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use http::StatusCode;
use wasip2::http::types::IncomingResponse;
use crate::http::body::{Body, BodyHint};
use crate::http::error::Error;
use crate::http::fields::{HeaderMap, header_map_from_wasi};
pub use http::response::{Builder, Response};
pub(crate) fn try_from_incoming(incoming: IncomingResponse) -> Result<Response<Body>, Error> {
let headers: HeaderMap = header_map_from_wasi(incoming.headers())?;
// TODO: Does WASI guarantee that the incoming status is valid?
let status = StatusCode::from_u16(incoming.status())
.map_err(|err| anyhow::anyhow!("wasi provided invalid status code ({err})"))?;
let hint = BodyHint::from_headers(&headers)?;
// `body_stream` is a child of `incoming_body` which means we cannot
// drop the parent before we drop the child
let incoming_body = incoming
.consume()
.expect("cannot call `consume` twice on incoming response");
let body = Body::from_incoming(incoming_body, hint);
let mut builder = Response::builder().status(status);
// The [`http::response::Builder`] keeps internal state of whether the
// builder has errored, which is only reachable by passing
// [`Builder::header`] an erroring `TryInto<HeaderName>` or
// `TryInto<HeaderValue>`. Since the `Builder::header` method is never
// used, we know `Builder::headers_mut` will never give the None case, nor
// will `Builder::body` give the error case. So, rather than treat those
// as control flow, we unwrap if this invariant is ever broken because
// that would only be possible due to some unrecoverable bug in wstd,
// rather than incorrect use or invalid input.
*builder.headers_mut().expect("builder has not errored") = headers;
Ok(builder
.body(body)
.expect("response builder should not error"))
}