{-# LANGUAGE CPP, ForeignFunctionInterface #-}
{-# OPTIONS_NHC98 -cpp #-}
{-# OPTIONS_JHC -fcpp -fffi #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Distribution.Simple.Utils
-- Copyright   :  Isaac Jones, Simon Marlow 2003-2004
--                portions Copyright (c) 2007, Galois Inc.
--
-- Maintainer  :  cabal-devel@haskell.org
-- Portability :  portable
--
-- A large and somewhat miscellaneous collection of utility functions used
-- throughout the rest of the Cabal lib and in other tools that use the Cabal
-- lib like @cabal-install@. It has a very simple set of logging actions. It
-- has low level functions for running programs, a bunch of wrappers for
-- various directory and file functions that do extra logging.

{- All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above
      copyright notice, this list of conditions and the following
      disclaimer in the documentation and/or other materials provided
      with the distribution.

    * Neither the name of Isaac Jones nor the names of other
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -}

module Distribution.Simple.Utils (
        cabalVersion,

        -- * logging and errors
        die,
        dieWithLocation,
        topHandler,
        warn, notice, setupMessage, info, debug,
        chattyTry,

        -- * running programs
        rawSystemExit,
        rawSystemExitWithEnv,
        rawSystemStdout,
        rawSystemStdInOut,
        maybeExit,
        xargs,
        findProgramLocation,
        findProgramVersion,

        -- * copying files
        smartCopySources,
        createDirectoryIfMissingVerbose,
        copyFileVerbose,
        copyDirectoryRecursiveVerbose,
        copyFiles,

        -- * installing files
        installOrdinaryFile,
        installExecutableFile,
        installOrdinaryFiles,
        installDirectoryContents,

        -- * file names
        currentDir,

        -- * finding files
        findFile,
        findFileWithExtension,
        findFileWithExtension',
        findModuleFile,
        findModuleFiles,
        getDirectoryContentsRecursive,

        -- * simple file globbing
        matchFileGlob,
        matchDirFileGlob,
        parseFileGlob,
        FileGlob(..),

        -- * temp files and dirs
        withTempFile,
        withTempDirectory,

        -- * .cabal and .buildinfo files
        defaultPackageDesc,
        findPackageDesc,
        defaultHookedPackageDesc,
        findHookedPackageDesc,

        -- * reading and writing files safely
        withFileContents,
        writeFileAtomic,
        rewriteFile,

        -- * Unicode
        fromUTF8,
        toUTF8,
        readUTF8File,
        withUTF8FileContents,
        writeUTF8File,
        normaliseLineEndings,

        -- * generic utils
        equating,
        comparing,
        isInfixOf,
        intercalate,
        lowercase,
        wrapText,
        wrapLine,
  ) where

import Control.Monad
    ( when, unless, filterM )
#ifdef __GLASGOW_HASKELL__
import Control.Concurrent.MVar
    ( newEmptyMVar, putMVar, takeMVar )
#endif
import Data.List
    ( nub, unfoldr, isPrefixOf, tails, intersperse )
import Data.Char as Char
    ( toLower, chr, ord )
import Data.Bits
    ( Bits((.|.), (.&.), shiftL, shiftR) )

import System.Directory
    ( getDirectoryContents, doesDirectoryExist, doesFileExist, removeFile
    , findExecutable )
import System.Environment
    ( getProgName )
import System.Cmd
    ( rawSystem )
import System.Exit
    ( exitWith, ExitCode(..) )
import System.FilePath
    ( normalise, (</>), (<.>), takeDirectory, splitFileName
    , splitExtension, splitExtensions, splitDirectories )
import System.Directory
    ( createDirectory, renameFile, removeDirectoryRecursive )
import System.IO
    ( Handle, openFile, openBinaryFile, IOMode(ReadMode), hSetBinaryMode
    , hGetContents, stderr, stdout, hPutStr, hFlush, hClose )
import System.IO.Error as IO.Error
    ( try, isDoesNotExistError, isAlreadyExistsError
    , ioeSetFileName, ioeGetFileName, ioeGetErrorString )
#if !(defined(__HUGS__) || (defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ < 608))
import System.IO.Error
    ( ioeSetLocation, ioeGetLocation )
#endif
import System.IO.Unsafe
    ( unsafeInterleaveIO )
import qualified Control.Exception as Exception

import Distribution.Text
    ( display, simpleParse )
import Distribution.Package
    ( PackageIdentifier )
import Distribution.ModuleName (ModuleName)
import qualified Distribution.ModuleName as ModuleName
import Distribution.Version
    (Version(..))

import Control.Exception (evaluate)
import System.Process (runProcess)

#ifdef __GLASGOW_HASKELL__
import Control.Concurrent (forkIO)
import System.Process (runInteractiveProcess, waitForProcess)
#else
import System.Cmd (system)
import System.Directory (getTemporaryDirectory)
#endif

import Distribution.Compat.CopyFile
         ( copyFile, copyOrdinaryFile, copyExecutableFile
         , setDirOrdinary )
import Distribution.Compat.TempFile
         ( openTempFile, openNewBinaryFile, createTempDirectory )
import Distribution.Compat.Exception
         ( IOException, throwIOIO, catchIO, catchExit, onException )
import Distribution.Verbosity

