;;Degree Grammar
;;Adam Nelson
;;Chet Tobrey

;;;  the functions and grammar in this file generate a cs/ee/cpe degree plans for wvu
(defun mappend (fn list)
  "Append the results of calling fn on each element of the list.
  Like mancon, but uses append instead of nconc."
  (apply #'append (mapcar fn list)))

(defparameter *degree*
  '((CPE -> (cemr-core cpe-core cpe-electives cpe-electives general-electives general-electives))
    (CS -> (cemr-core cs-core cs-electives cs-electives cs-electives general-electives general-electives))
    (EE ->  (cemr-core ee-core ee-electives ee-electives general-electives general-electives))
    (cs-core -> (cs-110 cs-111 cpe-271 cpe-272 cs-210 cs-220 cs-310 cs-311 cs-221 cs-230 cs-310 cs-350))
    (ee-core -> (math-251
                 math-261
                 cpe-271 cpe-272 cs-110 ee-223
                 ee-224 ee-251 ee-252 ee-327
                 ee-335 ee-356 ee-355 ee-356
                 cep-310 cpe-311 ee-328 ee-329
                 basket-weaving ))
    (cpe-core -> (cpe-271 cpe-272 math-251 math-261
                  ee-221 ee-222 cs-110 ee-223
                  ee-224 ee-251 ee-252 cpe-310
                  cpe-311 cs-111 ee-327 ee-355 ee-356 math-375
                  cpe-312 cpe-313 cs-230 cs-350 cs-450 ))
    (cemr-core -> (engr-101 engr-199 engr-102
                   engl-101 engl-102 math-155
                   math-156 phys-111 phys-112
                   stat-215 econ-201 econ-202
                   Senior-Project ))
    (cs-electives -> cs-315 cs-101 cs-410 cs-415 cs-420 cs-430 cs-440 cs-422 cs-451 cs-472 cs-453 cs-470)
    (ee-electives -> ee-293 ee-336 ee-345 ee-421 ee-426 ee-436 ee-437 ee-445 ee-450 ee-455 ee-461)
    (cpe-electives -> cpe-435 cpe-442 cpe-450 cpe-454 cpe-462 cpe-470 cpe-471)
    (general-electives -> cake-baking-101 hum-101 span-101 hist-102 pols-102 mus-101 art-101))
  "A grammar for cs/cpe/ee degree programs at WVU.")

(defvar *grammar* *degree*)

(defun one-of (set)
  "picks an element of a set, and makes a list of it."
  (list (random-elt set)))



(defun random-elt(choices)
  "Chooses and element randomly from a list"
  (elt choices (random (length choices))))

(defun rule-lhs (rule)
  "left hand side of a rule"
  (first rule))

(defun rule-rhs(rule)
  "right hand side of a rule"
  (rest (rest rule)))

(defun rewrites (category)
  "return a list of possible rewrites for this category"
  (rule-rhs (assoc category *grammar*)))

(defun generate (phrase)
  "Generate a random sentence or phrase"
  (cond ((listp phrase)
         (mappend #'generate phrase))
        ((rewrites phrase)
         (generate (random-elt(rewrites phrase))))
        (t (list phrase))))



 (egs :degree
      (eg '(generate 'CPE)
         :of "Generate a CPE major...")
      (eg '(generate 'EE)
         :of "Generate an EE major...")
      (eg '(generate 'Cs)
         :of "Generate a CS major..."))