#lang racket
(require racket/tcp)

(define outs '())

(define (write-all data out)
  (for-each
   (lambda (o)
     (cond [(not (eq? o out)) (displayln data o)]))
   outs))

(define (worker in out)
  (define (loop msg)
    (if (equal? msg eof)
        (begin (close-input-port in)
               (close-output-port out)
               (set! outs (remove out outs)))
        (let ([data (read-line in)])
          (displayln data)
          (write-all (string-append ">>> " data) out)
          (loop data))))
  (loop 'y))

(define (listener sock)
  (define-values (in-conn out-conn) (tcp-accept sock))
  (file-stream-buffer-mode in-conn 'none)
  (file-stream-buffer-mode out-conn 'none)
  (thread (lambda () (worker in-conn out-conn)))
  (set! outs (cons out-conn outs))
  (writeln (length outs))
  (listener sock))

(define sock (tcp-listen 1678 4 #t))
(listener sock)
(tcp-close sock)