WIP add networkmanager xmobar plugin

bin/xmobar.hs

@@ -1,5 +1,6 @@
 import Xmobar.Plugins.Bluetooth
 import Xmobar.Plugins.IntelBacklight
+import Xmobar.Plugins.NetworkManager
 import Xmobar.Plugins.Screensaver
 
 import qualified Theme as T
@@ -29,6 +30,7 @@ myTemplate = formatTemplate left right
             , "%intelbacklight%"
             , "%bluetooth%"
             , "%screensaver%"
+            , "%networkmanager%"
             , "%locks%"
             , "%date%"
             ]
@@ -126,6 +128,8 @@ config confDir = defaultConfig
       , Run $ Bluetooth ("<fn=1>\xf293</fn>", T.fgColor, T.backdropFgColor)
 
       , Run UnsafeStdinReader
+
+      , Run $ NetworkManager ("VPN", T.fgColor, T.backdropFgColor)
       ]
   }
 

lib/Xmobar/Plugins/NetworkManager.hs

@@ -0,0 +1,43 @@
+{-# LANGUAGE LambdaCase        #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Xmobar.Plugins.NetworkManager where
+
+import Control.Concurrent
+import Control.Monad
+
+import DBus
+import DBus.Client
+import DBus.Internal.Types
+
+import Xmobar
+
+newtype NetworkManager =  NetworkManager (String, String, String)
+  deriving (Read, Show)
+
+rule :: MatchRule
+rule = matchAny
+  { matchInterface = Just "org.freedesktop.NetworkManager.VPN.Connection"
+  , matchMember = Just "VpnStateChanged"
+  }
+
+-- TODO would polling be better for this? Using events means that we need
+-- to catch all of them perfectly to stay synchronized...which *might* happen
+
+instance Exec NetworkManager where
+  alias (NetworkManager _) = "networkmanager"
+  start (NetworkManager (text, colorOn, colorOff)) cb = do
+  -- start (NetworkManager _) cb = do
+    client <- connectSystem
+    -- TODO initialize
+    _ <- addMatch client rule $ cb . fmtState . getVPNState . signalBody
+    forever (threadDelay 5000000)
+    where
+      getVPNState = \case
+        [Variant (ValueAtom (AtomWord32 s)), _] -> Just s
+        _                                       -> Nothing
+      fmtState = \case
+        -- state = 5 means VPN is connected
+        Just s -> wrapColor text $ if s == 5 then colorOn else colorOff
+        Nothing -> "N/A"
+      wrapColor s c = "<fc=" ++ c ++ ">" ++ s ++ "</fc>"

my-xmonad.cabal

@@ -16,6 +16,7 @@ library
                    , DBus.Screensaver
                    , Xmobar.Plugins.Bluetooth
                    , Xmobar.Plugins.IntelBacklight
+                   , Xmobar.Plugins.NetworkManager
                    , Xmobar.Plugins.Screensaver
     build-depends: base
                  , X11 >= 1.9.1