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 y
  | odd (y `mod` 2) = 1 + mySnd ((y - 1) `div` 2)
  | otherwise = 0

{-H1.1c)-}
myFst :: Integer -> Integer
myFst x
  | odd x = myFst (x `div` 2)
  | otherwise = x `div` 2

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

{-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-}

{-
  Eingabe wird evaluiert
-}
numberToEo :: Integer -> String
numberToEo n
  | n < 10 = digitToEo n
  | n < 100 = calc n 10 "dek"
  | n < 1000 = calc n 100 "cent"
  | n < 1000000 = unwords(words(calc n 1000 " mil"))
  | otherwise = calcMil n $calcPot n 6

{-
  Zahlen unter 10^6 erhalten kein unu vor dek/cent/mil
  Aufteilung is Zahl + Rest
-}
calc :: Integer -> Integer -> String -> String
calc n x s = (if y /= 1 || n >= 1000000 then numberToEo y else "") ++ s ++ if r /= 0 then " " ++ numberToEo r else ""
  where
    y = n `div` x
    r = n `mod` x

{-
  Berechnen der 10er Potenz (10^x)
-}
calcPot :: Integer -> Integer -> Integer
calcPot n x
  | n `div` 10 ^ x < 1000 = x
  | otherwise = calcPot n $x + 3

{-
  Bonusaufgabe - Berechne für mil...
-}
calcMil :: Integer -> Integer -> String
calcMil n x
  | x == 6 = calc n y $evalMultiply n y " miliono"
  | x == 9 = calc n y $evalMultiply n y " miliardo"
  | even x = calcMilBig n x y "iliono"
  | otherwise = calcMilBig n x y "iliardo"
  where
    y = 10 ^ x
{-
  Hilfsfunktion
-}
calcMilBig :: Integer -> Integer -> Integer -> String -> String
calcMilBig n x y s = calc n y $evalMultiply n y $" " ++ numberToEo (x `div` 6) ++ s

{-
  j oder kein j - Das ist hier die Frage
-}
evalMultiply :: Integer -> Integer -> String -> String
evalMultiply n x t = if n `div` x /= 1 then t ++ "j" else t
{-TTEW-}