(require picturing-programs)
;(require docmotests.rkt)

;explosion: list-of-numbers num(boom) -> list-of-numbers
;each number within the explosion radius of 3 is omitted from the list

(define (previous3 lon boom)
  (cond [(= boom (first (rest (rest (rest lon))))) true]
        [(= boom (first (rest (rest lon)))) true]
        [(= boom (first (rest lon))) true]
        [else false]))

(define (theboom lon boom)
  (cond [(= boom (first (rest (rest (rest lon)))))
         (rest (rest (rest (rest (rest (rest (rest lon)))))))]
        [(= boom (first (rest (rest lon))))
         (rest (rest (rest (rest (rest (rest lon))))))]
        [(= boom (first (rest lon)))
         (rest (rest (rest (rest (rest lon)))))]))

(define (explosion lon boom)
  (cond [(boolean=? true (previous3 lon boom))
         (theboom lon boom)]
        [else (list* (first lon) (explosion (rest lon) boom))]))

(check-expect (explosion (list 1 2 3 4 5 6 7 8) 5)
              (list 1))
;doesn't work when boom is within the last 3 items in the list
(check-expect (explosion (list 14 385 204 22 9 19 57 83 6) 6)
              (list 14 385 204 22 9))
(check-expect (explosion (list 10 9 8 7 6 5 4 3 2 1 0) 8)
              (list 4 3 2 1 0))

;I think there's a better way of doing the explosion function. Having nested rests is messy and clunky.
;I also didn't finish omitting the three items following the boom.

;zero-the-missing: list-of-numbers(xs) list-of-numbers(guesses) -> list-of-numbers
;change the items in xs that are not in the guesses into 0s

(define (in-guesses? num guesses)
  (cond [(= num (first guesses)) true]
        [(empty? guesses) false]
        [else (in-guesses? num (rest guesses))]))

(define (zero-the-missing xs guesses)
  (cond [(empty? xs) empty]
        [(boolean=? true (in-guesses? (first xs) guesses))
         (list* (first xs) (zero-the-missing (rest xs) guesses))]
        [(boolean=? false (in-guesses? (first xs) guesses))
         (list* 0 (zero-the-missing (rest xs) guesses))]))

;check-expects don't work, there's an error with a first somewhere. Otherwise, I think this should work? :(

(check-expect (zero-the-missing (list 1 2) (list 3 4)) (list 1 2))
(check-expect (zero-the-missing (list 1 3 5 7 9) (list 1 2 3))
              (list 1 3 0 0 0))
(check-expect (zero-the-missing (list 1 2) (list 1))
              (list 1 0))