;; lib/dream/websocket.sx — Dream-on-SX WebSockets.
;; dream-websocket wraps a (fn (ws) ...) handler into an ordinary handler that
;; returns a 101 upgrade response carrying the ws handler. The host detects the
;; upgrade, builds a ws backed by host IO, and runs the handler. The ws carries an
;; injectable io fn — a mock in-memory ws for tests, (perform op) in production.
;; Depends on types.sx.

;; ── upgrade response ───────────────────────────────────────────────
(define dream-websocket (fn (handler) (fn (req) {:websocket handler :body "" :headers {:connection "Upgrade" :upgrade "websocket"} :status 101})))

(define
  dream-websocket?
  (fn (resp) (and (dict? resp) (has-key? resp :websocket))))
(define dream-ws-handler (fn (resp) (get resp :websocket)))

;; ── ws operations (over an injectable io) ──────────────────────────
(define dream-send (fn (ws msg) ((get ws :io) {:op "ws/send" :msg msg})))
(define dream-receive (fn (ws) ((get ws :io) {:op "ws/receive"})))
(define dream-close (fn (ws) ((get ws :io) {:op "ws/close"})))
(define dream-ws-open? (fn (ws) ((get ws :io) {:op "ws/open?"})))
(define
  dream-ws-broadcast
  (fn (wss msg) (for-each (fn (ws) (dream-send ws msg)) wss)))

;; production io: every op suspends to the host
(define dream-ws-perform-io (fn (op) (perform op)))
(define dream-ws-from-io (fn (io) {:io io}))

;; ── in-memory mock ws (tests + demos) ──────────────────────────────
;; incoming is a list of messages dream-receive will yield in order.
(define
  dream-mock-ws
  (fn
    (incoming)
    (let ((inbox incoming) (outbox (list)) (closed false)) {:closed? (fn () closed) :outbox (fn () outbox) :io (fn (op) (cond ((= (get op :op) "ws/send") (begin (set! outbox (concat outbox (list (get op :msg)))) true)) ((= (get op :op) "ws/receive") (if (empty? inbox) nil (let ((m (first inbox))) (begin (set! inbox (rest inbox)) m)))) ((= (get op :op) "ws/close") (begin (set! closed true) true)) ((= (get op :op) "ws/open?") (not closed)) (else nil)))})))

;; test/demo introspection
(define dream-ws-sent (fn (ws) ((get ws :outbox))))
(define dream-ws-closed? (fn (ws) ((get ws :closed?))))

;; drive a ws handler (from an upgrade response) against a ws
(define dream-ws-run (fn (resp ws) ((dream-ws-handler resp) ws)))