PolyCommand.hs

-- |Used to make shell-like command, however with graphical interface.
-- In the Future it should gracefully use console mode, when no
-- graphical display is available.
module Graphics.UI.AF.PolyCommand
    ( polyCommand
    , module Graphics.UI.AF.WxFormAll
    )
where

import Graphics.UI.AF.WxFormAll
import Graphics.UI.AF.CForm.CFormAll

import System

polyCommand :: (ECCreator a, GCForm a) =>
	       a
            -> (a -> IO String)
            -> IO ()
polyCommand input action
    = do available <- isDisplayAvailable
         let command' proxy = command proxy (mkCom input) action
         if available
            then command' wxParentProxy
            else command' consoleParentProxy
         

-- We can also use System.Info.os, which returns the OS name, but
-- just returns linux. I would rather have a functions like isPosix and isMSWindows.
--
-- We could also use some compile flags to destinguish OS'es.

-- getEnv throws isDoesNotExistError
--
-- WARNING: This function has only been tested on Linux.
isDisplayAvailable :: IO Bool
isDisplayAvailable = do isWindows <- isSet "SystemDrive"
                        if isWindows
                           then return True
                           else isSet "DISPLAY" -- We are geussing it's an Posix-OS.
                              
    where
    isSet environmentVariable = catch (do getEnv environmentVariable
                                          return True
                                      ) (\_ -> return False)