#lang racket/base

(provide define/chk 
         x-place?
         y-place?
         mode?
         angle?
         side-count?
         image-color?
         pen-style? 
         pen-cap?
         pen-join?
         real-valued-posn?
         check-mode/color-combination)

(require htdp/error
         racket/class
         lang/posn
         racket/draw
         mrlib/image-core
         (for-syntax racket/base
                     racket/list))

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(define-syntax define/chk
  (λ (stx)
    (define (adjust-case fn-name case-args bodies)
      (syntax-case case-args ()
        [(args ... . final-arg)
         (identifier? #'final-arg)
         (let ([len (length (syntax->list #'(args ...)))])
           (with-syntax ([(i ...) (build-list len add1)])
             #`((args ... . final-arg)
                (let ([args (check/normalize '#,fn-name 'args args i)] ...
                      [final-arg 
                       (for/list ([x (in-list final-arg)]
                                  [j (in-naturals #,(+ len 1))])
                         (check/normalize 'fn-name 'final-arg x j))])
                  #,@bodies))))]
        [(args ...)
         (with-syntax ([(i ...) (build-list (length (syntax->list #'(args ...))) add1)]
                       [(arg-ids ...)
                        (map (λ (arg)
                               (syntax-case arg ()
                                 [x 
                                  (identifier? #'x)
                                  #'x]
                                 [(x y)
                                  (identifier? #'x)
                                  #'x]
                                 [_
                                  (raise-syntax-error 'define/chk "unknown argument spec" stx arg)]))
                             (syntax->list #'(args ...)))])
           #`((args ...)
              (let ([arg-ids (check/normalize '#,fn-name 'arg-ids arg-ids i)] ...)
                #,@bodies)))]))
    (syntax-case stx (case-lambda)
      [(define/chk fn-name (case-lambda [in-args in-body ...] ...))
       (with-syntax ([((args body) ...) (map (lambda (a b) (adjust-case #'fn-name a b))
                                             (syntax->list #'(in-args ...))
                                             (syntax->list #'((in-body ...) ...)))])
         #'(define fn-name
             (case-lambda
               [args body] ...)))]
      [(define/chk (fn-name . args) body ...)
       (with-syntax ([(args body) (adjust-case #'fn-name #'args #'(body ...))])
         #`(define (fn-name . args) body))])))

