//! The compiled Svelte interface: static files, SPA fallback, cache policy.

use axum::body::Body;
use axum::http::Request;
use axum::http::header::{CACHE_CONTROL, HeaderValue};
use axum::response::Response;
use std::path::Path;
use tower::ServiceExt;
use tower::util::BoxCloneSyncService;
use tower_http::services::{ServeDir, ServeFile};

pub type WebService = BoxCloneSyncService<Request<Body>, Response, std::convert::Infallible>;

/// Hashed assets are immutable; everything else (index.html) is revalidated.
pub fn service(dir: &Path) -> WebService {
    let index = dir.join("index.html");
    let serve = ServeDir::new(dir).precompressed_gzip().fallback(ServeFile::new(index));
    let svc = tower::service_fn(move |req: Request<Body>| {
        let immutable = req.uri().path().starts_with("/_app/immutable/");
        let serve = serve.clone();
        async move {
            let res = serve.oneshot(req).await.unwrap_or_else(|e| match e {});
            let mut res = res.map(Body::new);
            let policy = if immutable { "public, max-age=31536000, immutable" } else { "no-cache" };
            res.headers_mut().insert(CACHE_CONTROL, HeaderValue::from_static(policy));
            Ok::<_, std::convert::Infallible>(res)
        }
    });
    BoxCloneSyncService::new(svc)
}