;; lib/host/server.sx — the live wiring: bridge the native OCaml http-listen
;; server to the Dream-shaped host app, and serve. The native server hands a
;; handler a STRING-keyed request dict {"method" "path" "query" "headers" "body"}
;; and expects back {:status :headers :body}. The host app (host/make-app ->
;; dream-router) is a fn dream-request -> dream-response. This module adapts
;; between the two shapes and calls http-listen.
;; Depends on lib/dream/* (dream-request/response accessors) + lib/host/router.sx
;; + the kernel http-listen primitive.

;; ── native request -> dream request ─────────────────────────────────
;; Reassemble path + query into the target string dream-request parses, and carry
;; method/headers/body. Missing fields default empty.
(define host/-native->dream
  (fn (req)
    (let ((path (or (get req "path") "/"))
          (query (or (get req "query") ""))
          (method (or (get req "method") "GET"))
          (headers (or (get req "headers") {}))
          (body (or (get req "body") "")))
      (let ((target (if (> (len query) 0) (str path "?" query) path)))
        (dream-request method target headers body)))))

;; ── dream response -> native response ───────────────────────────────
;; dream-response is already {:body :headers :status}; the native server wants
;; {:status :headers :body}. Same keys — normalise the shape explicitly so the
;; contract is visible (and headers/body never nil).
(define host/-dream->native
  (fn (resp)
    {:status (dream-status resp)
     :headers (or (dream-headers resp) {})
     :body (or (dream-resp-body resp) "")}))

;; ── adapter + serve ─────────────────────────────────────────────────
;; Wrap a Dream app as a native http-listen handler.
(define host/native-handler
  (fn (app)
    (fn (req)
      (host/-dream->native (app (host/-native->dream req))))))

;; Build the app from route groups and start the native server on `port`.
;; Blocks (the http-listen primitive runs the server loop).
(define host/serve
  (fn (port groups)
    (http-listen port (host/native-handler (host/make-app groups)))))