#ifdef VERSION_base
import qualified Paths_Cabal (version)
#endif

-- We only get our own version number when we're building with ourselves
cabalVersion :: Version
#if defined(VERSION_base)
cabalVersion = Paths_Cabal.version
#elif defined(CABAL_VERSION)
cabalVersion = Version [CABAL_VERSION] []
#else
cabalVersion = Version [1,9999] []  --used when bootstrapping
#endif

-- ----------------------------------------------------------------------------
-- Exception and logging utils

dieWithLocation :: FilePath -> Maybe Int -> String -> IO a
dieWithLocation filename lineno msg =
  ioError . setLocation lineno
          . flip ioeSetFileName (normalise filename)
          $ userError msg
  where
#if defined(__HUGS__) || (defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ < 608)
    setLocation _        err = err
#else
    setLocation Nothing  err = err
    setLocation (Just n) err = ioeSetLocation err (show n)
#endif

die :: String -> IO a
die msg = ioError (userError msg)

topHandler :: IO a -> IO a
topHandler prog = catch prog handle
  where
    handle ioe = do
      hFlush stdout
      pname <- getProgName
      hPutStr stderr (mesage pname)
      exitWith (ExitFailure 1)
      where
        mesage pname = wrapText (pname ++ ": " ++ file ++ detail)
        file         = case ioeGetFileName ioe of
                         Nothing   -> ""
                         Just path -> path ++ location ++ ": "
#if defined(__HUGS__) || (defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ < 608)
        location     = ""
#else
        location     = case ioeGetLocation ioe of
                         l@(n:_) | n >= '0' && n <= '9' -> ':' : l
                         _                              -> ""
#endif
        detail       = ioeGetErrorString ioe

-- | Non fatal conditions that may be indicative of an error or problem.
--
-- We display these at the 'normal' verbosity level.
--
warn :: Verbosity -> String -> IO ()
warn verbosity msg =
  when (verbosity >= normal) $ do
    hFlush stdout
    hPutStr stderr (wrapText ("Warning: " ++ msg))

-- | Useful status messages.
--
-- We display these at the 'normal' verbosity level.
--
-- This is for the ordinary helpful status messages that users see. Just
-- enough information to know that things are working but not floods of detail.
--
notice :: Verbosity -> String -> IO ()
notice verbosity msg =
  when (verbosity >= normal) $
    putStr (wrapText msg)

setupMessage :: Verbosity -> String -> PackageIdentifier -> IO ()
setupMessage verbosity msg pkgid =
    notice verbosity (msg ++ ' ': display pkgid ++ "...")

-- | More detail on the operation of some action.
--
-- We display these messages when the verbosity level is 'verbose'
--
info :: Verbosity -> String -> IO ()
info verbosity msg =
  when (verbosity >= verbose) $
    putStr (wrapText msg)

-- | Detailed internal debugging information
--
-- We display these messages when the verbosity level is 'deafening'
--
debug :: Verbosity -> String -> IO ()
debug verbosity msg =
  when (verbosity >= deafening) $ do
    putStr (wrapText msg)
    hFlush stdout

-- | Perform an IO action, catching any IO exceptions and printing an error
--   if one occurs.
chattyTry :: String  -- ^ a description of the action we were attempting
          -> IO ()   -- ^ the action itself
          -> IO ()
chattyTry desc action =
  catchIO action $ \exception ->
    putStrLn $ "Error while " ++ desc ++ ": " ++ show exception

-- -----------------------------------------------------------------------------
-- Helper functions

-- | Wraps text to the default line width. Existing newlines are preserved.
wrapText :: String -> String
wrapText = unlines
         . concatMap (map unwords
                    . wrapLine 79
                    . words)
         . lines

-- | Wraps a list of words to a list of lines of words of a particular width.
wrapLine :: Int -> [String] -> [[String]]
wrapLine width = wrap 0 []
  where wrap :: Int -> [String] -> [String] -> [[String]]
        wrap 0   []   (w:ws)
          | length w + 1 > width
          = wrap (length w) [w] ws
        wrap col line (w:ws)
          | col + length w + 1 > width
          = reverse line : wrap 0 [] (w:ws)
        wrap col line (w:ws)
          = let col' = col + length w + 1
             in wrap col' (w:line) ws
        wrap _ []   [] = []
        wrap _ line [] = [reverse line]

-- -----------------------------------------------------------------------------
-- rawSystem variants
maybeExit :: IO ExitCode -> IO ()
maybeExit cmd = do
  res <- cmd
  unless (res == ExitSuccess) $ exitWith res

printRawCommandAndArgs :: Verbosity -> FilePath -> [String] -> IO ()
printRawCommandAndArgs verbosity path args
 | verbosity >= deafening = print (path, args)
 | verbosity >= verbose   = putStrLn $ unwords (path : args)
 | otherwise              = return ()

printRawCommandAndArgsAndEnv :: Verbosity
                             -> FilePath
                             -> [String]
                             -> [(String, String)]
                             -> IO ()
printRawCommandAndArgsAndEnv verbosity path args env
 | verbosity >= deafening = do putStrLn ("Environment: " ++ show env)
                               print (path, args)
 | verbosity >= verbose   = putStrLn $ unwords (path : args)
 | otherwise              = return ()

