1 files changed, 88 insertions, 0 deletions
diff --git a/src/setup/required.rs b/src/setup/required.rs
new file mode 100644
index 0000000..5b7fe5b
--- /dev/null
+++ b/src/setup/required.rs
@@ -0,0 +1,88 @@
+use axum::{
+    extract::Request,
+    http::StatusCode,
+    response::{IntoResponse, Response},
+};
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use tower::Service;
+
+use crate::{app::App, error::Internal};
+
+const UNAVAILABLE: (StatusCode, &str) = (
+    StatusCode::SERVICE_UNAVAILABLE,
+    "initial setup not completed",
+);
+
+#[derive(Clone)]
+pub struct Layer<F> {
+    app: App,
+    fallback: F,
+}
+
+impl Layer<(StatusCode, &'static str)> {
+    pub fn or_unavailable(app: App) -> Self {
+        Self::with_fallback(app, UNAVAILABLE)
+    }
+}
+
+impl<F> Layer<F> {
+    pub fn with_fallback(app: App, fallback: F) -> Self {
+        Layer { app, fallback }
+    }
+}
+
+impl<S, F> tower::Layer<S> for Layer<F>
+where
+    Self: Clone,
+{
+    type Service = Middleware<S, F>;
+
+    fn layer(&self, inner: S) -> Self::Service {
+        let Self { app, fallback } = self.clone();
+        Middleware {
+            inner,
+            app,
+            fallback,
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct Middleware<S, F> {
+    inner: S,
+    app: App,
+    fallback: F,
+}
+
+impl<S, F> Service<Request> for Middleware<S, F>
+where
+    Self: Clone,
+    S: Service<Request, Response = Response> + Send + 'static,
+    S::Future: Send,
+    F: IntoResponse + Clone + Send + 'static,
+{
+    type Response = S::Response;
+    type Error = S::Error;
+    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;
+
+    fn poll_ready(&mut self, ctx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.inner.poll_ready(ctx)
+    }
+
+    fn call(&mut self, req: Request) -> Self::Future {
+        let Self {
+            mut inner,
+            app,
+            fallback,
+        } = self.clone();
+
+        Box::pin(async move {
+            match app.setup().completed().await {
+                Ok(true) => inner.call(req).await,
+                Ok(false) => Ok(fallback.into_response()),
+                Err(error) => Ok(Internal::from(error).into_response()),
+            }
+        })
+    }
+}