mohws-0.1: src/ErrorLogger.hs

-- -----------------------------------------------------------------------------
-- Copyright 2002, Simon Marlow.
-- Copyright 2006, Bjorn Bringert.
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are
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--    this list of conditions and the following disclaimer.
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--  * Redistributions in binary form must reproduce the above copyright
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-- -----------------------------------------------------------------------------

module ErrorLogger (
                    ErrorLoggerHandle,
                    startErrorLogger, 
                    stopErrorLogger, 
                    logErrorMessage
                   ) where

import Logger
import LogLevel
import Util

import System.IO
import System.Time

data ErrorLoggerHandle = ErrorLoggerHandle 
    { 
     errorLogger ::LoggerHandle ErrorLoggerMessage,
     errorMinLevel :: LogLevel
    }

data ErrorLoggerMessage = ErrorLoggerMessage
    {
     errorTime   :: ClockTime,
     errorString :: String
    }


startErrorLogger :: FilePath -> LogLevel -> IO ErrorLoggerHandle
startErrorLogger file level = 
    do l <- startLogger format file
       let h = ErrorLoggerHandle {
                                  errorLogger = l,
                                  errorMinLevel = level
                                 }
       logErrorMessage h LogWarn $ "Starting error logger with log level " 
                                    ++ show level ++ "..."
       return h
  where format m = formatTimeSensibly (toUTCTime (errorTime m))
                   ++ "  " ++ errorString m

stopErrorLogger :: ErrorLoggerHandle -> IO ()
stopErrorLogger l = do logErrorMessage l LogWarn "Stopping error logger..."
                       stopLogger (errorLogger l)

logErrorMessage :: ErrorLoggerHandle -> LogLevel -> String -> IO ()
logErrorMessage l level s 
    | level < errorMinLevel l = return ()
    | otherwise = do time <- getClockTime
                     logMessage (errorLogger l) (ErrorLoggerMessage time s)