module Files
    (createDirectory,doesFileExist,doesDirectoryExist,
    reportError,baseName,newSuffix,isNewer)
where

import Directory
    (createDirectory,getModificationTime,doesFileExist,doesDirectoryExist)

import Control.Exception (tryJust,ioErrors)

import System.IO (stderr,hPutStrLn)

import Regex (mkRegex,mkSub,doSub,isMatch)

reportError :: String -> String -> IO ()
reportError msg who = hPutStrLn stderr $ "annote: " ++ who ++ ": " ++ msg

baseName :: FilePath -> FilePath
baseName name =
    doSub name $ mkSub ("^.*/", "")

newSuffix :: FilePath -> String -> FilePath
newSuffix name ext =
    if isMatch name $ mkRegex "[.]"
        then doSub name $ mkSub ("[.][^.]*$", suffix)
        else name ++ suffix
    where suffix = '.' : ext

isNewer :: FilePath -> FilePath -> IO Bool
isNewer name1 name2 =
    do  exists1 <- doesFileExist name1
        if exists1
            then do
                exists2 <- doesFileExist name2
                if exists2
                    then do
                        try <- tryJust ioErrors newer
                        case try of
                            Right t -> return t
                            Left _  -> do
                                reportError perr $ name1 ++ " or " ++ name2
                                return False
                    else do
                        return True
            else do
                reportError derr name1 
                return False
    where newer = do
              t1 <- getModificationTime name1
              t2 <- getModificationTime name2
              return $ t1 > t2
          derr = "file does not exist"
          perr = "file permission error"