content: {-# LANGUAGE CPP #-}
  
  -- Copyright (c) 2005-2011 Stefan Wehr - http://www.stefanwehr.de
  --
  -- This library is free software; you can redistribute it and/or
  -- modify it under the terms of the GNU Lesser General Public
  -- License as published by the Free Software Foundation; either
  -- version 2.1 of the License, or (at your option) any later version.
  --
  -- This library is distributed in the hope that it will be useful,
  -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  -- Lesser General Public License for more details.
  --
  -- You should have received a copy of the GNU Lesser General Public
  -- License along with this library; if not, write to the Free Software
  -- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  
  module UI.HSCurses.Logging (trace, debug) where
  
  import Control.Monad.Trans
  
  #if DEBUG
  
  import System.IO
  import System.IO.Unsafe (unsafePerformIO)
  import qualified Data.Time as Time
  
  #endif
  
  trace :: String -> a -> a
  debug :: (MonadIO m) => String -> m ()
  
  #if DEBUG
  
  logFile :: Handle
  logFile = unsafePerformIO $ do h <- openFile ".hscurses.log" AppendMode
                                 debug_ h "logging initialized"
                                 return h
  {-# NOINLINE logFile #-}
  
  formatTime :: IO String
  formatTime = do
    let fmt = "%Y-%m-%d %H:%M:%S%03Q"
    now <- Time.getZonedTime
    return $ Time.formatTime Time.defaultTimeLocale fmt now
  
  debug_ :: Handle -> String -> IO ()
  debug_ f s =
      do ts <- formatTime
         hPutStrLn f ("[" ++ ts ++ "] " ++ s)
         hFlush f
  
  trace s x =
      unsafePerformIO $ do debug s
                           return x
  debug s = liftIO $ debug_ logFile s
  
  #else
  
  trace _ x = x
  debug _ = return ()
  
  #endif
  