#lang racket/base
;; Trivial demonstration of an os2.rkt virtual machine.

(require "os2.rkt")
(require "os2-timer.rkt")
(require racket/pretty)

(define (sleep state n k)
  (define id (gensym 'sleep-id))
  (transition state
    (send-message (set-timer id n 'relative))
    (role (topic-subscriber (timer-expired id (wild)))
      #:name id
      #:state state
      [(timer-expired (== id) now)
       (sequence-actions (transition state)
	 k
	 (delete-role id))])))

(define (example-process delay)
  (write `(sleeping for ,delay milliseconds))
  (newline)
  (sleep 'no-state
	 delay
	 (lambda (state)
	   (if (> delay 1500)
	       (error 'example-process "Oh noes!")
	       (begin (write `(awoke after ,delay milliseconds))
		      (newline)
		      (transition state (quit)))))))

(define spy
  (lambda (spy-pid)
    (define (hs label)
      (define ((w kind) . args) (write `(,label ,kind ,@args)) (newline) transition)
      (handlers (w 'presence)
		(w 'absence)
		(w 'message)))
    (transition 'spy-state
      (add-role 's->p (topic-publisher (wild) #:monitor? 'everything) (hs 'subscriber->publisher))
      (add-role 'p->s (topic-subscriber (wild) #:monitor? 'everything) (hs 'publisher->subscriber)))))

(ground-vm (lambda (boot-pid)
	     (transition 'no-state
	       (spawn (timer-driver 'example-timer-driver))
	       (spawn spy)
	       (spawn (lambda (pid) (example-process 1000)))
	       (spawn (lambda (pid) (example-process 2000)))
	       (quit))))