module WordNumber where

import Data.Array (reverse)
import Data.Maybe (Maybe(..))
import Data.String (joinWith)
import Data.Tuple (Tuple(..))
import Data.Unfoldable (unfoldr)
import Prelude

digitToWord :: Int -> String
digitToWord 0 = "null"
digitToWord 1 = "one"
digitToWord 2 = "two"
digitToWord 3 = "three"
digitToWord 4 = "four"
digitToWord 5 = "five" 
digitToWord 6 = "six"
digitToWord 7 = "seven"
digitToWord 8 = "eight"
digitToWord 9 = "nine"
digitToWord _ = ""

digits :: Int -> Array Int
digits n = reverse $ unfoldr unfold n
    where unfold x
              | x == 0    = Nothing
              | otherwise = Just (Tuple (mod x 10) (div x 10))

wordNumber :: Int -> String
wordNumber n = joinWith "-" $ map digitToWord (digits n)