{-| Basic padding and "justification" of lists.  -}
module Padding
    ( leftPad
    , rightPad
    , midPad
    , midPadL
    , rotU
    , rotD
    )
    where
leftPad :: Int -> a -> [a] -> [a]
{-# INLINE leftPad #-}
leftPad i x xs = reverse $ take i $ reverse (take i xs) ++ repeat x

rightPad :: Int -> a -> [a] -> [a]
{-# INLINE rightPad #-}
rightPad i x xs = take i $ xs ++ repeat x

midPad :: Int -> a -> [a] -> [a] -> [a]
{-# INLINE midPad #-}
midPad i x xs ys = xs ++ replicate j x ++ ys
  where 
    j = i - (length xs + length ys)

midPadL :: Int -> a -> [a] -> [a] -> [a]
{-# INLINE midPadL #-}
midPadL i x xs ys = take j (xs ++ repeat x) ++ ys
  where 
    j = i - length ys

rotU :: [a] -> [a]
{-# INLINE rotU #-}
rotU [] = []
rotU (x:xs) = xs ++ [x]

rotD :: [a] -> [a]
{-# INLINE rotD #-}
rotD [] = []
rotD xs = last xs : init xs