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diff --git a/Plugins/MBox.hs b/Plugins/MBox.hs
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+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Plugins.MBox
+-- Copyright   :  (c) Jose A Ortega Ruiz
+-- License     :  BSD-style (see LICENSE)
+--
+-- Maintainer  :  Jose A Ortega Ruiz <jao@gnu.org>
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A plugin for checking mail in mbox files.
+--
+-----------------------------------------------------------------------------
+
+module Plugins.MBox (MBox(..)) where
+
+import Prelude hiding (catch)
+import System.IO
+import Plugins
+
+import Control.Monad
+import Control.Concurrent.STM
+
+import System.Directory
+import System.FilePath
+import System.INotify
+
+import Data.List (isPrefixOf)
+
+-- | A list of display names, paths to mbox files and display colours,
+-- followed by a directory to resolve relative path names (can be "")
+data MBox = MBox [(String, FilePath, String)] FilePath
+          deriving (Read, Show)
+
+instance Exec MBox where
+  start (MBox ms dir) cb = do
+    vs <- mapM (const $ newTVarIO ("", 0 :: Int)) ms
+
+    dirExists <- doesDirectoryExist dir
+    let ts = map (\(t, _, _) -> t) ms
+        sec = \(_, f, _) -> f
+        md = if dirExists then (dir </>) . sec else sec
+        fs = map md ms
+        cs = map (\(_, _, c) -> c) ms
+        ev = [Modify, Create]
+
+    i <- initINotify
+    zipWithM_ (\f v -> addWatch i ev f (handle v)) fs vs
+
+    forM (zip fs vs) $ \(f, v) -> do
+      exists <- doesFileExist f
+      n <- if exists then countMails f else return 0
+      atomically $ writeTVar v (f, n)
+
+    changeLoop (mapM (fmap snd . readTVar) vs) $ \ns ->
+      cb . unwords $ [ showC m n c | (m, n, c) <- zip3 ts ns cs, n /= 0 ]
+
+showC :: String -> Int -> String -> String
+showC m n c =
+  if c == "" then msg else "<fc=" ++ c ++ ">" ++ msg ++ "</fc>"
+    where msg = m ++ show n
+
+countMails :: FilePath -> IO Int
+countMails f = do
+  txt <- readFileSafe f
+  return $ length . filter (isPrefixOf "From ") . lines $ txt
+
+handle :: TVar (FilePath, Int) -> Event -> IO ()
+handle v _ =  do
+  (p, _) <- atomically $ readTVar v
+  n <- countMails p
+  atomically $ writeTVar v (p, n)
+
+changeLoop :: Eq a => STM a -> (a -> IO ()) -> IO ()
+changeLoop s f = atomically s >>= go
+ where
+    go old = do
+        f old
+        go =<< atomically (do
+            new <- s
+            guard (new /= old)
+            return new)