-- Exit with the same exitcode if the subcommand fails
rawSystemExit :: Verbosity -> FilePath -> [String] -> IO ()
rawSystemExit verbosity path args = do
  printRawCommandAndArgs verbosity path args
  hFlush stdout
  exitcode <- rawSystem path args
  unless (exitcode == ExitSuccess) $ do
    debug verbosity $ path ++ " returned " ++ show exitcode
    exitWith exitcode

rawSystemExitWithEnv :: Verbosity
                     -> FilePath
                     -> [String]
                     -> [(String, String)]
                     -> IO ()
rawSystemExitWithEnv verbosity path args env = do
    printRawCommandAndArgsAndEnv verbosity path args env
    hFlush stdout
    ph <- runProcess path args Nothing (Just env) Nothing Nothing Nothing
    exitcode <- waitForProcess ph
    unless (exitcode == ExitSuccess) $ do
        debug verbosity $ path ++ " returned " ++ show exitcode
        exitWith exitcode

-- | Run a command and return its output.
--
-- The output is assumed to be text in the locale encoding.
--
rawSystemStdout :: Verbosity -> FilePath -> [String] -> IO String
rawSystemStdout verbosity path args = do
  (output, errors, exitCode) <- rawSystemStdInOut verbosity path args
                                                  Nothing False
  when (exitCode /= ExitSuccess) $
    die errors
  return output

-- | Run a command and return its output, errors and exit status. Optionally
-- also supply some input. Also provides control over whether the binary/text
-- mode of the input and output.
--
rawSystemStdInOut :: Verbosity
                  -> FilePath -> [String]
                  -> Maybe (String, Bool) -- ^ input text and binary mode
                  -> Bool                 -- ^ output in binary mode
                  -> IO (String, String, ExitCode) -- ^ output, errors, exit
rawSystemStdInOut verbosity path args input outputBinary = do
  printRawCommandAndArgs verbosity path args

#ifdef __GLASGOW_HASKELL__
  Exception.bracket
     (runInteractiveProcess path args Nothing Nothing)
     (\(inh,outh,errh,_) -> hClose inh >> hClose outh >> hClose errh)
    $ \(inh,outh,errh,pid) -> do

      -- output mode depends on what the caller wants
      hSetBinaryMode outh outputBinary
      -- but the errors are always assumed to be text (in the current locale)
      hSetBinaryMode errh False

      -- fork off a couple threads to pull on the stderr and stdout
      -- so if the process writes to stderr we do not block.

      err <- hGetContents errh
      out <- hGetContents outh

      mv <- newEmptyMVar
      let force str = (evaluate (length str) >> return ())
            `Exception.finally` putMVar mv ()
          --TODO: handle exceptions like text decoding.
      _ <- forkIO $ force out
      _ <- forkIO $ force err

      -- push all the input, if any
      case input of
        Nothing -> return ()
        Just (inputStr, inputBinary) -> do
                -- input mode depends on what the caller wants
          hSetBinaryMode inh inputBinary
          hPutStr inh inputStr
          hClose inh
          --TODO: this probably fails if the process refuses to consume
          -- or if it closes stdin (eg if it exits)

      -- wait for both to finish, in either order
      takeMVar mv
      takeMVar mv

      -- wait for the program to terminate
      exitcode <- waitForProcess pid
      unless (exitcode == ExitSuccess) $
        debug verbosity $ path ++ " returned " ++ show exitcode
                       ++ if null err then "" else
                          " with error message:\n" ++ err

      return (out, err, exitcode)
#else
  tmpDir <- getTemporaryDirectory
  withTempFile tmpDir ".cmd.stdout" $ \outName outHandle ->
   withTempFile tmpDir ".cmd.stdin" $ \inName inHandle -> do
    hClose outHandle

    case input of
      Nothing -> return ()
      Just (inputStr, inputBinary) -> do
        hSetBinaryMode inHandle inputBinary
        hPutStr inHandle inputStr
    hClose inHandle

    let quote name = "'" ++ name ++ "'"
        cmd = unwords (map quote (path:args))
           ++ " <" ++ quote inName
           ++ " >" ++ quote outName
    exitcode <- system cmd

    unless (exitcode == ExitSuccess) $
      debug verbosity $ path ++ " returned " ++ show exitcode

    Exception.bracket (openFile outName ReadMode) hClose $ \hnd -> do
      hSetBinaryMode hnd outputBinary
      output <- hGetContents hnd
      length output `seq` return (output, "", exitcode)
#endif


-- | Look for a program on the path.
findProgramLocation :: Verbosity -> FilePath -> IO (Maybe FilePath)
findProgramLocation verbosity prog = do
  debug verbosity $ "searching for " ++ prog ++ " in path."
  res <- findExecutable prog
  case res of
      Nothing   -> debug verbosity ("Cannot find " ++ prog ++ " on the path")
      Just path -> debug verbosity ("found " ++ prog ++ " at "++ path)
  return res


