--
-- |
-- Module      : Utils
-- Author      : Sean Seefried (http://www.cse.unsw.edu.au/~sseefried)
-- Copyright   : (c) 2005
-- License     : BSD3
-- Created     : 18 Jun 2005
--
module Utils
where

import System.IO
import Data.List
import Data.Char
import System.Info
import System.Directory
import System.Time

--
-- These functions taken gratefully from Don Stewart. Modified by
-- shelarcy for windows.
--

--
-- | dirname : return the directory portion of a file path
-- if null, return "."
--
dirname :: FilePath -> FilePath
dirname p  =
  let x = findIndices (== '\\') p
      y = findIndices (== '/') p
  in
  if not $ null x
    then if not $ null y
        then if (maximum x) > (maximum y)
                then dirname' '\\' p else dirname' '/' p
        else dirname' '\\' p
    else dirname' '/' p
  where
      dirname' separator p =
          case reverse $ dropWhile (/= separator) $ reverse p of
              [] -> "."
              p' -> p'

--
-- | basename : return the filename portion of a path
--
basename :: FilePath -> FilePath
basename p =
    let x = findIndices (== '\\') p
        y = findIndices (== '/') p
    in
    if not $ null x
      then if not $ null y
          then if (maximum x) > (maximum y) then basename' '\\' p else basename' '/' p
          else basename' '\\' p
      else basename' '/' p
    where
        basename' chr p = reverse $ takeWhile (/= chr) $ reverse p

--
-- drop suffix
--
dropSuffix :: FilePath -> FilePath
dropSuffix f = reverse . tail . dropWhile (/= '.') $ reverse f

--
-- e.g. /home/dons/foo.rc -> /home/dons/foo.o
--
-- we depend on the suffix we are given having a lead '.'
--
replaceSuffix :: FilePath -> String -> FilePath
replaceSuffix [] _ = [] -- ?
replaceSuffix f suf =
    case reverse $ dropWhile (/= '.') $ reverse f of
        [] -> f  ++ suf                 -- no '.' in file name
        f' -> f' ++ tail suf

--
-- Checks for an absolute path
--
absolutePath :: FilePath -> Bool
absolutePath str = if os == "mingw32"
                     then absolutePathForWindows str
                     else absolutePath' str
  where
    absolutePath' ('/':_) = True
    absolutePath' ('~':_) = True
    absolutePath' _       = False
    absolutePathForWindows (x:xs@(y:_)) = isAlpha x && (y == ':' || y == '\\')

--
-- Expects a path beginnning with a tilde. Replaces it with the
-- home direcotory
--
expandTilde :: FilePath -> IO FilePath
expandTilde ('~':path) = do
  homeDir <- getHomeDirectory
  return (homeDir ++ path)
expandTilde path = return path

-- |  Debug putStr
dPutStr :: String -> IO ()
dPutStr str = do putStr str
                 hFlush stdout


timeFromStart (TOD s1 ps1) =
    do (TOD s2 ps2) <- getClockTime
       return $ (fromIntegral (s2-s1) + (fromIntegral (ps2-ps1) / 10^12))