From 25886ea48e9083240ce09f42755f6ef11455e51f Mon Sep 17 00:00:00 2001
From: Spencer Janssen <sjanssen@cse.unl.edu>
Date: Wed, 6 Aug 2008 22:40:47 +0200
Subject: Add mail watcher plugin

darcs-hash:20080806204047-a5988-a8917d4a02c8ddf9afa34780e6794d3f141d16a0.gz
---
 Plugins/Mail.hs | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 Plugins/Mail.hs

(limited to 'Plugins/Mail.hs')

diff --git a/Plugins/Mail.hs b/Plugins/Mail.hs
new file mode 100644
index 0000000..0a8507a
--- /dev/null
+++ b/Plugins/Mail.hs
@@ -0,0 +1,78 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Plugins.Mail
+-- Copyright   :  (c) Spencer Janssen
+-- License     :  BSD-style (see LICENSE)
+--
+-- Maintainer  :  Spencer Janssen <sjanssen@cse.unl.edu>
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A plugin for checking mail.
+--
+-----------------------------------------------------------------------------
+
+module Plugins.Mail 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)
+import Data.Set (Set)
+import qualified Data.Set as S
+
+data Mail = Mail [(String, FilePath)]
+    deriving (Read, Show)
+
+instance Exec Mail where
+    start (Mail ms) cb = do
+        vs <- mapM (const $ newTVarIO S.empty) ms
+
+        let ts = map fst ms
+            ds = map ((</> "new") . snd) ms
+            ev = [Move, MoveIn, MoveOut, Create, Delete]
+
+        i <- initINotify
+        zipWithM_ (\d v -> addWatch i ev d (handle v)) ds vs
+
+        forM (zip ds vs) $ \(d, v) -> do
+            s <- fmap (S.fromList . filter (not . isPrefixOf "."))
+                    $ getDirectoryContents d
+            atomically $ modifyTVar v (S.union s)
+
+        changeLoop (mapM (fmap S.size . readTVar) vs) $ \ns -> do
+            cb . unwords $ [m ++ ":" ++  show n
+                                    | (m, n) <- zip ts ns
+                                    , n /= 0 ]
+
+modifyTVar :: TVar a -> (a -> a) -> STM ()
+modifyTVar v f = readTVar v >>= writeTVar v . f
+
+handle :: TVar (Set String) -> Event -> IO ()
+handle v e = atomically $ modifyTVar v $ case e of
+    Created  {} -> create
+    MovedIn  {} -> create
+    Deleted  {} -> delete
+    MovedOut {} -> delete
+    _           -> id
+ where
+    delete = S.delete (filePath e)
+    create = S.insert (filePath e)
+
+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)
-- 
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