-- | Look for a program and try to find it's version number. It can accept
-- either an absolute path or the name of a program binary, in which case we
-- will look for the program on the path.
--
findProgramVersion :: String             -- ^ version args
                   -> (String -> String) -- ^ function to select version
                                         --   number from program output
                   -> Verbosity
                   -> FilePath           -- ^ location
                   -> IO (Maybe Version)
findProgramVersion versionArg selectVersion verbosity path = do
  str <- rawSystemStdout verbosity path [versionArg]
         `catchIO`   (\_ -> return "")
         `catchExit` (\_ -> return "")
  let version :: Maybe Version
      version = simpleParse (selectVersion str)
  case version of
      Nothing -> warn verbosity $ "cannot determine version of " ++ path
                               ++ " :\n" ++ show str
      Just v  -> debug verbosity $ path ++ " is version " ++ display v
  return version


-- | Like the unix xargs program. Useful for when we've got very long command
-- lines that might overflow an OS limit on command line length and so you
-- need to invoke a command multiple times to get all the args in.
--
-- Use it with either of the rawSystem variants above. For example:
--
-- > xargs (32*1024) (rawSystemExit verbosity) prog fixedArgs bigArgs
--
xargs :: Int -> ([String] -> IO ())
      -> [String] -> [String] -> IO ()
xargs maxSize rawSystemFun fixedArgs bigArgs =
  let fixedArgSize = sum (map length fixedArgs) + length fixedArgs
      chunkSize = maxSize - fixedArgSize
   in mapM_ (rawSystemFun . (fixedArgs ++)) (chunks chunkSize bigArgs)

  where chunks len = unfoldr $ \s ->
          if null s then Nothing
                    else Just (chunk [] len s)

        chunk acc _   []     = (reverse acc,[])
        chunk acc len (s:ss)
          | len' < len = chunk (s:acc) (len-len'-1) ss
          | otherwise  = (reverse acc, s:ss)
          where len' = length s

-- ------------------------------------------------------------
-- * File Utilities
-- ------------------------------------------------------------

----------------
-- Finding files

-- | Find a file by looking in a search path. The file path must match exactly.
--
findFile :: [FilePath]    -- ^search locations
         -> FilePath      -- ^File Name
         -> IO FilePath
findFile searchPath fileName =
  findFirstFile id
    [ path </> fileName
    | path <- nub searchPath]
  >>= maybe (die $ fileName ++ " doesn't exist") return

-- | Find a file by looking in a search path with one of a list of possible
-- file extensions. The file base name should be given and it will be tried
-- with each of the extensions in each element of the search path.
--
findFileWithExtension :: [String]
                      -> [FilePath]
                      -> FilePath
                      -> IO (Maybe FilePath)
findFileWithExtension extensions searchPath baseName =
  findFirstFile id
    [ path </> baseName <.> ext
    | path <- nub searchPath
    , ext <- nub extensions ]

-- | Like 'findFileWithExtension' but returns which element of the search path
-- the file was found in, and the file path relative to that base directory.
--
findFileWithExtension' :: [String]
                       -> [FilePath]
                       -> FilePath
                       -> IO (Maybe (FilePath, FilePath))
findFileWithExtension' extensions searchPath baseName =
  findFirstFile (uncurry (</>))
    [ (path, baseName <.> ext)
    | path <- nub searchPath
    , ext <- nub extensions ]

findFirstFile :: (a -> FilePath) -> [a] -> IO (Maybe a)
findFirstFile file = findFirst
  where findFirst []     = return Nothing
        findFirst (x:xs) = do exists <- doesFileExist (file x)
                              if exists
                                then return (Just x)
                                else findFirst xs

-- | Finds the files corresponding to a list of Haskell module names.
--
-- As 'findModuleFile' but for a list of module names.
--
findModuleFiles :: [FilePath]   -- ^ build prefix (location of objects)
                -> [String]     -- ^ search suffixes
                -> [ModuleName] -- ^ modules
                -> IO [(FilePath, FilePath)]
findModuleFiles searchPath extensions moduleNames =
  mapM (findModuleFile searchPath extensions) moduleNames

-- | Find the file corresponding to a Haskell module name.
--
-- This is similar to 'findFileWithExtension'' but specialised to a module
-- name. The function fails if the file corresponding to the module is missing.
--
findModuleFile :: [FilePath]  -- ^ build prefix (location of objects)
               -> [String]    -- ^ search suffixes
               -> ModuleName  -- ^ module
               -> IO (FilePath, FilePath)
findModuleFile searchPath extensions moduleName =
      maybe notFound return
  =<< findFileWithExtension' extensions searchPath
                             (ModuleName.toFilePath moduleName)
  where
    notFound = die $ "Error: Could not find module: " ++ display moduleName
                  ++ " with any suffix: " ++ show extensions
                  ++ " in the search path: " ++ show searchPath

