#lang racket

(define (make-data-frame . args)
  (let* ([column-names (list->vector (map car args))]
         [data-store (list->vector (map (compose list->vector cdr) args))])

    (define (get-row n)
      (vector-map
       (λ (v) (vector-ref v n))
       data-store))

    (define (get-data-length)
      (vector-length (vector-ref data-store 0)))


    (define (format-row n)
      (define (default-format-function x)
        (~a x
            #:max-width 8
            #:min-width 8
            #:limit-marker "…"
            #:align 'center
            #:left-pad-string " "
            #:right-pad-string " "))

      (let* ([nth-row   (get-row n)]
             [formatted (vector-map default-format-function nth-row)])
        (string-append* (vector->list formatted))))


    (define (format-first-rows n)
      (string-join
       (map format-row (range n))
       "\n"))

    (define (format-column)
      (define (default-format-function x)
        (~a x
            #:max-width 8
            #:min-width 8
            #:limit-marker "…"
            #:align 'center
            #:left-pad-string " "
            #:right-pad-string " "))

      (let* ([column-formatted (vector-map default-format-function column-names)]
             [column-string (string-append* (vector->list column-formatted))])
        (string-append
         column-string "\n"
         (make-string (string-length column-string) #\―))))


    (define (show-columns)
      (display (format-column)) (display "\n"))

    (define (show-row n)
      (display (format-row n))
      (display "\n"))

    (define (show-rows [n 10])
      (display (format-first-rows (min n (get-data-length))))
      (display "\n"))
    (define (show-data [n 10])
      (show-columns)
      (show-rows n))



    (case-lambda
      [() (show-data)]

      [(op)
       (match op
         ['show-columns (show-columns)]
         ['show (show-data)]
         ['length (get-data-length)]
         ['columns column-names]
         ['data-store data-store]
         )]

      [(op n)
       (match `(,op ,n)
         [(list 'show-row n)
          (show-columns)
          (show-row (sub1 n))]

         [(list 'show 'all)
          (show-data (get-data-length))]

         [(list 'show n)
          (show-data n)]
         )])

    ))


(define df (make-data-frame `[x . ,(range 100)] `[y . ,(range 100)]))