{-
  Functions to handle the hashell configuration file.
  Copyright (C) 2005, 2008 Luis Francisco Araujo
-}

module ConfigFile
    where

import Environment (getEnvVariable)
import System.Posix.Files (fileExist)

{-
   | Read and parse configuration file.
-}
----------------------------------------------------------------------------------
-- | Take a filepath and return all the
-- information in a list of tuples in the form
-- of (Variable , Value).
globalConfig :: [FilePath] -> IO [(String,String)]
globalConfig [] = do
                  home <- getEnvVariable "HOME"
                  let cfg = (home ++ "/.hashell_config")
                  fileExist cfg >>=
                      \ s -> case s of
                                 True -> readConfig cfg >>=
                                         makeVarValTuples
                                 False -> return []
globalConfig (cfg:_) = readConfig cfg >>= makeVarValTuples

-- | Read and filter comments from file.
-- Return each line of the configuration file
-- inside a list as strings.
readConfig :: FilePath -> IO [String]
readConfig = (return . filterComment . lines =<<) . readFile

----------------------------------------------------------------------------------
-- | Filter all the comments lines.
filterComment :: [String] -> [String]
filterComment [] = []
filterComment (('-':_):xss) = filterComment xss
filterComment ([]:xss) = filterComment xss
filterComment ((' ':_):xss) = filterComment xss
filterComment (xs:xss) = xs : filterComment xss

-- | Make a list of (Variables, Values) out of
-- the list containing the configuration file information.
makeVarValTuples :: [String] -> IO [(String,String)]
makeVarValTuples xs = return [ (v,r) | x <- xs , let (v,(_:r)) = break (== ' ') x ]