-- | List all the files in a directory and all subdirectories.
--
-- The order places files in sub-directories after all the files in their
-- parent directories. The list is generated lazily so is not well defined if
-- the source directory structure changes before the list is used.
--
getDirectoryContentsRecursive :: FilePath -> IO [FilePath]
getDirectoryContentsRecursive topdir = recurseDirectories [""]
  where
    recurseDirectories :: [FilePath] -> IO [FilePath]
    recurseDirectories []         = return []
    recurseDirectories (dir:dirs) = unsafeInterleaveIO $ do
      (files, dirs') <- collect [] [] =<< getDirectoryContents (topdir </> dir)
      files' <- recurseDirectories (dirs' ++ dirs)
      return (files ++ files')

      where
        collect files dirs' []              = return (reverse files, reverse dirs')
        collect files dirs' (entry:entries) | ignore entry
                                            = collect files dirs' entries
        collect files dirs' (entry:entries) = do
          let dirEntry = dir </> entry
          isDirectory <- doesDirectoryExist (topdir </> dirEntry)
          if isDirectory
            then collect files (dirEntry:dirs') entries
            else collect (dirEntry:files) dirs' entries

        ignore ['.']      = True
        ignore ['.', '.'] = True
        ignore _          = False

----------------
-- File globbing

data FileGlob
   -- | No glob at all, just an ordinary file
   = NoGlob FilePath

   -- | dir prefix and extension, like @\"foo\/bar\/\*.baz\"@ corresponds to
   --    @FileGlob \"foo\/bar\" \".baz\"@
   | FileGlob FilePath String

parseFileGlob :: FilePath -> Maybe FileGlob
parseFileGlob filepath = case splitExtensions filepath of
  (filepath', ext) -> case splitFileName filepath' of
    (dir, "*") | '*' `elem` dir
              || '*' `elem` ext
              || null ext            -> Nothing
               | null dir            -> Just (FileGlob "." ext)
               | otherwise           -> Just (FileGlob dir ext)
    _          | '*' `elem` filepath -> Nothing
               | otherwise           -> Just (NoGlob filepath)

matchFileGlob :: FilePath -> IO [FilePath]
matchFileGlob = matchDirFileGlob "."

matchDirFileGlob :: FilePath -> FilePath -> IO [FilePath]
matchDirFileGlob dir filepath = case parseFileGlob filepath of
  Nothing -> die $ "invalid file glob '" ++ filepath
                ++ "'. Wildcards '*' are only allowed in place of the file"
                ++ " name, not in the directory name or file extension."
                ++ " If a wildcard is used it must be with an file extension."
  Just (NoGlob filepath') -> return [filepath']
  Just (FileGlob dir' ext) -> do
    files <- getDirectoryContents (dir </> dir')
    case   [ dir' </> file
           | file <- files
           , let (name, ext') = splitExtensions file
           , not (null name) && ext' == ext ] of
      []      -> die $ "filepath wildcard '" ++ filepath
                    ++ "' does not match any files."
      matches -> return matches

----------------------------------------
-- Copying and installing files and dirs

-- | Same as 'createDirectoryIfMissing' but logs at higher verbosity levels.
--
createDirectoryIfMissingVerbose :: Verbosity
                                -> Bool     -- ^ Create its parents too?
                                -> FilePath
                                -> IO ()
createDirectoryIfMissingVerbose verbosity create_parents path0
  | create_parents = createDirs (parents path0)
  | otherwise      = createDirs (take 1 (parents path0))
  where
    parents = reverse . scanl1 (</>) . splitDirectories . normalise

    createDirs []         = return ()
    createDirs (dir:[])   = createDir dir throwIOIO
    createDirs (dir:dirs) =
      createDir dir $ \_ -> do
        createDirs dirs
        createDir dir throwIOIO

    createDir :: FilePath -> (IOException -> IO ()) -> IO ()
    createDir dir notExistHandler = do
      r <- try $ createDirectoryVerbose verbosity dir
      case (r :: Either IOException ()) of
        Right ()                   -> return ()
        Left  e
          | isDoesNotExistError  e -> notExistHandler e
          -- createDirectory (and indeed POSIX mkdir) does not distinguish
          -- between a dir already existing and a file already existing. So we
          -- check for it here. Unfortunately there is a slight race condition
          -- here, but we think it is benign. It could report an exeption in
          -- the case that the dir did exist but another process deletes the
          -- directory and creates a file in its place before we can check
          -- that the directory did indeed exist.
          | isAlreadyExistsError e -> (do
              isDir <- doesDirectoryExist dir
              if isDir then return ()
                       else throwIOIO e
              ) `catch` ((\_ -> return ()) :: IOException -> IO ())
          | otherwise              -> throwIOIO e

createDirectoryVerbose :: Verbosity -> FilePath -> IO ()
createDirectoryVerbose verbosity dir = do
  info verbosity $ "creating " ++ dir
  createDirectory dir
  setDirOrdinary dir

-- | Copies a file without copying file permissions. The target file is created
-- with default permissions. Any existing target file is replaced.
--
-- At higher verbosity levels it logs an info message.
--
copyFileVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
copyFileVerbose verbosity src dest = do
  info verbosity ("copy " ++ src ++ " to " ++ dest)
  copyFile src dest

