use global webapp redirects when shutting down

Assistant/WebApp/Control.hs

@@ -1,6 +1,6 @@
 {- git-annex assistant webapp control
  -
- - Copyright 2012 Joey Hess <joey@kitenet.net>
+ - Copyright 2012, 2013 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -10,15 +10,17 @@
 module Assistant.WebApp.Control where
 
 import Assistant.WebApp.Common
-import Utility.LogFile
 import Assistant.DaemonStatus
 import Assistant.Alert
 import Assistant.TransferSlots
 import Assistant.Restart
+import Utility.LogFile
+import Utility.NotificationBroadcaster
 
 import Control.Concurrent
 import System.Posix (getProcessID, signalProcess, sigTERM)
 import qualified Data.Map as M
+import qualified Data.Text as T
 
 getShutdownR :: Handler Html
 getShutdownR = page "Shutdown" Nothing $
@@ -37,12 +39,25 @@ getShutdownConfirmedR = do
 		ts <- M.keys . currentTransfers <$> getDaemonStatus
 		mapM_ pauseTransfer ts
 	page "Shutdown" Nothing $ do
+		webapp <- getYesod
+		let url = T.unpack $ yesodRender webapp (T.pack "") NotRunningR []
+		{- Signal any other web browsers. -}
+		liftAssistant $ do
+			modifyDaemonStatus_ $ \status -> status { globalRedirUrl = Just url }
+			liftIO . sendNotification . globalRedirNotifier =<< getDaemonStatus
 		{- Wait 2 seconds before shutting down, to give the web
 		 - page time to load in the browser. -}
 		void $ liftIO $ forkIO $ do
 			threadDelay 2000000
 			signalProcess sigTERM =<< getProcessID
-		$(widgetFile "control/shutdownconfirmed")
+		redirect NotRunningR
+
+{- Use a custom page to avoid putting long polling elements on it that will 
+ - fail and cause the web browser to show an error once the webapp is
+ - truely stopped. -}
+getNotRunningR :: Handler Html
+getNotRunningR = customPage' False Nothing $
+	$(widgetFile "control/notrunning")
 
 getRestartR :: Handler Html
 getRestartR = do