module Log.Rotate where

import Control.Monad
import System.Directory
import Log.Types

rotate :: FileLogSpec -> IO ()
rotate spec = mapM_ move srcdsts
  where
    path = log_file spec
    n = log_backup_number spec
    dsts' = reverse . ("":) . map (('.':). show) $ [0..n-1]
    dsts = map (path++) dsts'
    srcs = tail dsts
    srcdsts = zip srcs dsts
    move (src,dst) = do
        exist <- doesFileExist src
        when exist $ renameFile src dst