-- | Install an ordinary file. This is like a file copy but the permissions
-- are set appropriately for an installed file. On Unix it is \"-rw-r--r--\"
-- while on Windows it uses the default permissions for the target directory.
--
installOrdinaryFile :: Verbosity -> FilePath -> FilePath -> IO ()
installOrdinaryFile verbosity src dest = do
  info verbosity ("Installing " ++ src ++ " to " ++ dest)
  copyOrdinaryFile src dest

-- | Install an executable file. This is like a file copy but the permissions
-- are set appropriately for an installed file. On Unix it is \"-rwxr-xr-x\"
-- while on Windows it uses the default permissions for the target directory.
--
installExecutableFile :: Verbosity -> FilePath -> FilePath -> IO ()
installExecutableFile verbosity src dest = do
  info verbosity ("Installing executable " ++ src ++ " to " ++ dest)
  copyExecutableFile src dest

-- | Copies a bunch of files to a target directory, preserving the directory
-- structure in the target location. The target directories are created if they
-- do not exist.
--
-- The files are identified by a pair of base directory and a path relative to
-- that base. It is only the relative part that is preserved in the
-- destination.
--
-- For example:
--
-- > copyFiles normal "dist/src"
-- >    [("", "src/Foo.hs"), ("dist/build/", "src/Bar.hs")]
--
-- This would copy \"src\/Foo.hs\" to \"dist\/src\/src\/Foo.hs\" and
-- copy \"dist\/build\/src\/Bar.hs\" to \"dist\/src\/src\/Bar.hs\".
--
-- This operation is not atomic. Any IO failure during the copy (including any
-- missing source files) leaves the target in an unknown state so it is best to
-- use it with a freshly created directory so that it can be simply deleted if
-- anything goes wrong.
--
copyFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
copyFiles verbosity targetDir srcFiles = do

  -- Create parent directories for everything
  let dirs = map (targetDir </>) . nub . map (takeDirectory . snd) $ srcFiles
  mapM_ (createDirectoryIfMissingVerbose verbosity True) dirs

  -- Copy all the files
  sequence_ [ let src  = srcBase   </> srcFile
                  dest = targetDir </> srcFile
               in copyFileVerbose verbosity src dest
            | (srcBase, srcFile) <- srcFiles ]

-- | This is like 'copyFiles' but uses 'installOrdinaryFile'.
--
installOrdinaryFiles :: Verbosity -> FilePath -> [(FilePath, FilePath)] -> IO ()
installOrdinaryFiles verbosity targetDir srcFiles = do

  -- Create parent directories for everything
  let dirs = map (targetDir </>) . nub . map (takeDirectory . snd) $ srcFiles
  mapM_ (createDirectoryIfMissingVerbose verbosity True) dirs

  -- Copy all the files
  sequence_ [ let src  = srcBase   </> srcFile
                  dest = targetDir </> srcFile
               in installOrdinaryFile verbosity src dest
            | (srcBase, srcFile) <- srcFiles ]

-- | This installs all the files in a directory to a target location,
-- preserving the directory layout. All the files are assumed to be ordinary
-- rather than executable files.
--
installDirectoryContents :: Verbosity -> FilePath -> FilePath -> IO ()
installDirectoryContents verbosity srcDir destDir = do
  info verbosity ("copy directory '" ++ srcDir ++ "' to '" ++ destDir ++ "'.")
  srcFiles <- getDirectoryContentsRecursive srcDir
  installOrdinaryFiles verbosity destDir [ (srcDir, f) | f <- srcFiles ]

---------------------------------
-- Deprecated file copy functions

{-# DEPRECATED smartCopySources
      "Use findModuleFiles and copyFiles or installOrdinaryFiles" #-}
smartCopySources :: Verbosity -> [FilePath] -> FilePath
                 -> [ModuleName] -> [String] -> IO ()
smartCopySources verbosity searchPath targetDir moduleNames extensions =
      findModuleFiles searchPath extensions moduleNames
  >>= copyFiles verbosity targetDir

{-# DEPRECATED copyDirectoryRecursiveVerbose
      "You probably want installDirectoryContents instead" #-}
copyDirectoryRecursiveVerbose :: Verbosity -> FilePath -> FilePath -> IO ()
copyDirectoryRecursiveVerbose verbosity srcDir destDir = do
  info verbosity ("copy directory '" ++ srcDir ++ "' to '" ++ destDir ++ "'.")
  srcFiles <- getDirectoryContentsRecursive srcDir
  copyFiles verbosity destDir [ (srcDir, f) | f <- srcFiles ]

---------------------------
-- Temporary files and dirs

-- | Use a temporary filename that doesn't already exist.
--
withTempFile :: FilePath -- ^ Temp dir to create the file in
             -> String   -- ^ File name template. See 'openTempFile'.
             -> (FilePath -> Handle -> IO a) -> IO a
withTempFile tmpDir template action =
  Exception.bracket
    (openTempFile tmpDir template)
    (\(name, handle) -> hClose handle >> removeFile name)
    (uncurry action)

