module Exercise01 where

import Test.QuickCheck

{-H1.1a)-}
myPair :: Integer -> Integer -> Integer
myPair x y = (2 ^ y) * (2 * x + 1) - 1

{-H1.1b)-}
mySnd :: Integer -> Integer
mySnd x = if even x then 0 else 1 + mySnd (div x 2)

{-H1.1c)-}
myFst :: Integer -> Integer
myFst x = div (x + 1) (2 ^ (mySnd x + 1))

{-H1.1d)-}
prop_myPair :: Integer -> Integer -> Integer -> Property
prop_myPair p x y =
    x>=0 && y>=0 && p>=0 ==> (myFst p == x) && (mySnd p == y)

{-H2-}
digitToEo :: Integer -> String
digitToEo 0 = "nul"
digitToEo 1 = "unu"
digitToEo 2 = "du"
digitToEo 3 = "tri"
digitToEo 4 = "kvar"
digitToEo 5 = "kvin"
digitToEo 6 = "ses"
digitToEo 7 = "sep"
digitToEo 8 = "ok"
digitToEo 9 = "nau"

{-WETT-}
digits = ["nul", "unu", "du", "tri", "kvar", "kvin", "ses", "sep", "ok", "nau", "dek"]

pat1 = ["", "dek", "cent"]

fullPat = "":[" mil", " miliono", " miliardo"]
        ++ [" "++x++y | x <- drop 2 digits, y <- ["iliono", "iliardo"]]

plural x
    | fst x == 1 = x
    | otherwise  = (fst x, snd x++"j")

numberToEo :: Integer -> String
numberToEo 0 = "nul"
numberToEo x = 
    unwords (reverse [uncurry process z | z <- take 2 xs ++ [plural y | y <- drop 2 xs] , fst z > 0])
        where xs = zip (listefy x 1000) fullPat

listefy 0 _ = []
listefy x y = mod x y:listefy (div x y) y

process val str 
    | str == " mil" && val == 1 = "mil"
    | otherwise = unwords (reverse [uncurry chn z | z <- xs, uncurry chn z /= ""])++str
        where 
            xs = zip (listefy val 10) pat1
            chn x s 
                | x == 0 = ""
                | x == 1 = if null s then "unu" else s
                | otherwise  = (digits!!fromInteger x) ++ s
{-TTEW-}