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 = helper (x + 1) 0
 where 
  helper x c
   | mod x 2 == 0 = helper (div x 2) (c + 1)
   | otherwise = c 


{-H1.1c)-}
myFst :: Integer -> Integer
myFst x = helper (x + 1)
 where 
  helper x
   | mod x 2 == 0 = helper (div x 2)
   | otherwise = div (x - 1) 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-}

joins :: String -> String -> String
joins s1 s2 = if (s1 == "" || s2 == "") then s1 ++ s2 else s1 ++ " " ++ s2

poof :: String -> Bool -> String
poof s b = if b then s else ""

blockParse :: Integer -> Bool -> [String]
blockParse i b = if b then [] else [(poof (digitToEo div100) (div100 > 1)) ++ (poof "cent" (div100 >= 1))] ++ [(poof (digitToEo divmod100) (divmod100 > 1)) ++ (poof "dek" (divmod100 >= 1))] ++ [poof (digitToEo mod10) (mod10 > 0)] 
 where
  div100 = div i 100
  divmod100 = div (mod i 100) 10
  mod10 = mod i 10

blockSuffix :: Integer -> Bool -> String
blockSuffix 0 b = []
blockSuffix n True = (blockSuffix n False) ++ "j"
blockSuffix n False
 | n==1 = "mil"
 | n==2 = "miliono"
 | n==3 = "miliardo"
 | mod n 2 == 0 = bPJ n ++ "iliono"
 | mod n 2 == 1 = bPJ (n-1) ++ "iliardo"
 where
  bPJ n = (foldr joins "" (blockParse (div n 2) False))

parse :: Integer -> Integer -> [String] -> [String]
parse step i out
 | i >= 1000 = parse (step + 1) (div i 1000) extension
 | otherwise = extension 
 where
  mod1000 = mod i 1000
  extension = (blockParse mod1000 (mod1000 * step == 1)) ++ [poof (blockSuffix step (step > 1 && mod1000 > 1)) (mod1000 > 0)] ++ out
  

numberToEo :: Integer -> String
numberToEo 0 = digitToEo 0
numberToEo n = foldr joins "" (parse 0 n [])
{-TTEW-}