module Test.Haddock.Utils where

import Control.Monad

import Data.Maybe

import System.Directory
import System.FilePath

mlast :: [a] -> Maybe a
mlast = listToMaybe . reverse

partitionM :: Monad m => (a -> m Bool) -> [a] -> m ([a], [a])
partitionM _ [] = pure ([], [])
partitionM p (x : xs) = do
  (ss, fs) <- partitionM p xs
  b <- p x
  pure $ if b then (x : ss, fs) else (ss, x : fs)

whenM :: Monad m => m Bool -> m () -> m ()
whenM mb action = mb >>= \b -> when b action

getDirectoryTree :: FilePath -> IO [FilePath]
getDirectoryTree path = do
  (dirs, files) <- partitionM isDirectory =<< contents
  subfiles <- fmap concat . forM dirs $ \dir ->
    map (dir </>) <$> getDirectoryTree (path </> dir)
  pure $ files ++ subfiles
  where
    contents = filter realEntry <$> getDirectoryContents path
    isDirectory entry = doesDirectoryExist $ path </> entry
    realEntry entry = not $ entry == "." || entry == ".."

createEmptyDirectory :: FilePath -> IO ()
createEmptyDirectory path = do
  whenM (doesDirectoryExist path) $ removeDirectoryRecursive path
  createDirectory path

-- | Just like 'copyFile' but output directory path is not required to exist.
copyFile' :: FilePath -> FilePath -> IO ()
copyFile' old new = do
  createDirectoryIfMissing True $ takeDirectory new
  copyFile old new

crlfToLf :: String -> String
crlfToLf "" = ""
crlfToLf ('\r' : '\n' : rest) = '\n' : crlfToLf rest
crlfToLf ('\r' : rest) = '\n' : crlfToLf rest
crlfToLf (other : rest) = other : crlfToLf rest
