module Logging (
  init_logging,
  log_debug,
  log_error,
  log_info,
  log_warning )
where

import System.Log.Formatter ( simpleLogFormatter )
import System.Log.Handler ( setFormatter )
import System.Log.Handler.Simple ( fileHandler )
import System.Log.Handler.Syslog (
  Facility ( USER ),
  openlog )
import System.Log.Logger (
  Priority ( DEBUG, INFO ),
  debugM,
  errorM,
  infoM,
  rootLoggerName,
  setHandlers,
  setLevel,
  updateGlobalLogger,
  warningM )


log_debug :: String -> IO ()
log_debug = debugM rootLoggerName

log_error :: String -> IO ()
log_error = errorM rootLoggerName

log_info :: String -> IO ()
log_info = infoM rootLoggerName

log_warning :: String -> IO ()
log_warning = warningM rootLoggerName


-- | Why don't we take a Configuration as an argument? Because it
--   would create circular imports!
init_logging :: FilePath -> Priority -> Bool -> IO ()
init_logging log_file log_level syslog
  | syslog == True = do
      handler' <- openlog rootLoggerName [] USER level
      -- Syslog should output the date by itself.
      let slf = simpleLogFormatter "htsn[$pid] $prio: $msg"
      let handler = setFormatter handler' slf
      updateGlobalLogger rootLoggerName (setLevel level . setHandlers [handler])
  | otherwise = do
      handler' <- fileHandler log_file level
      let slf = simpleLogFormatter "$time: htsn[$pid] $prio: $msg"
      let handler = setFormatter handler' slf
      updateGlobalLogger rootLoggerName (setLevel level . setHandlers [handler])
  where
    min_level = if syslog then INFO else DEBUG
    level = if log_level < min_level then min_level else log_level