{-
  Environment variables functions.
  Copyright (C) 2005, 2008 Luis Francisco Araujo
-}

module Environment
    where

import System.Posix.Env (getEnv, putEnv)
import Text.Regex (mkRegex, splitRegex)

data Alias = Alias { command
                   , newcommand :: String }
             deriving (Show, Eq)

type Prompt = String
type FileOpts = [(String, String)]
type ExecutionEnv = (Prompt , [Alias])

{-
   | Setup and get specific values from environment variables.
-}
----------------------------------------------------------------------------------
-- | Setup all the enviromment variables specified in the configuration file.
getVariables :: FileOpts -> IO ()
getVariables xs = mapM_ (\ (a , b) -> putEnv (a ++ "=" ++ b)) xs

-- | Setup environment variables.
setEnvVar :: IO ExecutionEnv
setEnvVar = do
            prompt <- getShellPrompt
            lalias <- getAlias
            return (prompt, lalias)

----------------------------------------------------------------------------------
-- | PROMPT variable.
getShellPrompt :: IO String
getShellPrompt = do
                 sp <- getEnv "PROMPT"
                 case sp of
                         Nothing -> return []
                         Just a -> return a

----------------------------------------------------------------------------------
-- | ALIAS variable.
getAlias :: IO [Alias]
getAlias = do
           v <- getEnv "ALIAS"
           alias <- case v of{ Nothing -> return [] ; Just a -> return a }
           return $ map (\ s -> Alias { command = s !! 0, newcommand = s !! 1 })
                        (aliaslist alias)
    where
    aliaslist = map (splitRegex (mkRegex ":")) . splitRegex (mkRegex "\\|")

----------------------------------------------------------------------------------
-- | Get the value of any variable.
getEnvVariable :: String -> IO String
getEnvVariable v = do
                  env <- getEnv v
                  case env of
                      Nothing -> return []
                      Just n -> return n