(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 (graph ldist ldepd)
  (begin
    ;; ltimes -> list of times
    (define ltimes (map 
		    (lambda (node-dist) (cons (car node-dist) ((cdr node-dist)))) 
		    ldist))
    ;; start -> initializes alist of (TX . -1)
    (define start (lambda (lst) 
		    (map (lambda (node) (cons (car node) -1)) 
			 lst)))
    ;; initialize the var dictionary
    (define globassoc (start ldist))
    ;; nodesleft? -> is there any node with -1?
    (define nodesleft? (any (lambda (x) (= -1 (cdr x))) globassoc))
    ;; dependency -> dependencies of a certain element
    (define (dependency token) (cdr (assq token ldepd)))
    ;;depsolved -> all dependencies already have their value != 1
    (define (depsolved? token) 
      (not (any (lambda (dep) (= -1 (cdr (assq dep globassoc)))) 
		 (dependency token))))
    ;; need-n-ready -> items which have both all deps and need a time
    (define need-n-ready 
      (filter (lambda (node)
		(and (= -1 (cdr node)) 
		     (depsolved? (car node)))) 
	      globassoc))
    ;; computeReadyNodes -> compute nodes which have no precedence problem
    (define computeReadyNodes
      (for-each (lambda (globassocnodes) 
		  (set-cdr! globassocnodes 
			    (+ ((cdr (assq (car globassocnodes) ldist)))
			       (apply 
				max 
				(cons 0 (map 
				 (lambda (x) (cdr (assq x ltimes))) 
				 (dependency globassocnodes)))))))
    
      (need-n-ready)))
  (while (nodesleft?)
	 (computeReadyNodes)
	 globassoc)))


(define obra (graph 
	      `( ;; 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))))
	      '( ;; dependencies
		(T1 . '())
		(T2 . (T1)) 
		(T3 . (T1 T2))
		(T4 . (T2))
		(T5 . (T2 T3))
		(T6 . (T2)) 
		(T7 . (T2 T4 T5))
		(T8 . (T4 T5 T6 T7)))))