; TODO: model the semantic network below as a list of nodes, that refer to each other by name

; example semantic network:
; the Toyota Prius is a a japanese hybrid car
; cars have a mean power of 120hp
; a hybrid car is a combination of an electric car with a gasoline car
; japanese cars have about 160hp
; however, japanese electric cars have about 130 hp
; Chevrolet Volt is an american electric car
; most electric cars have a power of 150hp
(define db
  '((Car (power 120))
  (Electric (aka Car) (power 150))
  (Gasoline (aka Car))
  (Hybrid (aka Electric) (aka Gasoline))
  (Japanese (aka Car) (power 160))
  (American (aka Car))
  (AE (aka American) (aka Electric))
  (JE (aka Japanese) (aka Electric) (power 130))
  (JH (aka Japanese) (aka Hybrid))
  (TP (isa JH))
  (CV (isa AE))
  ))
; TODO: implement the functions below to determine the power of the Toyota Prius and the Chevrolet Volt


; in: name of the searched node; the semantic network
; returns: node in the semantic net with the specified name
(define (find-node name net)
  (if (null? net)
      '()
      (if (equal? (caar net) name)
          (car net)
          (find-node name (cdr net)))

  ))


(find-node 'TP db)
; in: node; attribute name
; returns: the value of the attribute for the node, if defined (not inferred)
(define (get-attr node attr-name)
 (map
  (lambda (x)
    (cadr x)
  )
  (filter
   (lambda (x)
    (equal? (car x) attr-name)
  )
  (cdr node)
)))


(get-attr (find-node 'Electric db) 'power)
; in: node
; returns: the list of nodes to which the node is related by ISA relations (for instances (objects))

(define (make-isa-ancestor-list node)
 (map
  (lambda (x)
    (cadr x)
  )
  (filter
   (lambda (x)
    (equal? (car x) 'isa)
  )
  (cdr node)
)))

(make-isa-ancestor-list (find-node 'TP db))
; in: node
; returns: the list of nodes to which the node is related by AKO relations (for classes (concepts))
(define (make-ako-ancestor-list node)
 (map
  (lambda (x)
    (cadr x)
  )
  (filter
   (lambda (x)
    (equal? (car x) 'aka)
  )
  (cdr node)
)))

(make-ako-ancestor-list (find-node 'JH db))
; in: node; attribute name
; returns: the value of the attribute for the node, inferred from the semantic network
; note: one inheritance path mandatory; bonus for multiple inheritance paths

(define (infer-attr node attr-name)
  (if (null? node)
      '()
      (if (null? (car (get-attr (find-node node db) attr-name)))
          (infer-attr (car (make-ako-ancestor-list (find-node node db)) attr-name))
          (car (get-attr (find-node node db) attr-name)))))

(infer-attr 'Electric 'power)