module Exercise01 where

import Data.List
import Foreign.Marshal.Utils
import Test.QuickCheck

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

{-H1.1b)-}
mySnd :: Integer -> Integer
mySnd pair = mySndHelper (pair + 1) 0

mySndHelper :: Integer -> Integer -> Integer
mySndHelper pair count
  | rest /= 0 = count
  | otherwise = mySndHelper newPair (count + 1)
  where
    (newPair, rest) = pair `quotRem` 2

{-H1.1c)-}
myFst :: Integer -> Integer
myFst pair = myFstHelper (pair + 1)

myFstHelper :: Integer -> Integer
myFstHelper pair
  | rest /= 0 = (pair - 1) `quot` 2
  | otherwise = myFstHelper newPair
  where
    (newPair, rest) = pair `quotRem` 2

{-H1.1d)-}
prop_myPair :: Integer -> Integer -> Integer -> Property
prop_myPair p x y = p >= 0 && x >= 0 && y >= 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-}
numberToEo :: Integer -> String
numberToEo 0 = "nul"
numberToEo num = unwords $ words $ numberToEoHelper num 0

repl :: Char -> Char
repl c = if c == '.' then ' ' else c

numberToEoHelper :: Integer -> Integer -> String
numberToEoHelper 0 _ = ""
numberToEoHelper num depth
  | depth <= 2 = jWS 10 $ pluralize depth $ digitToEo $ num `rem` 10
  | otherwise = jWS 1000 $ pluralize depth $ numberToEo $ num `rem` 1000
  where
    suffix = words "[unused] dek cent mil miliono miliardo duiliono duiliardo triiliono triiliardo kvariliono kvariliardo kviniliono kviniliardo sesiliono sesiliardo sepiliono sepiliardo okiliono okiliardo nauiliono nauiliardo dekiliono dekiliardo" `genericIndex` depth
    jWS a b = quot num a `numberToEoHelper` succ depth ++ " " ++ b
    pluralize _ "nul" = ""
    pluralize 0 noW = noW
    pluralize dep "unu"
      | dep <= 3 = suffix
      | otherwise = "unu " ++ suffix
    pluralize 3 noW = noW ++ " mil"
    pluralize dep noW
      | dep < 3 = noW ++ suffix
      | otherwise = noW ++ " " ++ suffix ++ "j"

{-TTEW-}