module AlBhed
    ( -- * Classes
      Primer (..)
    , Volume (..)
      -- * Conversions
    , fromVolume
    , toRoman
    , toVolume
    ) where
import           Data.List
import           Data.Maybe
import qualified Data.Text  as T
data Volume
    = One
    | Two
    | Three
    | Four
    | Five
    | Six
    | Seven
    | Eight
    | Nine
    | Ten
    | Eleven
    | Twelve
    | Thirteen
    | Fourteen
    | Fifteen
    | Sixteen
    | Seventeen
    | Eigthteen
    | Nineteen
    | Twenty
    | TwentyOne
    | TwentyTwo
    | TwentyThree
    | TwentyFour
    | TwentyFive
    | TwentySix
    deriving (Enum, Bounded)
data Primer = Primer
    { primerVolume  :: Volume
    , primerEnglish :: Char
    , primerAlBhed  :: Char
    }
toVolume :: Int -> Maybe Volume
toVolume x
    | x >= 1 && x <= 26 = Just $ toEnum (x - 1)
    | otherwise = Nothing
fromVolume :: Volume -> Int
fromVolume = fromEnum
toRoman :: Volume -> T.Text
toRoman x = T.pack $ go (fromEnum x + 1)
  where
    go 0 = []
    go x =
        let (break, roman) = fromMaybe undefined (findClosestRoman x)
        in roman ++ go (x - break)
romanSymbols :: [(Int, String)]
romanSymbols =
    [ (10, "X")
    , (9, "IX")
    , (5, "V")
    , (4, "IV")
    , (1, "I")
    ]
findClosestRoman :: Int -> Maybe (Int, String)
findClosestRoman x = find ((x >=) . fst) romanSymbols

        , AlBhed