{-# LANGUAGE ScopedTypeVariables #-}
module Main (main) where
import Data.List()
import Data.String()
import Data.List.Split
import Data.Function
import Data.Maybe
import System.Environment
main = do
args <- getArgs
putStrLn $ base64encode $ head args
intToBase64 = (fromJust.) $ flip lookup $ zip [0..63] "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
base64ToInt = (fromJust.) $ flip lookup $ zip "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" [0..63]
base64encode :: String -> String
base64encode = concatMap translate . chunksOf 6 . concatMap (toBits8 . fromEnum)
translate x =
(intToBase64 . binToInt) x : case length x of
2 -> "=="
4 -> "="
6 -> ""
binToInt :: [Bool] -> Int
binToInt = sum . mulWeight . map fromEnum
where
mulWeight = map (\(i,x)->x * 2^i) . zip [0..] . reverse
boolToString :: Bool -> String
boolToString True = "1"
boolToString False = "0"
toBitsBySize :: forall a t. (Integral t, Integral a) => t -> a -> [Bool]
toBitsBySize 0 x = []
toBitsBySize sz 0 = [False | i <- [1..sz]]
toBitsBySize sz x = if k == 0
then False : toBitsBySize n x
else True : toBitsBySize n (x - k*m)
where n = sz - 1
m = 2^n
k = x `div` m
toBits8 = toBitsBySize 8