;; check/normalize : symbol symbol any number -> any
;; based on the name of the argument, checks to see if the input
;; is valid and, if so, transforms it to a specific kind of value
;;   width, height -> number
;;   mode -> 'outline 'solid
;;   color -> (is-a?/c color<%>)
(define (check/normalize fn-name argname arg i)
  (case argname
    [(x-place)
     (check-arg fn-name
                (x-place? arg)
                'x-place
                i
                arg)
     (let ([sym (if (string? arg)
                    (string->symbol arg)
                    arg)])
       (if (eq? sym 'center)
           'middle
           sym))]
    [(y-place) 
     (check-arg fn-name
                (y-place? arg)
                'y-place
                i
                arg)
     (let ([sym (if (string? arg)
                    (string->symbol arg)
                    arg)])
       (if (eq? sym 'center)
           'middle
           sym))]
    [(image image1 image2 image3) 
     (check-arg fn-name
                (image? arg)
                'image
                i
                arg)
     (to-img arg)]
    [(mode)
     (check-arg fn-name
                (mode? arg)
                'mode
                i
                arg)
     (cond
       [(or (equal? arg "solid")
            (equal? arg 'solid))
        255]
       [(equal? arg "outline")
        'outline]
       [(and (integer? arg)
             (not (exact? arg)))
        (inexact->exact arg)]
       [else arg])]
    [(width height radius radius1 radius2 side-length side-length1 side-length2
            side-a side-b side-c)
     (check-arg fn-name
                (and (real? arg)
                     (not (negative? arg)))
                'non\ negative\ real\ number
                i arg)
     arg]
    [(point-count)
     (check-arg fn-name
                (and (integer? arg)
                     (>= arg 2))
                'integer\ greater\ than\ 2
                i arg)
     arg]
    [(dx dy x y x1 y1 x2 y2 pull1 pull2)
     (check-arg fn-name
                (real? arg)
                'real\ number
                i arg)
     arg]
    [(factor x-factor y-factor)
     (check-arg fn-name
                (and (real? arg)
                     (positive? arg))
                'positive\ real\ number
                i arg)
     arg]
    [(side-count)
     (check-arg fn-name
                (side-count? arg)
                'side-count
                i arg)
     arg]
    [(step-count)
     (check-arg fn-name
                (step-count? arg)
                'step-count
                i arg)
     arg]
    [(angle angle1 angle2 angle-a angle-b angle-c)
     (check-arg fn-name
                (angle? arg)
                'angle\ in\ degrees
                i arg)
     (if (< arg 0)
         (+ arg 360)
         arg)]
    [(color)
     (check-arg fn-name (or (image-color? arg) (pen? arg)) 'image-color-or-pen i arg)
     ;; return either a string, color, or a pen,
     ;; (technically, the string case is redundant,
     ;;  but since there may be saved files that have 
     ;;  strings in the color positions we leave them
     ;;  here too; note that using a pen struct means
     ;;  'smoothed mode, but a color (or string) means
     ;;  'aligned mode, so that's not redundant).
     (cond
       [(color? arg) arg]
       [(pen? arg) arg]
       [else
        (let* ([color-str
                (if (symbol? arg)
                    (symbol->string arg)
                    arg)])
          (if (send the-color-database find-color color-str)
              color-str
              "black"))])]
    [(color-list)
     (check-arg fn-name (and (list? arg) (andmap image-color? arg)) 'color-list i arg)
     arg]
    [(string)
     (check-arg fn-name (string? arg) 'string i arg)
     arg]
    [(font-size)
     (check-arg fn-name (and (integer? arg) (<= 1 arg 255)) 'font-size i arg)
     (if (exact? arg)
         arg
         (inexact->exact arg))]
    [(face)
     (check-arg fn-name (or (not arg) (string? arg)) 'face i arg)
     arg]
    [(family)
     (check-arg fn-name (memq arg '(default decorative roman script swiss modern symbol system)) 'family i arg)
     arg]
    [(style)
     (check-arg fn-name (memq arg '(normal italic slant)) 'style i arg)
     arg]
    [(weight)
     (check-arg fn-name (memq arg '(normal bold light)) 'weight i arg)
     arg]
    [(underline)
     (and arg #t)]
    [(posns)
     (check-arg fn-name
                (and (list? arg)
                     (andmap posn? arg))
                'list-of-posns
                i arg)
     (check-arg fn-name
                (andmap real-valued-posn? arg)
                'list-of-posns-with-real-valued-x-and-y-coordinates
                i arg)
     (check-arg fn-name
                (>= (length arg) 3)
                'list-of-at-least-three-posns
                i arg)
     arg]
    [(int0-255-1 int0-255-2 int0-255-3 int0-255-4)
     (check-arg fn-name (and (integer? arg) (<= 0 arg 255)) 
                'integer\ between\ 0\ and\ 255 i arg)
     arg]
    [(real-0-255)
     (check-arg fn-name (and (integer? arg) (<= 0 arg 255)) 
                'real\ number\ between\ 0\ and\ 255 i arg)
     arg]
    
    [(pen-style)
     (check-arg fn-name (pen-style? arg) 'pen-style i arg)
     (if (string? arg)
         (string->symbol arg)
         arg)]
    [(pen-cap)
     (check-arg fn-name (pen-cap? arg) 'pen-cap i arg)
     (if (string? arg)
         (string->symbol arg)
         arg)]
    [(pen-join)
     (check-arg fn-name (pen-join? arg) 'pen-join i arg)
     (if (string? arg)
         (string->symbol arg)
         arg)]
    [(filename)
     (check-arg fn-name (path-string? arg) 'path-string i arg)
     arg]
    [else
     (error 'check "the function ~a has an argument with an unknown name: ~s"
            fn-name
            argname)]))

(define (y-place? arg)
  (member arg '("top" top "bottom" bottom "middle" middle "center" center "baseline" baseline "pinhole" pinhole)))
(define (x-place? arg)
  (member arg '("left" left "right" right "middle" middle "center" center "pinhole" pinhole)))
(define (mode? arg)
  (or (member arg '(solid outline "solid" "outline"))
      (and (integer? arg)
           (<= 0 arg 255))))
(define (angle? arg)
  (and (real? arg)
       (< -360 arg 360)))
(define (side-count? i)
  (and (integer? i)
       (3 . <= .  i)))
(define (step-count? i)
  (and (integer? i)
       (1 . <= .  i)))
(define (image-color? c) (or (symbol? c) (string? c) (color? c)))
(define (pen-style? arg) 
  (member (if (string? arg) (string->symbol arg) arg)
          '(solid dot long-dash short-dash dot-dash)))
(define (pen-cap? arg)
  (member (if (string? arg) (string->symbol arg) arg)
          '(round projecting butt)))
(define (pen-join? arg)
  (member (if (string? arg) (string->symbol arg) arg)
          '(round bevel miter)))
(define (real-valued-posn? arg)
  (and (posn? arg)
       (real? (posn-x arg))
       (real? (posn-y arg))))


;; checks the dependent part of the 'color' specification
(define (check-mode/color-combination fn-name i mode color)
  (cond
    [(or (eq? mode 'solid)
         (number? mode))
     (check-arg fn-name (image-color? color) 'image-color i color)]
    [(eq? mode 'outline)
     (void)]))