(use srfi-27)
(use srfi-1)

(define-syntax while 
  (syntax-rules ()
    ((while condition things ... )
     (do () ((not condition)) things ...))))


(define (uniform min max)
  (+ min (* (- max min) (random-real))))
(define (dag-compute list-distributions list-dependencies) 
  (define samples (map (lambda (node-distribution) (cons (car node-distribution) ((cdr node-distribution)))) list-distributions))
  (define global-counter (map (lambda (node-distribution) (cons (car node-distribution) -1)) list-distributions))
  (define (dependencies node) (cdr (assq node list-dependencies)))
  (define (dependencies-solved node) (every (lambda (dependent-node) (not (= -1 (cdr (assq dependent-node global-counter))))) (dependencies node)))
  (define (dependency-times node) (cons 0 (map (lambda (dependent-node) (cdr (assq dependent-node samples))) (dependencies node))))
  (define abc 
    (begin
      (define ready-list (filter (lambda (node-times) (and (= -1 (cdr node-times)) (dependencies-solved (car node-times)))) global-counter))
      (define nodesleft? (any (lambda (node-times) (= -1 (cdr node-times))) global-counter))
      (define compute-next-times (for-each (lambda (node-times) (set-cdr! node-times (+ (cdr (assq (car node-times) samples))
											(apply max (dependency-times (car node-times)))))) ready-list))
      (while (nodesleft?)
	     (compute-next-times))
      global-counter)))

(define ob1 	      `( ;; nodes and distributions
		(T1 . ,(lambda () (uniform 32 48)))
		(T2 . ,(lambda () (uniform 40 60)))
		(T3 . ,(lambda () (uniform 15 25)))
		(T4 . ,(lambda () (uniform 10 15)))
		(T5 . ,(lambda () (uniform 10 15)))
		(T6 . ,(lambda () (uniform 6 10)))
		(T7 . ,(lambda () (uniform 18 24)))
		(T8 . ,(lambda () (uniform 4 8)))))
(define ob2 
	      '( ;; dependencies
		(T1)
		(T2 . (T1)) 
		(T3 . (T1 T2))
		(T4 . (T2))
		(T5 . (T2 T3))
		(T6 . (T2)) 
		(T7 . (T2 T4 T5))
		(T8 . (T4 T5 T6 T7))))
(define obra (dag-compute ob1 ob2))