break;
}
}
Err(err) => {
match err {
EventSourceError::StreamEnded => {}
EventSourceError::InvalidStatusCode(status, res) => {
let text = res.text().await?;
let data: Value = match text.parse() {
Ok(data) => data,
Err(_) => {
bail!(
"Invalid response data: {text} (status: {})",
status.as_u16()
);
}
};
catch_error(&data, status.as_u16())?;
}
EventSourceError::InvalidContentType(header_value, res) => {
let text = res.text().await?;
bail!(
"Invalid response event-stream. content-type: {}, data: {text}",
header_value.to_str().unwrap_or_default()
);
}
_ => {
bail!("{}", err);
}
}
es.close();
}
}
}
Ok(())
}
pub async fn json_stream<S, F, E>(mut stream: S, mut handle: F) -> Result<()>
where
S: Stream<Item = Result<bytes::Bytes, E>> + Unpin,
F: FnMut(&str) -> Result<()>,
E: std::error::Error,
{
let mut parser = JsonStreamParser::default();
let mut unparsed_bytes = vec![];
while let Some(chunk_bytes) = stream.next().await {
let chunk_bytes =
chunk_bytes.map_err(|err| anyhow!("Failed to read json stream, {err}"))?;
unparsed_bytes.extend(chunk_bytes);
match std::str::from_utf8(&unparsed_bytes) {
Ok(text) => {
parser.process(text, &mut handle)?;
unparsed_bytes.clear();
}
Err(_) => {
continue;
}
}
}
if !unparsed_bytes.is_empty() {
let text = std::str::from_utf8(&unparsed_bytes)?;
parser.process(text, &mut handle)?;
}
Ok(())
}
#[derive(Debug, Default)]
struct JsonStreamParser {
buffer: Vec<char>,
cursor: usize,
start: Option<usize>,
balances: Vec<char>,
quoting: bool,
escape: bool,
}
impl JsonStreamParser {
fn process<F>(&mut self, text: &str, handle: &mut F) -> Result<()>
where
F: FnMut(&str) -> Result<()>,
{
self.buffer.extend(text.chars());
for i in self.cursor..self.buffer.len() {
let ch = self.buffer[i];
if self.quoting {
if ch == '\\' {
self.escape = !self.escape;
} else {
if !self.escape && ch == '"' {
self.quoting = false;
}
self.escape = false;
}
continue;
}
match ch {
'"' => {
self.quoting = true;
self.escape = false;
}
'{' => {
if self.balances.is_empty() {
self.start = Some(i);
}
self.balances.push(ch);
}
'[' => {
if self.start.is_some() {
self.balances.push(ch);
}
}
'}' => {
self.balances.pop();
if self.balances.is_empty() {
if let Some(start) = self.start.take() {
let value: String = self.buffer[start..=i].iter().collect();
handle(&value)?;
}
}
}
']' => {
self.balances.pop();
}
_ => {}
}
}
self.cursor = self.buffer.len();
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use bytes::Bytes;
use futures_util::stream;
use rand::Rng;
fn split_chunks(text: &str) -> Vec<Vec<u8>> {
let mut rng = rand::rng();
let len = text.len();
let cut1 = rng.random_range(1..len - 1);
let cut2 = rng.random_range(cut1 + 1..len);
let chunk1 = text.as_bytes()[..cut1].to_vec();
let chunk2 = text.as_bytes()[cut1..cut2].to_vec();
let chunk3 = text.as_bytes()[cut2..].to_vec();
vec![chunk1, chunk2, chunk3]
}
macro_rules! assert_json_stream {
($input:expr, $output:expr) => {
let chunks: Vec<_> = split_chunks($input)
.into_iter()
.map(|chunk| Ok::<_, std::convert::Infallible>(Bytes::from(chunk)))
.collect();
let stream = stream::iter(chunks);
let mut output = vec![];
let ret = json_stream(stream, |data| {
output.push(data.to_string());
Ok(())
})
.await;
assert!(ret.is_ok());
assert_eq!($output.replace("\r\n", "\n"), output.join("\n"))
};
}
#[tokio::test]
async fn test_json_stream_ndjson() {
let data = r#"{"key": "value"}
{"key": "value2"}
{"key": "value3"}"#;
assert_json_stream!(data, data);
}
#[tokio::test]
async fn test_json_stream_array() {
let input = r#"[
{"key": "value"},
{"key": "value2"},
{"key": "value3"},"#;
let output = r#"{"key": "value"}
{"key": "value2"}
{"key": "value3"}"#;
assert_json_stream!(input, output);
}
}