(require picturing-programs)

; when a letter in the word is pressed, only those letters show up
; when a letter not in the word is pressed, part of the hangman is drawn

(define (string-contains-letter? str letter)
  (cond [(string=? letter (substring str 0 1)) true]
        [(= (string-length str) 1) false]
        [else (string-contains-letter? (substring str 1) letter)]))
(check-expect (string-contains-letter? "ice cream" "a") true)
(check-expect (string-contains-letter? "ice cream" "z") false)

(define (omit word letter)
  (cond [(or (string=? "" word) (string=? "" letter)) ""]
        [(string=? letter (substring word 0 1)) (omit (substring word 1) letter)]
        [(= (string-length word) 1) word]
        [else (string-append (substring word 0 1) (omit (substring word 1) letter))]))
(check-expect (omit "word" "w") "ord")
(check-expect (omit "hangman" "a") "hngmn")
(check-expect (omit "nothing" "z") "nothing")

(define (wipeout word letters)
  (cond [(or (string=? "" word) (string=? "" letters)) ""]
        [(= 1 (string-length letters)) (omit word letters)]
        [else (wipeout (omit word (substring letters 0 1)) (substring letters 1))]))
(check-expect (wipeout "Williams" "li") "Wams")
(check-expect (wipeout "penguin" "dinosaur") "peg")


(define (help-under word letters-guessed)
  (cond [(or (= 0 (string-length word)) (= 0 (string-length letters-guessed))) ""]
        [(string=? (substring (wipeout word letters-guessed) 0 1)
                   (substring word 0 1))
         true]
        [else false]))

(define (underscorizer word letters-guessed)
  (cond [(or (> 1 (string-length word)) (> 1 (string-length letters-guessed))) ""]
        [(boolean=? true (help-under word letters-guessed))
         (string-append "_" (underscorizer (substring word 1) letters-guessed))]
        [else
         (string-append (substring word 0 1) (underscorizer (substring word 1) letters-guessed))]))
(check-expect (underscorizer "wow" "w") "w_w") ;fail
(check-expect (underscorizer "williams" "li") "_illi___") ;no fail :)
(check-expect (underscorizer "wow" "ow") "wow") ;fail
(check-expect (underscorizer "frustration" "rain") "_r____a_i_n") ;fail

(define-struct m (secret-word
                  letters-right
                  letters-wrong
                  right-count
                  wrong-count))

;(define (keyh structmodel key)
 ; (cond [(string=? key (substring (m secret-word