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use std::{
marker::PhantomData,
pin::Pin,
task::{Context, Poll},
};
use aws_smithy_http_server::{
body::{Body, BoxBody},
response::IntoResponse,
};
use futures::{ready, Future};
use http::{Request, Response};
use pin_project_lite::pin_project;
use pyo3_asyncio::TaskLocals;
use tower::{Layer, Service};
use crate::{middleware::PyFuture, PyMiddlewareException, PyMiddlewares};
#[derive(Debug, Clone)]
pub struct PyMiddlewareLayer<P> {
handlers: PyMiddlewares,
locals: TaskLocals,
_protocol: PhantomData<P>,
}
impl<P> PyMiddlewareLayer<P> {
pub fn new(handlers: PyMiddlewares, locals: TaskLocals) -> Self {
Self {
handlers,
locals,
_protocol: PhantomData,
}
}
}
impl<S, P> Layer<S> for PyMiddlewareLayer<P>
where
PyMiddlewareException: IntoResponse<P>,
{
type Service = PyMiddlewareService<S>;
fn layer(&self, inner: S) -> Self::Service {
PyMiddlewareService::new(inner, self.handlers.clone(), self.locals.clone())
}
}
#[derive(Clone, Debug)]
pub struct PyMiddlewareService<S> {
inner: S,
handlers: PyMiddlewares,
locals: TaskLocals,
}
impl<S> PyMiddlewareService<S> {
pub fn new(inner: S, handlers: PyMiddlewares, locals: TaskLocals) -> PyMiddlewareService<S> {
Self {
inner,
handlers,
locals,
}
}
}
impl<S> Service<Request<Body>> for PyMiddlewareService<S>
where
S: Service<Request<Body>, Response = Response<BoxBody>> + Clone,
{
type Response = Response<BoxBody>;
type Error = S::Error;
type Future = ResponseFuture<S>;
fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
self.inner.poll_ready(cx)
}
fn call(&mut self, req: Request<Body>) -> Self::Future {
let clone = self.inner.clone();
let inner = std::mem::replace(&mut self.inner, clone);
let run = self.handlers.run(req, self.locals.clone());
ResponseFuture {
middleware: State::Running { run },
service: inner,
}
}
}
pin_project! {
pub struct ResponseFuture<S>
where
S: Service<Request<Body>>,
{
#[pin]
middleware: State<PyFuture, S::Future>,
service: S,
}
}
pin_project! {
#[project = StateProj]
enum State<A, Fut> {
Running {
#[pin]
run: A,
},
Done {
#[pin]
fut: Fut
}
}
}
impl<S> Future for ResponseFuture<S>
where
S: Service<Request<Body>, Response = Response<BoxBody>>,
{
type Output = Result<Response<BoxBody>, S::Error>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
let mut this = self.project();
loop {
match this.middleware.as_mut().project() {
StateProj::Running { run } => {
let run = ready!(run.poll(cx));
match run {
Ok(req) => {
let fut = this.service.call(req);
this.middleware.set(State::Done { fut });
}
Err(res) => return Poll::Ready(Ok(res)),
}
}
StateProj::Done { fut } => return fut.poll(cx),
}
}
}
}
#[cfg(test)]
mod tests {
use std::error::Error;
use super::*;
use aws_smithy_http_server::body::to_boxed;
use aws_smithy_http_server::proto::rest_json_1::RestJson1;
use pyo3::prelude::*;
use tower::{Service, ServiceBuilder, ServiceExt};
use crate::middleware::PyMiddlewareHandler;
use crate::{PyMiddlewareException, PyMiddlewareType, PyRequest};
async fn echo(req: Request<Body>) -> Result<Response<BoxBody>, Box<dyn Error + Send + Sync>> {
Ok(Response::new(to_boxed(req.into_body())))
}
#[tokio::test]
async fn request_middlewares_are_chained_inside_layer() -> PyResult<()> {
let locals = crate::tests::initialize();
let mut middlewares = PyMiddlewares::new::<RestJson1>(vec![]);
Python::with_gil(|py| {
let middleware = PyModule::new(py, "middleware").unwrap();
middleware.add_class::<PyRequest>().unwrap();
middleware.add_class::<PyMiddlewareException>().unwrap();
let pycode = r#"
def first_middleware(request: Request):
request.set_header("x-amzn-answer", "42")
return request
def second_middleware(request: Request):
if request.get_header("x-amzn-answer") != "42":
raise MiddlewareException("wrong answer", 401)
"#;
py.run(pycode, Some(middleware.dict()), None)?;
let all = middleware.index()?;
let first_middleware = PyMiddlewareHandler {
func: middleware.getattr("first_middleware")?.into_py(py),
is_coroutine: false,
name: "first".to_string(),
_type: PyMiddlewareType::Request,
};
all.append("first_middleware")?;
middlewares.push(first_middleware);
let second_middleware = PyMiddlewareHandler {
func: middleware.getattr("second_middleware")?.into_py(py),
is_coroutine: false,
name: "second".to_string(),
_type: PyMiddlewareType::Request,
};
all.append("second_middleware")?;
middlewares.push(second_middleware);
Ok::<(), PyErr>(())
})?;
let mut service = ServiceBuilder::new()
.layer(PyMiddlewareLayer::<RestJson1>::new(middlewares, locals))
.service_fn(echo);
let request = Request::get("/").body(Body::empty()).unwrap();
let res = service.ready().await.unwrap().call(request).await.unwrap();
assert_eq!(res.status(), 200);
Ok(())
}
}