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 p = div2 p 0
  where
    div2 :: Integer -> Integer -> Integer
    div2 p y
      | even p = y
      | odd p = div2 (div p 2) $ y + 1

{-H1.1c)-}
myFst :: Integer -> Integer
myFst p
  | even p = div p 2
  | odd p = myFst $ div p 2

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

numberToEo :: Integer -> String
numberToEo 0 = "nul"
numberToEo n = tail $ n2E n 0
  where
    n2E 1 3 = " mil"
    n2E n i
      | n > 999 =
        n2E (div n 1000) (i + 3)
          ++ n2E (mod n 1000) i
      | otherwise = n2E3d n 0 ++ position n i
      where
        n2E3d 0 _ = ""
        n2E3d n i =
          n2E3d (div n 10) (i + 1)
            ++ if d /= 0
              then
                " "
                  ++ (if d /= 1 || i == 0 then digitToEo d else "")
                  ++ position n i
              else ""
          where
            d = mod n 10
        position n i
          | n == 0 || i == 0 = ""
          | i == 1 = "dek"
          | i == 2 = "cent"
          | i == 3 = " mil"
          | otherwise =
            " "
              ++ ( if i > 9
                     then numberToEo $ div i 6
                     else "m"
                 )
              ++ ( if mod i 6 == 0
                     then "iliono"
                     else "iliardo"
                 )
              ++ ( if n /= 1
                     then "j"
                     else ""
                 )

pr :: [String] -> IO ()
pr [] = print ""
pr i = do
  print $ head i
  pr $ tail i

{-TTEW-}