writeonce/docs/examples/writeonce-framework/app.wo

-- app.wo — the assembly: an App holds the middleware chain and the route
-- table, satisfies internal's Dispatcher interface, and serves.
--
--   let app = App { middleware: [], routes: [] };
--   app.use_mw(Mw { m: Auth { token: t } });
--   app.add(Route { method: "GET", pattern: "/products/:id", h: Show {} });
--   return app.serve("127.0.0.1", port);
--
-- Dispatch order: middleware in registration order (a Resp short-circuits),
-- then the first matching route (method + pattern), else the framework 404.
-- The serve loop wraps dispatch in `try`, so a trapping handler answers 500
-- and the server survives.
use http
use router
-- iteration 17: the serve loop is library-internal now (internal/serve.wo).
-- Legal here: the `internal/` boundary refuses CONSUMERS, not the library.
use internal

pub class App {
  middleware: multi Mw
  routes:     multi Route

  fn use_mw(take m: Mw) {
    push(self.middleware, m);
  }

  fn add(take r: Route) {
    push(self.routes, r);
  }

  -- Registration helpers — the ctor-literal-into-take shape, per method.
  fn get(pattern: Text, take h: Handler) {
    push(self.routes, Route { method: "GET", pattern: pattern, h: h });
  }

  fn post(pattern: Text, take h: Handler) {
    push(self.routes, Route { method: "POST", pattern: pattern, h: h });
  }

  fn put(pattern: Text, take h: Handler) {
    push(self.routes, Route { method: "PUT", pattern: pattern, h: h });
  }

  fn delete_(pattern: Text, take h: Handler) {
    push(self.routes, Route { method: "DELETE", pattern: pattern, h: h });
  }

  fn dispatch(mut req: Req) -> Resp {
    for mw in self.middleware {
      let short = mw.m.before(req);
      if short != nil { return short; }
    }
    -- Path-first matching so a wrong-method hit on a known path answers
    -- 405 with the Allow header (registration order) instead of a 404.
    let allow = "";
    for r in self.routes {
      let params: map<Text, Text> = {};
      if route_match(r.pattern, req.path, params) {
        if r.method == req.method {
          -- captures land on the borrowed request itself (mut) — a failed
          -- match above never touched it, since captures collect locally
          for k, v in params { req.params[k] = v; }
          return r.h.handle(req);
        }
        if allow == "" { allow = "${r.method}"; } else { allow = "${allow}, ${r.method}"; }
      }
    }
    if allow != "" { return method_not_allowed(allow); }
    return not_found();
  }

  fn serve(host: Text, port: Int) -> Int {
    return internal.serve(host, port, self);
  }
}