module Exercise01 where

import Test.QuickCheck

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

{-H1.1b)-}
mySndHelper :: Integer -> Integer
mySndHelper z = if z `mod` 2 == 0 then 1 + mySndHelper(z `div` 2) else 0

mySnd :: Integer -> Integer
mySnd z = mySndHelper (z + 1)


{-H1.1c)-}
--myFstHelper :: Integer -> Integer
{-myFstHelper p
      | p `mod` 2 == 0        = myFstHelper(p `div` 2)
      | otherwise             = (p - 1) `div` 2-}

myFstHelper p = if p `mod` 2 == 0 then myFstHelper(p `div` 2) else (p - 1) `div` 2

myFst :: Integer -> Integer
myFst z = myFstHelper (z + 1)

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



{-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-}
changeNul 0 = ""
changeNul x = digitToEo x

numberToEo :: Integer -> String
numberToEo 0 = "nul"
numberToEo n = numRecursiveEo n

numRecursiveEo:: Integer -> String
numRecursiveEo x
        |count <= 6 = generalHisp x
        |otherwise = generalHisp(x `div` nThree)
                      ++ spaceHelp(getXillardo $ div (count-1) 6)
                      ++ higherNumberName (count-1)
                      ++ multiJ (x `div` nThree)
                      ++ spaceHelp(numRecursiveEo $  mod x nThree)
        where count = countIntLength x
              nThree = 10^(getExponent(count - 1))


higherNumberName c
            | c `mod` 6 < 3 = "iliono"
            | otherwise      = "iliardo"

getExponent c
            | c `mod` 6 >= 3 = ( c `div` 6 ) * 6 + 3
            | otherwise  = ( c `div` 6 ) * 6

getXillardo :: Integer -> String
getXillardo 1 = "m"
getXillardo 10 = "dek"
getXillardo c = changeNul c

multiJ :: Integer -> [Char]
multiJ z
        | z == 1 = ""
        | otherwise = "j"

generalHisp :: Integer -> String
generalHisp x
          | x >= 2000 = generalHisp (x `div` 1000) ++ " mil" ++ spaceHelp(generalHisp $ mod x 1000)
          | x >= t && t>=10 = firstDigit x t ++ names x ++ spaceHelp(generalHisp $ mod x t)
          | otherwise = changeNul x
        where t = 10^(countIntLength x - 1)


firstDigit :: Integer -> Integer -> String
firstDigit x y = if x >= 2*y then changeNul $ div x y else ""


names :: Integer -> String
names x
      | x < 100 = "dek"
      | x < 1000 = "cent"
      | otherwise = "mil"




--fügt Leerzeichen hinzu, wenn nötig
spaceHelp :: String -> String
spaceHelp s
            |length s > 0 = " " ++ s
            |otherwise = ""

countIntLength x = if x < 10 then 1 else (1 + countIntLength(div x 10))
{-TTEW-}