{-# LANGUAGE ViewPatterns, StandaloneDeriving #-}
  
import System.FilePath.Glob (glob)
import System.Environment (setEnv, getArgs)
import System.Process (spawnProcess, waitForProcess)
import System.Exit (exitWith, ExitCode(..))

import Data.List (isPrefixOf, dropWhile, dropWhileEnd, init)
import Data.Char (isSpace, toLower, toUpper)

import Control.Monad (forM_, void)

import qualified Libnotify as Notify
import Data.Monoid

import System.Console.GetOpt.Simple

import qualified Data.Map as Map

import Data.Maybe
import Text.Read (readMaybe)

deriving instance Read Notify.Urgency

main :: IO ()
main = do
  envFiles <- glob "@home@/.dbus/session-bus/*"
  forM_ envFiles $ \envFile -> do
    sessionAddr <- unQuote . tail . snd . break (== '=') . head . filter ("DBUS_SESSION_BUS_ADDRESS=" `isPrefixOf`) . lines <$> readFile envFile
    setEnv "DBUS_SESSION_BUS_ADDRESS" sessionAddr
    lines <- lines <$> getContents
    case lines of
      ((trim -> summary):(trim . unlines -> contents)) -> do
        (opts, _) <- flip getUsingConf [] [ (arg, "urgency", Optional, "")
                                          , (arg, "app-name", Optional, "")
                                          , (arg, "category", Optional, "")
                                          ]
        let
          urgency = fromMaybe Notify.Normal $ readMaybe . caseForRead =<< Map.lookup "urgency" opts
          appName = fromMaybe "notify-@user@" $ Map.lookup "app-name" opts
          category = fromMaybe "" $ Map.lookup "category" opts
        Notify.display_ $ Notify.summary summary <> Notify.body contents <> Notify.appName appName <> Notify.urgency urgency <> Notify.category category
      _ -> exitWith $ ExitFailure 2
  where
    trim = dropWhileEnd isSpace . dropWhile isSpace
    unQuote ('\'':xs) = init xs
    unQuote ('"':xs) = init xs
    unQuote xs = xs
    caseForRead [] = []
    caseForRead (x:xs) = toUpper x : map toLower xs