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

-- router/router.wo — the handler model and the route table.
--
-- No function values in this language, by doctrine — so a handler is a
-- CLASS satisfying the Handler interface (its fields are the closure
-- substitute), dispatched structurally (ICALL). A class missing `handle`
-- is a compile error (WO-E205). Middleware is its own interface because
-- the signature differs: `before` returns `?Resp` — nil means continue,
-- a Resp short-circuits (401 gates, redirects).

pub interface Handler {
  fn handle(req: Req) -> Resp
}

-- `mut req`: middleware may WRITE the request — auth attaches the
-- authenticated principal (req.principal) for downstream handlers.
pub interface Middleware {
  fn before(mut req: Req) -> ?Resp
}

-- framework v1 slice 2: the response half of the chain. `after` runs on
-- EVERY response leaving dispatch — handler answers, middleware
-- short-circuits, the framework 404/405 — so security headers and CORS
-- reach all of them. It mutates, never replaces (no ?Resp: an after that
-- could swallow the response would be a second handler).
pub interface After {
  fn after(req: Req, mut r: Resp)
}

-- Wrapper record, same reason as Mw/Route.
pub class Aw {
  a: After
}

-- One route: method + pattern + the handler value. Built with a ctor
-- literal at the registration site (`Route { method: "GET", pattern:
-- "/products/:id", h: ProductShow {} }`) — the exact ownership shape the
-- conformance corpus pins (run/container-owned-move).
pub class Route {
  method:  Text
  pattern: Text
  h:       Handler
}

-- Middleware wrapper record, same shape as Route for the same reason.
pub class Mw {
  m: Middleware
}

-- Request-line logging, the one middleware every framework ships: method +
-- path to stderr, never short-circuits. `pad` is the record-class ctor
-- convention (every stateless handler carries one Int field).
pub class Logging {
  pad: Int
  fn before(mut req: Req) -> ?Resp {
    print_err("${req.method} ${req.path}");
    return nil;
  }
}

-- Does `pattern` match `path`? Fills `params` with :name captures.
-- Segments split on '/', empties dropped (so "/a//b" == "/a/b" and the
-- root "/" is the empty segment list). First mismatch wins; a :segment
-- captures anything non-empty. A LAST segment `*name` (framework v1
-- slice 2) captures the whole rest — zero or more segments, re-joined
-- with '/' — so "/files/*path" matches "/files" (path = "") and
-- "/files/a/b" (path = "a/b"). A `*` anywhere else never matches:
-- precedence stays registration order, wildcards last by construction.
pub fn route_match(pattern: Text, path: Text, mut params: map<Text, Text>) -> Bool {
  let ps = split(pattern, "/");
  let xs = split(path, "/");
  let psegs: multi Text = [];
  for s in ps { if s != "" { push(psegs, s); } }
  let xsegs: multi Text = [];
  for s in xs { if s != "" { push(xsegs, s); } }
  let np = len(psegs);
  let wild = false;
  if np > 0 {
    if starts_with(psegs[np - 1], "*") { wild = true; }
  }
  if wild == false {
    if np != len(xsegs) { return false; }
  } else {
    if len(xsegs) < np - 1 { return false; }
  }
  let i = 0;
  while i < np {
    let p = psegs[i];
    if wild and i == np - 1 {
      let rest = "";
      let j = i;
      while j < len(xsegs) {
        if rest == "" { rest = xsegs[j]; } else { rest = "${rest}/${xsegs[j]}"; }
        j = j + 1;
      }
      params[substr(p, 1, len(p) - 1)] = rest;
      return true;
    }
    if starts_with(p, "*") { return false; }
    let x = xsegs[i];
    if starts_with(p, ":") {
      params[substr(p, 1, len(p) - 1)] = x;
    } else {
      if p != x { return false; }
    }
    i = i + 1;
  }
  return true;
}

-- framework v1 slice 2: a route GROUP — a prefix plus its own routes and
-- its own before-middleware, mounted into an App in one move. The group
-- prefixes patterns at REGISTRATION (the mount is a plain move); its
-- middleware becomes prefix-scoped on the App: it runs only for paths
-- under the prefix, after the global chain, before the route scan.
pub class Group {
  prefix:     Text
  routes:     multi Route = []
  middleware: multi Mw = []

  fn get(pattern: Text, take h: Handler) {
    push(self.routes, Route { method: "GET", pattern: "${self.prefix}${pattern}", h: h });
  }

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

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

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

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

-- A prefix-scoped middleware entry on the App (what mounting a group's
-- middleware becomes).
pub class Gmw {
  prefix: Text
  m:      Middleware
}