-- | Create and use a temporary directory.
--
-- Creates a new temporary directory inside the given directory, making use
-- of the template. The temp directory is deleted after use. For example:
--
-- > withTempDirectory verbosity "src" "sdist." $ \tmpDir -> do ...
--
-- The @tmpDir@ will be a new subdirectory of the given directory, e.g.
-- @src/sdist.342@.
--
withTempDirectory :: Verbosity -> FilePath -> String -> (FilePath -> IO a) -> IO a
withTempDirectory _verbosity targetDir template =
  Exception.bracket
    (createTempDirectory targetDir template)
    (removeDirectoryRecursive)

-----------------------------------
-- Safely reading and writing files

-- | Gets the contents of a file, but guarantee that it gets closed.
--
-- The file is read lazily but if it is not fully consumed by the action then
-- the remaining input is truncated and the file is closed.
--
withFileContents :: FilePath -> (String -> IO a) -> IO a
withFileContents name action =
  Exception.bracket (openFile name ReadMode) hClose
                    (\hnd -> hGetContents hnd >>= action)

-- | Writes a file atomically.
--
-- The file is either written sucessfully or an IO exception is raised and
-- the original file is left unchanged.
--
-- On windows it is not possible to delete a file that is open by a process.
-- This case will give an IO exception but the atomic property is not affected.
--
writeFileAtomic :: FilePath -> String -> IO ()
writeFileAtomic targetFile content = do
  (tmpFile, tmpHandle) <- openNewBinaryFile targetDir template
  do  hPutStr tmpHandle content
      hClose tmpHandle
      renameFile tmpFile targetFile
   `onException` do hClose tmpHandle
                    removeFile tmpFile
  where
    template = targetName <.> "tmp"
    targetDir | null targetDir_ = currentDir
              | otherwise       = targetDir_
    --TODO: remove this when takeDirectory/splitFileName is fixed
    --      to always return a valid dir
    (targetDir_,targetName) = splitFileName targetFile

-- | Write a file but only if it would have new content. If we would be writing
-- the same as the existing content then leave the file as is so that we do not
-- update the file's modification time.
--
rewriteFile :: FilePath -> String -> IO ()
rewriteFile path newContent =
  flip catch mightNotExist $ do
    existingContent <- readFile path
    _ <- evaluate (length existingContent)
    unless (existingContent == newContent) $
      writeFileAtomic path newContent
  where
    mightNotExist e | isDoesNotExistError e = writeFileAtomic path newContent
                    | otherwise             = ioError e

-- | The path name that represents the current directory.
-- In Unix, it's @\".\"@, but this is system-specific.
-- (E.g. AmigaOS uses the empty string @\"\"@ for the current directory.)
currentDir :: FilePath
currentDir = "."

-- ------------------------------------------------------------
-- * Finding the description file
-- ------------------------------------------------------------

-- |Package description file (/pkgname/@.cabal@)
defaultPackageDesc :: Verbosity -> IO FilePath
defaultPackageDesc _verbosity = findPackageDesc currentDir

-- |Find a package description file in the given directory.  Looks for
-- @.cabal@ files.
findPackageDesc :: FilePath    -- ^Where to look
                -> IO FilePath -- ^<pkgname>.cabal
findPackageDesc dir
 = do files <- getDirectoryContents dir
      -- to make sure we do not mistake a ~/.cabal/ dir for a <pkgname>.cabal
      -- file we filter to exclude dirs and null base file names:
      cabalFiles <- filterM doesFileExist
                       [ dir </> file
                       | file <- files
                       , let (name, ext) = splitExtension file
                       , not (null name) && ext == ".cabal" ]
      case cabalFiles of
        []          -> noDesc
        [cabalFile] -> return cabalFile
        multiple    -> multiDesc multiple

  where
    noDesc :: IO a
    noDesc = die $ "No cabal file found.\n"
                ++ "Please create a package description file <pkgname>.cabal"

    multiDesc :: [String] -> IO a
    multiDesc l = die $ "Multiple cabal files found.\n"
                    ++ "Please use only one of: "
                    ++ show l

-- |Optional auxiliary package information file (/pkgname/@.buildinfo@)
defaultHookedPackageDesc :: IO (Maybe FilePath)
defaultHookedPackageDesc = findHookedPackageDesc currentDir

-- |Find auxiliary package information in the given directory.
-- Looks for @.buildinfo@ files.
findHookedPackageDesc
    :: FilePath                 -- ^Directory to search
    -> IO (Maybe FilePath)      -- ^/dir/@\/@/pkgname/@.buildinfo@, if present
findHookedPackageDesc dir = do
    files <- getDirectoryContents dir
    buildInfoFiles <- filterM doesFileExist
                        [ dir </> file
                        | file <- files
                        , let (name, ext) = splitExtension file
                        , not (null name) && ext == buildInfoExt ]
    case buildInfoFiles of
        [] -> return Nothing
        [f] -> return (Just f)
        _ -> die ("Multiple files with extension " ++ buildInfoExt)

buildInfoExt  :: String
buildInfoExt = ".buildinfo"

-- ------------------------------------------------------------
-- * Unicode stuff
-- ------------------------------------------------------------

-- This is a modification of the UTF8 code from gtk2hs and the
-- utf8-string package.

