import System.IO (openTempFile, hClose)
import System.Directory (getCurrentDirectory, getDirectoryContents, removeFile,
                            renameFile)
import System.Posix.Files (FileStatus, isDirectory, getFileStatus)
import System.FilePath.Posix (replaceBaseName)

main :: IO ()
main = do
    cwd <- getCurrentDirectory
    getFiles cwd
    files <- getFiles cwd
    randommv files
    newfiles <- getFiles cwd
    mv newfiles 1

getFiles :: String -> IO [String]
getFiles cwd = do
    files <- getDirectoryContents cwd
    filesanddata <- mapM getMetaData files
    return (myfilter isDirectory filesanddata)

getMetaData :: String -> IO (String, FileStatus)
getMetaData file = do
    metadata <- getFileStatus file
    return (file, metadata)

{-
This function takes a function with takes the
second item of the tuple and returns a bool, if
the return of the function is true, the item is
dropped and if it is false, the first item of the
tuple is added to the list returned by the function
-}

myfilter :: (b -> Bool) -> [(a,b)] -> [a]
myfilter _ [] = []
myfilter f ((x,y):xs)
    | not (f y) = x : myfilter f xs
    | otherwise = myfilter f xs

--Renames file to random name to avoid overwrites
randommv :: [String] -> IO ()
randommv [] = return ()
randommv (x:xs) = do
    cwd <- getCurrentDirectory
    (tempName, tempHandle) <- openTempFile cwd "foo"
    hClose tempHandle
    removeFile tempName
    let newname = replaceBaseName x tempName
    renameFile x newname
    randommv xs

mv :: [String] -> Int -> IO ()
mv [] _ = return ()
mv (x:xs) n = do
    let newname = replaceBaseName x (show n)
    renameFile x newname
mv xs (succ n)