;; lib/dream/demos/chat.sx — multi-room WebSocket chat (chat.ml).
;; A room registry holds the live connections per room; each ws session joins its
;; room, broadcasts every received message to the room, and leaves on close.

(define dream-chat-rooms (fn () (let ((rooms {})) {:join (fn (room ws) (set! rooms (assoc rooms room (concat (or (get rooms room) (list)) (list ws))))) :broadcast (fn (room msg) (for-each (fn (w) (dream-send w msg)) (or (get rooms room) (list)))) :members (fn (room) (or (get rooms room) (list))) :leave (fn (room ws) (set! rooms (assoc rooms room (filter (fn (w) (not (= w ws))) (or (get rooms room) (list))))))})))

(define
  dream-chat-loop
  (fn
    (rooms room ws)
    (let
      ((m (dream-receive ws)))
      (if
        (nil? m)
        (begin ((get rooms :leave) room ws) (dream-close ws))
        (begin
          ((get rooms :broadcast) room m)
          (dream-chat-loop rooms room ws))))))

(define
  dream-chat-session
  (fn
    (rooms room)
    (fn
      (ws)
      (begin ((get rooms :join) room ws) (dream-chat-loop rooms room ws)))))

(define
  dream-chat-route
  (fn
    (rooms)
    (fn
      (req)
      ((dream-websocket (dream-chat-session rooms (dream-param req "room")))
        req))))

(define
  dream-chat-app-with
  (fn
    (rooms)
    (dream-router
      (list
        (dream-get "/" (fn (req) (dream-html "<h1>Rooms</h1>")))
        (dream-get "/chat/:room" (dream-chat-route rooms))))))

;; entry point: (dream-run (dream-chat-app-with (dream-chat-rooms)))