fromUTF8 :: String -> String
fromUTF8 []     = []
fromUTF8 (c:cs)
  | c <= '\x7F' = c : fromUTF8 cs
  | c <= '\xBF' = replacementChar : fromUTF8 cs
  | c <= '\xDF' = twoBytes c cs
  | c <= '\xEF' = moreBytes 3 0x800     cs (ord c .&. 0xF)
  | c <= '\xF7' = moreBytes 4 0x10000   cs (ord c .&. 0x7)
  | c <= '\xFB' = moreBytes 5 0x200000  cs (ord c .&. 0x3)
  | c <= '\xFD' = moreBytes 6 0x4000000 cs (ord c .&. 0x1)
  | otherwise   = replacementChar : fromUTF8 cs
  where
    twoBytes c0 (c1:cs')
      | ord c1 .&. 0xC0 == 0x80
      = let d = ((ord c0 .&. 0x1F) `shiftL` 6)
             .|. (ord c1 .&. 0x3F)
         in if d >= 0x80
               then  chr d           : fromUTF8 cs'
               else  replacementChar : fromUTF8 cs'
    twoBytes _ cs' = replacementChar : fromUTF8 cs'

    moreBytes :: Int -> Int -> [Char] -> Int -> [Char]
    moreBytes 1 overlong cs' acc
      | overlong <= acc && acc <= 0x10FFFF
     && (acc < 0xD800 || 0xDFFF < acc)
     && (acc < 0xFFFE || 0xFFFF < acc)
      = chr acc : fromUTF8 cs'

      | otherwise
      = replacementChar : fromUTF8 cs'

    moreBytes byteCount overlong (cn:cs') acc
      | ord cn .&. 0xC0 == 0x80
      = moreBytes (byteCount-1) overlong cs'
          ((acc `shiftL` 6) .|. ord cn .&. 0x3F)

    moreBytes _ _ cs' _
      = replacementChar : fromUTF8 cs'

    replacementChar = '\xfffd'

toUTF8 :: String -> String
toUTF8 []        = []
toUTF8 (c:cs)
  | c <= '\x07F' = c
                 : toUTF8 cs
  | c <= '\x7FF' = chr (0xC0 .|. (w `shiftR` 6))
                 : chr (0x80 .|. (w .&. 0x3F))
                 : toUTF8 cs
  | c <= '\xFFFF'= chr (0xE0 .|.  (w `shiftR` 12))
                 : chr (0x80 .|. ((w `shiftR` 6)  .&. 0x3F))
                 : chr (0x80 .|.  (w .&. 0x3F))
                 : toUTF8 cs
  | otherwise    = chr (0xf0 .|.  (w `shiftR` 18))
                 : chr (0x80 .|. ((w `shiftR` 12)  .&. 0x3F))
                 : chr (0x80 .|. ((w `shiftR` 6)  .&. 0x3F))
                 : chr (0x80 .|.  (w .&. 0x3F))
                 : toUTF8 cs
  where w = ord c

-- | Ignore a Unicode byte order mark (BOM) at the beginning of the input
--
ignoreBOM :: String -> String
ignoreBOM ('\xFEFF':string) = string
ignoreBOM string            = string

-- | Reads a UTF8 encoded text file as a Unicode String
--
-- Reads lazily using ordinary 'readFile'.
--
readUTF8File :: FilePath -> IO String
readUTF8File f = fmap (ignoreBOM . fromUTF8)
               . hGetContents =<< openBinaryFile f ReadMode

-- | Reads a UTF8 encoded text file as a Unicode String
--
-- Same behaviour as 'withFileContents'.
--
withUTF8FileContents :: FilePath -> (String -> IO a) -> IO a
withUTF8FileContents name action =
  Exception.bracket
    (openBinaryFile name ReadMode)
    hClose
    (\hnd -> hGetContents hnd >>= action . ignoreBOM . fromUTF8)

-- | Writes a Unicode String as a UTF8 encoded text file.
--
-- Uses 'writeFileAtomic', so provides the same guarantees.
--
writeUTF8File :: FilePath -> String -> IO ()
writeUTF8File path = writeFileAtomic path . toUTF8

-- | Fix different systems silly line ending conventions
normaliseLineEndings :: String -> String
normaliseLineEndings [] = []
normaliseLineEndings ('\r':'\n':s) = '\n' : normaliseLineEndings s -- windows
normaliseLineEndings ('\r':s)      = '\n' : normaliseLineEndings s -- old osx
normaliseLineEndings (  c :s)      =   c  : normaliseLineEndings s

-- ------------------------------------------------------------
-- * Common utils
-- ------------------------------------------------------------

equating :: Eq a => (b -> a) -> b -> b -> Bool
equating p x y = p x == p y

comparing :: Ord a => (b -> a) -> b -> b -> Ordering
comparing p x y = p x `compare` p y

isInfixOf :: String -> String -> Bool
isInfixOf needle haystack = any (isPrefixOf needle) (tails haystack)

intercalate :: [a] -> [[a]] -> [a]
intercalate sep = concat . intersperse sep

lowercase :: String -> String
lowercase = map Char.toLower