xmonad-config/lib/ACPI.hs

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{-# LANGUAGE OverloadedStrings #-}
module ACPI
( ACPIEvent(..)
, acpiMagic
, isDischarging
, runPowermon
) where
import SendXMsg
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import Control.Exception
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import Control.Monad
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import Data.ByteString hiding (readFile)
import Data.ByteString.Char8 as C hiding (readFile)
import Data.Connection
import System.IO.Streams.Internal as S (read)
import System.IO.Streams.UnixSocket
data ACPIEvent = Power
| Sleep
| LidClose
deriving (Eq)
instance Enum ACPIEvent where
toEnum 0 = Power
toEnum 1 = Sleep
toEnum 2 = LidClose
toEnum _ = errorWithoutStackTrace "ACPI.Enum.ACPIEvent.toEnum"
fromEnum Power = 0
fromEnum Sleep = 1
fromEnum LidClose = 2
sendACPIEvent :: ACPIEvent -> IO ()
sendACPIEvent = sendXMsg acpiMagic . show . fromEnum
parseLine :: ByteString -> Maybe ACPIEvent
parseLine line =
case splitLine line of
(_:"PBTN":_) -> Just Power
(_:"PWRF":_) -> Just Power
(_:"SLPB":_) -> Just Sleep
(_:"SBTN":_) -> Just Sleep
(_:"LID":"close":_) -> Just LidClose
_ -> Nothing
where
splitLine = C.words . C.reverse . C.dropWhile (== '\n') . C.reverse
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isDischarging :: IO (Maybe Bool)
isDischarging = do
status <- try $ readFile "/sys/class/power_supply/BAT0/status"
:: IO (Either IOException String)
case status of
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Left _ -> return Nothing
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Right s -> return $ Just (s == "Discharging")
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-- TODO use a data type that enforces strings of max length 5
acpiMagic :: String
acpiMagic = "%acpi"
runPowermon :: IO ()
runPowermon = do
-- TODO barf when the socket doesn't exist
Connection { source = s } <- connect "/var/run/acpid.socket"
forever $ readStream s
where
readStream s = do
out <- S.read s
mapM_ sendACPIEvent $ parseLine =<< out