//! A streaming Cargo response. Dropping the body cancels the builder's native process group.
use crate::builder::Event;
use bytes::Bytes;
use http::{Request, Response};
use http_body_util::BodyExt;
use std::{
    pin::Pin,
    task::{Context, Poll},
};
struct Body(tokio::sync::mpsc::Receiver<Event>);
impl http_body::Body for Body {
    type Data = Bytes;
    type Error = wasmtime_wasi_http::Error;
    fn poll_frame(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Option<Result<http_body::Frame<Bytes>, Self::Error>>> {
        self.0.poll_recv(cx).map(|event| {
            event.map(|event| {
                let mut bytes = serde_json::to_vec(&event).expect("Cargo event");
                bytes.push(b'\n');
                Ok(http_body::Frame::data(Bytes::from(bytes)))
            })
        })
    }
}
pub(crate) fn stream(
    api: &super::Api,
    request: Request<Bytes>,
) -> Response<wasmtime_wasi_http::WasiBody> {
    let (tx, rx) = tokio::sync::mpsc::channel(16);
    let builder = api.builder.get().cloned();
    let request = serde_json::from_slice::<crate::builder::Request>(request.body());
    tokio::spawn(async move {
        let result = async {
            builder
                .ok_or_else(|| anyhow::anyhow!("builder unavailable"))?
                .execute(request?, &tx)
                .await
        }
        .await;
        if let Err(error) = result {
            let _ = tx
                .send(Event::Stderr {
                    bytes: format!("cargo: {error:#}\n").into_bytes(),
                })
                .await;
            let _ = tx
                .send(Event::Exit {
                    code: 1,
                    executables: Vec::new(),
                })
                .await;
        }
    });
    Response::builder()
        .header("content-type", "application/x-ndjson")
        .body(Body(rx).boxed_unsync())
        .unwrap()
}