From 5bd986f199edc542b0bdd7fa99e36c379e99828f Mon Sep 17 00:00:00 2001
From: itowlson <ivan.towlson@fermyon.com>
Date: Tue, 29 Apr 2025 15:16:19 +1200
Subject: [PATCH] Routing modes

Signed-off-by: itowlson <ivan.towlson@fermyon.com>
---
 src/http/router.rs | 78 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 76 insertions(+), 2 deletions(-)

diff --git a/src/http/router.rs b/src/http/router.rs
index 8f43033..6383d02 100644
--- a/src/http/router.rs
+++ b/src/http/router.rs
@@ -154,9 +154,42 @@ pub type Params = Captures<'static, 'static>;
 /// # fn handle_single_segment(req: Request, params: Params) -> anyhow::Result<Response> { todo!() }
 /// # fn handle_exact(req: Request, params: Params) -> anyhow::Result<Response> { todo!() }
 /// ```
+///
+/// Route based on the trailing segment of a Spin wildcard route, instead of on the full path
+///
+/// ```no_run
+/// // spin.toml
+/// //
+/// // [[trigger.http]]
+/// // route = "/shop/..."
+///
+/// // component
+/// # use spin_sdk::http::{IntoResponse, Params, Request, Response, Router};
+/// fn handle_route(req: Request) -> Response {
+///     let mut router = Router::suffix();
+///     router.any("/users/*", handle_users);
+///     router.any("/products/*", handle_products);
+///     router.handle(req)
+/// }
+///
+/// // '/shop/users/1' is routed to `handle_users`
+/// // '/shop/products/1' is routed to `handle_products`
+/// # fn handle_users(req: Request, params: Params) -> anyhow::Result<Response> { todo!() }
+/// # fn handle_products(req: Request, params: Params) -> anyhow::Result<Response> { todo!() }
+/// ```
 pub struct Router {
     methods_map: HashMap<Method, MethodRouter<Box<dyn Handler>>>,
     any_methods: MethodRouter<Box<dyn Handler>>,
+    route_on: RouteOn,
+}
+
+/// Describes what part of the path the Router will route on.
+enum RouteOn {
+    /// The router will route on the full path.
+    FullPath,
+    /// The router expects the component to be handling a route with a trailing wildcard
+    /// (e.g. `route = /shop/...`), and will route on the trailing segment.
+    Suffix,
 }
 
 impl Default for Router {
@@ -203,7 +236,16 @@ impl Router {
             Err(e) => return e.into_response(),
         };
         let method = request.method.clone();
-        let path = &request.path();
+        let path = match self.route_on {
+            RouteOn::FullPath => request.path(),
+            RouteOn::Suffix => match trailing_suffix(&request) {
+                Some(path) => path,
+                None => {
+                    eprintln!("Internal error: Router configured with suffix routing but trigger route has no trailing wildcard");
+                    return responses::internal_server_error();
+                }
+            },
+        };
         let RouteMatch { params, handler } = self.find(path, method);
         handler.handle(request, params).await
     }
@@ -516,11 +558,22 @@ impl Router {
         self.add_async(path, Method::Options, handler)
     }
 
-    /// Construct a new Router.
+    /// Construct a new Router that matches on the full path.
     pub fn new() -> Self {
         Router {
             methods_map: HashMap::default(),
             any_methods: MethodRouter::new(),
+            route_on: RouteOn::FullPath,
+        }
+    }
+
+    /// Construct a new Router that matches on the trailing wildcard
+    /// component of the route.
+    pub fn suffix() -> Self {
+        Router {
+            methods_map: HashMap::default(),
+            any_methods: MethodRouter::new(),
+            route_on: RouteOn::Suffix,
         }
     }
 }
@@ -533,6 +586,11 @@ async fn method_not_allowed(_req: Request, _params: Params) -> Response {
     responses::method_not_allowed()
 }
 
+fn trailing_suffix(req: &Request) -> Option<&str> {
+    req.header("spin-path-info")
+        .and_then(|path_info| path_info.as_str())
+}
+
 /// A macro to help with constructing a Router from a stream of tokens.
 #[macro_export]
 macro_rules! http_router {
@@ -579,6 +637,12 @@ mod tests {
         Request::new(method, path)
     }
 
+    fn make_wildcard_request(method: Method, path: &str, trailing: &str) -> Request {
+        let mut req = Request::new(method, path);
+        req.set_header("spin-path-info", trailing);
+        req
+    }
+
     fn echo_param(_req: Request, params: Params) -> Response {
         match params.get("x") {
             Some(path) => Response::new(200, path),
@@ -666,6 +730,16 @@ mod tests {
         assert_eq!(res.body, "foo".to_owned().into_bytes());
     }
 
+    #[test]
+    fn test_spin_trailing_wildcard() {
+        let mut router = Router::suffix();
+        router.get("/:x/*", echo_param);
+
+        let req = make_wildcard_request(Method::Get, "/base/baser/foo/bar", "/foo/bar");
+        let res = router.handle(req);
+        assert_eq!(res.body, "foo".to_owned().into_bytes());
+    }
+
     #[test]
     fn test_router_display() {
         let mut router = Router::default();